Update base for Update on "[compiler][rewrite] PropagateScopeDeps hir rewrite"

\### Quick background:
\#### Rvalues / temporaries:
In the compiler, unnamed temporaries that represents the evaluation of an expression
In the code snippet below, $1, $2, $3, and $4 are temporaries.
```js
// input
function Component({ bar} ) {
  const x = {a: foo(bar), b: {}};
}
// gets lowered to
[1] $2 = LoadGlobal(global) foo
[2] $3 = LoadLocal bar$1
[3] $4 = Call $2(<unknown> $3)
[4] $5 = Object {  }
[5] $6 = Object { a: $4, b: $5 }
[6] $8 = StoreLocal Const x$7 = $6
```
The compiler currently treats temporaries and named variables (e.g. `x`) differently in this pass.
- named variables may be reassigned (in fact, since we're running after LeaveSSA, a single named identifier's IdentifierId may map to multiple `Identifier` instances -- each with its own scope and mutable range)
- temporaries are replaced with their represented expressions during codegen. This is correct (mostly correct, see #29878) as we're careful to always lower the correct evaluation semantics. However, since we rewrite reactive scopes entirely (to if/else blocks), we need to track temporaries that a scope produces in `ReactiveScope.declarations` and later promote them to named variables.
In the same example, $4, $5, and $6 need to be promoted: $2 ->`t0`,  $5 ->`t1`, and $6 ->`t2`.
```js
[1] $2 = LoadGlobal(global) foo
[2] $3 = LoadLocal bar$1
scope 0:
  [3] $4 = Call $2(<unknown> $3)
scope 1:
  [4] $5 = Object {  }
scope 2:
  [5] $6 = Object { a: $4, b: $5 }
[6] $8 = StoreLocal Const x$7 = $6
```

\#### Dependencies
`ReactiveScope.dependencies` records the set of (read-only) values that a reactive scope is dependent on. This is currently limited to just variables (named variables from source and promoted temporaries) and property-loads.
All dependencies we record need to be hoistable -- i.e. reordered to just before the ReactiveScope begins. Not all PropertyLoads are hoistable.

In this example, we should not evaluate `obj.a.b` without before creating x and checking `objIsNull`.
```js
// reduce-reactive-deps/no-uncond.js
function useFoo({ obj, objIsNull }) {
  const x = [];
  if (isFalse(objIsNull)) {
    x.push(obj.a.b);
  }
  return x;
}
```

While other memoization strategies with different constraints exist, the current compiler requires that `ReactiveScope.dependencies` be re-orderable to the beginning of the reactive scope. But.. `PropertyLoad`s from null values will throw `TypeError`. This means that evaluating hoisted dependencies should throw if and only if the source program throws. (It is also a bug if source throws and compiler output does not throw. See https://github.com/facebook/react-forget/pull/2709)

---
\### Rough high level overview
1. Pass 1
Walk over instructions to gather every temporary used outside of its defining scope (same as ReactiveFunction version). These determine the sidemaps we produce, as temporaries used outside of their declaring scopes get promoted to named variables later (and are not considered hoistable rvals).
2. Pass 2 (collectHoistablePropertyLoads)
Walk over instructions to generate sidemaps:
  a. temporary identifier -> named variable and property path (e.g. `$3 -> {obj: props, path: ["a", "b"]}`)
  b. block -> accessed variables and properties (e.g. `bb0 -> [ {obj: props, path: ["a", "b"]} ]`)
  c. Walk over control flow graph to understand the set of object and property paths that can be read by each basic block. This analysis:
    - relies on post-dominator trees
    - traverses the CFG from entry (producing the set of variables/paths unconditionally evaluated *before* a block).
    - traverses the CFG from exit (producing the set of variables/paths unconditionally evaluated *after* a block).
4. Pass 3: (collectDependencies)
Walks over instructions again to record dependencies and declarations, using the previously produced sidemaps

Will add more fixture tests (although most cases should be covered in `reduce-reactive-deps`).
Tested by syncing internally and checking compilation output differences ([internal link](https://fburl.com/wiki_markdown/nazsiszd))

---
\### Followups:
1. Rewrite function expression deps
This change produces much more optimal output as the compiler now uses the function CFG to understand which variables / paths are assumed to be non-null. However, it may exacerbate [this function-expr hoisting bug](https://github.com/facebook/react/blob/main/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-invalid-hoisting-functionexpr.ts). A short term fix here is to simply call some form of `collectNonNullObjects` on every function expression to find hoistable variable / paths. In the longer term, we should refactor out `FunctionExpression.deps`.

2. Enable optional paths
(a) don't count optional load temporaries as dependencies (e.g. `collectOptionalLoadRValues(...)`).
(b) add optional paths back. This is a bit tricky as we'll want to implement some merging logic for `ConditionalAccess | OptionalChain | UnconditionalAccess`. In addition, our current optional chain lowering is slightly incorrect / imprecise

[ghstack-poisoned]

.circleci/config.yml

@@ -0,0 +1,591 @@
+version: 2.1
+
+aliases:
+  - &docker
+    - image: cimg/node:18.20.1-browsers
+
+  - &environment
+    TZ: /usr/share/zoneinfo/America/Los_Angeles
+
+  - &restore_yarn_cache_fixtures_dom
+    restore_cache:
+      name: Restore yarn cache for fixtures/dom
+      keys:
+        - v2-yarn_cache-{{ arch }}-{{ checksum "yarn.lock" }}-fixtures/dom
+
+  - &yarn_install_fixtures_dom
+    run:
+      name: Install dependencies in fixtures/dom
+      working_directory: fixtures/dom
+      command: yarn install --frozen-lockfile --cache-folder ~/.cache/yarn
+
+  - &yarn_install_fixtures_dom_retry
+    run:
+      name: Install dependencies in fixtures/dom (retry)
+      when: on_fail
+      working_directory: fixtures/dom
+      command: yarn install --frozen-lockfile --cache-folder ~/.cache/yarn
+
+  - &save_yarn_cache_fixtures_dom
+    save_cache:
+      name: Save yarn cache for fixtures/dom
+      key: v2-yarn_cache-{{ arch }}-{{ checksum "yarn.lock" }}-fixtures/dom
+      paths:
+        - ~/.cache/yarn
+
+  - &TEST_PARALLELISM 20
+
+  - &attach_workspace
+    at: build
+
+commands:
+  setup_node_modules:
+    description: "Restore node_modules"
+    steps:
+      - restore_cache:
+          name: Restore yarn cache
+          keys:
+            - v2-yarn_cache-{{ arch }}-{{ checksum "yarn.lock" }}
+      - run:
+          name: Install dependencies
+          command: |
+            yarn install --frozen-lockfile --cache-folder ~/.cache/yarn
+            if [ $? -ne 0 ]; then
+              yarn install --frozen-lockfile --cache-folder ~/.cache/yarn
+            fi
+          environment:
+          # If we start needing the Electron binary, please ensure the binary is cached in CI following https://www.electronjs.org/docs/latest/tutorial/installation
+            ELECTRON_SKIP_BINARY_DOWNLOAD: 1
+      - save_cache:
+          name: Save yarn cache
+          key: v2-yarn_cache-{{ arch }}-{{ checksum "yarn.lock" }}
+          paths:
+            - ~/.cache/yarn
+
+# The CircleCI API doesn't yet support triggering a specific workflow, but it
+# does support triggering a pipeline. So as a workaround you can triggger the
+# entire pipeline and use parameters to disable everything except the workflow
+# you want. CircleCI recommends this workaround here:
+# https://support.circleci.com/hc/en-us/articles/360050351292-How-to-trigger-a-workflow-via-CircleCI-API-v2-
+parameters:
+  # This is only set when triggering the CI pipeline via an API request.
+  prerelease_commit_sha:
+    type: string
+    default: ''
+
+jobs:
+  scrape_warning_messages:
+    docker: *docker
+    environment: *environment
+
+    steps:
+      - checkout
+      - setup_node_modules
+      - run:
+          command: |
+            mkdir -p ./build/__test_utils__
+            node ./scripts/print-warnings/print-warnings.js > build/__test_utils__/ReactAllWarnings.js
+      - persist_to_workspace:
+          root: .
+          paths:
+            - build
+
+  yarn_build:
+    docker: *docker
+    environment: *environment
+    parallelism: 40
+    steps:
+      - checkout
+      - setup_node_modules
+      - run: yarn build
+      - persist_to_workspace:
+          root: .
+          paths:
+            - build
+
+  download_build:
+    docker: *docker
+    environment: *environment
+    parameters:
+      revision:
+        type: string
+    steps:
+      - checkout
+      - setup_node_modules
+      - run:
+          name: Download artifacts for revision
+          command: |
+              git fetch origin main
+              cd ./scripts/release && yarn && cd ../../
+              scripts/release/download-experimental-build.js --commit=<< parameters.revision >> --allowBrokenCI
+      - persist_to_workspace:
+          root: .
+          paths:
+            - build
+
+  download_base_build_for_sizebot:
+    docker: *docker
+    environment: *environment
+    steps:
+      - checkout
+      - setup_node_modules
+      - run:
+          name: Download artifacts for base revision
+          command: |
+            git fetch origin main
+            cd ./scripts/release && yarn && cd ../../
+            scripts/release/download-experimental-build.js --commit=$(git merge-base HEAD origin/main) --allowBrokenCI
+            mv ./build ./base-build
+
+      - run:
+          # TODO: The `download-experimental-build` script copies the npm
+          # packages into the `node_modules` directory. This is a historical
+          # quirk of how the release script works. Let's pretend they
+          # don't exist.
+          name: Delete extraneous files
+          command: rm -rf ./base-build/node_modules
+
+      - persist_to_workspace:
+          root: .
+          paths:
+            - base-build
+
+  process_artifacts_combined:
+    docker: *docker
+    environment: *environment
+    steps:
+      - checkout
+      - attach_workspace:
+          at: .
+      - setup_node_modules
+      - run: echo "<< pipeline.git.revision	>>" >> build/COMMIT_SHA
+        # Compress build directory into a single tarball for easy download
+      - run: tar -zcvf ./build.tgz ./build
+        # TODO: Migrate scripts to use `build` directory instead of `build2`
+      - run: cp ./build.tgz ./build2.tgz
+      - store_artifacts:
+          path: ./build2.tgz
+      - store_artifacts:
+          path: ./build.tgz
+
+  sizebot:
+    docker: *docker
+    environment: *environment
+    steps:
+      - checkout
+      - attach_workspace:
+          at: .
+      - run: echo "<< pipeline.git.revision	>>" >> build/COMMIT_SHA
+      - setup_node_modules
+      - run:
+          command: node ./scripts/tasks/danger
+      - store_artifacts:
+          path: sizebot-message.md
+
+  build_devtools_and_process_artifacts:
+    docker: *docker
+    environment: *environment
+    steps:
+      - checkout
+      - attach_workspace:
+          at: .
+      - setup_node_modules
+      - run:
+          environment:
+            RELEASE_CHANNEL: experimental
+          command: ./scripts/circleci/pack_and_store_devtools_artifacts.sh
+      - store_artifacts:
+          path: ./build/devtools.tgz
+      # Simplifies getting the extension for local testing
+      - store_artifacts:
+          path: ./build/devtools/chrome-extension.zip
+          destination: react-devtools-chrome-extension.zip
+      - store_artifacts:
+          path: ./build/devtools/firefox-extension.zip
+          destination: react-devtools-firefox-extension.zip
+
+  run_devtools_e2e_tests:
+    docker: *docker
+    environment: *environment
+    steps:
+      - checkout
+      - attach_workspace:
+          at: .
+      - setup_node_modules
+      - run:
+          name: Playwright install deps
+          command: |
+            npx playwright install
+            sudo npx playwright install-deps
+      - run:
+          environment:
+            RELEASE_CHANNEL: experimental
+          command: ./scripts/circleci/run_devtools_e2e_tests.js
+
+  run_fixtures_flight_tests:
+    docker: *docker
+    environment: *environment
+    steps:
+      - checkout
+      - attach_workspace:
+          at: .
+      # Fixture copies some built packages from the workroot after install.
+      # That means dependencies of the built packages are not installed.
+      # We need to install dependencies of the workroot to fulfill all dependency constraints
+      - setup_node_modules
+      - restore_cache:
+          name: Restore yarn cache of fixture
+          keys:
+            - v2-yarn_cache_fixtures_flight-{{ arch }}-{{ checksum "yarn.lock" }}
+      - run:
+          name: Install fixture dependencies
+          working_directory: fixtures/flight
+          command: |
+            yarn install --frozen-lockfile --cache-folder ~/.cache/yarn
+            if [ $? -ne 0 ]; then
+              yarn install --frozen-lockfile --cache-folder ~/.cache/yarn
+            fi
+      - save_cache:
+          name: Save yarn cache of fixture
+          key: v2-yarn_cache_fixtures_flight-{{ arch }}-{{ checksum "yarn.lock" }}
+          paths:
+            - ~/.cache/yarn
+      - run:
+          working_directory: fixtures/flight
+          name: Playwright install deps
+          command: |
+            npx playwright install
+            sudo npx playwright install-deps
+      - run:
+          name: Run tests
+          working_directory: fixtures/flight
+          command: yarn test
+          environment:
+          # Otherwise the webserver is a blackbox
+            DEBUG: pw:webserver
+      - store_artifacts:
+          path: fixtures/flight/playwright-report
+      - store_artifacts:
+          path: fixtures/flight/test-results
+
+  run_devtools_tests_for_versions:
+    docker: *docker
+    environment: *environment
+    parallelism: *TEST_PARALLELISM
+    parameters:
+      version:
+        type: string
+    steps:
+      - checkout
+      - attach_workspace:
+          at: .
+      - setup_node_modules
+      - run: ./scripts/circleci/download_devtools_regression_build.js << parameters.version >> --replaceBuild
+      - run: node ./scripts/jest/jest-cli.js --build --project devtools --release-channel=experimental --reactVersion << parameters.version >> --ci=circleci
+
+  run_devtools_e2e_tests_for_versions:
+    docker: *docker
+    environment: *environment
+    parallelism: *TEST_PARALLELISM
+    parameters:
+      version:
+        type: string
+    steps:
+      - checkout
+      - attach_workspace:
+          at: .
+      - setup_node_modules
+      - run:
+          name: Playwright install deps
+          command: |
+            npx playwright install
+            sudo npx playwright install-deps
+      - run: ./scripts/circleci/download_devtools_regression_build.js << parameters.version >>
+      - run:
+          environment:
+            RELEASE_CHANNEL: experimental
+          command: ./scripts/circleci/run_devtools_e2e_tests.js << parameters.version >>
+      - run:
+          name: Cleanup build regression folder
+          command: rm -r ./build-regression
+      - store_artifacts:
+          path: ./tmp/screenshots
+
+  yarn_lint_build:
+    docker: *docker
+    environment: *environment
+    steps:
+      - checkout
+      - attach_workspace:
+          at: .
+      - setup_node_modules
+      - run: yarn lint-build
+
+  yarn_check_release_dependencies:
+    docker: *docker
+    environment: *environment
+    steps:
+      - checkout
+      - attach_workspace:
+          at: .
+      - setup_node_modules
+      - run: yarn check-release-dependencies
+
+
+  check_error_codes:
+    docker: *docker
+    environment: *environment
+    steps:
+      - checkout
+      - attach_workspace: *attach_workspace
+      - setup_node_modules
+      - run:
+          name: Search build artifacts for unminified errors
+          command: |
+            yarn extract-errors
+            git diff --quiet || (echo "Found unminified errors. Either update the error codes map or disable error minification for the affected build, if appropriate." && false)
+
+  yarn_test_build:
+    docker: *docker
+    environment: *environment
+    parallelism: *TEST_PARALLELISM
+    parameters:
+      args:
+        type: string
+    steps:
+      - checkout
+      - attach_workspace:
+          at: .
+      - setup_node_modules
+      - run: yarn test --build <<parameters.args>> --ci=circleci
+
+  RELEASE_CHANNEL_stable_yarn_test_dom_fixtures:
+    docker: *docker
+    environment: *environment
+    steps:
+      - checkout
+      - attach_workspace:
+          at: .
+      - setup_node_modules
+      - *restore_yarn_cache_fixtures_dom
+      - *yarn_install_fixtures_dom
+      - *yarn_install_fixtures_dom_retry
+      - *save_yarn_cache_fixtures_dom
+      - run:
+          name: Run DOM fixture tests
+          environment:
+            RELEASE_CHANNEL: stable
+          working_directory: fixtures/dom
+          command: |
+            yarn predev
+            yarn test --maxWorkers=2
+
+  publish_prerelease:
+    parameters:
+      commit_sha:
+        type: string
+      release_channel:
+        type: string
+      dist_tag:
+        type: string
+    docker: *docker
+    environment: *environment
+    steps:
+      - checkout
+      - setup_node_modules
+      - run:
+          name: Run publish script
+          command: |
+            git fetch origin main
+            cd ./scripts/release && yarn && cd ../../
+            scripts/release/prepare-release-from-ci.js --skipTests -r << parameters.release_channel >> --commit=<< parameters.commit_sha >>
+            cp ./scripts/release/ci-npmrc ~/.npmrc
+            scripts/release/publish.js --ci --tags << parameters.dist_tag >>
+
+workflows:
+
+  build_and_test:
+    unless: << pipeline.parameters.prerelease_commit_sha >>
+    jobs:
+      - yarn_build:
+          filters:
+            branches:
+              ignore:
+                - builds/facebook-www
+      - scrape_warning_messages:
+          filters:
+            branches:
+              ignore:
+                - builds/facebook-www
+      - process_artifacts_combined:
+          requires:
+            - scrape_warning_messages
+            - yarn_build
+      - yarn_test_build:
+          requires:
+            - yarn_build
+          matrix:
+            parameters:
+              args:
+                # Intentionally passing these as strings instead of creating a
+                # separate parameter per CLI argument, since it's easier to
+                # control/see which combinations we want to run.
+                - "-r=stable --env=development"
+                - "-r=stable --env=production"
+                - "-r=experimental --env=development"
+                - "-r=experimental --env=production"
+
+                # Dev Tools
+                - "--project=devtools -r=experimental"
+
+                # TODO: Update test config to support www build tests
+                # - "-r=www-classic --env=development --variant=false"
+                # - "-r=www-classic --env=production --variant=false"
+                # - "-r=www-classic --env=development --variant=true"
+                # - "-r=www-classic --env=production --variant=true"
+                # - "-r=www-modern --env=development --variant=false"
+                # - "-r=www-modern --env=production --variant=false"
+                # - "-r=www-modern --env=development --variant=true"
+                # - "-r=www-modern --env=production --variant=true"
+
+                # TODO: Update test config to support xplat build tests
+                # - "-r=xplat --env=development --variant=false"
+                # - "-r=xplat --env=development --variant=true"
+                # - "-r=xplat --env=production --variant=false"
+                # - "-r=xplat --env=production --variant=true"
+
+                # TODO: Test more persistent configurations?
+      - download_base_build_for_sizebot:
+          filters:
+            branches:
+              ignore:
+                - main
+                - builds/facebook-www
+      - sizebot:
+          filters:
+            branches:
+              ignore:
+                - main
+          requires:
+            - download_base_build_for_sizebot
+            - yarn_build
+      - yarn_lint_build:
+          requires:
+            - yarn_build
+      - yarn_check_release_dependencies:
+          requires:
+            - yarn_build
+      - check_error_codes:
+          requires:
+            - yarn_build
+      - RELEASE_CHANNEL_stable_yarn_test_dom_fixtures:
+          requires:
+            - yarn_build
+      - build_devtools_and_process_artifacts:
+          requires:
+            - yarn_build
+      - run_devtools_e2e_tests:
+          requires:
+            - build_devtools_and_process_artifacts
+      - run_fixtures_flight_tests:
+          requires:
+            - yarn_build
+
+  devtools_regression_tests:
+    unless: << pipeline.parameters.prerelease_commit_sha >>
+    triggers:
+      - schedule:
+          # DevTools regression tests run once a day
+          cron: "0 0 * * *"
+          filters:
+            branches:
+              only:
+                - main
+    jobs:
+      - download_build:
+          revision: << pipeline.git.revision >>
+      - build_devtools_and_process_artifacts:
+          requires:
+            - download_build
+      - run_devtools_tests_for_versions:
+          requires:
+            - build_devtools_and_process_artifacts
+          matrix:
+            parameters:
+              version:
+                - "16.0"
+                - "16.5" # schedule package
+                - "16.8" # hooks
+                - "17.0"
+                - "18.0"
+      - run_devtools_e2e_tests_for_versions:
+          requires:
+            - build_devtools_and_process_artifacts
+          matrix:
+            parameters:
+              version:
+                - "16.0"
+                - "16.5" # schedule package
+                - "16.8" # hooks
+                - "17.0"
+                - "18.0"
+
+  # Used to publish a prerelease manually via the command line
+  publish_preleases:
+    when: << pipeline.parameters.prerelease_commit_sha >>
+    jobs:
+      - publish_prerelease:
+          name: Publish to Canary channel
+          commit_sha: << pipeline.parameters.prerelease_commit_sha >>
+          release_channel: stable
+          # The tags to use when publishing canaries. The main one we should
+          # always include is "canary" but we can use multiple (e.g. alpha,
+          # beta, rc). To declare multiple, use a comma-separated string, like
+          # this:
+          #   dist_tag: "canary,alpha,beta,rc"
+          #
+          # TODO: We currently tag canaries with "next" in addition to "canary"
+          # because this used to be called the "next" channel and some
+          # downstream consumers might still expect that tag. We can remove this
+          # after some time has elapsed and the change has been communicated.
+          dist_tag: "canary,next,rc"
+      - publish_prerelease:
+          name: Publish to Experimental channel
+          requires:
+            # NOTE: Intentionally running these jobs sequentially because npm
+            # will sometimes fail if you try to concurrently publish two
+            # different versions of the same package, even if they use different
+            # dist tags.
+            - Publish to Canary channel
+          commit_sha: << pipeline.parameters.prerelease_commit_sha >>
+          release_channel: experimental
+          dist_tag: experimental
+
+  # Publishes on a cron schedule
+  publish_preleases_nightly:
+    unless: << pipeline.parameters.prerelease_commit_sha >>
+    triggers:
+      - schedule:
+          # At 10 minutes past 16:00 on Mon, Tue, Wed, Thu, and Fri
+          cron: "10 16 * * 1,2,3,4,5"
+          filters:
+            branches:
+              only:
+                - main
+    jobs:
+      - publish_prerelease:
+          name: Publish to Canary channel
+          commit_sha: << pipeline.git.revision >>
+          release_channel: stable
+          dist_tag: "canary,next,rc"
+      - publish_prerelease:
+          name: Publish to Experimental channel
+          requires:
+            # NOTE: Intentionally running these jobs sequentially because npm
+            # will sometimes fail if you try to concurrently publish two
+            # different versions of the same package, even if they use different
+            # dist tags.
+            - Publish to Canary channel
+          commit_sha: << pipeline.git.revision >>
+          release_channel: experimental
+          dist_tag: experimental

.editorconfig

@@ -8,9 +8,11 @@ indent_size = 2
 indent_style = space
 insert_final_newline = true
 max_line_length = 80
+trim_trailing_whitespace = true
 
 [*.md]
 max_line_length = 0
+trim_trailing_whitespace = false
 
 [COMMIT_EDITMSG]
 max_line_length = 0

.eslintrc.js

@@ -23,7 +23,6 @@ module.exports = {
     'babel',
     'ft-flow',
     'jest',
-    'es',
     'no-for-of-loops',
     'no-function-declare-after-return',
     'react',
@@ -48,7 +47,7 @@ module.exports = {
     'ft-flow/no-unused-expressions': ERROR,
     // 'ft-flow/no-weak-types': WARNING,
     // 'ft-flow/require-valid-file-annotation': ERROR,
-    'es/no-optional-chaining': ERROR,
+
     'no-cond-assign': OFF,
     'no-constant-condition': OFF,
     'no-control-regex': OFF,
@@ -303,6 +302,7 @@ module.exports = {
       ERROR,
       {isProductionUserAppCode: true},
     ],
+    'react-internal/no-to-warn-dev-within-to-throw': ERROR,
     'react-internal/warning-args': ERROR,
     'react-internal/no-production-logging': ERROR,
   },
@@ -329,9 +329,7 @@ module.exports = {
         'packages/react-server-dom-esm/**/*.js',
         'packages/react-server-dom-webpack/**/*.js',
         'packages/react-server-dom-turbopack/**/*.js',
-        'packages/react-server-dom-parcel/**/*.js',
         'packages/react-server-dom-fb/**/*.js',
-        'packages/react-server-dom-unbundled/**/*.js',
         'packages/react-test-renderer/**/*.js',
         'packages/react-debug-tools/**/*.js',
         'packages/react-devtools-extensions/**/*.js',
@@ -437,7 +435,6 @@ module.exports = {
         'packages/react-dom/src/test-utils/*.js',
       ],
       rules: {
-        'es/no-optional-chaining': OFF,
         'react-internal/no-production-logging': OFF,
         'react-internal/warning-args': OFF,
         'react-internal/safe-string-coercion': [
@@ -447,7 +444,10 @@ module.exports = {
       },
     },
     {
-      files: ['scripts/eslint-rules/*.js'],
+      files: [
+        'scripts/eslint-rules/*.js',
+        'packages/eslint-plugin-react-hooks/src/*.js',
+      ],
       plugins: ['eslint-plugin'],
       rules: {
         'eslint-plugin/prefer-object-rule': ERROR,
@@ -479,12 +479,6 @@ module.exports = {
         __turbopack_require__: 'readonly',
       },
     },
-    {
-      files: ['packages/react-server-dom-parcel/**/*.js'],
-      globals: {
-        parcelRequire: 'readonly',
-      },
-    },
     {
       files: ['packages/scheduler/**/*.js'],
       globals: {
@@ -494,19 +488,14 @@ module.exports = {
     {
       files: [
         'packages/react-devtools-extensions/**/*.js',
-        'packages/react-devtools-shared/src/devtools/views/**/*.js',
         'packages/react-devtools-shared/src/hook.js',
         'packages/react-devtools-shared/src/backend/console.js',
-        'packages/react-devtools-shared/src/backend/shared/DevToolsComponentStackFrame.js',
-        'packages/react-devtools-shared/src/frontend/utils/withPermissionsCheck.js',
       ],
       globals: {
         __IS_CHROME__: 'readonly',
         __IS_FIREFOX__: 'readonly',
         __IS_EDGE__: 'readonly',
-        __IS_NATIVE__: 'readonly',
         __IS_INTERNAL_VERSION__: 'readonly',
-        chrome: 'readonly',
       },
     },
     {
@@ -515,26 +504,6 @@ module.exports = {
         __IS_INTERNAL_VERSION__: 'readonly',
       },
     },
-    {
-      files: ['packages/eslint-plugin-react-hooks/src/**/*'],
-      extends: ['plugin:@typescript-eslint/recommended'],
-      parser: '@typescript-eslint/parser',
-      plugins: ['@typescript-eslint', 'eslint-plugin'],
-      rules: {
-        '@typescript-eslint/no-explicit-any': OFF,
-        '@typescript-eslint/no-non-null-assertion': OFF,
-        '@typescript-eslint/array-type': [ERROR, {default: 'generic'}],
-
-        'es/no-optional-chaining': OFF,
-
-        'eslint-plugin/prefer-object-rule': ERROR,
-        'eslint-plugin/require-meta-fixable': [
-          ERROR,
-          {catchNoFixerButFixableProperty: true},
-        ],
-        'eslint-plugin/require-meta-has-suggestions': ERROR,
-      },
-    },
   ],
 
   env: {
@@ -596,7 +565,6 @@ module.exports = {
     React$Node: 'readonly',
     React$Portal: 'readonly',
     React$Ref: 'readonly',
-    React$RefSetter: 'readonly',
     ReadableStreamController: 'readonly',
     ReadableStreamReader: 'readonly',
     RequestInfo: 'readonly',
@@ -610,12 +578,6 @@ module.exports = {
     WheelEventHandler: 'readonly',
     FinalizationRegistry: 'readonly',
     Omit: 'readonly',
-    Keyframe: 'readonly',
-    PropertyIndexedKeyframes: 'readonly',
-    KeyframeAnimationOptions: 'readonly',
-    GetAnimationsOptions: 'readonly',
-    Animatable: 'readonly',
-    ScrollTimeline: 'readonly',
 
     spyOnDev: 'readonly',
     spyOnDevAndProd: 'readonly',

.git-blame-ignore-revs

@@ -1,2 +1 @@
 c998bb1ed4b3285398c9c7797135d3f060243c6a
-fd2b3e13d330a4559f5aa21462e1cb2cbbcf144b

.github/ISSUE_TEMPLATE/compiler_bug_report.yml

@@ -55,10 +55,3 @@ body:
       Please provide your React version in the app where this issue occurred.
   validations:
     required: true
-- type: input
-  attributes:
-    label: What version of React Compiler are you using?
-    description: |
-      Please provide the exact React Compiler version in the app where this issue occurred.
-  validations:
-    required: true

.github/dependabot.yml

@@ -1,10 +1,107 @@
 version: 2
 updates:
   - package-ecosystem: "npm"
-    directories:
-      - "/fixtures/*"
+    directory: "/fixtures/art"
     schedule:
-      interval: "monthly"
+      interval: "weekly"
+    open-pull-requests-limit: 0
+  - package-ecosystem: "npm"
+    directory: "/fixtures/attribute-behavior"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 0
+  - package-ecosystem: "npm"
+    directory: "/fixtures/concurrent"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 0
+  - package-ecosystem: "npm"
+    directory: "/fixtures/devtools"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 0
+  - package-ecosystem: "npm"
+    directory: "/fixtures/dom"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 0
+  - package-ecosystem: "npm"
+    directory: "/fixtures/eslint"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 0
+  - package-ecosystem: "npm"
+    directory: "/fixtures/expiration"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 0
+  - package-ecosystem: "npm"
+    directory: "/fixtures/fiber-debugger"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 0
+  - package-ecosystem: "npm"
+    directory: "/fixtures/fiber-triangle"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 0
+  - package-ecosystem: "npm"
+    directory: "/fixtures/fizz"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 0
+  - package-ecosystem: "npm"
+    directory: "/fixtures/fizz-ssr-browser"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 0
+  - package-ecosystem: "npm"
+    directory: "/fixtures/flight"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 0
+  - package-ecosystem: "npm"
+    directory: "/fixtures/flight-browser"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 0
+  - package-ecosystem: "npm"
+    directory: "/fixtures/flight-esm"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 0
+  - package-ecosystem: "npm"
+    directory: "/fixtures/legacy-jsx-runtimes"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 0
+  - package-ecosystem: "npm"
+    directory: "/fixtures/nesting"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 0
+  - package-ecosystem: "npm"
+    directory: "/fixtures/packaging"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 0
+  - package-ecosystem: "npm"
+    directory: "/fixtures/scheduler"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 0
+  - package-ecosystem: "npm"
+    directory: "/fixtures/ssr"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 0
+  - package-ecosystem: "npm"
+    directory: "/fixtures/ssr-2"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 0
+  - package-ecosystem: "npm"
+    directory: "/fixtures/stacks"
+    schedule:
+      interval: "weekly"
     open-pull-requests-limit: 0
-    ignore:
-      - dependency-name: "*"

.github/workflows/compiler_discord_notify.yml

@@ -1,35 +0,0 @@
-name: (Compiler) Discord Notify
-
-on:
-  pull_request:
-    types: [opened, ready_for_review]
-    paths:
-      - compiler/**
-      - .github/workflows/compiler_**.yml
-
-permissions: {}
-
-jobs:
-  check_maintainer:
-    uses: facebook/react/.github/workflows/shared_check_maintainer.yml@main
-    permissions:
-      # Used by check_maintainer
-      contents: read
-    with:
-      actor: ${{ github.event.pull_request.user.login }}
-
-  notify:
-    if: ${{ needs.check_maintainer.outputs.is_core_team == 'true' }}
-    needs: check_maintainer
-    runs-on: ubuntu-latest
-    steps:
-      - name: Discord Webhook Action
-        uses: tsickert/discord-webhook@86dc739f3f165f16dadc5666051c367efa1692f4
-        with:
-          webhook-url: ${{ secrets.COMPILER_DISCORD_WEBHOOK_URL }}
-          embed-author-name: ${{ github.event.pull_request.user.login }}
-          embed-author-url: ${{ github.event.pull_request.user.html_url }}
-          embed-author-icon-url: ${{ github.event.pull_request.user.avatar_url }}
-          embed-title: '#${{ github.event.number }} (+${{github.event.pull_request.additions}} -${{github.event.pull_request.deletions}}): ${{ github.event.pull_request.title }}'
-          embed-description: ${{ github.event.pull_request.body }}
-          embed-url: ${{ github.event.pull_request.html_url }}

.github/workflows/compiler_playground.yml

@@ -5,23 +5,12 @@ on:
     branches: [main]
   pull_request:
     paths:
-      - compiler/**
-      - .github/workflows/compiler_playground.yml
-
-permissions: {}
-
-concurrency:
-  group: ${{ github.workflow }}-${{ github.ref_name }}-${{ github.event.pull_request.number || github.run_id }}
-  cancel-in-progress: true
-
-env:
-  TZ: /usr/share/zoneinfo/America/Los_Angeles
-  # https://github.com/actions/cache/blob/main/tips-and-workarounds.md#cache-segment-restore-timeout
-  SEGMENT_DOWNLOAD_TIMEOUT_MINS: 1
+      - "compiler/**"
+      - .github/workflows/compiler-playground.yml
 
 defaults:
   run:
-    working-directory: compiler/apps/playground
+    working-directory: compiler
 
 jobs:
   playground:
@@ -31,37 +20,15 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: compiler/**/yarn.lock
+          node-version: 18.x
+          cache: "yarn"
+          cache-dependency-path: compiler/yarn.lock
       - name: Restore cached node_modules
         uses: actions/cache@v4
         id: node_modules
         with:
-          path: |
-            **/node_modules
-          key: compiler-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('compiler/**/yarn.lock') }}
+          path: "**/node_modules"
+          key: ${{ runner.arch }}-${{ runner.os }}-modules-${{ hashFiles('compiler/**/yarn.lock') }}
       - run: yarn install --frozen-lockfile
-      - name: Check Playwright version
-        id: playwright_version
-        run: echo "playwright_version=$(npm ls @playwright/test | grep @playwright | sed 's/.*@//' | head -1)" >> "$GITHUB_OUTPUT"
-      - name: Cache Playwright Browsers for version ${{ steps.playwright_version.outputs.playwright_version }}
-        id: cache_playwright_browsers
-        uses: actions/cache@v4
-        with:
-          path: ~/.cache/ms-playwright
-          key: playwright-browsers-v6-${{ runner.arch }}-${{ runner.os }}-${{ steps.playwright_version.outputs.playwright_version }}
       - run: npx playwright install --with-deps chromium
-        if: steps.cache_playwright_browsers.outputs.cache-hit != 'true'
-      - run: npx playwright install-deps
-        if: steps.cache_playwright_browsers.outputs.cache-hit == 'true'
-      - run: CI=true yarn test
-      - run: ls -R test-results
-        if: '!cancelled()'
-      - name: Archive test results
-        if: '!cancelled()'
-        uses: actions/upload-artifact@v4
-        with:
-          name: test-results
-          path: compiler/apps/playground/test-results
-          if-no-files-found: ignore
+      - run: yarn workspace playground test

.github/workflows/compiler_prereleases.yml

@@ -1,57 +0,0 @@
-name: (Compiler) Publish Prereleases
-
-on:
-  workflow_call:
-    inputs:
-      commit_sha:
-        required: true
-        default: ''
-        type: string
-      release_channel:
-        required: true
-        type: string
-      dist_tag:
-        required: true
-        type: string
-      version_name:
-        required: true
-        type: string
-    secrets:
-      NPM_TOKEN:
-        required: true
-
-permissions: {}
-
-env:
-  TZ: /usr/share/zoneinfo/America/Los_Angeles
-  # https://github.com/actions/cache/blob/main/tips-and-workarounds.md#cache-segment-restore-timeout
-  SEGMENT_DOWNLOAD_TIMEOUT_MINS: 1
-  NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
-
-defaults:
-  run:
-    working-directory: compiler
-
-jobs:
-  publish_prerelease:
-    name: Publish prelease (${{ inputs.release_channel }}) ${{ inputs.commit_sha }} @${{ inputs.dist_tag }}
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-node@v4
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: compiler/yarn.lock
-      - name: Restore cached node_modules
-        uses: actions/cache@v4
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: compiler-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('compiler/**/yarn.lock') }}
-      - run: yarn install --frozen-lockfile
-      - name: Publish packages to npm
-        run: |
-          cp ./scripts/release/ci-npmrc ~/.npmrc
-          scripts/release/publish.js --frfr --ci --versionName=${{ inputs.version_name }} --tag ${{ inputs.dist_tag }}

.github/workflows/compiler_prereleases_manual.yml

@@ -1,33 +0,0 @@
-name: (Compiler) Publish Prereleases Manual
-
-on:
-  workflow_dispatch:
-    inputs:
-      prerelease_commit_sha:
-        required: false
-      release_channel:
-        required: true
-        type: string
-      dist_tag:
-        required: true
-        type: string
-      version_name:
-        required: true
-        type: string
-
-permissions: {}
-
-env:
-  TZ: /usr/share/zoneinfo/America/Los_Angeles
-
-jobs:
-  publish_prerelease_experimental:
-    name: Publish to Experimental channel
-    uses: facebook/react/.github/workflows/compiler_prereleases.yml@main
-    with:
-      commit_sha: ${{ inputs.prerelease_commit_sha || github.sha }}
-      release_channel: ${{ inputs.release_channel }}
-      dist_tag: ${{ inputs.dist_tag }}
-      version_name: ${{ inputs.version_name }}
-    secrets:
-      NPM_TOKEN: ${{ secrets.NPM_TOKEN }}

.github/workflows/compiler_prereleases_nightly.yml

@@ -1,23 +0,0 @@
-name: (Compiler) Publish Prereleases Nightly
-
-on:
-  schedule:
-    # At 10 minutes past 16:00 on Mon, Tue, Wed, Thu, and Fri
-    - cron: 10 16 * * 1,2,3,4,5
-
-permissions: {}
-
-env:
-  TZ: /usr/share/zoneinfo/America/Los_Angeles
-
-jobs:
-  publish_prerelease_experimental:
-    name: Publish to Experimental channel
-    uses: facebook/react/.github/workflows/compiler_prereleases.yml@main
-    with:
-      commit_sha: ${{ github.sha }}
-      release_channel: experimental
-      dist_tag: experimental
-      version_name: '0.0.0'
-    secrets:
-      NPM_TOKEN: ${{ secrets.NPM_TOKEN }}

.github/workflows/compiler_prereleases_weekly.yml

@@ -1,23 +0,0 @@
-name: (Compiler) Publish Prereleases Weekly
-
-on:
-  schedule:
-    # At 10 minutes past 9:00 on Mon
-    - cron: 10 9 * * 1
-
-permissions: {}
-
-env:
-  TZ: /usr/share/zoneinfo/America/Los_Angeles
-
-jobs:
-  publish_prerelease_beta:
-    name: Publish to beta channel
-    uses: facebook/react/.github/workflows/compiler_prereleases.yml@main
-    with:
-      commit_sha: ${{ github.sha }}
-      release_channel: beta
-      dist_tag: beta
-      version_name: '19.0.0'
-    secrets:
-      NPM_TOKEN: ${{ secrets.NPM_TOKEN }}

.github/workflows/compiler_rust.yml

@@ -0,0 +1,72 @@
+name: (Compiler) Rust
+
+on:
+  push:
+    branches: ["main"]
+    paths:
+      - .github/workflows/**
+      - compiler/crates/**
+      - compiler/Cargo.*
+      - compiler/*.toml
+  pull_request:
+    paths:
+      - .github/workflows/**
+      - compiler/crates/**
+      - compiler/Cargo.*
+      - compiler/*.toml
+
+env:
+  CARGO_TERM_COLOR: always
+  RUSTFLAGS: -Dwarnings
+
+defaults:
+  run:
+    working-directory: compiler
+
+jobs:
+  test:
+    name: Rust Test (${{ matrix.target.os }})
+    strategy:
+      matrix:
+        target:
+          - target: ubuntu-latest
+            os: ubuntu-latest
+          # TODO: run on more platforms
+          # - target: macos-latest
+          #   os: macos-latest
+          # - target: windows-latest
+          #   os: windows-latest
+    runs-on: ${{ matrix.target.os }}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: Swatinem/rust-cache@v2
+      - name: cargo test
+        run: cargo test --manifest-path=Cargo.toml --locked ${{ matrix.target.features && '--features' }} ${{ matrix.target.features }}
+
+  lint:
+    name: Rust Lint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions-rs/toolchain@v1
+        with:
+          # NOTE: use `rustup run <toolchain> <command>` in commands below
+          # with this exact same toolchain value
+          toolchain: nightly-2023-08-01
+          override: true
+          components: rustfmt, clippy
+      - uses: Swatinem/rust-cache@v2
+      - name: rustfmt
+        run: grep -r --include "*.rs" --files-without-match "@generated" crates | xargs rustup run nightly-2023-08-01 rustfmt --check --config="skip_children=true"
+      # - name: cargo clippy
+      #   run: rustup run nightly-2023-08-01 cargo clippy -- -Dclippy::correctness
+
+  build:
+    name: Rust Build
+    runs-on: ubuntu-latest
+    # TODO: build on more platforms, deploy, etc
+    steps:
+      - uses: actions/checkout@v4
+      - uses: Swatinem/rust-cache@v2
+      - name: cargo build
+        run: cargo build --release

.github/workflows/compiler_typescript.yml

@@ -5,19 +5,8 @@ on:
     branches: [main]
   pull_request:
     paths:
-      - compiler/**
-      - .github/workflows/compiler_typescript.yml
-
-permissions: {}
-
-concurrency:
-  group: ${{ github.workflow }}-${{ github.ref_name }}-${{ github.event.pull_request.number || github.run_id }}
-  cancel-in-progress: true
-
-env:
-  TZ: /usr/share/zoneinfo/America/Los_Angeles
-  # https://github.com/actions/cache/blob/main/tips-and-workarounds.md#cache-segment-restore-timeout
-  SEGMENT_DOWNLOAD_TIMEOUT_MINS: 1
+      - "compiler/**"
+      - .github/workflows/compiler-typescript.yml
 
 defaults:
   run:
@@ -42,15 +31,14 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version-file: '.nvmrc'
-          cache: yarn
+          node-version: 18.x
+          cache: "yarn"
           cache-dependency-path: compiler/yarn.lock
       - name: Restore cached node_modules
         uses: actions/cache@v4
         with:
-          path: |
-            **/node_modules
-          key: compiler-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('compiler/**/yarn.lock') }}
+          path: "**/node_modules"
+          key: ${{ runner.arch }}-${{ runner.os }}-modules-${{ hashFiles('compiler/**/yarn.lock') }}
       - run: yarn install --frozen-lockfile
       - run: yarn workspace babel-plugin-react-compiler lint
 
@@ -62,16 +50,15 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version-file: '.nvmrc'
-          cache: yarn
+          node-version: 18.x
+          cache: "yarn"
           cache-dependency-path: compiler/yarn.lock
       - name: Restore cached node_modules
         uses: actions/cache@v4
         id: node_modules
         with:
-          path: |
-            **/node_modules
-          key: compiler-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('compiler/**/yarn.lock') }}
+          path: "**/node_modules"
+          key: ${{ runner.arch }}-${{ runner.os }}-modules-${{ hashFiles('compiler/**/yarn.lock') }}
       - run: yarn install --frozen-lockfile
       - run: yarn workspace babel-plugin-react-compiler jest
 
@@ -79,26 +66,22 @@ jobs:
     name: Test ${{ matrix.workspace_name }}
     needs: discover_yarn_workspaces
     runs-on: ubuntu-latest
+    continue-on-error: true
     strategy:
-      fail-fast: false
       matrix:
         workspace_name: ${{ fromJSON(needs.discover_yarn_workspaces.outputs.matrix) }}
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version-file: '.nvmrc'
-          cache: yarn
+          node-version: 18.x
+          cache: "yarn"
           cache-dependency-path: compiler/yarn.lock
       - name: Restore cached node_modules
         uses: actions/cache@v4
         id: node_modules
         with:
-          path: |
-            **/node_modules
-          key: compiler-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('compiler/**/yarn.lock') }}
+          path: "**/node_modules"
+          key: ${{ runner.arch }}-${{ runner.os }}-modules-${{ hashFiles('compiler/**/yarn.lock') }}
       - run: yarn install --frozen-lockfile
-      - run: xvfb-run -a yarn workspace ${{ matrix.workspace_name }} test
-        if: runner.os == 'Linux' && matrix.workspace_name == 'react-forgive'
       - run: yarn workspace ${{ matrix.workspace_name }} test
-        if: matrix.workspace_name != 'react-forgive'

.github/workflows/devtools_check_repro.yml

@@ -0,0 +1,205 @@
+name: (DevTools) Check for bug repro
+on:
+  issues:
+    types: [opened, edited]
+  issue_comment:
+    types: [created, edited]
+
+jobs:
+  check-repro:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/github-script@v3
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          script: |
+            const URL_REGEXP = /### Website or app[\r\n]+([^#]+)###/m;
+            const REPRO_STEPS_REGEXP = /### Repro steps[\r\n]+([^#]+)###/m;
+            const LABEL_NEEDS_MORE_INFORMATION = "Resolution: Needs More Information";
+            const LABEL_UNCONFIRMED = "Status: Unconfirmed";
+
+            function debug(...args) {
+              core.info(args.map(JSON.stringify).join(' '));
+            }
+
+            if (context.payload.comment) {
+              debug('Ignoring comment update.');
+              return;
+            }
+
+            const user = context.payload.sender.login;
+            const issue = context.payload.issue;
+            const body = issue.body;
+
+            const urlMatch = body.match(URL_REGEXP);
+            const reproStepsMatch = body.match(REPRO_STEPS_REGEXP);
+
+            const url = urlMatch !== null ? urlMatch[1].trim() : null;
+            const reproSteps = reproStepsMatch !== null ? reproStepsMatch[1].trim() : null;
+
+            if (!url || !reproSteps) {
+              debug('This issue is not a DevTools bug report.');
+              return;
+            }
+
+            debug(`found URL "${url}"`);
+            debug(`found repro steps "${reproSteps}"`);
+
+            async function createComment(comment) {
+              // Format
+              comment = comment
+                .split("\n")
+                .map((line) => line.trim())
+                .join("\n")
+                .trim();
+
+              await github.issues.createComment({
+                issue_number: context.issue.number,
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                body: comment,
+              });
+            }
+
+            async function getGitHubActionComments() {
+              debug(`Loading existing comments...`);
+
+              const comments = await github.issues.listComments({
+                issue_number: context.issue.number,
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+              });
+
+              return comments.data.filter(comment => {
+                debug(`comment by user: "${comment.user.login}"`);
+                return comment.user.login === 'github-actions[bot]';
+              });
+            }
+
+            async function getIssueLabels() {
+              const issues = await github.issues.listLabelsOnIssue({
+                issue_number: context.issue.number,
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+              });
+
+              return issues.data;
+            }
+
+            async function updateIssue(state, assignees = []) {
+              await github.issues.update({
+                issue_number: context.issue.number,
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                state,
+                assignees,
+              });
+            }
+
+            async function closeWithComment(comment) {
+              if (issue.state !== 'open') {
+                debug(`Issue is not open`);
+                return;
+              }
+
+              const labels = await getIssueLabels();
+              const label = labels.find(label => label.name === LABEL_UNCONFIRMED);
+              if (!label) {
+                debug(`Issue was not opened via DevTools bug report template`);
+                return;
+              }
+
+              const comments = await getGitHubActionComments();
+              if (comments.length > 0) {
+                debug(`Already commented on issue; won't comment again`);
+                return;
+              }
+
+              debug(`Missing required information`);
+
+              await github.issues.addLabels({
+                issue_number: context.issue.number,
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                labels: [LABEL_NEEDS_MORE_INFORMATION],
+              });
+
+              await createComment(comment);
+              await updateIssue('closed', [user]);
+            }
+
+            async function openWithComment(comment) {
+              if (issue.state !== 'closed') {
+                debug(`Issue is already open`);
+                return;
+              }
+
+              const labels = await getIssueLabels();
+              const label = labels.find(label => label.name === LABEL_NEEDS_MORE_INFORMATION);
+              if (!label) {
+                debug(`Issue was not tagged as needs information`);
+                return;
+              }
+
+              const comments = await getGitHubActionComments();
+              if (comments.length === 0) {
+                debug(`Issue was closed by someone else; won't reopen`);
+                return;
+              }
+
+              debug(`Re-opening closed issue`);
+
+              await github.issues.removeLabel({
+                issue_number: context.issue.number,
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                name: LABEL_NEEDS_MORE_INFORMATION,
+              });
+
+              await createComment(comment);
+              await updateIssue('open');
+            }
+
+            const PROBABLY_NOT_A_URL_REGEX = /(^Chrome$|^Firefox$| Website)/i;
+
+            const COMMENT_HEADER = `
+              @${user}: We're sorry you've seen this error. ❤️
+            `.trim();
+
+            const COMMENT_FOOTER = `
+              Please help us by providing a link to a CodeSandbox (https://codesandbox.io/s/new), a repository on GitHub, or a minimal code example that reproduces the problem. (Screenshots or videos can also be helpful if they help provide context on how to repro the bug.)
+
+              Here are some tips for providing a minimal example: https://stackoverflow.com/help/mcve
+
+              Issues without repros are automatically closed but we will re-open if you update with repro info.
+            `.trim();
+
+            if (url.includes("localhost")) {
+              closeWithComment(`
+                ${COMMENT_HEADER}
+
+                Unfortunately the URL you provided ("localhost") is not publicly accessible. (This means that we will not be able to reproduce the problem you're reporting.)
+
+                ${COMMENT_FOOTER}
+              `);
+            } else if (url.length < 10 || url.match(PROBABLY_NOT_A_URL_REGEX)) {
+              closeWithComment(`
+                ${COMMENT_HEADER}
+
+                It looks like you forgot to specify a valid URL. (This means that we will not be able to reproduce the problem you're reporting.)
+
+                ${COMMENT_FOOTER}
+              `);
+            } else if (reproSteps.length < 25) {
+              closeWithComment(`
+                ${COMMENT_HEADER}
+
+                Unfortunately, it doesn't look like this issue has enough info for one of us to reproduce and fix it though.
+
+                ${COMMENT_FOOTER}
+              `);
+            } else {
+              openWithComment(`
+                Thank you for providing repro steps! Re-opening issue now for triage.
+              `);
+            }

.github/workflows/devtools_regression_tests.yml

@@ -1,191 +0,0 @@
-name: (DevTools) Regression Tests
-
-on:
-  schedule:
-    - cron: 0 0 * * *
-  workflow_dispatch:
-    inputs:
-      commit_sha:
-        required: false
-        type: string
-
-permissions: {}
-
-env:
-  TZ: /usr/share/zoneinfo/America/Los_Angeles
-  # https://github.com/actions/cache/blob/main/tips-and-workarounds.md#cache-segment-restore-timeout
-  SEGMENT_DOWNLOAD_TIMEOUT_MINS: 1
-
-jobs:
-  download_build:
-    name: Download base build
-    runs-on: ubuntu-latest
-    permissions:
-      # We use github.token to download the build artifact from a previous runtime_build_and_test.yml run
-      actions: read
-    steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-node@v4
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: yarn.lock
-      - name: Restore cached node_modules
-        uses: actions/cache@v4
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: runtime-release-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'scripts/release/yarn.lock') }}
-      - name: Ensure clean build directory
-        run: rm -rf build
-      - run: yarn install --frozen-lockfile
-      - run: yarn --cwd scripts/release install --frozen-lockfile
-      - name: Download react-devtools artifacts for base revision
-        run: |
-          git fetch origin main
-          GH_TOKEN=${{ github.token }} scripts/release/download-experimental-build.js --commit=${{ inputs.commit_sha || '$(git rev-parse origin/main)' }}
-      - name: Display structure of build
-        run: ls -R build
-      - name: Archive build
-        uses: actions/upload-artifact@v4
-        with:
-          name: build
-          path: build
-          if-no-files-found: error
-
-  build_devtools_and_process_artifacts:
-    name: Build DevTools and process artifacts
-    needs: download_build
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-node@v4
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: yarn.lock
-      - name: Restore cached node_modules
-        uses: actions/cache@v4
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: runtime-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
-      - name: Ensure clean build directory
-        run: rm -rf build
-      - run: yarn install --frozen-lockfile
-      - name: Restore archived build
-        uses: actions/download-artifact@v4
-        with:
-          name: build
-          path: build
-      - run: ./scripts/ci/pack_and_store_devtools_artifacts.sh
-        env:
-          RELEASE_CHANNEL: experimental
-      - name: Display structure of build
-        run: ls -R build
-      - name: Archive devtools build
-        uses: actions/upload-artifact@v4
-        with:
-          name: react-devtools
-          path: build/devtools.tgz
-          if-no-files-found: error
-      # Simplifies getting the extension for local testing
-      - name: Archive chrome extension
-        uses: actions/upload-artifact@v4
-        with:
-          name: react-devtools-chrome-extension
-          path: build/devtools/chrome-extension.zip
-          if-no-files-found: error
-      - name: Archive firefox extension
-        uses: actions/upload-artifact@v4
-        with:
-          name: react-devtools-firefox-extension
-          path: build/devtools/firefox-extension.zip
-          if-no-files-found: error
-
-  run_devtools_tests_for_versions:
-    name: Run DevTools tests for versions
-    needs: build_devtools_and_process_artifacts
-    runs-on: ubuntu-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        version:
-          - "16.0"
-          - "16.5" # schedule package
-          - "16.8" # hooks
-          - "17.0"
-          - "18.0"
-          - "18.2" # compiler polyfill
-    steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-node@v4
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: yarn.lock
-      - name: Restore cached node_modules
-        uses: actions/cache@v4
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: runtime-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
-      - run: yarn install --frozen-lockfile
-      - name: Restore all archived build artifacts
-        uses: actions/download-artifact@v4
-      - name: Display structure of build
-        run: ls -R build
-      - run: ./scripts/ci/download_devtools_regression_build.js ${{ matrix.version }} --replaceBuild
-      - run: node ./scripts/jest/jest-cli.js --build --project devtools --release-channel=experimental --reactVersion ${{ matrix.version }} --ci
-
-  run_devtools_e2e_tests_for_versions:
-    name: Run DevTools e2e tests for versions
-    needs: build_devtools_and_process_artifacts
-    runs-on: ubuntu-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        version:
-          - "16.0"
-          - "16.5" # schedule package
-          - "16.8" # hooks
-          - "17.0"
-          - "18.0"
-    steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-node@v4
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: yarn.lock
-      - name: Restore cached node_modules
-        uses: actions/cache@v4
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: runtime-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
-      - run: yarn install --frozen-lockfile
-      - name: Restore all archived build artifacts
-        uses: actions/download-artifact@v4
-      - name: Display structure of build
-        run: ls -R build
-      - name: Playwright install deps
-        run: |
-          npx playwright install
-          sudo npx playwright install-deps
-      - run: ./scripts/ci/download_devtools_regression_build.js ${{ matrix.version }}
-      - run: ls -R build-regression
-      - run: ./scripts/ci/run_devtools_e2e_tests.js ${{ matrix.version }}
-        env:
-          RELEASE_CHANNEL: experimental
-      - name: Cleanup build regression folder
-        run: rm -r ./build-regression
-      - uses: actions/upload-artifact@v4
-        with:
-          name: screenshots
-          path: ./tmp/screenshots
-          if-no-files-found: warn

.github/workflows/runtime_build_and_test.yml

@@ -1,849 +0,0 @@
-name: (Runtime) Build and Test
-
-on:
-  push:
-    branches: [main]
-    tags:
-      # To get CI for backport releases.
-      # This will duplicate CI for releases from main which is acceptable
-      - "v*"
-  pull_request:
-    paths-ignore:
-      - compiler/**
-  workflow_dispatch:
-    inputs:
-      commit_sha:
-        required: false
-        type: string
-        default: ''
-
-permissions: {}
-
-concurrency:
-  group: ${{ github.workflow }}-${{ github.ref_name }}-${{ github.event.pull_request.number || github.run_id }}
-  cancel-in-progress: true
-
-env:
-  TZ: /usr/share/zoneinfo/America/Los_Angeles
-  # https://github.com/actions/cache/blob/main/tips-and-workarounds.md#cache-segment-restore-timeout
-  SEGMENT_DOWNLOAD_TIMEOUT_MINS: 1
-
-jobs:
-  # ----- NODE_MODULES CACHE -----
-  # Centralize the node_modules cache so it is saved once and each subsequent job only needs to
-  # restore the cache. Prevents race conditions where multiple workflows try to write to the cache.
-  runtime_node_modules_cache:
-    name: Cache Runtime node_modules
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
-      - name: Check cache hit
-        uses: actions/cache/restore@v4
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: runtime-node_modules-v7-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
-          lookup-only: true
-      - uses: actions/setup-node@v4
-        if: steps.node_modules.outputs.cache-hit != 'true'
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: yarn.lock
-      - name: Warm with old cache
-        if: steps.node_modules.outputs.cache-hit != 'true'
-        uses: actions/cache/restore@v4
-        with:
-          path: |
-            **/node_modules
-          key: runtime-node_modules-v7-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
-          # Don't use restore-keys here. Otherwise the cache grows indefinitely.
-      - run: yarn install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - name: Save cache
-        if: steps.node_modules.outputs.cache-hit != 'true'
-        uses: actions/cache/save@v4
-        with:
-          path: |
-            **/node_modules
-          key: runtime-node_modules-v7-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
-
-  runtime_compiler_node_modules_cache:
-    name: Cache Runtime, Compiler node_modules
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
-      - name: Check cache hit
-        uses: actions/cache/restore@v4
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: runtime-and-compiler-node_modules-v7-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'compiler/yarn.lock') }}
-          lookup-only: true
-      - uses: actions/setup-node@v4
-        if: steps.node_modules.outputs.cache-hit != 'true'
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: |
-            yarn.lock
-            compiler/yarn.lock
-      - name: Warm with old cache
-        if: steps.node_modules.outputs.cache-hit != 'true'
-        uses: actions/cache/restore@v4
-        with:
-          path: |
-            **/node_modules
-          key: runtime-and-compiler-node_modules-v7-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'compiler/yarn.lock') }}
-          # Don't use restore-keys here. Otherwise the cache grows indefinitely.
-      - run: yarn install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - run: yarn --cwd compiler install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - name: Save cache
-        if: steps.node_modules.outputs.cache-hit != 'true'
-        uses: actions/cache/save@v4
-        with:
-          path: |
-            **/node_modules
-          key: runtime-and-compiler-node_modules-v7-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'compiler/yarn.lock') }}
-
-  # ----- FLOW -----
-  discover_flow_inline_configs:
-    name: Discover flow inline configs
-    runs-on: ubuntu-latest
-    outputs:
-      matrix: ${{ steps.set-matrix.outputs.result }}
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
-      - uses: actions/github-script@v7
-        id: set-matrix
-        with:
-          script: |
-            const inlinedHostConfigs = require('./scripts/shared/inlinedHostConfigs.js');
-            return inlinedHostConfigs.map(config => config.shortName);
-
-  flow:
-    name: Flow check ${{ matrix.flow_inline_config_shortname }}
-    needs: [discover_flow_inline_configs, runtime_node_modules_cache]
-    runs-on: ubuntu-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        flow_inline_config_shortname: ${{ fromJSON(needs.discover_flow_inline_configs.outputs.matrix) }}
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
-      - uses: actions/setup-node@v4
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: yarn.lock
-      - name: Restore cached node_modules
-        uses: actions/cache/restore@v4
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: runtime-node_modules-v7-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
-          # Don't use restore-keys here. Otherwise the cache grows indefinitely.
-      - name: Ensure clean build directory
-        run: rm -rf build
-      - run: yarn install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - run: node ./scripts/tasks/flow-ci ${{ matrix.flow_inline_config_shortname }}
-
-  # ----- FIZZ -----
-  check_generated_fizz_runtime:
-    name: Confirm generated inline Fizz runtime is up to date
-    needs: [runtime_node_modules_cache]
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
-      - uses: actions/setup-node@v4
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: yarn.lock
-      - name: Restore cached node_modules
-        uses: actions/cache/restore@v4
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: runtime-node_modules-v7-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
-          # Don't use restore-keys here. Otherwise the cache grows indefinitely.
-      - name: Ensure clean build directory
-        run: rm -rf build
-      - run: yarn install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - run: |
-          yarn generate-inline-fizz-runtime
-          git diff --quiet || (echo "There was a change to the Fizz runtime. Run `yarn generate-inline-fizz-runtime` and check in the result." && false)
-
-  # ----- FEATURE FLAGS -----
-  flags:
-    name: Check flags
-    needs: [runtime_node_modules_cache]
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
-      - uses: actions/setup-node@v4
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: yarn.lock
-      - name: Restore cached node_modules
-        uses: actions/cache/restore@v4
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: runtime-node_modules-v7-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
-      - name: Ensure clean build directory
-        run: rm -rf build
-      - run: yarn install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - run: yarn flags
-
-  # ----- TESTS -----
-  test:
-    name: yarn test ${{ matrix.params }} (Shard ${{ matrix.shard }})
-    needs: [runtime_compiler_node_modules_cache]
-    runs-on: ubuntu-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        params:
-          - "-r=stable --env=development"
-          - "-r=stable --env=production"
-          - "-r=experimental --env=development"
-          - "-r=experimental --env=production"
-          - "-r=www-classic --env=development --variant=false"
-          - "-r=www-classic --env=production --variant=false"
-          - "-r=www-classic --env=development --variant=true"
-          - "-r=www-classic --env=production --variant=true"
-          - "-r=www-modern --env=development --variant=false"
-          - "-r=www-modern --env=production --variant=false"
-          - "-r=www-modern --env=development --variant=true"
-          - "-r=www-modern --env=production --variant=true"
-          - "-r=xplat --env=development --variant=false"
-          - "-r=xplat --env=development --variant=true"
-          - "-r=xplat --env=production --variant=false"
-          - "-r=xplat --env=production --variant=true"
-          # TODO: Test more persistent configurations?
-          - "-r=stable --env=development --persistent"
-          - "-r=experimental --env=development --persistent"
-        shard:
-          - 1/5
-          - 2/5
-          - 3/5
-          - 4/5
-          - 5/5
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
-      - uses: actions/setup-node@v4
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: |
-            yarn.lock
-            compiler/yarn.lock
-      - name: Restore cached node_modules
-        uses: actions/cache/restore@v4
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: runtime-and-compiler-node_modules-v7-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'compiler/yarn.lock') }}
-          # Don't use restore-keys here. Otherwise the cache grows indefinitely.
-      - name: Ensure clean build directory
-        run: rm -rf build
-      - run: yarn install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - run: yarn --cwd compiler install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - run: yarn test ${{ matrix.params }} --ci --shard=${{ matrix.shard }}
-
-  # Hardcoded to improve parallelism
-  test-linter:
-    name: Test eslint-plugin-react-hooks
-    needs: [runtime_compiler_node_modules_cache]
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-node@v4
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path:  |
-            yarn.lock
-            compiler/yarn.lock
-      - name: Restore cached node_modules
-        uses: actions/cache@v4
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: runtime-and-compiler-node_modules-v7-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'compiler/yarn.lock') }}
-      - name: Install runtime dependencies
-        run: yarn install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - name: Install compiler dependencies
-        run: yarn install --frozen-lockfile
-        working-directory: compiler
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - run: ./scripts/react-compiler/build-compiler.sh && ./scripts/react-compiler/link-compiler.sh
-      - run: yarn workspace eslint-plugin-react-hooks test
-        
-  # ----- BUILD -----
-  build_and_lint:
-    name: yarn build and lint
-    needs: [runtime_compiler_node_modules_cache]
-    runs-on: ubuntu-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        # yml is dumb. update the --total arg to yarn build if you change the number of workers
-        worker_id: [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24]
-        release_channel: [stable, experimental]
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
-      - uses: actions/setup-node@v4
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: |
-            yarn.lock
-            compiler/yarn.lock
-      - uses: actions/setup-java@v4
-        with:
-          distribution: temurin
-          java-version: 11.0.22
-      - name: Restore cached node_modules
-        uses: actions/cache/restore@v4
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: runtime-and-compiler-node_modules-v7-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'compiler/yarn.lock') }}
-          # Don't use restore-keys here. Otherwise the cache grows indefinitely.
-      - name: Ensure clean build directory
-        run: rm -rf build
-      - run: yarn install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - run: yarn --cwd compiler install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - run: yarn build --index=${{ matrix.worker_id }} --total=25 --r=${{ matrix.release_channel }} --ci
-        env:
-          CI: github
-          RELEASE_CHANNEL: ${{ matrix.release_channel }}
-          NODE_INDEX: ${{ matrix.worker_id }}
-      - name: Lint build
-        run: yarn lint-build
-      - name: Display structure of build
-        run: ls -R build
-      - name: Archive build
-        uses: actions/upload-artifact@v4
-        with:
-          name: _build_${{ matrix.worker_id }}_${{ matrix.release_channel }}
-          path: build
-          if-no-files-found: error
-
-  test_build:
-    name: yarn test-build
-    needs: [build_and_lint, runtime_compiler_node_modules_cache]
-    strategy:
-      fail-fast: false
-      matrix:
-        test_params: [
-          # Intentionally passing these as strings instead of creating a
-          # separate parameter per CLI argument, since it's easier to
-          # control/see which combinations we want to run.
-          -r=stable --env=development,
-          -r=stable --env=production,
-          -r=experimental --env=development,
-          -r=experimental --env=production,
-
-          # Dev Tools
-          --project=devtools -r=experimental,
-
-          # TODO: Update test config to support www build tests
-          # - "-r=www-classic --env=development --variant=false"
-          # - "-r=www-classic --env=production --variant=false"
-          # - "-r=www-classic --env=development --variant=true"
-          # - "-r=www-classic --env=production --variant=true"
-          # - "-r=www-modern --env=development --variant=false"
-          # - "-r=www-modern --env=production --variant=false"
-          # - "-r=www-modern --env=development --variant=true"
-          # - "-r=www-modern --env=production --variant=true"
-
-          # TODO: Update test config to support xplat build tests
-          # - "-r=xplat --env=development --variant=false"
-          # - "-r=xplat --env=development --variant=true"
-          # - "-r=xplat --env=production --variant=false"
-          # - "-r=xplat --env=production --variant=true"
-
-          # TODO: Test more persistent configurations?
-        ]
-        shard:
-          - 1/10
-          - 2/10
-          - 3/10
-          - 4/10
-          - 5/10
-          - 6/10
-          - 7/10
-          - 8/10
-          - 9/10
-          - 10/10
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
-      - uses: actions/setup-node@v4
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: |
-            yarn.lock
-            compiler/yarn.lock
-      - name: Restore cached node_modules
-        uses: actions/cache/restore@v4
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: runtime-and-compiler-node_modules-v7-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'compiler/yarn.lock') }}
-          # Don't use restore-keys here. Otherwise the cache grows indefinitely.
-      - name: Ensure clean build directory
-        run: rm -rf build
-      - run: yarn install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - run: yarn --cwd compiler install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - name: Restore archived build
-        uses: actions/download-artifact@v4
-        with:
-          pattern: _build_*
-          path: build
-          merge-multiple: true
-      - name: Display structure of build
-        run: ls -R build
-      - run: yarn test --build ${{ matrix.test_params }} --shard=${{ matrix.shard }} --ci
-
-  process_artifacts_combined:
-    name: Process artifacts combined
-    needs: [build_and_lint, runtime_node_modules_cache]
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
-      - uses: actions/setup-node@v4
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: yarn.lock
-      - name: Restore cached node_modules
-        uses: actions/cache/restore@v4
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: runtime-node_modules-v7-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
-          # Don't use restore-keys here. Otherwise the cache grows indefinitely.
-      - name: Ensure clean build directory
-        run: rm -rf build
-      - run: yarn install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - name: Restore archived build
-        uses: actions/download-artifact@v4
-        with:
-          pattern: _build_*
-          path: build
-          merge-multiple: true
-      - name: Display structure of build
-        run: ls -R build
-      - run: echo ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }} >> build/COMMIT_SHA
-      - name: Scrape warning messages
-        run: |
-          mkdir -p ./build/__test_utils__
-          node ./scripts/print-warnings/print-warnings.js > build/__test_utils__/ReactAllWarnings.js
-        # Compress build directory into a single tarball for easy download
-      - run: tar -zcvf ./build.tgz ./build
-        # TODO: Migrate scripts to use `build` directory instead of `build2`
-      - run: cp ./build.tgz ./build2.tgz
-      - name: Archive build artifacts
-        uses: actions/upload-artifact@v4
-        with:
-          name: artifacts_combined
-          path: |
-            ./build.tgz
-            ./build2.tgz
-          if-no-files-found: error
-
-  check_error_codes:
-    name: Search build artifacts for unminified errors
-    needs: [build_and_lint, runtime_node_modules_cache]
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
-      - uses: actions/setup-node@v4
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: yarn.lock
-      - name: Restore cached node_modules
-        uses: actions/cache/restore@v4
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: runtime-node_modules-v7-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
-          # Don't use restore-keys here. Otherwise the cache grows indefinitely.
-      - name: Ensure clean build directory
-        run: rm -rf build
-      - run: yarn install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - name: Restore archived build
-        uses: actions/download-artifact@v4
-        with:
-          pattern: _build_*
-          path: build
-          merge-multiple: true
-      - name: Display structure of build
-        run: ls -R build
-      - name: Search build artifacts for unminified errors
-        run: |
-          yarn extract-errors
-          git diff --quiet || (echo "Found unminified errors. Either update the error codes map or disable error minification for the affected build, if appropriate." && false)
-
-  check_release_dependencies:
-    name: Check release dependencies
-    needs: [build_and_lint, runtime_node_modules_cache]
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
-      - uses: actions/setup-node@v4
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: yarn.lock
-      - name: Restore cached node_modules
-        uses: actions/cache/restore@v4
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: runtime-node_modules-v7-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
-          # Don't use restore-keys here. Otherwise the cache grows indefinitely.
-      - name: Ensure clean build directory
-        run: rm -rf build
-      - run: yarn install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - name: Restore archived build
-        uses: actions/download-artifact@v4
-        with:
-          pattern: _build_*
-          path: build
-          merge-multiple: true
-      - name: Display structure of build
-        run: ls -R build
-      - run: yarn check-release-dependencies
-
-  RELEASE_CHANNEL_stable_yarn_test_dom_fixtures:
-    name: Check fixtures DOM (stable)
-    needs: build_and_lint
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
-      - uses: actions/setup-node@v4
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: yarn.lock
-      - name: Restore cached node_modules
-        uses: actions/cache@v4 # note: this does not reuse centralized cache since it has unique cache key
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: fixtures_dom-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'fixtures/dom/yarn.lock') }}
-      - name: Ensure clean build directory
-        run: rm -rf build
-      - run: yarn --cwd fixtures/dom install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - name: Restore archived build
-        uses: actions/download-artifact@v4
-        with:
-          pattern: _build_*
-          path: build
-          merge-multiple: true
-      - name: Display structure of build
-        run: ls -R build
-      - name: Run DOM fixture tests
-        run: |
-          yarn predev
-          yarn test
-        working-directory: fixtures/dom
-        env:
-          RELEASE_CHANNEL: stable
-
-  # ----- FLIGHT -----
-  run_fixtures_flight_tests:
-    name: Run fixtures Flight tests
-    needs: build_and_lint
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
-      - uses: actions/setup-node@v4
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: yarn.lock
-      # Fixture copies some built packages from the workroot after install.
-      # That means dependencies of the built packages are not installed.
-      # We need to install dependencies of the workroot to fulfill all dependency constraints
-      - name: Restore cached node_modules
-        uses: actions/cache@v4 # note: this does not reuse centralized cache since it has unique cache key
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: fixtures_flight-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'fixtures/flight/yarn.lock') }}
-      - name: Ensure clean build directory
-        run: rm -rf build
-      - run: yarn install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - run: yarn --cwd fixtures/flight install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - name: Check Playwright version
-        id: playwright_version
-        run: echo "playwright_version=$(npm ls @playwright/test | grep @playwright | sed 's/.*@//' | head -1)" >> "$GITHUB_OUTPUT"
-      - name: Cache Playwright Browsers for version ${{ steps.playwright_version.outputs.playwright_version }}
-        id: cache_playwright_browsers
-        uses: actions/cache@v4
-        with:
-          path: ~/.cache/ms-playwright
-          key: playwright-browsers-v6-${{ runner.arch }}-${{ runner.os }}-${{ steps.playwright_version.outputs.playwright_version }}
-      - name: Playwright install deps
-        if: steps.cache_playwright_browsers.outputs.cache-hit != 'true'
-        working-directory: fixtures/flight
-        run: npx playwright install --with-deps chromium
-      - name: Restore archived build
-        uses: actions/download-artifact@v4
-        with:
-          pattern: _build_*
-          path: build
-          merge-multiple: true
-      - name: Display structure of build
-        run: ls -R build
-      - name: Run tests
-        working-directory: fixtures/flight
-        run: yarn test
-        env:
-          # Otherwise the webserver is a blackbox
-          DEBUG: pw:webserver
-      - name: Archive Flight fixture artifacts
-        uses: actions/upload-artifact@v4
-        with:
-          name: flight-playwright-report
-          path: fixtures/flight/playwright-report
-          if-no-files-found: warn
-      - name: Archive Flight fixture artifacts
-        uses: actions/upload-artifact@v4
-        with:
-          name: flight-test-results
-          path: fixtures/flight/test-results
-          if-no-files-found: ignore
-
-  # ----- DEVTOOLS -----
-  build_devtools_and_process_artifacts:
-    name: Build DevTools and process artifacts
-    needs: [build_and_lint, runtime_node_modules_cache]
-    runs-on: ubuntu-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        browser: [chrome, firefox, edge]
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
-      - uses: actions/setup-node@v4
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: yarn.lock
-      - name: Restore cached node_modules
-        uses: actions/cache/restore@v4
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: runtime-node_modules-v7-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
-          # Don't use restore-keys here. Otherwise the cache grows indefinitely.
-      - name: Ensure clean build directory
-        run: rm -rf build
-      - run: yarn install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - name: Restore archived build
-        uses: actions/download-artifact@v4
-        with:
-          pattern: _build_*
-          path: build
-          merge-multiple: true
-      - run: ./scripts/ci/pack_and_store_devtools_artifacts.sh ${{ matrix.browser }}
-        env:
-          RELEASE_CHANNEL: experimental
-      - name: Display structure of build
-        run: ls -R build
-      # Simplifies getting the extension for local testing
-      - name: Archive ${{ matrix.browser }} extension
-        uses: actions/upload-artifact@v4
-        with:
-          name: react-devtools-${{ matrix.browser }}-extension
-          path: build/devtools/${{ matrix.browser }}-extension.zip
-          if-no-files-found: error
-
-  merge_devtools_artifacts:
-    name: Merge DevTools artifacts
-    needs: build_devtools_and_process_artifacts
-    runs-on: ubuntu-latest
-    steps:
-      - name: Merge artifacts
-        uses: actions/upload-artifact/merge@v4
-        with:
-          name: react-devtools
-          pattern: react-devtools-*-extension
-
-  run_devtools_e2e_tests:
-    name: Run DevTools e2e tests
-    needs: [build_and_lint, runtime_node_modules_cache]
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
-      - uses: actions/setup-node@v4
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: yarn.lock
-      - name: Restore cached node_modules
-        uses: actions/cache/restore@v4
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: runtime-node_modules-v7-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock') }}
-          # Don't use restore-keys here. Otherwise the cache grows indefinitely.
-      - name: Ensure clean build directory
-        run: rm -rf build
-      - run: yarn install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - name: Restore archived build
-        uses: actions/download-artifact@v4
-        with:
-          pattern: _build_*
-          path: build
-          merge-multiple: true
-      - run: |
-          npx playwright install
-          sudo npx playwright install-deps
-      - run: ./scripts/ci/run_devtools_e2e_tests.js
-        env:
-          RELEASE_CHANNEL: experimental
-
-  # ----- SIZEBOT -----
-  sizebot:
-    if: ${{ github.event_name == 'pull_request' && github.ref_name != 'main' && github.event.pull_request.base.ref == 'main' }}
-    name: Run sizebot
-    needs: [build_and_lint]
-    permissions:
-      # We use github.token to download the build artifact from a previous runtime_build_and_test.yml run
-      actions: read
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }}
-      - uses: actions/setup-node@v4
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: yarn.lock
-      - name: Restore cached node_modules
-        uses: actions/cache@v4 # note: this does not reuse centralized cache since it has unique cache key
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: runtime-release-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'scripts/release/yarn.lock') }}
-      - name: Ensure clean build directory
-        run: rm -rf build
-      - run: yarn install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - run: yarn --cwd scripts/release install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - name: Download artifacts for base revision
-        run: |
-          GH_TOKEN=${{ github.token }} scripts/release/download-experimental-build.js --commit=$(git rev-parse ${{ github.event.pull_request.base.sha }})
-          mv ./build ./base-build
-      # TODO: The `download-experimental-build` script copies the npm
-      # packages into the `node_modules` directory. This is a historical
-      # quirk of how the release script works. Let's pretend they
-      # don't exist.
-      - name: Delete extraneous files
-        run: rm -rf ./base-build/node_modules
-      - name: Display structure of base-build from origin/main
-        run: ls -R base-build
-      - name: Ensure clean build directory
-        run: rm -rf build
-      - name: Restore archived build for PR
-        uses: actions/download-artifact@v4
-        with:
-          pattern: _build_*
-          path: build
-          merge-multiple: true
-      - name: Scrape warning messages
-        run: |
-          mkdir -p ./build/__test_utils__
-          node ./scripts/print-warnings/print-warnings.js > build/__test_utils__/ReactAllWarnings.js
-      - name: Display structure of build for PR
-        run: ls -R build
-      - run: echo ${{ github.event.inputs.commit_sha != '' && github.event.inputs.commit_sha || github.event.pull_request.head.sha || github.sha }} >> build/COMMIT_SHA
-      - run: node ./scripts/tasks/danger
-      - name: Archive sizebot results
-        uses: actions/upload-artifact@v4
-        with:
-          name: sizebot-message
-          path: sizebot-message.md
-          if-no-files-found: ignore

.github/workflows/runtime_commit_artifacts.yml

@@ -1,71 +1,12 @@
-name: (Runtime) Commit Artifacts for Meta WWW and fbsource V2
+name: (Runtime) Commit Artifacts for Meta WWW and fbsource
 
 on:
-  workflow_run:
-    workflows: ["(Runtime) Build and Test"]
-    types: [completed]
-    branches:
-      - main
-  workflow_dispatch:
-    inputs:
-      commit_sha:
-        required: false
-        type: string
-      force:
-        description: 'Force a commit to the builds/... branches'
-        required: true
-        default: false
-        type: boolean
-      dry_run:
-        description: Perform a dry run (run everything except push)
-        required: true
-        default: false
-        type: boolean
-
-permissions: {}
-
-env:
-  TZ: /usr/share/zoneinfo/America/Los_Angeles
-  # https://github.com/actions/cache/blob/main/tips-and-workarounds.md#cache-segment-restore-timeout
-  SEGMENT_DOWNLOAD_TIMEOUT_MINS: 1
+  push:
+    branches: [main, meta-www, meta-fbsource]
 
 jobs:
   download_artifacts:
     runs-on: ubuntu-latest
-    permissions:
-      # We use github.token to download the build artifact from a previous runtime_build_and_test.yml run
-      actions: read
-    steps:
-      - uses: actions/checkout@v4
-      - name: Restore cached node_modules
-        uses: actions/cache@v4
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: runtime-release-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'scripts/release/yarn.lock') }}
-      - name: Ensure clean build directory
-        run: rm -rf build
-      - run: yarn install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - run: yarn --cwd scripts/release install --frozen-lockfile
-        if: steps.node_modules.outputs.cache-hit != 'true'
-      - name: Download artifacts for base revision
-        run: |
-          GH_TOKEN=${{ github.token }} scripts/release/download-experimental-build.js --commit=${{ inputs.commit_sha || github.event.workflow_run.head_sha || github.sha }}
-      - name: Display structure of build
-        run: ls -R build
-      - name: Archive build
-        uses: actions/upload-artifact@v4
-        with:
-          name: build
-          path: build/
-          if-no-files-found: error
-
-
-  process_artifacts:
-    runs-on: ubuntu-latest
-    needs: [download_artifacts]
     outputs:
       www_branch_count: ${{ steps.check_branches.outputs.www_branch_count }}
       fbsource_branch_count: ${{ steps.check_branches.outputs.fbsource_branch_count }}
@@ -105,23 +46,107 @@ jobs:
         run: |
           echo "www_branch_count=$(git ls-remote --heads origin "refs/heads/meta-www" | wc -l)" >> "$GITHUB_OUTPUT"
           echo "fbsource_branch_count=$(git ls-remote --heads origin "refs/heads/meta-fbsource" | wc -l)" >> "$GITHUB_OUTPUT"
-      - name: Restore downloaded build
-        uses: actions/download-artifact@v4
+      - name: Download and unzip artifacts
+        uses: actions/github-script@v6
+        env:
+          CIRCLECI_TOKEN: ${{secrets.CIRCLECI_TOKEN_DIFFTRAIN}}
         with:
-          name: build
-          path: build
-      - name: Display structure of build
-        run: ls -R build
+          script: |
+            // TODO: Move this to a script file.
+            const cp = require('child_process');
+
+            function sleep(ms) {
+              return new Promise(resolve => setTimeout(resolve, ms));
+            }
+
+            function execHelper(command, options, streamStdout = false) {
+              return new Promise((resolve, reject) => {
+                const proc = cp.exec(
+                  command,
+                  options,
+                  (error, stdout) => (error ? reject(error) : resolve(stdout.trim())),
+                );
+                if (streamStdout) {
+                  proc.stdout.pipe(process.stdout);
+                }
+              });
+            }
+
+            let artifactsUrl = null;
+            // This is a temporary, dirty hack to avoid needing a GitHub auth token in the circleci
+            // workflow to notify this GitHub action. Sorry!
+            let iter = 0;
+            spinloop: while (iter < 15) {
+              const res = await github.rest.repos.listCommitStatusesForRef({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                ref: context.sha
+              });
+              for (const status of res.data) {
+                if (/process_artifacts_combined/.test(status.context)) {
+                  switch (status.state) {
+                    case 'pending': {
+                      console.log(`${status.context} is still pending`);
+                      break;
+                    }
+                    case 'failure':
+                    case 'error': {
+                      throw new Error(`${status.context} has failed or errored`);
+                    }
+                    case 'success': {
+                      // The status does not include a build ID, but we can extract it
+                      // from the URL. I couldn't find a better way to do this.
+                      const ciBuildId = /\/facebook\/react\/([0-9]+)/.exec(
+                        status.target_url,
+                      )[1];
+                      if (Number.parseInt(ciBuildId, 10) + '' === ciBuildId) {
+                        artifactsUrl =
+                          `https://circleci.com/api/v1.1/project/github/facebook/react/${ciBuildId}/artifacts`;
+                        console.log(`Found artifactsUrl: ${artifactsUrl}`);
+                        break spinloop;
+                      } else {
+                        throw new Error(`${ciBuildId} isn't a number`);
+                      }
+                      break;
+                    }
+                    default: {
+                      throw new Error(`Unhandled status state: ${status.state}`);
+                      break;
+                    }
+                  }
+                }
+              }
+              iter++;
+              console.log("Sleeping for 60s...");
+              await sleep(60_000);
+            }
+            if (artifactsUrl != null) {
+              const {CIRCLECI_TOKEN} = process.env;
+              const res = await fetch(artifactsUrl, {
+                headers: {
+                  'Circle-Token': CIRCLECI_TOKEN
+                }
+              });
+              const data = await res.json();
+              if (!Array.isArray(data) && data.message != null) {
+                throw `CircleCI returned: ${data.message}`;
+              }
+              for (const artifact of data) {
+                if (artifact.path === 'build.tgz') {
+                  console.log(`Downloading and unzipping ${artifact.url}`);
+                  await execHelper(
+                    `curl -L ${artifact.url} -H "Circle-Token: ${CIRCLECI_TOKEN}" | tar -xvz`
+                  );
+                }
+              }
+            } else {
+              process.exitCode = 1;
+            }
       - name: Strip @license from eslint plugin and react-refresh
         run: |
           sed -i -e 's/ @license React*//' \
             build/oss-experimental/eslint-plugin-react-hooks/cjs/eslint-plugin-react-hooks.development.js \
             build/oss-experimental/react-refresh/cjs/react-refresh-babel.development.js
-      - name: Insert @headers into eslint plugin and react-refresh
-        run: |
-          sed -i -e 's/ LICENSE file in the root directory of this source tree./ LICENSE file in the root directory of this source tree.\n *\n * @noformat\n * @nolint\n * @lightSyntaxTransform\n * @preventMunge\n * @oncall react_core/' \
-            build/oss-experimental/eslint-plugin-react-hooks/cjs/eslint-plugin-react-hooks.development.js \
-            build/oss-experimental/react-refresh/cjs/react-refresh-babel.development.js
       - name: Move relevant files for React in www into compiled
         run: |
           # Move the facebook-www folder into compiled
@@ -132,10 +157,9 @@ jobs:
           mkdir ./compiled/facebook-www/__test_utils__
           mv build/__test_utils__/ReactAllWarnings.js ./compiled/facebook-www/__test_utils__/ReactAllWarnings.js
 
-          # Move eslint-plugin-react-hooks into eslint-plugin-react-hooks
-          mkdir ./compiled/eslint-plugin-react-hooks
+          # Move eslint-plugin-react-hooks into facebook-www
           mv build/oss-experimental/eslint-plugin-react-hooks/cjs/eslint-plugin-react-hooks.development.js \
-            ./compiled/eslint-plugin-react-hooks/index.js
+            ./compiled/facebook-www/eslint-plugin-react-hooks.js
 
           # Move unstable_server-external-runtime.js into facebook-www
           mv build/oss-experimental/react-dom/unstable_server-external-runtime.js \
@@ -151,14 +175,13 @@ jobs:
         run: |
           BASE_FOLDER='compiled-rn/facebook-fbsource/xplat/js'
           mkdir -p ${BASE_FOLDER}/react-native-github/Libraries/Renderer/
-          mkdir -p ${BASE_FOLDER}/RKJSModules/vendor/react/{scheduler,react,react-dom,react-is,react-test-renderer}/
+          mkdir -p ${BASE_FOLDER}/RKJSModules/vendor/react/{scheduler,react,react-is,react-test-renderer}/
 
           # Move React Native renderer
           mv build/react-native/implementations/ $BASE_FOLDER/react-native-github/Libraries/Renderer/
           mv build/react-native/shims/ $BASE_FOLDER/react-native-github/Libraries/Renderer/
           mv build/facebook-react-native/scheduler/cjs/ $BASE_FOLDER/RKJSModules/vendor/react/scheduler/
           mv build/facebook-react-native/react/cjs/ $BASE_FOLDER/RKJSModules/vendor/react/react/
-          mv build/facebook-react-native/react-dom/cjs/ $BASE_FOLDER/RKJSModules/vendor/react/react-dom/
           mv build/facebook-react-native/react-is/cjs/ $BASE_FOLDER/RKJSModules/vendor/react/react-is/
           mv build/facebook-react-native/react-test-renderer/cjs/ $BASE_FOLDER/RKJSModules/vendor/react/react-test-renderer/
 
@@ -173,9 +196,9 @@ jobs:
           ls -R ./compiled-rn
       - name: Add REVISION files
         run: |
-          echo ${{ inputs.commit_sha || github.event.workflow_run.head_sha || github.sha }} >> ./compiled/facebook-www/REVISION
+          echo ${{ github.sha }} >> ./compiled/facebook-www/REVISION
           cp ./compiled/facebook-www/REVISION ./compiled/facebook-www/REVISION_TRANSFORMS
-          echo ${{ inputs.commit_sha || github.event.workflow_run.head_sha || github.sha }} >> ./compiled-rn/facebook-fbsource/xplat/js/react-native-github/Libraries/Renderer/REVISION
+          echo ${{ github.sha }} >> ./compiled-rn/facebook-fbsource/xplat/js/react-native-github/Libraries/Renderer/REVISION
       - name: "Get current version string"
         id: get_current_version
         run: |
@@ -188,41 +211,36 @@ jobs:
           echo "current_version_classic=$VERSION_CLASSIC" >> "$GITHUB_OUTPUT"
           echo "current_version_modern=$VERSION_MODERN" >> "$GITHUB_OUTPUT"
           echo "current_version_rn=$VERSION_NATIVE_FB" >> "$GITHUB_OUTPUT"
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@v3
         with:
           name: compiled
           path: compiled/
-          if-no-files-found: error
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@v3
         with:
           name: compiled-rn
           path: compiled-rn/
-          if-no-files-found: error
 
   commit_www_artifacts:
-    needs: [download_artifacts, process_artifacts]
-    if: inputs.force == true || (github.ref == 'refs/heads/main' && needs.process_artifacts.outputs.www_branch_count == '0')
+    needs: download_artifacts
+    if: ${{ (github.ref == 'refs/heads/main' && needs.download_artifacts.outputs.www_branch_count == '0') || github.ref == 'refs/heads/meta-www' }}
     runs-on: ubuntu-latest
-    permissions:
-      # Used to push a commit to builds/facebook-www
-      contents: write
     steps:
       - uses: actions/checkout@v4
         with:
           ref: builds/facebook-www
       - name: Ensure clean directory
         run: rm -rf compiled
-      - uses: actions/download-artifact@v4
+      - uses: actions/download-artifact@v3
         with:
           name: compiled
           path: compiled/
       - name: Revert version changes
-        if: needs.process_artifacts.outputs.last_version_classic != '' && needs.process_artifacts.outputs.last_version_modern != ''
+        if: needs.download_artifacts.outputs.last_version_classic != '' && needs.download_artifacts.outputs.last_version_modern != ''
         env:
-          CURRENT_VERSION_CLASSIC: ${{ needs.process_artifacts.outputs.current_version_classic }}
-          CURRENT_VERSION_MODERN: ${{ needs.process_artifacts.outputs.current_version_modern }}
-          LAST_VERSION_CLASSIC: ${{ needs.process_artifacts.outputs.last_version_classic }}
-          LAST_VERSION_MODERN: ${{ needs.process_artifacts.outputs.last_version_modern }}
+          CURRENT_VERSION_CLASSIC: ${{ needs.download_artifacts.outputs.current_version_classic }}
+          CURRENT_VERSION_MODERN: ${{ needs.download_artifacts.outputs.current_version_modern }}
+          LAST_VERSION_CLASSIC: ${{ needs.download_artifacts.outputs.last_version_classic }}
+          LAST_VERSION_MODERN: ${{ needs.download_artifacts.outputs.last_version_modern }}
         run: |
           echo "Reverting $CURRENT_VERSION_CLASSIC to $LAST_VERSION_CLASSIC"
           grep -rl "$CURRENT_VERSION_CLASSIC" ./compiled || echo "No files found with $CURRENT_VERSION_CLASSIC"
@@ -234,7 +252,6 @@ jobs:
           grep -rl "$CURRENT_VERSION_MODERN" ./compiled | xargs -r sed -i -e "s/$CURRENT_VERSION_MODERN/$LAST_VERSION_MODERN/g"
           grep -rl "$CURRENT_VERSION_MODERN" ./compiled || echo "Modern version reverted"
       - name: Check for changes
-        if: inputs.force != true
         id: check_should_commit
         run: |
           echo "Full git status"
@@ -252,12 +269,12 @@ jobs:
             echo "should_commit=false" >> "$GITHUB_OUTPUT"
           fi
       - name: Re-apply version changes
-        if: inputs.force == true || (steps.check_should_commit.outputs.should_commit == 'true' && needs.process_artifacts.outputs.last_version_classic != '' && needs.process_artifacts.outputs.last_version_modern != '')
+        if: steps.check_should_commit.outputs.should_commit == 'true' && needs.download_artifacts.outputs.last_version_classic != '' && needs.download_artifacts.outputs.last_version_modern != ''
         env:
-          CURRENT_VERSION_CLASSIC: ${{ needs.process_artifacts.outputs.current_version_classic }}
-          CURRENT_VERSION_MODERN: ${{ needs.process_artifacts.outputs.current_version_modern }}
-          LAST_VERSION_CLASSIC: ${{ needs.process_artifacts.outputs.last_version_classic }}
-          LAST_VERSION_MODERN: ${{ needs.process_artifacts.outputs.last_version_modern }}
+          CURRENT_VERSION_CLASSIC: ${{ needs.download_artifacts.outputs.current_version_classic }}
+          CURRENT_VERSION_MODERN: ${{ needs.download_artifacts.outputs.current_version_modern }}
+          LAST_VERSION_CLASSIC: ${{ needs.download_artifacts.outputs.last_version_classic }}
+          LAST_VERSION_MODERN: ${{ needs.download_artifacts.outputs.last_version_modern }}
         run: |
           echo "Re-applying $LAST_VERSION_CLASSIC to $CURRENT_VERSION_CLASSIC"
           grep -rl "$LAST_VERSION_CLASSIC" ./compiled || echo "No files found with $LAST_VERSION_CLASSIC"
@@ -269,33 +286,26 @@ jobs:
           grep -rl "$LAST_VERSION_MODERN" ./compiled | xargs -r sed -i -e "s/$LAST_VERSION_MODERN/$CURRENT_VERSION_MODERN/g"
           grep -rl "$LAST_VERSION_MODERN" ./compiled || echo "Classic version re-applied"
       - name: Will commit these changes
-        if: inputs.force == true || steps.check_should_commit.outputs.should_commit == 'true'
+        if: steps.check_should_commit.outputs.should_commit == 'true'
         run: |
-          git add .
-          git status
-      - name: Check commit message
-        if: inputs.dry_run
-        run: |
-          git fetch origin --quiet
-          git show ${{ inputs.commit_sha || github.event.workflow_run.head_sha || github.sha }} --no-patch --pretty=format:"%B"
+          echo ":"
+          git status -u
       - name: Commit changes to branch
-        if: inputs.force == true || steps.check_should_commit.outputs.should_commit == 'true'
-        run: |
-          git config --global user.email "${{ format('{0}@users.noreply.github.com', github.triggering_actor) }}"
-          git config --global user.name "${{ github.triggering_actor }}"
+        if: steps.check_should_commit.outputs.should_commit == 'true'
+        uses: stefanzweifel/git-auto-commit-action@v4
+        with:
+          commit_message: |
+            ${{ github.event.head_commit.message }}
 
-          git fetch origin --quiet
-          git commit -m "$(git show ${{ inputs.commit_sha || github.event.workflow_run.head_sha || github.sha }} --no-patch --pretty=format:'%B%n%nDiffTrain build for [${{ inputs.commit_sha || github.event.workflow_run.head_sha || github.sha }}](https://github.com/facebook/react/commit/${{ inputs.commit_sha || github.event.workflow_run.head_sha || github.sha}})')" || echo "No changes to commit"
-      - name: Push changes to branch
-        if: inputs.dry_run == false && (inputs.force == true || steps.check_should_commit.outputs.should_commit == 'true')
-        run: git push
+            DiffTrain build for [${{ github.sha }}](https://github.com/facebook/react/commit/${{ github.sha }})
+          branch: builds/facebook-www
+          commit_user_name: ${{ github.actor }}
+          commit_user_email: ${{ github.actor }}@users.noreply.github.com
+          create_branch: true
 
   commit_fbsource_artifacts:
-    needs: [download_artifacts, process_artifacts]
-    permissions:
-      # Used to push a commit to builds/facebook-fbsource
-      contents: write
-    if: inputs.force == true || (github.ref == 'refs/heads/main' && needs.process_artifacts.outputs.fbsource_branch_count == '0')
+    needs: download_artifacts
+    if: ${{ (github.ref == 'refs/heads/main' && needs.download_artifacts.outputs.fbsource_branch_count == '0') || github.ref == 'refs/heads/meta-fbsource' }}
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
@@ -303,22 +313,21 @@ jobs:
           ref: builds/facebook-fbsource
       - name: Ensure clean directory
         run: rm -rf compiled-rn
-      - uses: actions/download-artifact@v4
+      - uses: actions/download-artifact@v3
         with:
           name: compiled-rn
           path: compiled-rn/
       - name: Revert version changes
-        if: needs.process_artifacts.outputs.last_version_rn != ''
+        if: needs.download_artifacts.outputs.last_version_rn != ''
         env:
-          CURRENT_VERSION: ${{ needs.process_artifacts.outputs.current_version_rn }}
-          LAST_VERSION: ${{ needs.process_artifacts.outputs.last_version_rn }}
+          CURRENT_VERSION: ${{ needs.download_artifacts.outputs.current_version_rn }}
+          LAST_VERSION: ${{ needs.download_artifacts.outputs.last_version_rn }}
         run: |
           echo "Reverting $CURRENT_VERSION to $LAST_VERSION"
           grep -rl "$CURRENT_VERSION" ./compiled-rn || echo "No files found with $CURRENT_VERSION"
           grep -rl "$CURRENT_VERSION" ./compiled-rn | xargs -r sed -i -e "s/$CURRENT_VERSION/$LAST_VERSION/g"
           grep -rl "$CURRENT_VERSION" ./compiled-rn || echo "Version reverted"
       - name: Check for changes
-        if: inputs.force != 'true'
         id: check_should_commit
         run: |
           echo "Full git status"
@@ -337,23 +346,23 @@ jobs:
             echo "should_commit=false" >> "$GITHUB_OUTPUT"
           fi
       - name: Re-apply version changes
-        if: inputs.force == true || (steps.check_should_commit.outputs.should_commit == 'true' && needs.process_artifacts.outputs.last_version_rn != '')
+        if: steps.check_should_commit.outputs.should_commit == 'true' && needs.download_artifacts.outputs.last_version_rn != ''
         env:
-          CURRENT_VERSION: ${{ needs.process_artifacts.outputs.current_version_rn }}
-          LAST_VERSION: ${{ needs.process_artifacts.outputs.last_version_rn }}
+          CURRENT_VERSION: ${{ needs.download_artifacts.outputs.current_version_rn }}
+          LAST_VERSION: ${{ needs.download_artifacts.outputs.last_version_rn }}
         run: |
           echo "Re-applying $LAST_VERSION to $CURRENT_VERSION"
           grep -rl "$LAST_VERSION" ./compiled-rn || echo "No files found with $LAST_VERSION"
           grep -rl "$LAST_VERSION" ./compiled-rn | xargs -r sed -i -e "s/$LAST_VERSION/$CURRENT_VERSION/g"
           grep -rl "$LAST_VERSION" ./compiled-rn || echo "Version re-applied"
       - name: Add files for signing
-        if: inputs.force == true || steps.check_should_commit.outputs.should_commit == 'true'
+        if: steps.check_should_commit.outputs.should_commit == 'true'
         run: |
           echo ":"
           git add .
       - name: Signing files
-        if: inputs.force == true || steps.check_should_commit.outputs.should_commit == 'true'
-        uses: actions/github-script@v7
+        if: steps.check_should_commit.outputs.should_commit == 'true'
+        uses: actions/github-script@v6
         with:
           script: |
             // TODO: Move this to a script file.
@@ -406,9 +415,8 @@ jobs:
             console.log('Signing files in directory:', directory);
             try {
               const result = execSync(`git status --porcelain ${directory}`, {encoding: 'utf8'});
-              console.log(result);
 
-              // Parse the git status output to get file paths!
+              // Parse the git status output to get file paths
               const files = result.split('\n').filter(file => file.endsWith('.js'));
 
               if (files.length === 0) {
@@ -417,14 +425,7 @@ jobs:
                 );
               } else {
                 files.forEach(line => {
-                  let file = null;
-                  if (line.startsWith('D ')) {
-                    return;
-                  } else if (line.startsWith('R ')) {
-                    file = line.slice(line.indexOf('->') + 3);
-                  } else {
-                    file = line.slice(3).trim();
-                  }
+                  const file = line.slice(3).trim();
                   if (file) {
                     console.log('  Signing file:', file);
                     const originalContents = fs.readFileSync(file, 'utf8');
@@ -443,23 +444,19 @@ jobs:
               console.error('Error signing files:', e);
             }
       - name: Will commit these changes
-        if: inputs.force == true || steps.check_should_commit.outputs.should_commit == 'true'
+        if: steps.check_should_commit.outputs.should_commit == 'true'
         run: |
           git add .
           git status
-      - name: Check commit message
-        if: inputs.dry_run
-        run: |
-          git fetch origin --quiet
-          git show ${{ inputs.commit_sha || github.event.workflow_run.head_sha || github.sha }} --no-patch --pretty=format:"%B"
       - name: Commit changes to branch
-        if: inputs.force == true || steps.check_should_commit.outputs.should_commit == 'true'
-        run: |
-          git config --global user.email "${{ format('{0}@users.noreply.github.com', github.triggering_actor) }}"
-          git config --global user.name "${{ github.triggering_actor }}"
+        if: steps.check_should_commit.outputs.should_commit == 'true'
+        uses: stefanzweifel/git-auto-commit-action@v4
+        with:
+          commit_message: |
+            ${{ github.event.head_commit.message }}
 
-          git fetch origin --quiet
-          git commit -m "$(git show ${{ inputs.commit_sha || github.event.workflow_run.head_sha || github.sha }} --no-patch --pretty=format:'%B%n%nDiffTrain build for [${{ inputs.commit_sha || github.event.workflow_run.head_sha || github.sha }}](https://github.com/facebook/react/commit/${{ inputs.commit_sha || github.event.workflow_run.head_sha || github.sha}})')" || echo "No changes to commit"
-      - name: Push changes to branch
-        if: inputs.dry_run == false && (inputs.force == true || steps.check_should_commit.outputs.should_commit == 'true')
-        run: git push
+            DiffTrain build for commit https://github.com/facebook/react/commit/${{ github.sha }}.
+          branch: builds/facebook-fbsource
+          commit_user_name: ${{ github.actor }}
+          commit_user_email: ${{ github.actor }}@users.noreply.github.com
+          create_branch: true

.github/workflows/runtime_discord_notify.yml

@@ -1,35 +0,0 @@
-name: (Runtime) Discord Notify
-
-on:
-  pull_request:
-    types: [opened, ready_for_review]
-    paths-ignore:
-      - compiler/**
-      - .github/workflows/compiler_**.yml
-
-permissions: {}
-
-jobs:
-  check_maintainer:
-    uses: facebook/react/.github/workflows/shared_check_maintainer.yml@main
-    permissions:
-      # Used by check_maintainer
-      contents: read
-    with:
-      actor: ${{ github.event.pull_request.user.login }}
-
-  notify:
-    if: ${{ needs.check_maintainer.outputs.is_core_team == 'true' }}
-    needs: check_maintainer
-    runs-on: ubuntu-latest
-    steps:
-      - name: Discord Webhook Action
-        uses: tsickert/discord-webhook@86dc739f3f165f16dadc5666051c367efa1692f4
-        with:
-          webhook-url: ${{ secrets.DISCORD_WEBHOOK_URL }}
-          embed-author-name: ${{ github.event.pull_request.user.login }}
-          embed-author-url: ${{ github.event.pull_request.user.html_url }}
-          embed-author-icon-url: ${{ github.event.pull_request.user.avatar_url }}
-          embed-title: '#${{ github.event.number }} (+${{github.event.pull_request.additions}} -${{github.event.pull_request.deletions}}): ${{ github.event.pull_request.title }}'
-          embed-description: ${{ github.event.pull_request.body }}
-          embed-url: ${{ github.event.pull_request.html_url }}

.github/workflows/runtime_eslint_plugin_e2e.yml

@@ -1,62 +0,0 @@
-name: (Runtime) ESLint Plugin E2E
-
-on:
-  push:
-    branches: [main]
-  pull_request:
-    paths-ignore:
-      - compiler/**
-
-permissions: {}
-
-concurrency:
-  group: ${{ github.workflow }}-${{ github.ref_name }}-${{ github.event.pull_request.number || github.run_id }}
-  cancel-in-progress: true
-
-env:
-  TZ: /usr/share/zoneinfo/America/Los_Angeles
-
-jobs:
-  # ----- TESTS -----
-  test:
-    name: ESLint v${{ matrix.eslint_major }}
-    runs-on: ubuntu-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        eslint_major:
-          - "6"
-          - "7"
-          - "8"
-          - "9"
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          ref: ${{ github.event.pull_request.head.sha || github.sha }}
-      - uses: actions/setup-node@v4
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: |
-            yarn.lock
-            compiler/yarn.lock
-      - name: Restore cached node_modules
-        uses: actions/cache@v4
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: runtime-and-compiler-eslint_e2e-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'compiler/yarn.lock') }}
-      - name: Ensure clean build directory
-        run: rm -rf build
-      - run: yarn install --frozen-lockfile
-      - run: yarn --cwd compiler install --frozen-lockfile
-      - name: Build plugin
-        working-directory: fixtures/eslint-v${{ matrix.eslint_major }}
-        run: node build.mjs
-      - name: Install fixture dependencies
-        working-directory: ./fixtures/eslint-v${{ matrix.eslint_major }}
-        run: yarn --frozen-lockfile
-      - name: Run lint test
-        working-directory: ./fixtures/eslint-v${{ matrix.eslint_major }}
-        run: yarn lint

.github/workflows/runtime_fizz.yml

@@ -0,0 +1,30 @@
+name: (Runtime) Fizz
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    paths-ignore:
+      - 'compiler/**'
+
+jobs:
+  check_generated_fizz_runtime:
+    name: Confirm generated inline Fizz runtime is up to date
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 18.x
+          cache: "yarn"
+          cache-dependency-path: yarn.lock
+      - name: Restore cached node_modules
+        uses: actions/cache@v4
+        id: node_modules
+        with:
+          path: "**/node_modules"
+          key: ${{ runner.arch }}-${{ runner.os }}-modules-${{ hashFiles('yarn.lock') }}
+      - run: yarn install --frozen-lockfile
+      - run: |
+          yarn generate-inline-fizz-runtime
+          git diff --quiet || (echo "There was a change to the Fizz runtime. Run `yarn generate-inline-fizz-runtime` and check in the result." && false)

.github/workflows/runtime_flags.yml

@@ -0,0 +1,28 @@
+name: (Runtime) Flags
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    paths-ignore:
+      - 'compiler/**'
+
+jobs:
+  flags:
+    name: Check flags
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 18.x
+          cache: "yarn"
+          cache-dependency-path: yarn.lock
+      - name: Restore cached node_modules
+        uses: actions/cache@v4
+        id: node_modules
+        with:
+          path: "**/node_modules"
+          key: ${{ runner.arch }}-${{ runner.os }}-modules-${{ hashFiles('yarn.lock') }}
+      - run: yarn install --frozen-lockfile
+      - run: yarn flags

.github/workflows/runtime_flow.yml

@@ -0,0 +1,47 @@
+name: (Runtime) Flow
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    paths-ignore:
+      - 'compiler/**'
+
+jobs:
+  discover_flow_inline_configs:
+    name: Discover flow inline configs
+    runs-on: ubuntu-latest
+    outputs:
+      matrix: ${{ steps.set-matrix.outputs.result }}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/github-script@v7
+        id: set-matrix
+        with:
+          script: |
+            const inlinedHostConfigs = require('./scripts/shared/inlinedHostConfigs.js');
+            return inlinedHostConfigs.map(config => config.shortName);
+
+  flow:
+    name: Flow check ${{ matrix.flow_inline_config_shortname }}
+    needs: discover_flow_inline_configs
+    runs-on: ubuntu-latest
+    continue-on-error: true
+    strategy:
+      matrix:
+        flow_inline_config_shortname: ${{ fromJSON(needs.discover_flow_inline_configs.outputs.matrix) }}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 18.x
+          cache: "yarn"
+          cache-dependency-path: yarn.lock
+      - name: Restore cached node_modules
+        uses: actions/cache@v4
+        id: node_modules
+        with:
+          path: "**/node_modules"
+          key: ${{ runner.arch }}-${{ runner.os }}-modules-${{ hashFiles('yarn.lock') }}
+      - run: yarn install --frozen-lockfile
+      - run: node ./scripts/tasks/flow-ci ${{ matrix.flow_inline_config_shortname }}

.github/workflows/runtime_fuzz_tests.yml

@@ -1,21 +1,20 @@
 name: (Runtime) Fuzz tests
-
 on:
   schedule:
-    - cron: 0 * * * *
+  - cron: 0 * * * *
   push:
     branches:
       - main
   workflow_dispatch:
-
-permissions: {}
-
-env:
-  TZ: /usr/share/zoneinfo/America/Los_Angeles
-
+    inputs:
+      prerelease_commit_sha:
+        required: false
 jobs:
   test_fuzz:
+    if: inputs.prerelease_commit_sha == ''
     runs-on: ubuntu-latest
+    env:
+      TZ: "/usr/share/zoneinfo/America/Los_Angeles"
     steps:
     - uses: actions/checkout@v4.1.0
     - uses: actions/setup-node@v4
@@ -29,5 +28,5 @@ jobs:
       shell: bash
     - name: Run fuzz tests
       run: |-
-        FUZZ_TEST_SEED=$RANDOM yarn test fuzz --ci
-        FUZZ_TEST_SEED=$RANDOM yarn test --prod fuzz --ci
+        FUZZ_TEST_SEED=$RANDOM yarn test fuzz --ci=github
+        FUZZ_TEST_SEED=$RANDOM yarn test --prod fuzz --ci=github

.github/workflows/runtime_prereleases.yml

@@ -1,53 +0,0 @@
-name: (Runtime) Publish Prereleases
-
-on:
-  workflow_call:
-    inputs:
-      commit_sha:
-        required: true
-        default: ''
-        type: string
-      release_channel:
-        required: true
-        type: string
-      dist_tag:
-        required: true
-        type: string
-    secrets:
-      NPM_TOKEN:
-        required: true
-
-permissions: {}
-
-env:
-  TZ: /usr/share/zoneinfo/America/Los_Angeles
-  # https://github.com/actions/cache/blob/main/tips-and-workarounds.md#cache-segment-restore-timeout
-  SEGMENT_DOWNLOAD_TIMEOUT_MINS: 1
-  NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
-
-jobs:
-  publish_prerelease:
-    name: Publish prelease (${{ inputs.release_channel }}) ${{ inputs.commit_sha }} @${{ inputs.dist_tag }}
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-node@v4
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: yarn.lock
-      - name: Restore cached node_modules
-        uses: actions/cache@v4
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: runtime-release-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'scripts/release/yarn.lock') }}
-      - name: Ensure clean build directory
-        run: rm -rf build
-      - run: yarn install --frozen-lockfile
-      - run: yarn --cwd scripts/release install --frozen-lockfile
-      - run: |
-          scripts/release/prepare-release-from-ci.js --skipTests -r ${{ inputs.release_channel }} --commit=${{ inputs.commit_sha }}
-          cp ./scripts/release/ci-npmrc ~/.npmrc
-          scripts/release/publish.js --ci --tags ${{ inputs.dist_tag }}

.github/workflows/runtime_prereleases_manual.yml

@@ -1,49 +0,0 @@
-name: (Runtime) Publish Prereleases Manual
-
-on:
-  workflow_dispatch:
-    inputs:
-      prerelease_commit_sha:
-        required: true
-
-permissions: {}
-
-env:
-  TZ: /usr/share/zoneinfo/America/Los_Angeles
-
-jobs:
-
-  publish_prerelease_canary:
-    name: Publish to Canary channel
-    uses: facebook/react/.github/workflows/runtime_prereleases.yml@main
-    with:
-      commit_sha: ${{ inputs.prerelease_commit_sha }}
-      release_channel: stable
-      # The tags to use when publishing canaries. The main one we should
-      # always include is "canary" but we can use multiple (e.g. alpha,
-      # beta, rc). To declare multiple, use a comma-separated string, like
-      # this:
-      #   dist_tag: "canary,alpha,beta,rc"
-      #
-      # TODO: We currently tag canaries with "next" in addition to "canary"
-      # because this used to be called the "next" channel and some
-      # downstream consumers might still expect that tag. We can remove this
-      # after some time has elapsed and the change has been communicated.
-      dist_tag: canary,next
-    secrets:
-      NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
-
-  publish_prerelease_experimental:
-    name: Publish to Experimental channel
-    uses: facebook/react/.github/workflows/runtime_prereleases.yml@main
-    # NOTE: Intentionally running these jobs sequentially because npm
-    # will sometimes fail if you try to concurrently publish two
-    # different versions of the same package, even if they use different
-    # dist tags.
-    needs: publish_prerelease_canary
-    with:
-      commit_sha: ${{ inputs.prerelease_commit_sha }}
-      release_channel: experimental
-      dist_tag: experimental
-    secrets:
-      NPM_TOKEN: ${{ secrets.NPM_TOKEN }}

.github/workflows/runtime_prereleases_nightly.yml

@@ -1,37 +0,0 @@
-name: (Runtime) Publish Prereleases Nightly
-
-on:
-  schedule:
-    # At 10 minutes past 16:00 on Mon, Tue, Wed, Thu, and Fri
-    - cron: 10 16 * * 1,2,3,4,5
-
-permissions: {}
-
-env:
-  TZ: /usr/share/zoneinfo/America/Los_Angeles
-
-jobs:
-  publish_prerelease_canary:
-    name: Publish to Canary channel
-    uses: facebook/react/.github/workflows/runtime_prereleases.yml@main
-    with:
-      commit_sha: ${{ github.sha }}
-      release_channel: stable
-      dist_tag: canary,next
-    secrets:
-      NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
-
-  publish_prerelease_experimental:
-    name: Publish to Experimental channel
-    uses: facebook/react/.github/workflows/runtime_prereleases.yml@main
-    # NOTE: Intentionally running these jobs sequentially because npm
-    # will sometimes fail if you try to concurrently publish two
-    # different versions of the same package, even if they use different
-    # dist tags.
-    needs: publish_prerelease_canary
-    with:
-      commit_sha: ${{ github.sha }}
-      release_channel: experimental
-      dist_tag: experimental
-    secrets:
-      NPM_TOKEN: ${{ secrets.NPM_TOKEN }}

.github/workflows/runtime_releases_from_npm_manual.yml

@@ -1,126 +0,0 @@
-name: (Runtime) Publish Releases from NPM Manual
-
-on:
-  workflow_dispatch:
-    inputs:
-      version_to_promote:
-        required: true
-        description: Current npm version (non-experimental) to promote
-        type: string
-      version_to_publish:
-        required: true
-        description: Version to publish for the specified packages
-        type: string
-      only_packages:
-        description: Packages to publish (space separated)
-        type: string
-      skip_packages:
-        description: Packages to NOT publish (space separated)
-        type: string
-      tags:
-        description: NPM tags (space separated)
-        type: string
-        default: untagged
-      dry:
-        required: true
-        description: Dry run instead of publish?
-        type: boolean
-        default: true
-      force_notify:
-        description: Force a Discord notification?
-        type: boolean
-        default: false
-
-permissions: {}
-
-env:
-  TZ: /usr/share/zoneinfo/America/Los_Angeles
-  # https://github.com/actions/cache/blob/main/tips-and-workarounds.md#cache-segment-restore-timeout
-  SEGMENT_DOWNLOAD_TIMEOUT_MINS: 1
-  NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
-
-jobs:
-  notify:
-    if: ${{ inputs.force_notify || inputs.dry == false || inputs.dry == 'false' }}
-    runs-on: ubuntu-latest
-    steps:
-      - name: Discord Webhook Action
-        uses: tsickert/discord-webhook@86dc739f3f165f16dadc5666051c367efa1692f4
-        with:
-          webhook-url: ${{ secrets.DISCORD_WEBHOOK_URL }}
-          embed-author-name: ${{ github.event.sender.login }}
-          embed-author-url: ${{ github.event.sender.html_url }}
-          embed-author-icon-url: ${{ github.event.sender.avatar_url }}
-          embed-title: "⚠️ Publishing release from NPM${{ (inputs.dry && ' (dry run)') || '' }}"
-          embed-description: |
-            ```json
-            ${{ toJson(inputs) }}
-            ```
-          embed-url: https://github.com/facebook/react/actions/runs/${{ github.run_id }}
-
-  publish:
-    name: Publish releases
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-node@v4
-        with:
-          node-version-file: '.nvmrc'
-          cache: yarn
-          cache-dependency-path: yarn.lock
-      - name: Restore cached node_modules
-        uses: actions/cache@v4
-        id: node_modules
-        with:
-          path: |
-            **/node_modules
-          key: runtime-release-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('yarn.lock', 'scripts/release/yarn.lock') }}
-      - name: Ensure clean build directory
-        run: rm -rf build
-      - run: yarn install --frozen-lockfile
-      - run: yarn --cwd scripts/release install --frozen-lockfile
-      - run: cp ./scripts/release/ci-npmrc ~/.npmrc
-      - if: '${{ inputs.only_packages }}'
-        name: 'Prepare ${{ inputs.only_packages }} from NPM'
-        run: |
-          scripts/release/prepare-release-from-npm.js \
-            --ci \
-            --skipTests \
-            --version=${{ inputs.version_to_promote }} \
-            --publishVersion=${{ inputs.version_to_publish }} \
-            --onlyPackages=${{ inputs.only_packages }}
-      - if: '${{ inputs.skip_packages }}'
-        name: 'Prepare all packages EXCEPT ${{ inputs.skip_packages }} from NPM'
-        run: |
-          scripts/release/prepare-release-from-npm.js \
-            --ci \
-            --skipTests \
-            --version=${{ inputs.version_to_promote }} \
-            --publishVersion=${{ inputs.version_to_publish }} \
-            --skipPackages=${{ inputs.skip_packages }}
-      - name: Check prepared files
-        run: ls -R build/node_modules
-      - if: '${{ inputs.only_packages }}'
-        name: 'Publish ${{ inputs.only_packages }}'
-        run: |
-          scripts/release/publish.js \
-            --ci \
-            --tags=${{ inputs.tags }} \
-            --publishVersion=${{ inputs.version_to_publish }} \
-            --onlyPackages=${{ inputs.only_packages }} ${{ (inputs.dry && '') || '\'}}
-            ${{ inputs.dry && '--dry'}}
-      - if: '${{ inputs.skip_packages }}'
-        name: 'Publish all packages EXCEPT ${{ inputs.skip_packages }}'
-        run: |
-          scripts/release/publish.js \
-            --ci \
-            --tags=${{ inputs.tags }} \
-            --publishVersion=${{ inputs.version_to_publish }} \
-            --skipPackages=${{ inputs.skip_packages }} ${{ (inputs.dry && '') || '\'}}
-            ${{ inputs.dry && '--dry'}}
-      - name: Archive released package for debugging
-        uses: actions/upload-artifact@v4
-        with:
-          name: build
-          path: |
-            ./build/node_modules

.github/workflows/runtime_test.yml

@@ -0,0 +1,85 @@
+name: (Runtime) Test
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    paths-ignore:
+      - 'compiler/**'
+
+env:
+  # Number of workers (one per shard) to spawn
+  SHARD_COUNT: 5
+
+jobs:
+  # Define the various test parameters and parallelism for this workflow
+  build_test_params:
+    name: Build test params
+    runs-on: ubuntu-latest
+    outputs:
+      params: ${{ steps.define-params.outputs.result }}
+      shard_id: ${{ steps.define-shards.outputs.result }}
+    steps:
+      - uses: actions/github-script@v7
+        id: define-shards
+        with:
+          script: |
+            function range(from, to) {
+              const arr = [];
+              for (let n = from; n <= to; n++) {
+                arr.push(n);
+              }
+              return arr;
+            }
+            return range(1, process.env.SHARD_COUNT);
+      - uses: actions/github-script@v7
+        id: define-params
+        with:
+          script: |
+            return [
+              "-r=stable --env=development",
+              "-r=stable --env=production",
+              "-r=experimental --env=development",
+              "-r=experimental --env=production",
+              "-r=www-classic --env=development --variant=false",
+              "-r=www-classic --env=production --variant=false",
+              "-r=www-classic --env=development --variant=true",
+              "-r=www-classic --env=production --variant=true",
+              "-r=www-modern --env=development --variant=false",
+              "-r=www-modern --env=production --variant=false",
+              "-r=www-modern --env=development --variant=true",
+              "-r=www-modern --env=production --variant=true",
+              "-r=xplat --env=development --variant=false",
+              "-r=xplat --env=development --variant=true",
+              "-r=xplat --env=production --variant=false",
+              "-r=xplat --env=production --variant=true",
+              // TODO: Test more persistent configurations?
+              "-r=stable --env=development --persistent",
+              "-r=experimental --env=development --persistent"
+            ];
+
+  # Spawn a job for each shard for a given set of test params
+  test:
+    name: yarn test ${{ matrix.params }} (Shard ${{ matrix.shard_id }})
+    runs-on: ubuntu-latest
+    needs: build_test_params
+    strategy:
+      matrix:
+        params: ${{ fromJSON(needs.build_test_params.outputs.params) }}
+        shard_id: ${{ fromJSON(needs.build_test_params.outputs.shard_id) }}
+    continue-on-error: true
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 18.x
+          cache: "yarn"
+          cache-dependency-path: yarn.lock
+      - name: Restore cached node_modules
+        uses: actions/cache@v4
+        id: node_modules
+        with:
+          path: "**/node_modules"
+          key: ${{ runner.arch }}-${{ runner.os }}-modules-${{ hashFiles('yarn.lock') }}
+      - run: yarn install --frozen-lockfile
+      - run: yarn test ${{ matrix.params }} --ci=github --shard=${{ matrix.shard_id }}/${{ env.SHARD_COUNT }}

.github/workflows/shared_check_maintainer.yml

@@ -1,76 +0,0 @@
-name: (Shared) Check maintainer
-
-on:
-  workflow_call:
-    inputs:
-      actor:
-        required: true
-        type: string
-      is_remote:
-        required: false
-        type: boolean
-        default: false
-    outputs:
-      is_core_team:
-        value: ${{ jobs.check_maintainer.outputs.is_core_team }}
-
-permissions: {}
-
-env:
-  TZ: /usr/share/zoneinfo/America/Los_Angeles
-  # https://github.com/actions/cache/blob/main/tips-and-workarounds.md#cache-segment-restore-timeout
-  SEGMENT_DOWNLOAD_TIMEOUT_MINS: 1
-
-jobs:
-  check_maintainer:
-    runs-on: ubuntu-latest
-    permissions:
-      # We fetch the contents of the MAINTAINERS file
-      contents: read
-    outputs:
-      is_core_team: ${{ steps.check_if_actor_is_maintainer.outputs.result }}
-    steps:
-      - uses: actions/checkout@v4
-      - name: Check if actor is maintainer
-        id: check_if_actor_is_maintainer
-        uses: actions/github-script@v7
-        with:
-          script: |
-            const fs = require('fs');
-            const actor = '${{ inputs.actor }}';
-            let isRemote = ${{ inputs.is_remote }};
-            if (typeof isRemote === 'string') {
-              isRemote = isRemote === 'true';
-            }
-            if (typeof isRemote !== 'boolean') {
-              throw new Error(`Invalid \`isRemote\` input. Expected a boolean, got: ${isRemote}`);
-            }
-
-            let content = null;
-            if (isRemote === true) {
-              const res = await github.rest.repos.getContent({
-                owner: 'facebook',
-                repo: 'react',
-                path: 'MAINTAINERS',
-                ref: 'main',
-                headers: { Accept: 'application/vnd.github+json' }
-              });
-              if (res.status !== 200) {
-                console.error(res);
-                throw new Error('Unable to fetch MAINTAINERS file');
-              }
-              content = Buffer.from(res.data.content, 'base64').toString();
-            } else {
-              content = await fs.readFileSync('./MAINTAINERS', { encoding: 'utf8' });
-            }
-            if (content === null) {
-              throw new Error('Unable to retrieve local or http MAINTAINERS file');
-            }
-
-            const maintainers = new Set(content.split('\n'));
-            if (maintainers.has(actor)) {
-              console.log(`🟢 ${actor} is a maintainer`);
-              return true;
-            }
-            console.log(`🔴 ${actor} is NOT a maintainer`);
-            return null;

.github/workflows/shared_cleanup_merged_branch_caches.yml

@@ -1,41 +0,0 @@
-# https://github.com/actions/cache/blob/main/tips-and-workarounds.md#force-deletion-of-caches-overriding-default-cache-eviction-policy
-
-name: (Shared) Cleanup Merged Branch Caches
-on:
-  pull_request:
-    types:
-      - closed
-  workflow_dispatch:
-    inputs:
-      pr_number:
-        required: true
-        type: string
-
-permissions: {}
-
-jobs:
-  cleanup:
-    runs-on: ubuntu-latest
-    permissions:
-      # `actions:write` permission is required to delete caches
-      #   See also: https://docs.github.com/en/rest/actions/cache?apiVersion=2022-11-28#delete-a-github-actions-cache-for-a-repository-using-a-cache-id
-      actions: write
-      contents: read
-    steps:
-      - name: Cleanup
-        run: |
-          echo "Fetching list of cache key"
-          cacheKeysForPR=$(gh cache list --ref $BRANCH --limit 100 --json id --jq '.[].id')
-
-          ## Setting this to not fail the workflow while deleting cache keys.
-          set +e
-          for cacheKey in $cacheKeysForPR
-          do
-              gh cache delete $cacheKey
-              echo "Deleting $cacheKey"
-          done
-          echo "Done"
-        env:
-          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-          GH_REPO: ${{ github.repository }}
-          BRANCH: refs/pull/${{ inputs.pr_number || github.event.pull_request.number }}/merge

.github/workflows/shared_cleanup_stale_branch_caches.yml

@@ -1,35 +0,0 @@
-# https://github.com/actions/cache/blob/main/tips-and-workarounds.md#force-deletion-of-caches-overriding-default-cache-eviction-policy
-
-name: (Shared) Cleanup Stale Branch Caches
-on:
-  schedule:
-    - cron: 0 0 * * *
-  workflow_dispatch:
-
-permissions: {}
-
-jobs:
-  cleanup:
-    runs-on: ubuntu-latest
-    permissions:
-      # `actions:write` permission is required to delete caches
-      #   See also: https://docs.github.com/en/rest/actions/cache?apiVersion=2022-11-28#delete-a-github-actions-cache-for-a-repository-using-a-cache-id
-      actions: write
-      contents: read
-    steps:
-      - name: Cleanup
-        run: |
-          echo "Fetching list of cache keys"
-          cacheKeysForPR=$(gh cache list --limit 100 --json id,ref --jq '.[] | select(.ref != "refs/heads/main") | .id')
-
-          ## Setting this to not fail the workflow while deleting cache keys.
-          set +e
-          for cacheKey in $cacheKeysForPR
-          do
-              gh cache delete $cacheKey
-              echo "Deleting $cacheKey"
-          done
-          echo "Done"
-        env:
-          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-          GH_REPO: ${{ github.repository }}

.github/workflows/shared_close_direct_sync_branch_prs.yml

@@ -1,42 +0,0 @@
-name: (Shared) Close Direct Sync Branch PRs
-
-on:
-  pull_request:
-    branches:
-      - 'builds/facebook-**'
-
-permissions: {}
-
-env:
-  TZ: /usr/share/zoneinfo/America/Los_Angeles
-  # https://github.com/actions/cache/blob/main/tips-and-workarounds.md#cache-segment-restore-timeout
-  SEGMENT_DOWNLOAD_TIMEOUT_MINS: 1
-
-jobs:
-  close_pr:
-    runs-on: ubuntu-latest
-    permissions:
-      # Used to create a review and close PRs
-      pull-requests: write
-    steps:
-      - name: Close PR
-        uses: actions/github-script@v7
-        with:
-          script: |
-            const owner = context.repo.owner;
-            const repo = context.repo.repo;
-            const pullNumber = ${{ github.event.number }};
-
-            await github.rest.pulls.createReview({
-              owner,
-              repo,
-              pull_number: pullNumber,
-              body: 'Do not land changes to `${{ github.event.pull_request.base.ref }}`. Please re-open your PR targeting `main` instead.',
-              event: 'REQUEST_CHANGES'
-            });
-            await github.rest.pulls.update({
-              owner,
-              repo,
-              pull_number: pullNumber,
-              state: 'closed'
-            });

.github/workflows/shared_label_core_team_prs.yml

@@ -1,41 +0,0 @@
-name: (Shared) Label Core Team PRs
-
-on:
-  pull_request:
-
-permissions: {}
-
-env:
-  TZ: /usr/share/zoneinfo/America/Los_Angeles
-  # https://github.com/actions/cache/blob/main/tips-and-workarounds.md#cache-segment-restore-timeout
-  SEGMENT_DOWNLOAD_TIMEOUT_MINS: 1
-
-jobs:
-  check_maintainer:
-    uses: facebook/react/.github/workflows/shared_check_maintainer.yml@main
-    permissions:
-      # Used by check_maintainer
-      contents: read
-    with:
-      actor: ${{ github.event.pull_request.user.login }}
-
-  label:
-    if: ${{ needs.check_maintainer.outputs.is_core_team == 'true' }}
-    runs-on: ubuntu-latest
-    needs: check_maintainer
-    permissions:
-      # Used to add labels on issues
-      issues: write
-      # Used to add labels on PRs
-      pull-requests: write
-    steps:
-      - name: Label PR as React Core Team
-        uses: actions/github-script@v7
-        with:
-          script: |
-            github.rest.issues.addLabels({
-              owner: context.repo.owner,
-              repo: context.repo.repo,
-              issue_number: ${{ github.event.number }},
-              labels: ['React Core Team']
-            });

.github/workflows/shared_lint.yml

@@ -5,17 +5,6 @@ on:
     branches: [main]
   pull_request:
 
-permissions: {}
-
-concurrency:
-  group: ${{ github.workflow }}-${{ github.ref_name }}-${{ github.event.pull_request.number || github.run_id }}
-  cancel-in-progress: true
-
-env:
-  TZ: /usr/share/zoneinfo/America/Los_Angeles
-  # https://github.com/actions/cache/blob/main/tips-and-workarounds.md#cache-segment-restore-timeout
-  SEGMENT_DOWNLOAD_TIMEOUT_MINS: 1
-
 jobs:
   prettier:
     name: Run prettier
@@ -24,17 +13,14 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version-file: '.nvmrc'
-          cache: yarn
+          node-version: 18.x
+          cache: "yarn"
           cache-dependency-path: yarn.lock
       - name: Restore cached node_modules
         uses: actions/cache@v4
         with:
-          path: |
-            **/node_modules
-          key: shared-lint-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('**/yarn.lock') }}
-      - name: Ensure clean build directory
-        run: rm -rf build
+          path: "**/node_modules"
+          key: ${{ runner.arch }}-${{ runner.os }}-modules-${{ hashFiles('**/yarn.lock') }}
       - run: yarn install --frozen-lockfile
       - run: yarn prettier-check
 
@@ -45,17 +31,14 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version-file: '.nvmrc'
-          cache: yarn
+          node-version: 18.x
+          cache: "yarn"
           cache-dependency-path: yarn.lock
       - name: Restore cached node_modules
         uses: actions/cache@v4
         with:
-          path: |
-            **/node_modules
-          key: shared-lint-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('**/yarn.lock') }}
-      - name: Ensure clean build directory
-        run: rm -rf build
+          path: "**/node_modules"
+          key: ${{ runner.arch }}-${{ runner.os }}-modules-${{ hashFiles('yarn.lock') }}
       - run: yarn install --frozen-lockfile
       - run: node ./scripts/tasks/eslint
 
@@ -66,19 +49,16 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version-file: '.nvmrc'
-          cache: yarn
+          node-version: 18.x
+          cache: "yarn"
           cache-dependency-path: yarn.lock
       - name: Restore cached node_modules
         uses: actions/cache@v4
         with:
-          path: |
-            **/node_modules
-          key: shared-lint-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('**/yarn.lock') }}
-      - name: Ensure clean build directory
-        run: rm -rf build
+          path: "**/node_modules"
+          key: ${{ runner.arch }}-${{ runner.os }}-modules-${{ hashFiles('yarn.lock') }}
       - run: yarn install --frozen-lockfile
-      - run: ./scripts/ci/check_license.sh
+      - run: ./scripts/circleci/check_license.sh
 
   test_print_warnings:
     name: Test print warnings
@@ -87,16 +67,13 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version-file: '.nvmrc'
-          cache: yarn
+          node-version: 18.x
+          cache: "yarn"
           cache-dependency-path: yarn.lock
       - name: Restore cached node_modules
         uses: actions/cache@v4
         with:
-          path: |
-            **/node_modules
-          key: shared-lint-node_modules-v6-${{ runner.arch }}-${{ runner.os }}-${{ hashFiles('**/yarn.lock') }}
-      - name: Ensure clean build directory
-        run: rm -rf build
+          path: "**/node_modules"
+          key: ${{ runner.arch }}-${{ runner.os }}-modules-${{ hashFiles('yarn.lock') }}
       - run: yarn install --frozen-lockfile
-      - run: ./scripts/ci/test_print_warnings.sh
+      - run: ./scripts/circleci/test_print_warnings.sh

.github/workflows/shared_stale.yml

@@ -4,12 +4,6 @@ on:
   schedule:
     # Run hourly
     - cron: '0 * * * *'
-  workflow_dispatch:
-
-permissions: {}
-
-env:
-  TZ: /usr/share/zoneinfo/America/Los_Angeles
 
 jobs:
   stale:

.gitignore

@@ -37,4 +37,3 @@ packages/react-devtools-fusebox/dist
 packages/react-devtools-inline/dist
 packages/react-devtools-shell/dist
 packages/react-devtools-timeline/dist
-

.nvmrc

@@ -1 +1 @@
-v18.20.1
+v18.20.0

.prettierignore

@@ -18,16 +18,14 @@ packages/react-devtools-timeline/static
 # react compiler
 compiler/**/dist
 compiler/**/__tests__/fixtures/**/*.expect.md
+compiler/**/__tests__/fixtures/**/*.flow.js
 compiler/**/.next
 
-# contains invalid graphql`...` which results in a promise rejection error from `yarn prettier-all`.
-compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.todo-kitchensink.js
-
 compiler/crates
-compiler/target
 compiler/apps/playground/public
 
 compiler/**/LICENSE
+compiler/.*
 compiler/*.md*
 compiler/*.json
 compiler/*.css

.prettierrc.js

@@ -1,15 +1,18 @@
 'use strict';
 
-const {esNextPaths} = require('./scripts/shared/pathsByLanguageVersion');
+const {
+  compilerPaths,
+  esNextPaths,
+  typescriptPaths,
+} = require('./scripts/shared/pathsByLanguageVersion');
 
 module.exports = {
-  plugins: ['prettier-plugin-hermes-parser'],
   bracketSpacing: false,
   singleQuote: true,
   bracketSameLine: true,
   trailingComma: 'es5',
   printWidth: 80,
-  parser: 'hermes',
+  parser: 'flow',
   arrowParens: 'avoid',
   overrides: [
     {
@@ -25,11 +28,25 @@ module.exports = {
       },
     },
     {
-      files: ['*.ts', '*.tsx'],
+      files: typescriptPaths,
       options: {
         trailingComma: 'all',
         parser: 'typescript',
       },
     },
+    {
+      files: compilerPaths,
+      options: {
+        requirePragma: false,
+        parser: 'babel-ts',
+        semi: true,
+        singleQuote: false,
+        trailingComma: 'es5',
+        bracketSpacing: true,
+        bracketSameLine: false,
+        printWidth: 80,
+        arrowParens: 'always',
+      },
+    },
   ],
 };

CHANGELOG.md

@@ -1,275 +1,3 @@
-## 19.0.0 (December 5, 2024)
-
-Below is a list of all new features, APIs, deprecations, and breaking changes. Read [React 19 release post](https://react.dev/blog/2024/04/25/react-19) and [React 19 upgrade guide](https://react.dev/blog/2024/04/25/react-19-upgrade-guide) for more information.
-
-> Note: To help make the upgrade to React 19 easier, we’ve published a react@18.3 release that is identical to 18.2 but adds warnings for deprecated APIs and other changes that are needed for React 19. We recommend upgrading to React 18.3.1 first to help identify any issues before upgrading to React 19.
-
-### New Features
-
-#### React
-
-* Actions: `startTransition` can now accept async functions. Functions passed to `startTransition` are called “Actions”. A given Transition can include one or more Actions which update state in the background and update the UI with one commit. In addition to updating state, Actions can now perform side effects including async requests, and the Action will wait for the work to finish before finishing the Transition. This feature allows Transitions to include side effects like `fetch()` in the pending state, and provides support for error handling, and optimistic updates.  
-* `useActionState`: is a new hook to order Actions inside of a Transition with access to the state of the action, and the pending state. It accepts a reducer that can call Actions, and the initial state used for first render. It also accepts an optional string that is used if the action is passed to a form `action` prop to support progressive enhancement in forms.  
-* `useOptimistic`: is a new hook to update state while a Transition is in progress. It returns the state, and a set function that can be called inside a transition to “optimistically” update the state to expected final value immediately while the Transition completes in the background. When the transition finishes, the state is updated to the new value.  
-* `use`: is a new API that allows reading resources in render. In React 19, `use` accepts a promise or Context. If provided a promise, `use` will suspend until a value is resolved. `use` can only be used in render but can be called conditionally.  
-* `ref` as a prop: Refs can now be used as props, removing the need for `forwardRef`.  
-* **Suspense sibling pre-warming**: When a component suspends, React will immediately commit the fallback of the nearest Suspense boundary, without waiting for the entire sibling tree to render. After the fallback commits, React will schedule another render for the suspended siblings to “pre-warm” lazy requests.
-
-#### React DOM Client
-
-* `<form> action` prop: Form Actions allow you to manage forms automatically and integrate with `useFormStatus`. When a `<form> action` succeeds, React will automatically reset the form for uncontrolled components. The form can be reset manually with the new `requestFormReset` API.  
-* `<button> and <input> formAction` prop: Actions can be passed to the `formAction` prop to configure form submission behavior. This allows using different Actions depending on the input.  
-* `useFormStatus`: is a new hook that provides the status of the parent `<form> action`, as if the form was a Context provider. The hook returns the values: `pending`, `data`, `method`, and `action`.  
-* Support for Document Metadata: We’ve added support for rendering document metadata tags in components natively. React will automatically hoist them into the `<head>` section of the document.  
-* Support for Stylesheets: React 19 will ensure stylesheets are inserted into the `<head>` on the client before revealing the content of a Suspense boundary that depends on that stylesheet.  
-* Support for async scripts: Async scripts can be rendered anywhere in the component tree and React will handle ordering and deduplication.  
-* Support for preloading resources: React 19 ships with `preinit`, `preload`, `prefetchDNS`, and `preconnect` APIs to optimize initial page loads by moving discovery of additional resources like fonts out of stylesheet loading. They can also be used to prefetch resources used by an anticipated navigation.
-
-#### React DOM Server
-
-* Added `prerender` and `prerenderToNodeStream` APIs for static site generation. They are designed to work with streaming environments like Node.js Streams and Web Streams. Unlike `renderToString`, they wait for data to load for HTML generation.
-
-#### React Server Components
-
-* RSC features such as directives, server components, and server functions are now stable. This means libraries that ship with Server Components can now target React 19 as a peer dependency with a react-server export condition for use in frameworks that support the Full-stack React Architecture. The underlying APIs used to implement a React Server Components bundler or framework do not follow semver and may break between minors in React 19.x. See [docs](https://19.react.dev/reference/rsc/server-components) for how to support React Server Components.
-
-### Deprecations
-
-* Deprecated: `element.ref` access: React 19 supports ref as a prop, so we’re deprecating `element.ref` in favor of `element.props.ref`. Accessing will result in a warning.  
-* `react-test-renderer`: In React 19, react-test-renderer logs a deprecation warning and has switched to concurrent rendering for web usage. We recommend migrating your tests to  [@testing-library/react](https://testing-library.com/docs/react-testing-library/intro/) or [@testing-library/react-native](https://testing-library.com/docs/react-native-testing-library/intro)
-
-### Breaking Changes
-
-React 19 brings in a number of breaking changes, including the removals of long-deprecated APIs. We recommend first upgrading to `18.3.1`, where we've added additional deprecation warnings. Check out the [upgrade guide](https://19.react.dev/blog/2024/04/25/react-19-upgrade-guide) for more details and guidance on codemodding.
-
-### React
-
-* New JSX Transform is now required: We introduced [a new JSX transform](https://legacy.reactjs.org/blog/2020/09/22/introducing-the-new-jsx-transform.html) in 2020 to improve bundle size and use JSX without importing React. In React 19, we’re adding additional improvements like using ref as a prop and JSX speed improvements that require the new transform.  
-* Errors in render are not re-thrown: Errors that are not caught by an Error Boundary are now reported to window.reportError. Errors that are caught by an Error Boundary are reported to console.error. We’ve introduced `onUncaughtError` and `onCaughtError` methods to `createRoot` and `hydrateRoot` to customize this error handling.  
-* Removed: `propTypes`: Using `propTypes` will now be silently ignored. If required, we recommend migrating to TypeScript or another type-checking solution.  
-* Removed: `defaultProps` for functions: ES6 default parameters can be used in place. Class components continue to support `defaultProps` since there is no ES6 alternative.  
-* Removed: `contextTypes` and `getChildContext`: Legacy Context for class components has been removed in favor of the `contextType` API.  
-* Removed: string refs: Any usage of string refs need to be migrated to ref callbacks.   
-* Removed: Module pattern factories: A rarely used pattern that can be migrated to regular functions.  
-* Removed: `React.createFactory`: Now that JSX is broadly supported, all `createFactory` usage can be migrated to JSX components.  
-* Removed: `react-test-renderer/shallow`: This has been a re-export of [react-shallow-renderer](https://github.com/enzymejs/react-shallow-renderer) since React 18\. If needed, you can continue to use the third-party package directly. We recommend using [@testing-library/react](https://testing-library.com/docs/react-testing-library/intro/) or [@testing-library/react-native](https://testing-library.com/docs/react-native-testing-library/intro) instead.
-
-#### React DOM
-
-* Removed: `react-dom/test-utils`: We’ve moved `act` from `react-dom/test-utils` to react. All other utilities have been removed.   
-* Removed: `ReactDOM`.`render`, `ReactDOM`.`hydrate`: These have been removed in favor of the concurrent equivalents: `ReactDOM`.`createRoot` and `ReactDOM.hydrateRoot`.  
-* Removed: `unmountComponentAtNode`: Removed in favor of `root.unmount()`.  
-* Removed: `ReactDOM`.`findDOMNode`: You can replace `ReactDOM`.`findDOMNode` with DOM Refs.
-
-### Notable Changes
-
-#### React
-
-* `<Context>` as a provider: You can now render `<Context>` as a provider instead of `<Context.Provider>`.  
-* Cleanup functions for refs: When the component unmounts, React will call the cleanup function returned from the ref callback.  
-* `useDeferredValue` initial value argument: When provided, `useDeferredValue` will return the initial value for the initial render of a component, then schedule a re-render in the background with the `deferredValue` returned.  
-* Support for Custom Elements: React 19 now passes all tests on [Custom Elements Everywhere](https://custom-elements-everywhere.com/).  
-* StrictMode changes: `useMemo` and `useCallback` will now reuse the memoized results from the first render, during the second render. Additionally, StrictMode will now double-invoke ref callback functions on initial mount.  
-* UMD builds removed: To load React 19 with a script tag, we recommend using an ESM-based CDN such as [esm.sh](http://esm.sh).
-
-#### React DOM
-
-* Diffs for hydration errors: In the case of a mismatch, React 19 logs a single error with a diff of the mismatched content.  
-* Compatibility with third-party scripts and extensions: React will now force a client re-render to fix up any mismatched content caused by elements inserted by third-party JS. 
-
-### TypeScript Changes
-
-The most common changes can be codemodded with `npx types-react-codemod@latest preset-19 ./path-to-your-react-ts-files`.
-
-* Removed deprecated TypeScript types:   
-  * `ReactChild` (replacement: `React.ReactElement | number | string)`  
-  * `ReactFragment` (replacement: `Iterable<React.ReactNode>`)  
-  * `ReactNodeArray` (replacement: `ReadonlyArray<React.ReactNode>`)  
-  * `ReactText` (replacement: `number | string`)  
-  * `VoidFunctionComponent` (replacement: `FunctionComponent`)  
-  * `VFC` (replacement: `FC`)  
-  * Moved to `prop-types`: `Requireable`, `ValidationMap`, `Validator`, `WeakValidationMap`  
-  * Moved to `create-react-class`: `ClassicComponentClass`, `ClassicComponent`, `ClassicElement`, `ComponentSpec`, `Mixin`, `ReactChildren`, `ReactHTML`, `ReactSVG`, `SFCFactory`  
-* Disallow implicit return in refs: refs can now accept cleanup functions. When you return something else, we can’t tell if you intentionally returned something not meant to clean up or returned the wrong value. Implicit returns of anything but functions will now error.   
-* Require initial argument to `useRef`: The initial argument is now required to match `useState`, `createContext` etc  
-* Refs are mutable by default: Ref objects returned from `useRef()` are now always mutable instead of sometimes being immutable. This feature was too confusing for users and conflicted with legit cases where refs were managed by React and manually written to.  
-* Strict `ReactElement` typing: The props of React elements now default to `unknown` instead of `any` if the element is typed as `ReactElement`  
-* JSX namespace in TypeScript: The global `JSX` namespace is removed to improve interoperability with other libraries using JSX. Instead, the JSX namespace is available from the React package: `import { JSX } from 'react'`  
-* Better `useReducer` typings: Most `useReducer` usage should not require explicit type arguments.  
-  For example,  
-  ```diff
-  -useReducer<React.Reducer<State, Action>>(reducer)
-  +useReducer(reducer)
-  ```
-  or
-  ```diff
-  -useReducer<React.Reducer<State, Action>>(reducer)
-  +useReducer<State, Action>(reducer)
-  ```
-
-### All Changes
-
-#### React
-
-* Add support for async Actions ([\#26621](https://github.com/facebook/react/pull/26621), [\#26726](https://github.com/facebook/react/pull/26726), [\#28078](https://github.com/facebook/react/pull/28078), [\#28097](https://github.com/facebook/react/pull/28097), [\#29226](https://github.com/facebook/react/pull/29226), [\#29618](https://github.com/facebook/react/pull/29618), [\#29670](https://github.com/facebook/react/pull/29670), [\#26716](https://github.com/facebook/react/pull/26716) by [@acdlite](https://github.com/acdlite) and [@sebmarkbage](https://github.com/sebmarkbage))  
-* Add `useActionState()` hook to update state based on the result of a Form Action ([\#27270](https://github.com/facebook/react/pull/27270), [\#27278](https://github.com/facebook/react/pull/27278), [\#27309](https://github.com/facebook/react/pull/27309), [\#27302](https://github.com/facebook/react/pull/27302), [\#27307](https://github.com/facebook/react/pull/27307), [\#27366](https://github.com/facebook/react/pull/27366), [\#27370](https://github.com/facebook/react/pull/27370), [\#27321](https://github.com/facebook/react/pull/27321), [\#27374](https://github.com/facebook/react/pull/27374), [\#27372](https://github.com/facebook/react/pull/27372), [\#27397](https://github.com/facebook/react/pull/27397), [\#27399](https://github.com/facebook/react/pull/27399), [\#27460](https://github.com/facebook/react/pull/27460), [\#28557](https://github.com/facebook/react/pull/28557), [\#27570](https://github.com/facebook/react/pull/27570), [\#27571](https://github.com/facebook/react/pull/27571), [\#28631](https://github.com/facebook/react/pull/28631), [\#28788](https://github.com/facebook/react/pull/28788), [\#29694](https://github.com/facebook/react/pull/29694), [\#29695](https://github.com/facebook/react/pull/29695), [\#29694](https://github.com/facebook/react/pull/29694), [\#29665](https://github.com/facebook/react/pull/29665), [\#28232](https://github.com/facebook/react/pull/28232), [\#28319](https://github.com/facebook/react/pull/28319) by [@acdlite](https://github.com/acdlite), [@eps1lon](https://github.com/eps1lon), and [@rickhanlonii](https://github.com/rickhanlonii))  
-* Add `use()` API to read resources in render ([\#25084](https://github.com/facebook/react/pull/25084), [\#25202](https://github.com/facebook/react/pull/25202), [\#25207](https://github.com/facebook/react/pull/25207), [\#25214](https://github.com/facebook/react/pull/25214), [\#25226](https://github.com/facebook/react/pull/25226), [\#25247](https://github.com/facebook/react/pull/25247), [\#25539](https://github.com/facebook/react/pull/25539), [\#25538](https://github.com/facebook/react/pull/25538), [\#25537](https://github.com/facebook/react/pull/25537), [\#25543](https://github.com/facebook/react/pull/25543), [\#25561](https://github.com/facebook/react/pull/25561), [\#25620](https://github.com/facebook/react/pull/25620), [\#25615](https://github.com/facebook/react/pull/25615), [\#25922](https://github.com/facebook/react/pull/25922), [\#25641](https://github.com/facebook/react/pull/25641), [\#25634](https://github.com/facebook/react/pull/25634), [\#26232](https://github.com/facebook/react/pull/26232), [\#26536](https://github.com/facebook/react/pull/26535), [\#26739](https://github.com/facebook/react/pull/26739), [\#28233](https://github.com/facebook/react/pull/28233) by [@acdlite](https://github.com/acdlite), [@MofeiZ](https://github.com/mofeiZ), [@sebmarkbage](https://github.com/sebmarkbage), [@sophiebits](https://github.com/sophiebits), [@eps1lon](https://github.com/eps1lon), and [@hansottowirtz](https://github.com/hansottowirtz))  
-* Add `useOptimistic()` hook to display mutated state optimistically during an async mutation ([\#26740](https://github.com/facebook/react/pull/26740), [\#26772](https://github.com/facebook/react/pull/26772), [\#27277](https://github.com/facebook/react/pull/27277), [\#27453](https://github.com/facebook/react/pull/27453), [\#27454](https://github.com/facebook/react/pull/27454), [\#27936](https://github.com/facebook/react/pull/27936) by [@acdlite](https://github.com/acdlite))  
-* Added an `initialValue` argument to `useDeferredValue()` hook ([\#27500](https://github.com/facebook/react/pull/27500), [\#27509](https://github.com/facebook/react/pull/27509), [\#27512](https://github.com/facebook/react/pull/27512), [\#27888](https://github.com/facebook/react/pull/27888), [\#27550](https://github.com/facebook/react/pull/27550) by [@acdlite](https://github.com/acdlite))  
-* Support refs as props, warn on `element.ref` access ([\#28348](https://github.com/facebook/react/pull/28348), [\#28464](https://github.com/facebook/react/pull/28464), [\#28731](https://github.com/facebook/react/pull/28731) by [@acdlite](https://github.com/acdlite))  
-* Support Custom Elements ([\#22184](https://github.com/facebook/react/pull/22184), [\#26524](https://github.com/facebook/react/pull/26524), [\#26523](https://github.com/facebook/react/pull/26523), [\#27511](https://github.com/facebook/react/pull/27511), [\#24541](https://github.com/facebook/react/pull/24541) by [@josepharhar](https://github.com/josepharhar), [@sebmarkbage](https://github.com/sebmarkbage), [@gnoff](https://github.com/gnoff) and [@eps1lon](https://github.com/eps1lon))  
-* Add ref cleanup function ([\#25686](https://github.com/facebook/react/pull/25686), [\#28883](https://github.com/facebook/react/pull/28883), [\#28910](https://github.com/facebook/react/pull/28910)  by [@sammy-SC](https://github.com/sammy-SC), [@jackpope](https://github.com/jackpope), and [@kassens](https://github.com/kassens))  
-* Sibling pre-rendering replaced by sibling pre-warming ([\#26380](https://github.com/facebook/react/pull/26380), [\#26549](https://github.com/facebook/react/pull/26549), [\#30761](https://github.com/facebook/react/pull/30761), [\#30800](https://github.com/facebook/react/pull/30800), [\#30762](https://github.com/facebook/react/pull/30762), [\#30879](https://github.com/facebook/react/pull/30879), [\#30934](https://github.com/facebook/react/pull/30934), [\#30952](https://github.com/facebook/react/pull/30952), [\#31056](https://github.com/facebook/react/pull/31056), [\#31452](https://github.com/facebook/react/pull/31452) by [@sammy-SC](https://github.com/sammy-SC), [@acdlite](https://github.com/acdlite), [@gnoff](https://github.com/gnoff), [@jackpope](https://github.com/jackpope), [@rickhanlonii](https://github.com/rickhanlonii))  
-* Don’t rethrow errors at the root ([\#28627](https://github.com/facebook/react/pull/28627), [\#28641](https://github.com/facebook/react/pull/28641) by [@sebmarkbage](https://github.com/sebmarkbage))  
-* Batch sync discrete, continuous, and default lanes ([\#25700](https://github.com/facebook/react/pull/25700) by [@tyao1](https://github.com/tyao1))  
-* Switch `<Context>` to mean `<Context.Provider>` ([\#28226](https://github.com/facebook/react/pull/28226) by [@gaearon](https://github.com/gaearon))  
-* Changes to *StrictMode*  
-  * Handle `info`, `group`, and `groupCollapsed` in *StrictMode* logging ([\#25172](https://github.com/facebook/react/pull/25172) by [@timneutkens](https://github.com/timneutkens))  
-  * Refs are now attached/detached/attached in *StrictMode* ([\#25049](https://github.com/facebook/react/pull/25049) by [@sammy-SC](https://github.com/sammy-SC))  
-  * Fix `useSyncExternalStore()` hydration in *StrictMode* ([\#26791](https://github.com/facebook/react/pull/26791) by [@sophiebits](https://github.com/sophiebits))  
-  * Always trigger `componentWillUnmount()` in *StrictMode* ([\#26842](https://github.com/facebook/react/pull/26842) by [@tyao1](https://github.com/tyao1))  
-  * Restore double invoking `useState()` and `useReducer()` initializer functions in *StrictMode* ([\#28248](https://github.com/facebook/react/pull/28248) by [@eps1lon](https://github.com/eps1lon))  
-  * Reuse memoized result from first pass ([\#25583](https://github.com/facebook/react/pull/25583) by [@acdlite](https://github.com/acdlite))  
-  * Fix `useId()` in *StrictMode* ([\#25713](https://github.com/facebook/react/pull/25713) by [@gnoff](https://github.com/gnoff))  
-  * Add component name to *StrictMode* error messages ([\#25718](https://github.com/facebook/react/pull/25718) by [@sammy-SC](https://github.com/sammy-SC))  
-* Add support for rendering BigInt ([\#24580](https://github.com/facebook/react/pull/24580) by [@eps1lon](https://github.com/eps1lon))  
-* `act()` no longer checks `shouldYield` which can be inaccurate in test environments ([\#26317](https://github.com/facebook/react/pull/26317) by [@acdlite](https://github.com/acdlite))  
-* Warn when keys are spread with props ([\#25697](https://github.com/facebook/react/pull/25697), [\#26080](https://github.com/facebook/react/pull/26080) by [@sebmarkbage](https://github.com/sebmarkbage) and [@kassens](https://github.com/kassens))  
-* Generate sourcemaps for production build artifacts ([\#26446](https://github.com/facebook/react/pull/26446) by [@markerikson](https://github.com/markerikson))  
-* Improve stack diffing algorithm ([\#27132](https://github.com/facebook/react/pull/27132) by [@KarimP](https://github.com/KarimP))  
-* Suspense throttling lowered from 500ms to 300ms ([\#26803](https://github.com/facebook/react/pull/26803) by [@acdlite](https://github.com/acdlite))  
-* Lazily propagate context changes ([\#20890](https://github.com/facebook/react/pull/20890) by [@acdlite](https://github.com/acdlite) and [@gnoff](https://github.com/gnoff))  
-* Immediately rerender pinged fiber ([\#25074](https://github.com/facebook/react/pull/25074) by [@acdlite](https://github.com/acdlite))  
-* Move update scheduling to microtask ([\#26512](https://github.com/facebook/react/pull/26512) by [@acdlite](https://github.com/acdlite))  
-* Consistently apply throttled retries ([\#26611](https://github.com/facebook/react/pull/26611), [\#26802](https://github.com/facebook/react/pull/26802) by [@acdlite](https://github.com/acdlite))  
-* Suspend Thenable/Lazy if it's used in React.Children ([\#28284](https://github.com/facebook/react/pull/28284) by [@sebmarkbage](https://github.com/sebmarkbage))  
-* Detect infinite update loops caused by render phase updates ([\#26625](https://github.com/facebook/react/pull/26625) by [@acdlite](https://github.com/acdlite))  
-* Update conditional hooks warning ([\#29626](https://github.com/facebook/react/pull/29626) by [@sophiebits](https://github.com/sophiebits))  
-* Update error URLs to go to new docs ([\#27240](https://github.com/facebook/react/pull/27240) by [@rickhanlonii](https://github.com/rickhanlonii))  
-* Rename the `react.element` symbol to `react.transitional.element` ([\#28813](https://github.com/facebook/react/pull/28813) by [@sebmarkbage](https://github.com/sebmarkbage))  
-* Fix crash when suspending in shell during `useSyncExternalStore()` re-render ([\#27199](https://github.com/facebook/react/pull/27199) by [@acdlite](https://github.com/acdlite))  
-* Fix incorrect “detected multiple renderers" error in tests ([\#22797](https://github.com/facebook/react/pull/22797) by [@eps1lon](https://github.com/eps1lon))  
-* Fix bug where effect cleanup may be called twice after bailout ([\#26561](https://github.com/facebook/react/pull/26561) by [@acdlite](https://github.com/acdlite))  
-* Fix suspending in shell during discrete update ([\#25495](https://github.com/facebook/react/pull/25495) by [@acdlite](https://github.com/acdlite))  
-* Fix memory leak after repeated setState bailouts ([\#25309](https://github.com/facebook/react/pull/25309) by [@acdlite](https://github.com/acdlite))  
-* Fix `useSyncExternalStore()` dropped update when state is dispatched in render phase ([\#25578](https://github.com/facebook/react/pull/25578) by [@pandaiolo](https://github.com/pandaiolo))  
-* Fix logging when rendering a lazy fragment ([\#30372](https://github.com/facebook/react/pull/30372) by [@tom-sherman](https://github.com/tom-sherman))  
-* Remove string refs ([\#25383](https://github.com/facebook/react/pull/25383), [\#28322](https://github.com/facebook/react/pull/28322) by [@eps1lon](https://github.com/eps1lon) and [@acdlite](https://github.com/acdlite))  
-* Remove Legacy Context (\#30319 by [@kassens](https://github.com/kassens))  
-* Remove `RefreshRuntime.findAffectedHostInstances` ([\#30538](https://github.com/facebook/react/pull/30538) by [@gaearon](https://github.com/gaearon))  
-* Remove client caching from `cache()` API ([\#27977](https://github.com/facebook/react/pull/27977), [\#28250](https://github.com/facebook/react/pull/28250) by [@acdlite](https://github.com/acdlite) and [@gnoff](https://github.com/gnoff))  
-* Remove `propTypes` ([\#28324](https://github.com/facebook/react/pull/28324), [\#28326](https://github.com/facebook/react/pull/28326) by [@gaearon](https://github.com/gaearon))  
-* Remove `defaultProps` support, except for classes ([\#28733](https://github.com/facebook/react/pull/28733) by [@acdlite](https://github.com/acdlite))  
-* Remove UMD builds ([\#28735](https://github.com/facebook/react/pull/28735) by [@gnoff](https://github.com/gnoff))  
-* Remove delay for non-transition updates ([\#26597](https://github.com/facebook/react/pull/26597) by [@acdlite](https://github.com/acdlite))  
-* Remove `createFactory` ([\#27798](https://github.com/facebook/react/pull/27798) by [@kassens](https://github.com/kassens))
-
-#### React DOM
-
-* Adds Form Actions to handle form submission ([\#26379](https://github.com/facebook/react/pull/26379), [\#26674](https://github.com/facebook/react/pull/26674), [\#26689](https://github.com/facebook/react/pull/26689), [\#26708](https://github.com/facebook/react/pull/26708), [\#26714](https://github.com/facebook/react/pull/26714),  [\#26735](https://github.com/facebook/react/pull/26735), [\#26846](https://github.com/facebook/react/pull/26846), [\#27358](https://github.com/facebook/react/pull/27358),  [\#28056](https://github.com/facebook/react/pull/28056) by [@sebmarkbage](https://github.com/sebmarkbage), [@acdlite](https://github.com/acdlite), and [@jupapios](https://github.com/jupapios))  
-* Add `useFormStatus()` hook to provide status information of the last form submission ([\#26719](https://github.com/facebook/react/pull/26719), [\#26722](https://github.com/facebook/react/pull/26722), [\#26788](https://github.com/facebook/react/pull/26788),  [\#29019](https://github.com/facebook/react/pull/29019), [\#28728](https://github.com/facebook/react/pull/28728), [\#28413](https://github.com/facebook/react/pull/28413) by [@acdlite](https://github.com/acdlite) and [@eps1lon](https://github.com/eps1lon))  
-* Support for Document Metadata. Adds `preinit`, `preinitModule`, `preconnect`, `prefetchDNS`, `preload`, and `preloadModule` APIs.  
-  * [\#25060](https://github.com/facebook/react/pull/25060), [\#25243](https://github.com/facebook/react/pull/25243), [\#25388](https://github.com/facebook/react/pull/25388), [\#25432](https://github.com/facebook/react/pull/25432), [\#25436](https://github.com/facebook/react/pull/25436), [\#25426](https://github.com/facebook/react/pull/25426), [\#25500](https://github.com/facebook/react/pull/25500), [\#25480](https://github.com/facebook/react/pull/25480), [\#25508](https://github.com/facebook/react/pull/25508), [\#25515](https://github.com/facebook/react/pull/25515), [\#25514](https://github.com/facebook/react/pull/25514), [\#25532](https://github.com/facebook/react/pull/25532), [\#25536](https://github.com/facebook/react/pull/25536), [\#25534](https://github.com/facebook/react/pull/25534), [\#25546](https://github.com/facebook/react/pull/25546), [\#25559](https://github.com/facebook/react/pull/25559), [\#25569](https://github.com/facebook/react/pull/25569), [\#25599](https://github.com/facebook/react/pull/25599), [\#25689](https://github.com/facebook/react/pull/25689), [\#26106](https://github.com/facebook/react/pull/26106), [\#26152](https://github.com/facebook/react/pull/26152), [\#26239](https://github.com/facebook/react/pull/26239), [\#26237](https://github.com/facebook/react/pull/26237), [\#26280](https://github.com/facebook/react/pull/26280), [\#26154](https://github.com/facebook/react/pull/26154), [\#26256](https://github.com/facebook/react/pull/26256), [\#26353](https://github.com/facebook/react/pull/26353), [\#26427](https://github.com/facebook/react/pull/26427), [\#26450](https://github.com/facebook/react/pull/26450), [\#26502](https://github.com/facebook/react/pull/26502),  [\#26514](https://github.com/facebook/react/pull/26514), [\#26531](https://github.com/facebook/react/pull/26531), [\#26532](https://github.com/facebook/react/pull/26532), [\#26557](https://github.com/facebook/react/pull/26557), [\#26871](https://github.com/facebook/react/pull/26871), [\#26881](https://github.com/facebook/react/pull/26881), [\#26877](https://github.com/facebook/react/pull/26877), [\#26873](https://github.com/facebook/react/pull/26873), [\#26880](https://github.com/facebook/react/pull/26880), [\#26942](https://github.com/facebook/react/pull/26942), [\#26938](https://github.com/facebook/react/pull/26938), [\#26940](https://github.com/facebook/react/pull/26940), [\#26939](https://github.com/facebook/react/pull/26939), [\#27030](https://github.com/facebook/react/pull/27030), [\#27201](https://github.com/facebook/react/pull/27201), [\#27212](https://github.com/facebook/react/pull/27212), [\#27217](https://github.com/facebook/react/pull/27217), [\#27218](https://github.com/facebook/react/pull/27218), [\#27220](https://github.com/facebook/react/pull/27220), [\#27224](https://github.com/facebook/react/pull/27224), [\#27223](https://github.com/facebook/react/pull/27223), [\#27269](https://github.com/facebook/react/pull/27269), [\#27260](https://github.com/facebook/react/pull/27260), [\#27347](https://github.com/facebook/react/pull/27347), [\#27346](https://github.com/facebook/react/pull/27346), [\#27361](https://github.com/facebook/react/pull/27361), [\#27400](https://github.com/facebook/react/pull/27400), [\#27541](https://github.com/facebook/react/pull/27541), [\#27610](https://github.com/facebook/react/pull/27610), [\#28110](https://github.com/facebook/react/pull/28110), [\#29693](https://github.com/facebook/react/pull/29693), [\#29732](https://github.com/facebook/react/pull/29732), [\#29811](https://github.com/facebook/react/pull/29811), [\#27586](https://github.com/facebook/react/pull/27586), [\#28069](https://github.com/facebook/react/pull/28069) by [@gnoff](https://github.com/gnoff), [@sebmarkbage](https://github.com/sebmarkbage), [@acdlite](https://github.com/acdlite), [@kassens](https://github.com/kassens), [@sokra](https://github.com/sokra), [@sweetliquid](https://github.com/sweetliquid)  
-* Add `fetchPriority` to `<img>` and `<link>` ([\#25927](https://github.com/facebook/react/pull/25927) by [@styfle](https://github.com/styfle))  
-* Add support for SVG `transformOrigin` prop ([\#26130](https://github.com/facebook/react/pull/26130) by [@arav-ind](https://github.com/arav-ind))  
-* Add support for `onScrollEnd` event ([\#26789](https://github.com/facebook/react/pull/26789) by [@devongovett](https://github.com/devongovett))  
-* Allow `<hr>` as child of `<select>` ([\#27632](https://github.com/facebook/react/pull/27632) by [@SouSingh](https://github.com/SouSingh))  
-* Add support for Popover API ([\#27981](https://github.com/facebook/react/pull/27981) by [@eps1lon](https://github.com/eps1lon))  
-* Add support for `inert` ([\#24730](https://github.com/facebook/react/pull/24730) by [@eps1lon](https://github.com/eps1lon))  
-* Add support for `imageSizes` and `imageSrcSet` ([\#22550](https://github.com/facebook/react/pull/22550) by [@eps1lon](https://github.com/eps1lon))  
-* Synchronously flush transitions in popstate events ([\#26025](https://github.com/facebook/react/pull/26025), [\#27559](https://github.com/facebook/react/pull/27559), [\#27505](https://github.com/facebook/react/pull/27505), [\#30759](https://github.com/facebook/react/pull/30759) by [@tyao1](https://github.com/tyao1) and [@acdlite](https://github.com/acdlite))  
-* `flushSync` exhausts queue even if something throws ([\#26366](https://github.com/facebook/react/pull/26366) by [@acdlite](https://github.com/acdlite))  
-* Throw error if `react` and `react-dom` versions don’t match ([\#29236](https://github.com/facebook/react/pull/29236) by [@acdlite](https://github.com/acdlite))  
-* Ensure `srcset` and `src` are assigned last on `<img>` instances ([\#30340](https://github.com/facebook/react/pull/30340) by [@gnoff](https://github.com/gnoff))  
-* Javascript URLs are replaced with functions that throw errors ([\#26507](https://github.com/facebook/react/pull/26507), [\#29808](https://github.com/facebook/react/pull/29808) by [@sebmarkbage](https://github.com/sebmarkbage) and [@kassens](https://github.com/kassens))  
-* Treat toggle and beforetoggle as discrete events ([\#29176](https://github.com/facebook/react/pull/29176) by [@eps1lon](https://github.com/eps1lon))  
-* Filter out empty `src` and `href` attributes (unless for `<a href=”” />`) ([\#18513](https://github.com/facebook/react/pull/18513), [\#28124](https://github.com/facebook/react/pull/28124) by [@bvaughn](https://github.com/bvaughn) and [@eps1lon](https://github.com/eps1lon))  
-* Fix unitless `scale` style property ([\#25601](https://github.com/facebook/react/pull/25601) by [@JonnyBurger](https://github.com/JonnyBurger))  
-* Fix `onChange` error message for controlled `<select>` ([\#27740](https://github.com/facebook/react/pull/27740) by [@Biki-das](https://github.com/Biki-das))  
-* Fix focus restore in child windows after element reorder ([\#30951](https://github.com/facebook/react/pull/30951) by [@ling1726](https://github.com/ling1726))  
-* Remove `render`, `hydrate`, `findDOMNode`, `unmountComponentAtNode`, `unstable_createEventHandle`, `unstable_renderSubtreeIntoContainer`, and `unstable_runWithPriority`. Move `createRoot` and `hydrateRoot` to `react-dom/client`. ([\#28271](https://github.com/facebook/react/pull/28271) by [@gnoff](https://github.com/gnoff))  
-* Remove `test-utils` ([\#28541](https://github.com/facebook/react/pull/28541) by [@eps1lon](https://github.com/eps1lon))  
-* Remove `unstable_flushControlled` ([\#26397](https://github.com/facebook/react/pull/26397) by [@kassens](https://github.com/kassens))  
-* Remove legacy mode ([\#28468](https://github.com/facebook/react/pull/28468) by [@gnoff](https://github.com/gnoff))  
-* Remove `renderToStaticNodeStream()` ([\#28873](https://github.com/facebook/react/pull/28873) by @gnoff)  
-* Remove `unstable_renderSubtreeIntoContainer` ([\#29771](https://github.com/facebook/react/pull/29771) by [@kassens](https://github.com/kassens))
-
-#### React DOM Server
-
-* Stable release of React Server Components ([Many, many PRs](https://github.com/facebook/react/pulls?q=is%3Apr+is%3Aclosed+%5BFlight%5D+in%3Atitle+created%3A%3C2024-12-01+) by [@sebmarkbage](https://github.com/sebmarkbage), [@acdlite](https://github.com/acdlite), [@gnoff](https://github.com/gnoff), [@sammy-SC](https://github.com/sammy-SC), [@gaearon](https://github.com/gaearon), [@sophiebits](https://github.com/sophiebits), [@unstubbable](https://github.com/unstubbable), [@lubieowoce](https://github.com/lubieowoce))
-* Support Server Actions ([\#26124](https://github.com/facebook/react/pull/26124), [\#26632](https://github.com/facebook/react/pull/26632), [\#27459](https://github.com/facebook/react/pull/27459) by [@sebmarkbage](https://github.com/sebmarkbage) and [@acdlite](https://github.com/acdlite))  
-* Changes to SSR  
-  * Add external runtime which bootstraps hydration on the client for binary transparency ([\#25437](https://github.com/facebook/react/pull/25437), [\#26169](https://github.com/facebook/react/pull/26169), [\#25499](https://github.com/facebook/react/pull/25499) by [@MofeiZ](https://github.com/mofeiZ) and [@acdlite](https://github.com/acdlite))  
-  * Support subresource integrity for `bootstrapScripts` and `bootstrapModules` ([\#25104](https://github.com/facebook/react/pull/25104) by [@gnoff](https://github.com/gnoff))  
-  * Fix null bytes written at text chunk boundaries ([\#26228](https://github.com/facebook/react/pull/26228) by [@sophiebits](https://github.com/sophiebits))  
-  * Fix logic around attribute serialization ([\#26526](https://github.com/facebook/react/pull/26526) by [@gnoff](https://github.com/gnoff))  
-  * Fix precomputed chunk cleared on Node 18 ([\#25645](https://github.com/facebook/react/pull/25645) by [@feedthejim](https://github.com/feedthejim))  
-  * Optimize end tag chunks ([\#27522](https://github.com/facebook/react/pull/27522) by [@yujunjung](https://github.com/yujunjung))  
-  * Gracefully handle suspending in DOM configs ([\#26768](https://github.com/facebook/react/pull/26768) by [@sebmarkbage](https://github.com/sebmarkbage))  
-  * Check for nullish values on ReactCustomFormAction ([\#26770](https://github.com/facebook/react/pull/26770) by [@sebmarkbage](https://github.com/sebmarkbage))  
-  * Preload `bootstrapModules`, `bootstrapScripts`, and update priority queue ([\#26754](https://github.com/facebook/react/pull/26754), [\#26753](https://github.com/facebook/react/pull/26753), [\#27190](https://github.com/facebook/react/pull/27190), [\#27189](https://github.com/facebook/react/pull/27189) by [@gnoff](https://github.com/gnoff))  
-  * Client render the nearest child or parent suspense boundary if replay errors or is aborted ([\#27386](https://github.com/facebook/react/pull/27386) by [@sebmarkbage](https://github.com/sebmarkbage))  
-  * Don't bail out of flushing if we still have pending root tasks ([\#27385](https://github.com/facebook/react/pull/27385) by [@sebmarkbage](https://github.com/sebmarkbage))  
-  * Ensure Resumable State is Serializable ([\#27388](https://github.com/facebook/react/pull/27388) by [@sebmarkbage](https://github.com/sebmarkbage))  
-  * Remove extra render pass when reverting to client render ([\#26445](https://github.com/facebook/react/pull/26445) by [@acdlite](https://github.com/acdlite))  
-  * Fix unwinding context during selective hydration ([\#25876](https://github.com/facebook/react/pull/25876) by [@tyao1](https://github.com/tyao1))  
-  * Stop flowing and then abort if a stream is cancelled ([\#27405](https://github.com/facebook/react/pull/27405) by [@sebmarkbage](https://github.com/sebmarkbage))  
-  * Pass cancellation reason to abort ([\#27536](https://github.com/facebook/react/pull/27536) by [@sebmarkbage](https://github.com/sebmarkbage))  
-  * Add `onHeaders` entrypoint option ([\#27641](https://github.com/facebook/react/pull/27641), [\#27712](https://github.com/facebook/react/pull/27712) by [@gnoff](https://github.com/gnoff))  
-  * Escape `<style>` and `<script>` textContent to enable rendering inner content without dangerouslySetInnerHTML ([\#28870](https://github.com/facebook/react/pull/28870), [\#28871](https://github.com/facebook/react/pull/28871) by [@gnoff](https://github.com/gnoff))  
-  * Fallback to client replaying actions for Blob serialization ([\#28987](https://github.com/facebook/react/pull/28987) by [@sebmarkbage](https://github.com/sebmarkbage))  
-  * Render Suspense fallback if boundary contains new stylesheet during sync update ([\#28965](https://github.com/facebook/react/pull/28965) by [@gnoff](https://github.com/gnoff))  
-  * Fix header length tracking (\#30327 by [@gnoff](https://github.com/gnoff))  
-  * Use `srcset` to trigger load event on mount (\#30351 by [@gnoff](https://github.com/gnoff))  
-  * Don't perform work when closing stream (\#30497 by [@gnoff](https://github.com/gnoff))  
-  * Allow aborting during render (\#30488, [\#30730](https://github.com/facebook/react/pull/30730) by [@gnoff](https://github.com/gnoff))  
-  * Start initial work immediately (\#31079 by [@gnoff](https://github.com/gnoff))  
-  * A transition flowing into a dehydrated boundary no longer suspends when showing fallback ([\#27230](https://github.com/facebook/react/pull/27230) by [@acdlite](https://github.com/acdlite))  
-  * Fix selective hydration triggers false update loop error ([\#27439](https://github.com/facebook/react/pull/27439) by [@acdlite](https://github.com/acdlite))  
-  * Warn for Child Iterator of all types but allow Generator Components ([\#28853](https://github.com/facebook/react/pull/28853) by [@sebmarkbage](https://github.com/sebmarkbage))  
-  * Include regular stack trace in serialized errors ([\#28684](https://github.com/facebook/react/pull/28684), [\#28738](https://github.com/facebook/react/pull/28738) by [@sebmarkbage](https://github.com/sebmarkbage))  
-  * Aborting early no longer infinitely suspends ([\#24751](https://github.com/facebook/react/pull/24751) by [@sebmarkbage](https://github.com/sebmarkbage))  
-  * Fix hydration warning suppression in text comparisons ([\#24784](https://github.com/facebook/react/pull/24784) by [@gnoff](https://github.com/gnoff))  
-  * Changes to error handling in SSR
-    * Add diffs to hydration warnings ([\#28502](https://github.com/facebook/react/pull/28502), [\#28512](https://github.com/facebook/react/pull/28512) by [@sebmarkbage](https://github.com/sebmarkbage))  
-    * Make Error creation lazy ([\#24728](https://github.com/facebook/react/pull/24728) by [@sebmarkbage](https://github.com/sebmarkbage))  
-    * Remove recoverable error when a sync update flows into a dehydrated boundary ([\#25692](https://github.com/facebook/react/pull/25692) by [@sebmarkbage](https://github.com/sebmarkbage))  
-    * Don't "fix up" mismatched text content with suppressedHydrationWarning ([\#26391](https://github.com/facebook/react/pull/26391) by [@sebmarkbage](https://github.com/sebmarkbage))  
-    * Fix component stacks in errors ([\#27456](https://github.com/facebook/react/pull/27456) by [@sebmarkbage](https://github.com/sebmarkbage))  
-    * Add component stacks to `onError` ([\#27761](https://github.com/facebook/react/pull/27761), [\#27850](https://github.com/facebook/react/pull/27850) by [@gnoff](https://github.com/gnoff) and [@sebmarkbage](https://github.com/sebmarkbage))  
-    * Throw hydration mismatch errors once ([\#28502](https://github.com/facebook/react/pull/28502) by [@sebmarkbage](https://github.com/sebmarkbage))  
-* Add Bun streaming server renderer ([\#25597](https://github.com/facebook/react/pull/25597) by [@colinhacks](https://github.com/colinhacks))  
-* Add nonce support to bootstrap scripts ([\#26738](https://github.com/facebook/react/pull/26738) by [@danieltott](https://github.com/danieltott))  
-* Add `crossorigin` support to bootstrap scripts ([\#26844](https://github.com/facebook/react/pull/26844) by [@HenriqueLimas](https://github.com/HenriqueLimas))  
-* Support `nonce` and `fetchpriority` in preload links ([\#26826](https://github.com/facebook/react/pull/26826) by [@liuyenwei](https://github.com/liuyenwei))  
-* Add `referrerPolicy` to `ReactDOM.preload()` ([\#27096](https://github.com/facebook/react/pull/27096) by [@styfle](https://github.com/styfle))  
-* Add server condition for `react/jsx-dev-runtime` ([\#28921](https://github.com/facebook/react/pull/28921) by [@himself65](https://github.com/himself65))   
-* Export version ([\#29596](https://github.com/facebook/react/pull/29596) by [@unstubbable](https://github.com/unstubbable))  
-* Rename the secret export of Client and Server internals ([\#28786](https://github.com/facebook/react/pull/28786), [\#28789](https://github.com/facebook/react/pull/28789) by [@sebmarkbage](https://github.com/sebmarkbage))  
-* Remove layout effect warning on server ([\#26395](https://github.com/facebook/react/pull/26395) by [@rickhanlonii](https://github.com/rickhanlonii))  
-* Remove `errorInfo.digest` from `onRecoverableError` ([\#28222](https://github.com/facebook/react/pull/28222) by [@gnoff](https://github.com/gnoff))
-
-#### ReactTestRenderer
-
-* Add deprecation error to `react-test-renderer` on web ([\#27903](https://github.com/facebook/react/pull/27903), [\#28904](https://github.com/facebook/react/pull/28904) by [@jackpope](https://github.com/jackpope) and [@acdlite](https://github.com/acdlite))  
-* Render with ConcurrentRoot on web ([\#28498](https://github.com/facebook/react/pull/28498) by [@jackpope](https://github.com/jackpope))  
-* Remove `react-test-renderer/shallow` export ([\#25475](https://github.com/facebook/react/pull/25475), [\#28497](https://github.com/facebook/react/pull/28497) by [@sebmarkbage](https://github.com/sebmarkbage) and [@jackpope](https://github.com/jackpope))
-
-#### React Reconciler
-
-* Enable suspending commits without blocking render ([\#26398](https://github.com/facebook/react/pull/26398), [\#26427](https://github.com/facebook/react/pull/26427) by [@acdlite](https://github.com/acdlite))  
-* Remove `prepareUpdate` ([\#26583](https://github.com/facebook/react/pull/26583), [\#27409](http://github.com/facebook/react/pull/27409) by [@sebmarkbage](https://github.com/sebmarkbage) and [@sophiebits](https://github.com/sophiebits))
-
-#### React-Is
-
-* Enable tree shaking ([\#27701](https://github.com/facebook/react/pull/27701) by [@markerikson](https://github.com/markerikson))  
-* Remove `isConcurrentMode` and `isAsyncMode` methods ([\#28224](https://github.com/facebook/react/pull/28224) by @gaearon)
-
-#### useSyncExternalStore
-
-* Remove React internals access ([\#29868](https://github.com/facebook/react/pull/29868) by [@phryneas](https://github.com/phryneas))  
-* Fix stale selectors keeping previous store references ([\#25969](https://github.com/facebook/react/pull/25968) by [@jellevoost](https://github.com/jellevoost))
-
 ## 18.3.1 (April 26, 2024)
 
 - Export `act` from `react` [f1338f](https://github.com/facebook/react/commit/f1338f8080abd1386454a10bbf93d67bfe37ce85)

MAINTAINERS

@@ -1,22 +0,0 @@
-acdlite
-eps1lon
-gaearon
-gnoff
-unstubbable
-hoxyq
-jackpope
-jbonta
-jbrown215
-josephsavona
-kassens
-mattcarrollcode
-mofeiZ
-mvitousek
-pieterv
-poteto
-rickhanlonii
-sebmarkbage
-sethwebster
-sophiebits
-elicwhite
-yuzhi

README.md

@@ -1,4 +1,4 @@
-# [React](https://react.dev/) · [![GitHub license](https://img.shields.io/badge/license-MIT-blue.svg)](https://github.com/facebook/react/blob/main/LICENSE) [![npm version](https://img.shields.io/npm/v/react.svg?style=flat)](https://www.npmjs.com/package/react) [![(Runtime) Build and Test](https://github.com/facebook/react/actions/workflows/runtime_build_and_test.yml/badge.svg)](https://github.com/facebook/react/actions/workflows/runtime_build_and_test.yml) [![(Compiler) TypeScript](https://github.com/facebook/react/actions/workflows/compiler_typescript.yml/badge.svg?branch=main)](https://github.com/facebook/react/actions/workflows/compiler_typescript.yml) [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg)](https://legacy.reactjs.org/docs/how-to-contribute.html#your-first-pull-request)
+# [React](https://react.dev/) · [![GitHub license](https://img.shields.io/badge/license-MIT-blue.svg)](https://github.com/facebook/react/blob/main/LICENSE) [![npm version](https://img.shields.io/npm/v/react.svg?style=flat)](https://www.npmjs.com/package/react) [![CircleCI Status](https://circleci.com/gh/facebook/react.svg?style=shield)](https://circleci.com/gh/facebook/react) [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg)](https://legacy.reactjs.org/docs/how-to-contribute.html#your-first-pull-request)
 
 React is a JavaScript library for building user interfaces.
 
@@ -18,7 +18,7 @@ React has been designed for gradual adoption from the start, and **you can use a
 
 ## Documentation
 
-You can find the React documentation [on the website](https://react.dev/).
+You can find the React documentation [on the website](https://react.dev/).  
 
 Check out the [Getting Started](https://react.dev/learn) page for a quick overview.
 
@@ -55,7 +55,7 @@ root.render(<HelloMessage name="Taylor" />);
 
 This example will render "Hello Taylor" into a container on the page.
 
-You'll notice that we used an HTML-like syntax; [we call it JSX](https://react.dev/learn#writing-markup-with-jsx). JSX is not required to use React, but it makes code more readable, and writing it feels like writing HTML.
+You'll notice that we used an HTML-like syntax; [we call it JSX](https://react.dev/learn#writing-markup-with-jsx). JSX is not required to use React, but it makes code more readable, and writing it feels like writing HTML. 
 
 ## Contributing
 

ReactVersions.js

@@ -7,53 +7,52 @@
 //
 // The @latest channel uses the version as-is, e.g.:
 //
-//   19.1.3
+//   19.0.0
 //
 // The @canary channel appends additional information, with the scheme
 // <version>-<label>-<commit_sha>, e.g.:
 //
-//   19.1.3-canary-a1c2d3e4
+//   19.0.0-canary-a1c2d3e4
 //
 // The @experimental channel doesn't include a version, only a date and a sha, e.g.:
 //
 //   0.0.0-experimental-241c4467e-20200129
 
-const ReactVersion = '19.1.3';
+const ReactVersion = '19.0.0';
 
 // The label used by the @canary channel. Represents the upcoming release's
 // stability. Most of the time, this will be "canary", but we may temporarily
 // choose to change it to "alpha", "beta", "rc", etc.
 //
 // It only affects the label used in the version string. To customize the
-// npm dist tags used during publish, refer to .github/workflows/runtime_prereleases_*.yml.
-const canaryChannelLabel = 'canary';
+// npm dist tags used during publish, refer to .circleci/config.yml.
+const canaryChannelLabel = 'rc';
 
 // If the canaryChannelLabel is "rc", the build pipeline will use this to build
 // an RC version of the packages.
 const rcNumber = 0;
 
 const stablePackages = {
-  'eslint-plugin-react-hooks': '5.2.0',
+  'eslint-plugin-react-hooks': '5.1.0',
   'jest-react': '0.16.0',
   react: ReactVersion,
   'react-art': ReactVersion,
   'react-dom': ReactVersion,
   'react-server-dom-webpack': ReactVersion,
   'react-server-dom-turbopack': ReactVersion,
-  'react-server-dom-parcel': ReactVersion,
   'react-is': ReactVersion,
-  'react-reconciler': '0.32.0',
-  'react-refresh': '0.17.0',
+  'react-reconciler': '0.31.0',
+  'react-refresh': '0.16.0',
   'react-test-renderer': ReactVersion,
-  'use-subscription': '1.11.0',
-  'use-sync-external-store': '1.5.0',
-  scheduler: '0.26.0',
+  'use-subscription': '1.10.0',
+  'use-sync-external-store': '1.4.0',
+  scheduler: '0.25.0',
 };
 
 // These packages do not exist in the @canary or @latest channel, only
 // @experimental. We don't use semver, just the commit sha, so this is just a
 // list of package names instead of a map.
-const experimentalPackages = ['react-markup'];
+const experimentalPackages = [];
 
 module.exports = {
   ReactVersion,

babel.config-react-compiler.js

@@ -1,19 +0,0 @@
-'use strict';
-
-/**
- * HACK: @poteto React Compiler inlines Zod in its build artifact. Zod spreads values passed to .map
- * which causes issues in @babel/plugin-transform-spread in loose mode, as it will result in
- * {undefined: undefined} which fails to parse.
- *
- * [@babel/plugin-transform-block-scoping', {throwIfClosureRequired: true}] also causes issues with
- * the built version of the compiler. The minimal set of plugins needed for this file is reexported
- * from babel.config-ts.
- *
- * I will remove this hack later when we move eslint-plugin-react-hooks into the compiler directory.
- **/
-
-const baseConfig = require('./babel.config-ts');
-
-module.exports = {
-  plugins: baseConfig.plugins,
-};

babel.config-ts.js

@@ -1,17 +0,0 @@
-/**
- * This file is purely being used for local jest runs, and doesn't participate in the build process.
- */
-'use strict';
-
-module.exports = {
-  plugins: [
-    '@babel/plugin-syntax-jsx',
-    '@babel/plugin-transform-flow-strip-types',
-    ['@babel/plugin-transform-class-properties', {loose: true}],
-    '@babel/plugin-transform-classes',
-  ],
-  presets: [
-    ['@babel/preset-env', {targets: {node: 'current'}}],
-    '@babel/preset-typescript',
-  ],
-};

compiler/.gitignore

@@ -21,8 +21,4 @@ dist
 .spr.yml
 testfilter.txt
 
-bundle-oss.sh
-
-# forgive
-*.vsix
-.vscode-test
+bundle-oss.sh

compiler/.watchmanconfig

@@ -0,0 +1 @@
+{}

compiler/CODE_OF_CONDUCT.md

@@ -0,0 +1,80 @@
+# Code of Conduct
+
+## Our Pledge
+
+In the interest of fostering an open and welcoming environment, we as
+contributors and maintainers pledge to make participation in our project and
+our community a harassment-free experience for everyone, regardless of age, body
+size, disability, ethnicity, sex characteristics, gender identity and expression,
+level of experience, education, socio-economic status, nationality, personal
+appearance, race, religion, or sexual identity and orientation.
+
+## Our Standards
+
+Examples of behavior that contributes to creating a positive environment
+include:
+
+* Using welcoming and inclusive language
+* Being respectful of differing viewpoints and experiences
+* Gracefully accepting constructive criticism
+* Focusing on what is best for the community
+* Showing empathy towards other community members
+
+Examples of unacceptable behavior by participants include:
+
+* The use of sexualized language or imagery and unwelcome sexual attention or
+  advances
+* Trolling, insulting/derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or electronic
+  address, without explicit permission
+* Other conduct which could reasonably be considered inappropriate in a
+  professional setting
+
+## Our Responsibilities
+
+Project maintainers are responsible for clarifying the standards of acceptable
+behavior and are expected to take appropriate and fair corrective action in
+response to any instances of unacceptable behavior.
+
+Project maintainers have the right and responsibility to remove, edit, or
+reject comments, commits, code, wiki edits, issues, and other contributions
+that are not aligned to this Code of Conduct, or to ban temporarily or
+permanently any contributor for other behaviors that they deem inappropriate,
+threatening, offensive, or harmful.
+
+## Scope
+
+This Code of Conduct applies within all project spaces, and it also applies when
+an individual is representing the project or its community in public spaces.
+Examples of representing a project or community include using an official
+project e-mail address, posting via an official social media account, or acting
+as an appointed representative at an online or offline event. Representation of
+a project may be further defined and clarified by project maintainers.
+
+This Code of Conduct also applies outside the project spaces when there is a
+reasonable belief that an individual's behavior may have a negative impact on
+the project or its community.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be
+reported by contacting the project team at <opensource-conduct@fb.com>. All
+complaints will be reviewed and investigated and will result in a response that
+is deemed necessary and appropriate to the circumstances. The project team is
+obligated to maintain confidentiality with regard to the reporter of an incident.
+Further details of specific enforcement policies may be posted separately.
+
+Project maintainers who do not follow or enforce the Code of Conduct in good
+faith may face temporary or permanent repercussions as determined by other
+members of the project's leadership.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 1.4,
+available at https://www.contributor-covenant.org/version/1/4/code-of-conduct.html
+
+[homepage]: https://www.contributor-covenant.org
+
+For answers to common questions about this code of conduct, see
+https://www.contributor-covenant.org/faq

compiler/CONTRIBUTING.md

@@ -0,0 +1,31 @@
+# Contributing to react-forget
+We want to make contributing to this project as easy and transparent as
+possible.
+
+## Pull Requests
+We actively welcome your pull requests.
+
+1. Fork the repo and create your branch from `main`.
+2. If you've added code that should be tested, add tests.
+3. If you've changed APIs, update the documentation.
+4. Ensure the test suite passes.
+5. Make sure your code lints.
+6. If you haven't already, complete the Contributor License Agreement ("CLA").
+
+## Contributor License Agreement ("CLA")
+In order to accept your pull request, we need you to submit a CLA. You only need
+to do this once to work on any of Facebook's open source projects.
+
+Complete your CLA here: <https://code.facebook.com/cla>
+
+## Issues
+We use GitHub issues to track public bugs. Please ensure your description is
+clear and has sufficient instructions to be able to reproduce the issue.
+
+Facebook has a [bounty program](https://www.facebook.com/whitehat/) for the safe
+disclosure of security bugs. In those cases, please go through the process
+outlined on that page and do not file a public issue.
+
+## License
+By contributing to react-forget, you agree that your contributions will be licensed
+under the LICENSE file in the root directory of this source tree.

compiler/Cargo.toml

@@ -0,0 +1,61 @@
+[workspace]
+resolver = "2"
+members = ["crates/*"]
+
+[workspace.package]
+authors     = ["The React Team https://react.dev/community/team"]
+description = "React Compiler"
+edition     = "2021"
+homepage    = "https://github.com/facebook/react"
+keywords    = ["JavaScript", "TypeScript", "React", "React Compiler", "Compiler"]
+license     = "MIT"
+repository  = "https://github.com/facebook/react"
+
+[workspace.dependencies]
+# workspace crates
+react_build_hir = { path = "crates/react_build_hir" }
+react_diagnostics = { path = "crates/react_diagnostics" }
+react_estree = { path = "crates/react_estree" }
+react_estree_codegen = { path = "crates/react_estree_codegen" }
+react_fixtures = { path = "crates/react_fixtures" }
+react_hermes_parser = { path = "crates/react_hermes_parser" }
+react_hir = { path = "crates/react_hir" }
+react_optimization = { path = "crates/react_optimization" }
+react_semantic_analysis = { path = "crates/react_semantic_analysis" }
+react_ssa = { path = "crates/react_ssa" }
+react_utils = { path = "crates/react_utils" }
+
+# dependencies
+indexmap = { version = "2.0.0", features = ["serde"] }
+insta = { version = "1.30.0", features = ["glob"] }
+miette = { version = "5.9.0" }
+prettyplease = "0.2.10"
+quote = "1.0.29"
+serde = { version = "1.0.167", features = ["serde_derive"] }
+serde_json = "1.0.100"
+stacker = "0.1.15"
+static_assertions = "1.1.0"
+syn = "2.0.23"
+thiserror = "1.0.41"
+hermes = { git = "https://github.com/facebook/hermes.git" }
+juno_support = { git = "https://github.com/facebook/hermes.git" }
+
+[profile.release]
+# configuration adapted from oxc
+# https://github.com/Boshen/oxc/blob/ea85ee9f2d64dd284c5b7410f491d81fb879abae/Cargo.toml#L89-L97
+opt-level     = 3
+lto           = "fat"
+codegen-units = 1
+strip         = "symbols"
+debug         = false
+panic         = "abort"   # Let it crash and force ourselves to write safe Rust.
+
+# Make insta run faster by compiling with release mode optimizations
+# https://docs.rs/insta/latest/insta/#optional-faster-runs
+[profile.dev.package.insta]
+opt-level = 3
+
+# Make insta diffing libary faster by compiling with release mode optimizations
+# https://docs.rs/insta/latest/insta/#optional-faster-runs
+[profile.dev.package.similar]
+opt-level = 3

compiler/apps/playground/README.md

@@ -26,13 +26,6 @@ $ npm run dev
 $ yarn
 ```
 
-## Testing
-```sh
-# Install playwright browser binaries
-$ npx playwright install --with-deps
-# Run tests
-$ yarn test
-```
 ## Deployment
 
 This project has been deployed using Vercel. Vercel does the exact same thing as we would

compiler/apps/playground/__tests__/e2e/__snapshots__/page.spec.ts/01-user-output.txt

@@ -1,14 +0,0 @@
-import { c as _c } from "react/compiler-runtime";
-export default function TestComponent(t0) {
-  const $ = _c(2);
-  const { x } = t0;
-  let t1;
-  if ($[0] !== x) {
-    t1 = <Button>{x}</Button>;
-    $[0] = x;
-    $[1] = t1;
-  } else {
-    t1 = $[1];
-  }
-  return t1;
-}

compiler/apps/playground/__tests__/e2e/__snapshots__/page.spec.ts/02-default-output.txt

@@ -1,12 +0,0 @@
-import { c as _c } from "react/compiler-runtime";
-export default function MyApp() {
-  const $ = _c(1);
-  let t0;
-  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
-    t0 = <div>Hello World</div>;
-    $[0] = t0;
-  } else {
-    t0 = $[0];
-  }
-  return t0;
-}

compiler/apps/playground/__tests__/e2e/__snapshots__/page.spec.ts/compilationMode-all-output.txt

@@ -1,13 +0,0 @@
-import { c as _c } from "react/compiler-runtime"; // 
-        @compilationMode(all)
-function nonReactFn() {
-  const $ = _c(1);
-  let t0;
-  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
-    t0 = {};
-    $[0] = t0;
-  } else {
-    t0 = $[0];
-  }
-  return t0;
-}

compiler/apps/playground/__tests__/e2e/__snapshots__/page.spec.ts/compilationMode-infer-output.txt

@@ -1,4 +0,0 @@
-// @compilationMode(infer)
-function nonReactFn() {
-  return {};
-}

compiler/apps/playground/__tests__/e2e/__snapshots__/page.spec.ts/default-input.txt

@@ -0,0 +1,11 @@
+function MyApp() {
+  const $ = _c(1);
+  let t0;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    t0 = <div>Hello World</div>;
+    $[0] = t0;
+  } else {
+    t0 = $[0];
+  }
+  return t0;
+}

compiler/apps/playground/__tests__/e2e/__snapshots__/page.spec.ts/function-scope-beats-module-scope-output.txt

@@ -1,14 +0,0 @@
-function TestComponent(t0) {
-  "use memo";
-  const $ = _c(2);
-  const { x } = t0;
-  let t1;
-  if ($[0] !== x) {
-    t1 = <Button>{x}</Button>;
-    $[0] = x;
-    $[1] = t1;
-  } else {
-    t1 = $[1];
-  }
-  return t1;
-}

compiler/apps/playground/__tests__/e2e/__snapshots__/page.spec.ts/module-scope-use-memo-output.txt

@@ -1,15 +0,0 @@
-"use memo";
-import { c as _c } from "react/compiler-runtime";
-export default function TestComponent(t0) {
-  const $ = _c(2);
-  const { x } = t0;
-  let t1;
-  if ($[0] !== x) {
-    t1 = <Button>{x}</Button>;
-    $[0] = x;
-    $[1] = t1;
-  } else {
-    t1 = $[1];
-  }
-  return t1;
-}

compiler/apps/playground/__tests__/e2e/__snapshots__/page.spec.ts/module-scope-use-no-memo-output.txt

@@ -1,4 +0,0 @@
-"use no memo";
-export default function TestComponent({ x }) {
-  return <Button>{x}</Button>;
-}

compiler/apps/playground/__tests__/e2e/__snapshots__/page.spec.ts/parse-flow-output.txt

@@ -1,14 +0,0 @@
-import { c as _c } from "react/compiler-runtime";
-function useFoo(propVal) {
-  const $ = _c(2);
-  const t0 = (propVal.baz: number);
-  let t1;
-  if ($[0] !== t0) {
-    t1 = <div>{t0}</div>;
-    $[0] = t0;
-    $[1] = t1;
-  } else {
-    t1 = $[1];
-  }
-  return t1;
-}

compiler/apps/playground/__tests__/e2e/__snapshots__/page.spec.ts/parse-typescript-output.txt

@@ -1,20 +0,0 @@
-import { c as _c } from "react/compiler-runtime";
-function Foo() {
-  const $ = _c(2);
-  let t0;
-  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
-    t0 = foo();
-    $[0] = t0;
-  } else {
-    t0 = $[0];
-  }
-  const x = t0 as number;
-  let t1;
-  if ($[1] === Symbol.for("react.memo_cache_sentinel")) {
-    t1 = <div>{x}</div>;
-    $[1] = t1;
-  } else {
-    t1 = $[1];
-  }
-  return t1;
-}

compiler/apps/playground/__tests__/e2e/__snapshots__/page.spec.ts/todo-function-scope-does-not-beat-module-scope-output.txt

@@ -1,5 +0,0 @@
-"use no memo";
-function TestComponent({ x }) {
-  "use memo";
-  return <Button>{x}</Button>;
-}

compiler/apps/playground/__tests__/e2e/__snapshots__/page.spec.ts/use-memo-output.txt

@@ -1,29 +0,0 @@
-import { c as _c } from "react/compiler-runtime";
-function TestComponent(t0) {
-  "use memo";
-  const $ = _c(2);
-  const { x } = t0;
-  let t1;
-  if ($[0] !== x) {
-    t1 = <Button>{x}</Button>;
-    $[0] = x;
-    $[1] = t1;
-  } else {
-    t1 = $[1];
-  }
-  return t1;
-}
-const TestComponent2 = (t0) => {
-  "use memo";
-  const $ = _c(2);
-  const { x } = t0;
-  let t1;
-  if ($[0] !== x) {
-    t1 = <Button>{x}</Button>;
-    $[0] = x;
-    $[1] = t1;
-  } else {
-    t1 = $[1];
-  }
-  return t1;
-};

compiler/apps/playground/__tests__/e2e/__snapshots__/page.spec.ts/use-no-memo-output.txt

@@ -1,8 +0,0 @@
-const TestComponent = function () {
-  "use no memo";
-  return <Button>{x}</Button>;
-};
-const TestComponent2 = ({ x }) => {
-  "use no memo";
-  return <Button>{x}</Button>;
-};

compiler/apps/playground/__tests__/e2e/__snapshots__/page.spec.ts/user-input.txt

@@ -0,0 +1,13 @@
+function TestComponent(t0) {
+  const $ = _c(2);
+  const { x } = t0;
+  let t1;
+  if ($[0] !== x) {
+    t1 = <Button>{x}</Button>;
+    $[0] = x;
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  return t1;
+}

compiler/apps/playground/__tests__/e2e/page.spec.ts

@@ -5,193 +5,45 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {expect, test} from '@playwright/test';
-import {encodeStore, type Store} from '../../lib/stores';
-import {format} from 'prettier';
+import { expect, test } from "@playwright/test";
+import { encodeStore, type Store } from "../../lib/stores";
 
-function isMonacoLoaded(): boolean {
-  return (
-    typeof window['MonacoEnvironment'] !== 'undefined' &&
-    window['__MONACO_LOADED__'] === true
-  );
-}
-
-function formatPrint(data: Array<string>): Promise<string> {
-  return format(data.join(''), {parser: 'babel'});
-}
-
-const TEST_CASE_INPUTS = [
-  {
-    name: 'module-scope-use-memo',
-    input: `
-'use memo';
-export default function TestComponent({ x }) {
+const STORE: Store = {
+  source: `export default function TestComponent({ x }) {
   return <Button>{x}</Button>;
-}`,
-  },
-  {
-    name: 'module-scope-use-no-memo',
-    input: `
-'use no memo';
-export default function TestComponent({ x }) {
-  return <Button>{x}</Button>;
-}`,
-  },
-  {
-    name: 'use-memo',
-    input: `
-function TestComponent({ x }) {
-  'use memo';
-  return <Button>{x}</Button>;
-}
-const TestComponent2 = ({ x }) => {
-  'use memo';
-  return <Button>{x}</Button>;
-};`,
-  },
-  {
-    name: 'use-no-memo',
-    input: `
-const TestComponent = function() {
-  'use no memo';
-  return <Button>{x}</Button>;
-};
-const TestComponent2 = ({ x }) => {
-  'use no memo';
-  return <Button>{x}</Button>;
-};`,
-  },
-  {
-    name: 'todo-function-scope-does-not-beat-module-scope',
-    input: `
-'use no memo';
-function TestComponent({ x }) {
-  'use memo';
-  return <Button>{x}</Button>;
-}`,
-  },
-  {
-    name: 'parse-typescript',
-    input: `
-function Foo() {
-  const x = foo() as number;
-  return <div>{x}</div>;
 }
 `,
-    noFormat: true,
-  },
-  {
-    name: 'parse-flow',
-    input: `
-// @flow
-function useFoo(propVal: {+baz: number}) {
-  return <div>{(propVal.baz as number)}</div>;
-}
-    `,
-    noFormat: true,
-  },
-  {
-    name: 'compilationMode-infer',
-    input: `// @compilationMode(infer)
-function nonReactFn() {
-  return {};
-}
-    `,
-    noFormat: true,
-  },
-  {
-    name: 'compilationMode-all',
-    input: `// @compilationMode(all)
-function nonReactFn() {
-  return {};
-}
-    `,
-    noFormat: true,
-  },
-];
+};
+const HASH = encodeStore(STORE);
 
-test('editor should open successfully', async ({page}) => {
-  await page.goto(`/`, {waitUntil: 'networkidle'});
-  await page.waitForFunction(isMonacoLoaded);
+function concat(data: Array<string>): string {
+  return data.join("");
+}
+
+test("editor should compile successfully", async ({ page }) => {
+  await page.goto(`/#${HASH}`, { waitUntil: "networkidle" });
   await page.screenshot({
     fullPage: true,
-    path: 'test-results/00-fresh-page.png',
+    path: "test-results/00-on-networkidle.png",
   });
-});
-
-test('editor should compile from hash successfully', async ({page}) => {
-  const store: Store = {
-    source: `export default function TestComponent({ x }) {
-      return <Button>{x}</Button>;
-    }
-    `,
-  };
-  const hash = encodeStore(store);
-  await page.goto(`/#${hash}`, {waitUntil: 'networkidle'});
-  await page.waitForFunction(isMonacoLoaded);
 
   // User input from hash compiles
   await page.screenshot({
     fullPage: true,
-    path: 'test-results/01-compiles-from-hash.png',
+    path: "test-results/01-show-js-before.png",
   });
-  const text =
-    (await page.locator('.monaco-editor').nth(1).allInnerTexts()) ?? [];
-  const output = await formatPrint(text);
-
-  expect(output).not.toEqual('');
-  expect(output).toMatchSnapshot('01-user-output.txt');
-});
-
-test('reset button works', async ({page}) => {
-  const store: Store = {
-    source: `export default function TestComponent({ x }) {
-      return <Button>{x}</Button>;
-    }
-    `,
-  };
-  const hash = encodeStore(store);
-  await page.goto(`/#${hash}`, {waitUntil: 'networkidle'});
-  await page.waitForFunction(isMonacoLoaded);
+  const userInput =
+    (await page.locator(".monaco-editor").nth(2).allInnerTexts()) ?? [];
+  expect(concat(userInput)).toMatchSnapshot("user-input.txt");
 
   // Reset button works
-  page.on('dialog', dialog => dialog.accept());
-  await page.getByRole('button', {name: 'Reset'}).click();
+  page.on("dialog", (dialog) => dialog.accept());
+  await page.getByRole("button", { name: "Reset" }).click();
   await page.screenshot({
     fullPage: true,
-    path: 'test-results/02-reset-button-works.png',
+    path: "test-results/02-show-js-after.png",
   });
-  const text =
-    (await page.locator('.monaco-editor').nth(1).allInnerTexts()) ?? [];
-  const output = await formatPrint(text);
-
-  expect(output).not.toEqual('');
-  expect(output).toMatchSnapshot('02-default-output.txt');
+  const defaultInput =
+    (await page.locator(".monaco-editor").nth(2).allInnerTexts()) ?? [];
+  expect(concat(defaultInput)).toMatchSnapshot("default-input.txt");
 });
-
-TEST_CASE_INPUTS.forEach((t, idx) =>
-  test(`playground compiles: ${t.name}`, async ({page}) => {
-    const store: Store = {
-      source: t.input,
-    };
-    const hash = encodeStore(store);
-    await page.goto(`/#${hash}`, {waitUntil: 'networkidle'});
-    await page.waitForFunction(isMonacoLoaded);
-    await page.screenshot({
-      fullPage: true,
-      path: `test-results/03-0${idx}-${t.name}.png`,
-    });
-
-    const text =
-      (await page.locator('.monaco-editor').nth(1).allInnerTexts()) ?? [];
-    let output: string;
-    if (t.noFormat) {
-      output = text.join('');
-    } else {
-      output = await formatPrint(text);
-    }
-
-    expect(output).not.toEqual('');
-    expect(output).toMatchSnapshot(`${t.name}-output.txt`);
-  }),
-);

compiler/apps/playground/app/index.tsx

@@ -5,24 +5,25 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import type {NextPage} from 'next';
-import Head from 'next/head';
-import {SnackbarProvider} from 'notistack';
-import {Editor, Header, StoreProvider} from '../components';
-import MessageSnackbar from '../components/Message';
+import type { NextPage } from "next";
+import Head from "next/head";
+import { SnackbarProvider } from "notistack";
+import { Editor, Header, StoreProvider } from "../components";
+import MessageSnackbar from "../components/Message";
 
 const Home: NextPage = () => {
   return (
     <div className="flex flex-col w-screen h-screen font-light">
       <Head>
         <title>
-          {process.env.NODE_ENV === 'development'
-            ? '[DEV] React Compiler Playground'
-            : 'React Compiler Playground'}
+          {process.env.NODE_ENV === "development"
+            ? "[DEV] React Compiler Playground"
+            : "React Compiler Playground"}
         </title>
         <meta
           name="viewport"
-          content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=0"></meta>
+          content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=0"
+        ></meta>
         <link rel="icon" href="/favicon.ico" />
         <link rel="manifest" href="/site.webmanifest" />
         <link
@@ -44,7 +45,8 @@ const Home: NextPage = () => {
         <SnackbarProvider
           preventDuplicate
           maxSnack={10}
-          Components={{message: MessageSnackbar}}>
+          Components={{ message: MessageSnackbar }}
+        >
           <Header />
           <Editor />
         </SnackbarProvider>

compiler/apps/playground/app/layout.tsx

@@ -5,25 +5,26 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import '../styles/globals.css';
+import "../styles/globals.css";
 
 export default function RootLayout({
   children,
 }: {
   children: React.ReactNode;
-}): JSX.Element {
-  'use no memo';
+}) {
+  "use no memo";
   return (
     <html lang="en">
       <head>
         <title>
-          {process.env.NODE_ENV === 'development'
-            ? '[DEV] React Compiler Playground'
-            : 'React Compiler Playground'}
+          {process.env.NODE_ENV === "development"
+            ? "[DEV] React Compiler Playground"
+            : "React Compiler Playground"}
         </title>
         <meta
           name="viewport"
-          content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=0"></meta>
+          content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=0"
+        ></meta>
         <link rel="icon" href="/favicon.ico" />
         <link rel="manifest" href="/site.webmanifest" />
         <link

compiler/apps/playground/app/page.tsx

@@ -5,19 +5,20 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-'use client';
+"use client";
 
-import {SnackbarProvider} from 'notistack';
-import {Editor, Header, StoreProvider} from '../components';
-import MessageSnackbar from '../components/Message';
+import { SnackbarProvider } from "notistack";
+import { Editor, Header, StoreProvider } from "../components";
+import MessageSnackbar from "../components/Message";
 
-export default function Page(): JSX.Element {
+export default function Hoot() {
   return (
     <StoreProvider>
       <SnackbarProvider
         preventDuplicate
         maxSnack={10}
-        Components={{message: MessageSnackbar}}>
+        Components={{ message: MessageSnackbar }}
+      >
         <Header />
         <Editor />
       </SnackbarProvider>

compiler/apps/playground/babel.config.js

@@ -0,0 +1,21 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+module.exports = function (api) {
+  api.cache(true);
+  return {
+    presets: ["next/babel"],
+    plugins: [
+      [
+        "babel-plugin-react-compiler",
+        {
+          runtimeModule: "react-compiler-runtime",
+        },
+      ],
+    ],
+  };
+};

compiler/apps/playground/colors.js

@@ -11,86 +11,86 @@
 
 module.exports = {
   // Text colors
-  primary: '#23272F', // gray-90
-  'primary-dark': '#F6F7F9', // gray-5
-  secondary: '#404756', // gray-70
-  'secondary-dark': '#EBECF0', // gray-10
-  link: '#087EA4', // blue-50
-  'link-dark': '#149ECA', // blue-40
-  syntax: '#EBECF0', // gray-10
-  wash: '#FFFFFF',
-  'wash-dark': '#23272F', // gray-90
-  card: '#F6F7F9', // gray-05
-  'card-dark': '#343A46', // gray-80
-  highlight: '#E6F7FF', // blue-10
-  'highlight-dark': 'rgba(88,175,223,.1)',
-  border: '#EBECF0', // gray-10
-  'border-dark': '#343A46', // gray-80
-  'secondary-button': '#EBECF0', // gray-10
-  'secondary-button-dark': '#404756', // gray-70
+  primary: "#23272F", // gray-90
+  "primary-dark": "#F6F7F9", // gray-5
+  secondary: "#404756", // gray-70
+  "secondary-dark": "#EBECF0", // gray-10
+  link: "#087EA4", // blue-50
+  "link-dark": "#149ECA", // blue-40
+  syntax: "#EBECF0", // gray-10
+  wash: "#FFFFFF",
+  "wash-dark": "#23272F", // gray-90
+  card: "#F6F7F9", // gray-05
+  "card-dark": "#343A46", // gray-80
+  highlight: "#E6F7FF", // blue-10
+  "highlight-dark": "rgba(88,175,223,.1)",
+  border: "#EBECF0", // gray-10
+  "border-dark": "#343A46", // gray-80
+  "secondary-button": "#EBECF0", // gray-10
+  "secondary-button-dark": "#404756", // gray-70
 
   // Gray
-  'gray-95': '#16181D',
-  'gray-90': '#23272F',
-  'gray-80': '#343A46',
-  'gray-70': '#404756',
-  'gray-60': '#4E5769',
-  'gray-50': '#5E687E', // unused
-  'gray-40': '#78839B',
-  'gray-30': '#99A1B3',
-  'gray-20': '#BCC1CD',
-  'gray-10': '#EBECF0',
-  'gray-5': '#F6F7F9',
+  "gray-95": "#16181D",
+  "gray-90": "#23272F",
+  "gray-80": "#343A46",
+  "gray-70": "#404756",
+  "gray-60": "#4E5769",
+  "gray-50": "#5E687E", // unused
+  "gray-40": "#78839B",
+  "gray-30": "#99A1B3",
+  "gray-20": "#BCC1CD",
+  "gray-10": "#EBECF0",
+  "gray-5": "#F6F7F9",
 
   // Blue
-  'blue-60': '#045975',
-  'blue-50': '#087EA4',
-  'blue-40': '#149ECA', // Brand Blue
-  'blue-30': '#58C4DC', // unused
-  'blue-20': '#ABE2ED',
-  'blue-10': '#E6F7FF', // todo: doesn't match illustrations
-  'blue-5': '#E6F6FA',
+  "blue-60": "#045975",
+  "blue-50": "#087EA4",
+  "blue-40": "#149ECA", // Brand Blue
+  "blue-30": "#58C4DC", // unused
+  "blue-20": "#ABE2ED",
+  "blue-10": "#E6F7FF", // todo: doesn't match illustrations
+  "blue-5": "#E6F6FA",
 
   // Yellow
-  'yellow-60': '#B65700',
-  'yellow-50': '#C76A15',
-  'yellow-40': '#DB7D27', // unused
-  'yellow-30': '#FABD62', // unused
-  'yellow-20': '#FCDEB0', // unused
-  'yellow-10': '#FDE7C7',
-  'yellow-5': '#FEF5E7',
+  "yellow-60": "#B65700",
+  "yellow-50": "#C76A15",
+  "yellow-40": "#DB7D27", // unused
+  "yellow-30": "#FABD62", // unused
+  "yellow-20": "#FCDEB0", // unused
+  "yellow-10": "#FDE7C7",
+  "yellow-5": "#FEF5E7",
 
   // Purple
-  'purple-60': '#2B3491', // unused
-  'purple-50': '#575FB7',
-  'purple-40': '#6B75DB',
-  'purple-30': '#8891EC',
-  'purple-20': '#C3C8F5', // unused
-  'purple-10': '#E7E9FB',
-  'purple-5': '#F3F4FD',
+  "purple-60": "#2B3491", // unused
+  "purple-50": "#575FB7",
+  "purple-40": "#6B75DB",
+  "purple-30": "#8891EC",
+  "purple-20": "#C3C8F5", // unused
+  "purple-10": "#E7E9FB",
+  "purple-5": "#F3F4FD",
 
   // Green
-  'green-60': '#2B6E62',
-  'green-50': '#388F7F',
-  'green-40': '#44AC99',
-  'green-30': '#7FCCBF',
-  'green-20': '#ABDED5',
-  'green-10': '#E5F5F2',
-  'green-5': '#F4FBF9',
+  "green-60": "#2B6E62",
+  "green-50": "#388F7F",
+  "green-40": "#44AC99",
+  "green-30": "#7FCCBF",
+  "green-20": "#ABDED5",
+  "green-10": "#E5F5F2",
+  "green-5": "#F4FBF9",
 
   // RED
-  'red-60': '#712D28',
-  'red-50': '#A6423A', // unused
-  'red-40': '#C1554D',
-  'red-30': '#D07D77',
-  'red-20': '#E5B7B3', // unused
-  'red-10': '#F2DBD9', // unused
-  'red-5': '#FAF1F0',
+  "red-60": "#712D28",
+  "red-50": "#A6423A", // unused
+  "red-40": "#C1554D",
+  "red-30": "#D07D77",
+  "red-20": "#E5B7B3", // unused
+  "red-10": "#F2DBD9", // unused
+  "red-5": "#FAF1F0",
 
   // MISC
-  'code-block': '#99a1b30f', // gray-30 @ 6%
-  'gradient-blue': '#58C4DC', // Only used for the landing gradient for now.
+  "code-block": "#99a1b30f", // gray-30 @ 6%
+  "gradient-blue": "#58C4DC", // Only used for the landing gradient for now.
   github: {
-    highlight: '#fffbdd',
+    highlight: "#fffbdd",
   },
 };

compiler/apps/playground/components/Editor/EditorImpl.tsx

@@ -5,96 +5,99 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {parse as babelParse, ParseResult} from '@babel/parser';
-import * as HermesParser from 'hermes-parser';
-import * as t from '@babel/types';
-import BabelPluginReactCompiler, {
+import { parse, ParserPlugin } from "@babel/parser";
+import traverse, { NodePath } from "@babel/traverse";
+import * as t from "@babel/types";
+import {
   CompilerError,
   CompilerErrorDetail,
   Effect,
   ErrorSeverity,
-  parseConfigPragmaForTests,
+  parseConfigPragma,
+  printHIR,
+  printReactiveFunction,
+  run,
   ValueKind,
   type Hook,
-  PluginOptions,
-  CompilerPipelineValue,
-  parsePluginOptions,
-} from 'babel-plugin-react-compiler/src';
-import clsx from 'clsx';
-import invariant from 'invariant';
-import {useSnackbar} from 'notistack';
-import {useDeferredValue, useMemo} from 'react';
-import {useMountEffect} from '../../hooks';
-import {defaultStore} from '../../lib/defaultStore';
+} from "babel-plugin-react-compiler/src";
+import { type ReactFunctionType } from "babel-plugin-react-compiler/src/HIR/Environment";
+import clsx from "clsx";
+import invariant from "invariant";
+import { useSnackbar } from "notistack";
+import { useDeferredValue, useMemo } from "react";
+import { useMountEffect } from "../../hooks";
+import { defaultStore } from "../../lib/defaultStore";
 import {
   createMessage,
   initStoreFromUrlOrLocalStorage,
   MessageLevel,
   MessageSource,
   type Store,
-} from '../../lib/stores';
-import {useStore, useStoreDispatch} from '../StoreContext';
-import Input from './Input';
+} from "../../lib/stores";
+import { useStore, useStoreDispatch } from "../StoreContext";
+import Input from "./Input";
 import {
   CompilerOutput,
-  CompilerTransformOutput,
   default as Output,
   PrintedCompilerPipelineValue,
-} from './Output';
-import {printFunctionWithOutlined} from 'babel-plugin-react-compiler/src/HIR/PrintHIR';
-import {printReactiveFunctionWithOutlined} from 'babel-plugin-react-compiler/src/ReactiveScopes/PrintReactiveFunction';
-import {transformFromAstSync} from '@babel/core';
+} from "./Output";
 
-function parseInput(
-  input: string,
-  language: 'flow' | 'typescript',
-): ParseResult<t.File> {
-  // Extract the first line to quickly check for custom test directives
-  if (language === 'flow') {
-    return HermesParser.parse(input, {
-      babel: true,
-      flow: 'all',
-      sourceType: 'module',
-      enableExperimentalComponentSyntax: true,
+function parseFunctions(
+  source: string
+): Array<
+  NodePath<
+    t.FunctionDeclaration | t.ArrowFunctionExpression | t.FunctionExpression
+  >
+> {
+  const items: Array<
+    NodePath<
+      t.FunctionDeclaration | t.ArrowFunctionExpression | t.FunctionExpression
+    >
+  > = [];
+  try {
+    const isFlow = source
+      .trim()
+      .split("\n", 1)[0]
+      .match(/\s*\/\/\s*\@flow\s*/);
+    let type_transform: ParserPlugin;
+    if (isFlow) {
+      type_transform = "flow";
+    } else {
+      type_transform = "typescript";
+    }
+    const ast = parse(source, {
+      plugins: [type_transform, "jsx"],
+      sourceType: "module",
+    });
+    traverse(ast, {
+      FunctionDeclaration(nodePath) {
+        items.push(nodePath);
+        nodePath.skip();
+      },
+      ArrowFunctionExpression(nodePath) {
+        items.push(nodePath);
+        nodePath.skip();
+      },
+      FunctionExpression(nodePath) {
+        items.push(nodePath);
+        nodePath.skip();
+      },
+    });
+  } catch (e) {
+    console.error(e);
+    CompilerError.throwInvalidJS({
+      reason: String(e),
+      description: null,
+      loc: null,
+      suggestions: null,
     });
-  } else {
-    return babelParse(input, {
-      plugins: ['typescript', 'jsx'],
-      sourceType: 'module',
-    }) as ParseResult<t.File>;
   }
-}
-
-function invokeCompiler(
-  source: string,
-  language: 'flow' | 'typescript',
-  options: PluginOptions,
-): CompilerTransformOutput {
-  const ast = parseInput(source, language);
-  let result = transformFromAstSync(ast, source, {
-    filename: '_playgroundFile.js',
-    highlightCode: false,
-    retainLines: true,
-    plugins: [[BabelPluginReactCompiler, options]],
-    ast: true,
-    sourceType: 'module',
-    configFile: false,
-    sourceMaps: true,
-    babelrc: false,
-  });
-  if (result?.ast == null || result?.code == null || result?.map == null) {
-    throw new Error('Expected successful compilation');
-  }
-  return {
-    code: result.code,
-    sourceMaps: result.map,
-    language,
-  };
+  return items;
 }
 
 const COMMON_HOOKS: Array<[string, Hook]> = [
   [
-    'useFragment',
+    "useFragment",
     {
       valueKind: ValueKind.Frozen,
       effectKind: Effect.Freeze,
@@ -103,7 +106,7 @@ const COMMON_HOOKS: Array<[string, Hook]> = [
     },
   ],
   [
-    'usePaginationFragment',
+    "usePaginationFragment",
     {
       valueKind: ValueKind.Frozen,
       effectKind: Effect.Freeze,
@@ -112,7 +115,7 @@ const COMMON_HOOKS: Array<[string, Hook]> = [
     },
   ],
   [
-    'useRefetchableFragment',
+    "useRefetchableFragment",
     {
       valueKind: ValueKind.Frozen,
       effectKind: Effect.Freeze,
@@ -121,7 +124,7 @@ const COMMON_HOOKS: Array<[string, Hook]> = [
     },
   ],
   [
-    'useLazyLoadQuery',
+    "useLazyLoadQuery",
     {
       valueKind: ValueKind.Frozen,
       effectKind: Effect.Freeze,
@@ -130,7 +133,7 @@ const COMMON_HOOKS: Array<[string, Hook]> = [
     },
   ],
   [
-    'usePreloadedQuery',
+    "usePreloadedQuery",
     {
       valueKind: ValueKind.Frozen,
       effectKind: Effect.Freeze,
@@ -140,10 +143,30 @@ const COMMON_HOOKS: Array<[string, Hook]> = [
   ],
 ];
 
-function compile(source: string): [CompilerOutput, 'flow' | 'typescript'] {
-  const results = new Map<string, Array<PrintedCompilerPipelineValue>>();
+function isHookName(s: string): boolean {
+  return /^use[A-Z0-9]/.test(s);
+}
+
+function getReactFunctionType(
+  id: NodePath<t.Identifier | null | undefined>
+): ReactFunctionType {
+  if (id && id.node && id.isIdentifier()) {
+    if (isHookName(id.node.name)) {
+      return "Hook";
+    }
+
+    const isPascalCaseNameSpace = /^[A-Z].*/;
+    if (isPascalCaseNameSpace.test(id.node.name)) {
+      return "Component";
+    }
+  }
+  return "Other";
+}
+
+function compile(source: string): CompilerOutput {
+  const results = new Map<string, PrintedCompilerPipelineValue[]>();
   const error = new CompilerError();
-  const upsert: (result: PrintedCompilerPipelineValue) => void = result => {
+  const upsert = (result: PrintedCompilerPipelineValue) => {
     const entry = results.get(result.name);
     if (Array.isArray(entry)) {
       entry.push(result);
@@ -151,81 +174,99 @@ function compile(source: string): [CompilerOutput, 'flow' | 'typescript'] {
       results.set(result.name, [result]);
     }
   };
-  let language: 'flow' | 'typescript';
-  if (source.match(/\@flow/)) {
-    language = 'flow';
-  } else {
-    language = 'typescript';
-  }
-  let transformOutput;
   try {
     // Extract the first line to quickly check for custom test directives
-    const pragma = source.substring(0, source.indexOf('\n'));
-    const logIR = (result: CompilerPipelineValue): void => {
-      switch (result.kind) {
-        case 'ast': {
-          break;
-        }
-        case 'hir': {
-          upsert({
-            kind: 'hir',
-            fnName: result.value.id,
-            name: result.name,
-            value: printFunctionWithOutlined(result.value),
-          });
-          break;
-        }
-        case 'reactive': {
-          upsert({
-            kind: 'reactive',
-            fnName: result.value.id,
-            name: result.name,
-            value: printReactiveFunctionWithOutlined(result.value),
-          });
-          break;
-        }
-        case 'debug': {
-          upsert({
-            kind: 'debug',
-            fnName: null,
-            name: result.name,
-            value: result.value,
-          });
-          break;
-        }
-        default: {
-          const _: never = result;
-          throw new Error(`Unhandled result ${result}`);
+    const pragma = source.substring(0, source.indexOf("\n"));
+    const config = parseConfigPragma(pragma);
+
+    for (const fn of parseFunctions(source)) {
+      if (!fn.isFunctionDeclaration()) {
+        error.pushErrorDetail(
+          new CompilerErrorDetail({
+            reason: `Unexpected function type ${fn.node.type}`,
+            description:
+              "Playground only supports parsing function declarations",
+            severity: ErrorSeverity.Todo,
+            loc: fn.node.loc ?? null,
+            suggestions: null,
+          })
+        );
+        continue;
+      }
+
+      const id = fn.get("id");
+      for (const result of run(
+        fn,
+        {
+          ...config,
+          customHooks: new Map([...COMMON_HOOKS]),
+        },
+        getReactFunctionType(id),
+        "_c",
+        null,
+        null,
+        null
+      )) {
+        const fnName = fn.node.id?.name ?? null;
+        switch (result.kind) {
+          case "ast": {
+            upsert({
+              kind: "ast",
+              fnName,
+              name: result.name,
+              value: {
+                type: "FunctionDeclaration",
+                id: result.value.id,
+                async: result.value.async,
+                generator: result.value.generator,
+                body: result.value.body,
+                params: result.value.params,
+              },
+            });
+            break;
+          }
+          case "hir": {
+            upsert({
+              kind: "hir",
+              fnName,
+              name: result.name,
+              value: printHIR(result.value.body),
+            });
+            break;
+          }
+          case "reactive": {
+            upsert({
+              kind: "reactive",
+              fnName,
+              name: result.name,
+              value: printReactiveFunction(result.value),
+            });
+            break;
+          }
+          case "debug": {
+            upsert({
+              kind: "debug",
+              fnName,
+              name: result.name,
+              value: result.value,
+            });
+            break;
+          }
+          default: {
+            const _: never = result;
+            throw new Error(`Unhandled result ${result}`);
+          }
         }
       }
-    };
-    const parsedOptions = parseConfigPragmaForTests(pragma, {
-      compilationMode: 'infer',
-    });
-    const opts: PluginOptions = parsePluginOptions({
-      ...parsedOptions,
-      environment: {
-        ...parsedOptions.environment,
-        customHooks: new Map([...COMMON_HOOKS]),
-      },
-      logger: {
-        debugLogIRs: logIR,
-        logEvent: () => {},
-      },
-    });
-    transformOutput = invokeCompiler(source, language, opts);
+    }
   } catch (err) {
-    /**
-     * error might be an invariant violation or other runtime error
-     * (i.e. object shape that is not CompilerError)
-     */
+    // error might be an invariant violation or other runtime error
+    // (i.e. object shape that is not CompilerError)
     if (err instanceof CompilerError && err.details.length > 0) {
       error.details.push(...err.details);
     } else {
-      /**
-       * Handle unexpected failures by logging (to get a stack trace)
-       * and reporting
-       */
+      // Handle unexpected failures by logging (to get a stack trace)
+      // and reporting
       console.error(err);
       error.details.push(
         new CompilerErrorDetail({
@@ -233,24 +274,24 @@ function compile(source: string): [CompilerOutput, 'flow' | 'typescript'] {
           reason: `Unexpected failure when transforming input! ${err}`,
           loc: null,
           suggestions: null,
-        }),
+        })
       );
     }
   }
   if (error.hasErrors()) {
-    return [{kind: 'err', results, error: error}, language];
+    return { kind: "err", results, error: error };
   }
-  return [{kind: 'ok', results, transformOutput}, language];
+  return { kind: "ok", results };
 }
 
-export default function Editor(): JSX.Element {
+export default function Editor() {
   const store = useStore();
   const deferredStore = useDeferredValue(store);
   const dispatchStore = useStoreDispatch();
-  const {enqueueSnackbar} = useSnackbar();
-  const [compilerOutput, language] = useMemo(
+  const { enqueueSnackbar } = useSnackbar();
+  const compilerOutput = useMemo(
     () => compile(deferredStore.source),
-    [deferredStore.source],
+    [deferredStore.source]
   );
 
   useMountEffect(() => {
@@ -258,35 +299,34 @@ export default function Editor(): JSX.Element {
     try {
       mountStore = initStoreFromUrlOrLocalStorage();
     } catch (e) {
-      invariant(e instanceof Error, 'Only Error may be caught.');
+      invariant(e instanceof Error, "Only Error may be caught.");
       enqueueSnackbar(e.message, {
-        variant: 'warning',
+        variant: "message",
         ...createMessage(
-          'Bad URL - fell back to the default Playground.',
+          "Bad URL - fell back to the default Playground.",
           MessageLevel.Info,
-          MessageSource.Playground,
+          MessageSource.Playground
         ),
       });
       mountStore = defaultStore;
     }
     dispatchStore({
-      type: 'setStore',
-      payload: {store: mountStore},
+      type: "setStore",
+      payload: { store: mountStore },
     });
   });
 
   return (
     <>
       <div className="relative flex basis top-14">
-        <div className={clsx('relative sm:basis-1/4')}>
+        <div className={clsx("relative sm:basis-1/4")}>
           <Input
-            language={language}
             errors={
-              compilerOutput.kind === 'err' ? compilerOutput.error.details : []
+              compilerOutput.kind === "err" ? compilerOutput.error.details : []
             }
           />
         </div>
-        <div className={clsx('flex sm:flex flex-wrap')}>
+        <div className={clsx("flex sm:flex flex-wrap")}>
           <Output store={deferredStore} compilerOutput={compilerOutput} />
         </div>
       </div>

compiler/apps/playground/components/Editor/Input.tsx

@@ -5,27 +5,27 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import MonacoEditor, {loader, type Monaco} from '@monaco-editor/react';
-import {CompilerErrorDetail} from 'babel-plugin-react-compiler/src';
-import invariant from 'invariant';
-import type {editor} from 'monaco-editor';
-import * as monaco from 'monaco-editor';
-import {Resizable} from 're-resizable';
-import {useEffect, useState} from 'react';
-import {renderReactCompilerMarkers} from '../../lib/reactCompilerMonacoDiagnostics';
-import {useStore, useStoreDispatch} from '../StoreContext';
-import {monacoOptions} from './monacoOptions';
-// @ts-expect-error TODO: Make TS recognize .d.ts files, in addition to loading them with webpack.
-import React$Types from '../../node_modules/@types/react/index.d.ts';
+import MonacoEditor, { loader, type Monaco } from "@monaco-editor/react";
+import { CompilerErrorDetail } from "babel-plugin-react-compiler/src";
+import invariant from "invariant";
+import type { editor } from "monaco-editor";
+import * as monaco from "monaco-editor";
+import { Resizable } from "re-resizable";
+import { useEffect, useState } from "react";
+import { renderReactCompilerMarkers } from "../../lib/reactCompilerMonacoDiagnostics";
+import { useStore, useStoreDispatch } from "../StoreContext";
+import { monacoOptions } from "./monacoOptions";
+// TODO: Make TS recognize .d.ts files, in addition to loading them with webpack.
+// @ts-ignore
+import React$Types from "../../node_modules/@types/react/index.d.ts";
 
-loader.config({monaco});
+loader.config({ monaco });
 
 type Props = {
-  errors: Array<CompilerErrorDetail>;
-  language: 'flow' | 'typescript';
+  errors: CompilerErrorDetail[];
 };
 
-export default function Input({errors, language}: Props): JSX.Element {
+export default function Input({ errors }: Props) {
   const [monaco, setMonaco] = useState<Monaco | null>(null);
   const store = useStore();
   const dispatchStore = useStoreDispatch();
@@ -35,75 +35,48 @@ export default function Input({errors, language}: Props): JSX.Element {
     if (!monaco) return;
     const uri = monaco.Uri.parse(`file:///index.js`);
     const model = monaco.editor.getModel(uri);
-    invariant(model, 'Model must exist for the selected input file.');
-    renderReactCompilerMarkers({monaco, model, details: errors});
-    /**
-     * N.B. that `tabSize` is a model property, not an editor property.
-     * So, the tab size has to be set per model.
-     */
-    model.updateOptions({tabSize: 2});
+    invariant(model, "Model must exist for the selected input file.");
+    renderReactCompilerMarkers({ monaco, model, details: errors });
+    // N.B. that `tabSize` is a model property, not an editor property.
+    // So, the tab size has to be set per model.
+    model.updateOptions({ tabSize: 2 });
   }, [monaco, errors]);
 
-  useEffect(() => {
-    /**
-     * Ignore "can only be used in TypeScript files." errors, since
-     * we want to support syntax highlighting for Flow (*.js) files
-     * and Flow is not a built-in language.
-     */
-    if (!monaco) return;
-    monaco.languages.typescript.javascriptDefaults.setDiagnosticsOptions({
-      diagnosticCodesToIgnore: [
-        8002,
-        8003,
-        8004,
-        8005,
-        8006,
-        8008,
-        8009,
-        8010,
-        8011,
-        8012,
-        8013,
-        ...(language === 'flow'
-          ? [7028 /* unused label */, 6133 /* var declared but not read */]
-          : []),
-      ],
-      noSemanticValidation: true,
-      // Monaco can't validate Flow component syntax
-      noSyntaxValidation: language === 'flow',
-    });
-  }, [monaco, language]);
-
-  const handleChange: (value: string | undefined) => void = value => {
+  const handleChange = (value: string | undefined) => {
     if (!value) return;
 
     dispatchStore({
-      type: 'updateFile',
+      type: "updateFile",
       payload: {
         source: value,
       },
     });
   };
 
-  const handleMount: (
-    _: editor.IStandaloneCodeEditor,
-    monaco: Monaco,
-  ) => void = (_, monaco) => {
-    if (typeof window !== 'undefined') {
-      window['__MONACO_LOADED__'] = true;
-    }
+  const handleMount = (_: editor.IStandaloneCodeEditor, monaco: Monaco) => {
     setMonaco(monaco);
 
+    // Ignore "can only be used in TypeScript files." errors, since
+    // we want to support syntax highlighting for Flow (*.js) files
+    // and Flow is not a built-in language.
+    monaco.languages.typescript.javascriptDefaults.setDiagnosticsOptions({
+      diagnosticCodesToIgnore: [
+        8002, 8003, 8004, 8005, 8006, 8008, 8009, 8010, 8011, 8012, 8013,
+      ],
+      noSemanticValidation: true,
+      noSyntaxValidation: false,
+    });
+
     const tscOptions = {
       allowNonTsExtensions: true,
       target: monaco.languages.typescript.ScriptTarget.ES2015,
       moduleResolution: monaco.languages.typescript.ModuleResolutionKind.NodeJs,
       jsx: monaco.languages.typescript.JsxEmit.Preserve,
-      typeRoots: ['node_modules/@types'],
+      typeRoots: ["node_modules/@types"],
       allowSyntheticDefaultImports: true,
     };
     monaco.languages.typescript.javascriptDefaults.setCompilerOptions(
-      tscOptions,
+      tscOptions
     );
     monaco.languages.typescript.typescriptDefaults.setCompilerOptions({
       ...tscOptions,
@@ -114,17 +87,15 @@ export default function Input({errors, language}: Props): JSX.Element {
     // Add React type declarations to Monaco
     const reactLib = [
       React$Types,
-      'file:///node_modules/@types/react/index.d.ts',
+      "file:///node_modules/@types/react/index.d.ts",
     ] as [any, string];
     monaco.languages.typescript.javascriptDefaults.addExtraLib(...reactLib);
     monaco.languages.typescript.typescriptDefaults.addExtraLib(...reactLib);
 
-    /**
-     * Remeasure the font in case the custom font is loaded only after
-     * Monaco Editor is mounted.
-     * N.B. that this applies also to the output editor as it seems
-     * Monaco Editor instances share the same font config.
-     */
+    // Remeasure the font in case the custom font is loaded only after
+    // Monaco Editor is mounted.
+    // N.B. that this applies also to the output editor as it seems
+    // Monaco Editor instances share the same font config.
     document.fonts.ready.then(() => {
       monaco.editor.remeasureFonts();
     });
@@ -134,20 +105,17 @@ export default function Input({errors, language}: Props): JSX.Element {
     <div className="relative flex flex-col flex-none border-r border-gray-200">
       <Resizable
         minWidth={650}
-        enable={{right: true}}
-        /**
-         * Restrict MonacoEditor's height, since the config autoLayout:true
-         * will grow the editor to fit within parent element
-         */
-        className="!h-[calc(100vh_-_3.5rem)]">
+        enable={{ right: true }}
+        // Restrict MonacoEditor's height, since the config autoLayout:true
+        // will grow the editor to fit within parent element
+        className="!h-[calc(100vh_-_3.5rem)]"
+      >
         <MonacoEditor
-          path={'index.js'}
-          /**
-           * .js and .jsx files are specified to be TS so that Monaco can actually
-           * check their syntax using its TS language service. They are still JS files
-           * due to their extensions, so TS language features don't work.
-           */
-          language={'javascript'}
+          path={"index.js"}
+          // .js and .jsx files are specified to be TS so that Monaco can actually
+          // check their syntax using its TS language service. They are still JS files
+          // due to their extensions, so TS language features don't work.
+          language={"javascript"}
           value={store.source}
           onMount={handleMount}
           onChange={handleChange}

compiler/apps/playground/components/Editor/Output.tsx

@@ -5,49 +5,47 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+import generate from "@babel/generator";
+import * as t from "@babel/types";
 import {
   CodeIcon,
   DocumentAddIcon,
   InformationCircleIcon,
-} from '@heroicons/react/outline';
-import MonacoEditor, {DiffEditor} from '@monaco-editor/react';
-import {type CompilerError} from 'babel-plugin-react-compiler/src';
-import parserBabel from 'prettier/plugins/babel';
-import * as prettierPluginEstree from 'prettier/plugins/estree';
-import * as prettier from 'prettier/standalone';
-import {memo, ReactNode, useEffect, useState} from 'react';
-import {type Store} from '../../lib/stores';
-import TabbedWindow from '../TabbedWindow';
-import {monacoOptions} from './monacoOptions';
-import {BabelFileResult} from '@babel/core';
+} from "@heroicons/react/outline";
+import MonacoEditor, { DiffEditor } from "@monaco-editor/react";
+import { type CompilerError } from "babel-plugin-react-compiler/src";
+import parserBabel from "prettier/plugins/babel";
+import * as prettierPluginEstree from "prettier/plugins/estree";
+import * as prettier from "prettier/standalone";
+import { memo, useEffect, useState } from "react";
+import { type Store } from "../../lib/stores";
+import TabbedWindow from "../TabbedWindow";
+import { monacoOptions } from "./monacoOptions";
 const MemoizedOutput = memo(Output);
 
 export default MemoizedOutput;
 
 export type PrintedCompilerPipelineValue =
   | {
-      kind: 'hir';
+      kind: "ast";
+      name: string;
+      fnName: string | null;
+      value: t.FunctionDeclaration;
+    }
+  | {
+      kind: "hir";
       name: string;
       fnName: string | null;
       value: string;
     }
-  | {kind: 'reactive'; name: string; fnName: string | null; value: string}
-  | {kind: 'debug'; name: string; fnName: string | null; value: string};
+  | { kind: "reactive"; name: string; fnName: string | null; value: string }
+  | { kind: "debug"; name: string; fnName: string | null; value: string };
 
-export type CompilerTransformOutput = {
-  code: string;
-  sourceMaps: BabelFileResult['map'];
-  language: 'flow' | 'typescript';
-};
 export type CompilerOutput =
+  | { kind: "ok"; results: Map<string, PrintedCompilerPipelineValue[]> }
   | {
-      kind: 'ok';
-      transformOutput: CompilerTransformOutput;
-      results: Map<string, Array<PrintedCompilerPipelineValue>>;
-    }
-  | {
-      kind: 'err';
-      results: Map<string, Array<PrintedCompilerPipelineValue>>;
+      kind: "err";
+      results: Map<string, PrintedCompilerPipelineValue[]>;
       error: CompilerError;
     };
 
@@ -56,18 +54,16 @@ type Props = {
   compilerOutput: CompilerOutput;
 };
 
-async function tabify(
-  source: string,
-  compilerOutput: CompilerOutput,
-): Promise<Map<string, ReactNode>> {
+async function tabify(source: string, compilerOutput: CompilerOutput) {
   const tabs = new Map<string, React.ReactNode>();
   const reorderedTabs = new Map<string, React.ReactNode>();
   const concattedResults = new Map<string, string>();
+  let topLevelFnDecls: Array<t.FunctionDeclaration> = [];
   // Concat all top level function declaration results into a single tab for each pass
   for (const [passName, results] of compilerOutput.results) {
     for (const result of results) {
       switch (result.kind) {
-        case 'hir': {
+        case "hir": {
           const prev = concattedResults.get(result.name);
           const next = result.value;
           const identName = `function ${result.fnName}`;
@@ -78,7 +74,7 @@ async function tabify(
           }
           break;
         }
-        case 'reactive': {
+        case "reactive": {
           const prev = concattedResults.get(passName);
           const next = result.value;
           if (prev != null) {
@@ -88,58 +84,56 @@ async function tabify(
           }
           break;
         }
-        case 'debug': {
+        case "ast":
+          topLevelFnDecls.push(result.value);
+          break;
+        case "debug": {
           concattedResults.set(passName, result.value);
           break;
         }
         default: {
           const _: never = result;
-          throw new Error('Unexpected result kind');
+          throw new Error("Unexpected result kind");
         }
       }
     }
   }
   let lastPassOutput: string | null = null;
-  let nonDiffPasses = ['HIR', 'BuildReactiveFunction', 'EnvironmentConfig'];
   for (const [passName, text] of concattedResults) {
     tabs.set(
       passName,
       <TextTabContent
         output={text}
-        diff={lastPassOutput}
-        showInfoPanel={!nonDiffPasses.includes(passName)}></TextTabContent>,
+        diff={passName !== "HIR" ? lastPassOutput : null}
+        showInfoPanel={true}
+      ></TextTabContent>
     );
     lastPassOutput = text;
   }
   // Ensure that JS and the JS source map come first
-  if (compilerOutput.kind === 'ok') {
-    const {transformOutput} = compilerOutput;
-    const sourceMapUrl = getSourceMapUrl(
-      transformOutput.code,
-      JSON.stringify(transformOutput.sourceMaps),
-    );
-    const code = await prettier.format(transformOutput.code, {
-      semi: true,
-      parser: transformOutput.language === 'flow' ? 'babel-flow' : 'babel-ts',
-      plugins: [parserBabel, prettierPluginEstree],
-    });
+  if (topLevelFnDecls.length > 0) {
+    // Make a synthetic Program so we can have a single AST with all the top level
+    // FunctionDeclarations
+    const ast = t.program(topLevelFnDecls);
+    const { code, sourceMapUrl } = await codegen(ast, source);
     reorderedTabs.set(
-      'JS',
+      "JS",
       <TextTabContent
         output={code}
         diff={null}
-        showInfoPanel={false}></TextTabContent>,
+        showInfoPanel={false}
+      ></TextTabContent>
     );
     if (sourceMapUrl) {
       reorderedTabs.set(
-        'SourceMap',
+        "SourceMap",
         <>
           <iframe
             src={sourceMapUrl}
             className="w-full h-monaco_small sm:h-monaco"
             title="Generated Code"
           />
-        </>,
+        </>
       );
     }
   }
@@ -149,6 +143,27 @@ async function tabify(
   return reorderedTabs;
 }
 
+async function codegen(
+  ast: t.Program,
+  source: string
+): Promise<{ code: any; sourceMapUrl: string | null }> {
+  const generated = generate(
+    ast,
+    { sourceMaps: true, sourceFileName: "input.js" },
+    source
+  );
+  const sourceMapUrl = getSourceMapUrl(
+    generated.code,
+    JSON.stringify(generated.map)
+  );
+  const codegenOutput = await prettier.format(generated.code, {
+    semi: true,
+    parser: "babel",
+    plugins: [parserBabel, prettierPluginEstree],
+  });
+  return { code: codegenOutput, sourceMapUrl };
+}
+
 function utf16ToUTF8(s: string): string {
   return unescape(encodeURIComponent(s));
 }
@@ -157,30 +172,30 @@ function getSourceMapUrl(code: string, map: string): string | null {
   code = utf16ToUTF8(code);
   map = utf16ToUTF8(map);
   return `https://evanw.github.io/source-map-visualization/#${btoa(
-    `${code.length}\0${code}${map.length}\0${map}`,
+    `${code.length}\0${code}${map.length}\0${map}`
   )}`;
 }
 
-function Output({store, compilerOutput}: Props): JSX.Element {
-  const [tabsOpen, setTabsOpen] = useState<Set<string>>(() => new Set(['JS']));
+function Output({ store, compilerOutput }: Props) {
+  const [tabsOpen, setTabsOpen] = useState<Set<string>>(() => new Set(["JS"]));
   const [tabs, setTabs] = useState<Map<string, React.ReactNode>>(
-    () => new Map(),
+    () => new Map()
   );
   useEffect(() => {
-    tabify(store.source, compilerOutput).then(tabs => {
+    tabify(store.source, compilerOutput).then((tabs) => {
       setTabs(tabs);
     });
   }, [store.source, compilerOutput]);
 
-  const changedPasses: Set<string> = new Set(['JS', 'HIR']); // Initial and final passes should always be bold
-  let lastResult: string = '';
+  const changedPasses: Set<string> = new Set();
+  let lastResult: string = "";
   for (const [passName, results] of compilerOutput.results) {
     for (const result of results) {
-      let currResult = '';
-      if (result.kind === 'hir' || result.kind === 'reactive') {
+      let currResult = "";
+      if (result.kind === "hir" || result.kind === "reactive") {
         currResult += `function ${result.fnName}\n\n${result.value}`;
       }
-      if (currResult !== lastResult) {
+      if (passName !== "HIR" && currResult !== lastResult) {
         changedPasses.add(passName);
       }
       lastResult = currResult;
@@ -196,16 +211,18 @@ function Output({store, compilerOutput}: Props): JSX.Element {
         tabs={tabs}
         changedPasses={changedPasses}
       />
-      {compilerOutput.kind === 'err' ? (
+      {compilerOutput.kind === "err" ? (
         <div
           className="flex flex-wrap absolute bottom-0 bg-white grow border-y border-grey-200 transition-all ease-in"
-          style={{width: 'calc(100vw - 650px)'}}>
+          style={{ width: "calc(100vw - 650px)" }}
+        >
           <div className="w-full p-4 basis-full border-b">
             <h2>COMPILER ERRORS</h2>
           </div>
           <pre
             className="p-4 basis-full text-red-600 overflow-y-scroll whitespace-pre-wrap"
-            style={{width: 'calc(100vw - 650px)', height: '150px'}}>
+            style={{ width: "calc(100vw - 650px)", height: "150px" }}
+          >
             <code>{compilerOutput.error.toString()}</code>
           </pre>
         </div>
@@ -222,20 +239,19 @@ function TextTabContent({
   output: string;
   diff: string | null;
   showInfoPanel: boolean;
-}): JSX.Element {
+}) {
   const [diffMode, setDiffMode] = useState(false);
   return (
-    /**
-     * Restrict MonacoEditor's height, since the config autoLayout:true
-     * will grow the editor to fit within parent element
-     */
+    // Restrict MonacoEditor's height, since the config autoLayout:true
+    // will grow the editor to fit within parent element
     <div className="w-full h-monaco_small sm:h-monaco">
       {showInfoPanel ? (
         <div className="flex items-center gap-1 bg-amber-50 p-2">
           {diff != null && output !== diff ? (
             <button
               className="flex items-center gap-1 transition-colors duration-150 ease-in text-secondary hover:text-link"
-              onClick={() => setDiffMode(diffMode => !diffMode)}>
+              onClick={() => setDiffMode((diffMode) => !diffMode)}
+            >
               {!diffMode ? (
                 <>
                   <DocumentAddIcon className="w-5 h-5" /> Show Diff
@@ -263,7 +279,7 @@ function TextTabContent({
           options={{
             ...monacoOptions,
             readOnly: true,
-            lineNumbers: 'off',
+            lineNumbers: "off",
             glyphMargin: false,
             // Undocumented see https://github.com/Microsoft/vscode/issues/30795#issuecomment-410998882
             lineDecorationsWidth: 0,
@@ -277,7 +293,7 @@ function TextTabContent({
           options={{
             ...monacoOptions,
             readOnly: true,
-            lineNumbers: 'off',
+            lineNumbers: "off",
             glyphMargin: false,
             // Undocumented see https://github.com/Microsoft/vscode/issues/30795#issuecomment-410998882
             lineDecorationsWidth: 0,

compiler/apps/playground/components/Editor/index.tsx

@@ -5,13 +5,11 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import dynamic from 'next/dynamic';
+import dynamic from "next/dynamic";
 
-/**
- * monaco-editor is currently not compatible with ssr
- * https://github.com/vercel/next.js/issues/31692
- */
-const Editor = dynamic(() => import('./EditorImpl'), {
+// monaco-editor is currently not compatible with ssr
+// https://github.com/vercel/next.js/issues/31692
+const Editor = dynamic(() => import("./EditorImpl"), {
   ssr: false,
 });
 

compiler/apps/playground/components/Editor/monacoOptions.ts

@@ -5,11 +5,11 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import type {EditorProps} from '@monaco-editor/react';
+import type { EditorProps } from "@monaco-editor/react";
 
-export const monacoOptions: Partial<EditorProps['options']> = {
+export const monacoOptions: Partial<EditorProps["options"]> = {
   fontSize: 14,
-  padding: {top: 8},
+  padding: { top: 8 },
   scrollbar: {
     verticalScrollbarSize: 10,
     alwaysConsumeMouseWheel: false,
@@ -22,11 +22,11 @@ export const monacoOptions: Partial<EditorProps['options']> = {
   fontFamily: '"Source Code Pro", monospace',
   glyphMargin: true,
 
-  autoClosingBrackets: 'languageDefined',
-  autoClosingDelete: 'always',
-  autoClosingOvertype: 'always',
+  autoClosingBrackets: "languageDefined",
+  autoClosingDelete: "always",
+  autoClosingOvertype: "always",
 
   automaticLayout: true,
-  wordWrap: 'on',
-  wrappingIndent: 'deepIndent',
+  wordWrap: "on",
+  wrappingIndent: "deepIndent",
 };

compiler/apps/playground/components/Header.tsx

@@ -5,39 +5,39 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {RefreshIcon, ShareIcon} from '@heroicons/react/outline';
-import {CheckIcon} from '@heroicons/react/solid';
-import clsx from 'clsx';
-import Link from 'next/link';
-import {useSnackbar} from 'notistack';
-import {useState} from 'react';
-import {defaultStore} from '../lib/defaultStore';
-import {IconGitHub} from './Icons/IconGitHub';
-import Logo from './Logo';
-import {useStoreDispatch} from './StoreContext';
+import { RefreshIcon, ShareIcon } from "@heroicons/react/outline";
+import { CheckIcon } from "@heroicons/react/solid";
+import clsx from "clsx";
+import Link from "next/link";
+import { useSnackbar } from "notistack";
+import { useState } from "react";
+import { defaultStore } from "../lib/defaultStore";
+import { IconGitHub } from "./Icons/IconGitHub";
+import Logo from "./Logo";
+import { useStoreDispatch } from "./StoreContext";
 
-export default function Header(): JSX.Element {
+export default function Header() {
   const [showCheck, setShowCheck] = useState(false);
   const dispatchStore = useStoreDispatch();
-  const {enqueueSnackbar, closeSnackbar} = useSnackbar();
+  const { enqueueSnackbar, closeSnackbar } = useSnackbar();
 
-  const handleReset: () => void = () => {
-    if (confirm('Are you sure you want to reset the playground?')) {
-      /**
-       * Close open snackbars if any. This is necessary because when displaying
-       * outputs (Preview or not), we only close previous snackbars if we received
-       * new messages, which is needed in order to display "Bad URL" or success
-       * messages when loading Playground for the first time. Otherwise, messages
-       * such as "Bad URL" will be closed by the outputs calling `closeSnackbar`.
-       */
+  const handleReset = () => {
+    if (confirm("Are you sure you want to reset the playground?")) {
+      /*
+        Close open snackbars if any. This is necessary because when displaying
+        outputs (Preview or not), we only close previous snackbars if we received
+        new messages, which is needed in order to display "Bad URL" or success
+        messages when loading Playground for the first time. Otherwise, messages
+        such as "Bad URL" will be closed by the outputs calling `closeSnackbar`.
+      */
       closeSnackbar();
-      dispatchStore({type: 'setStore', payload: {store: defaultStore}});
+      dispatchStore({ type: "setStore", payload: { store: defaultStore } });
     }
   };
 
-  const handleShare: () => void = () => {
+  const handleShare = () => {
     navigator.clipboard.writeText(location.href).then(() => {
-      enqueueSnackbar('URL copied to clipboard');
+      enqueueSnackbar("URL copied to clipboard");
       setShowCheck(true);
       // Show the check mark icon briefly after URL is copied
       setTimeout(() => setShowCheck(false), 1000);
@@ -49,8 +49,8 @@ export default function Header(): JSX.Element {
       <div className="flex items-center flex-none h-full gap-2 text-lg">
         <Logo
           className={clsx(
-            'w-8 h-8 text-link',
-            process.env.NODE_ENV === 'development' && 'text-yellow-600',
+            "w-8 h-8 text-link",
+            process.env.NODE_ENV === "development" && "text-yellow-600"
           )}
         />
         <p className="hidden select-none sm:block">React Compiler Playground</p>
@@ -60,7 +60,8 @@ export default function Header(): JSX.Element {
           title="Reset Playground"
           aria-label="Reset Playground"
           className="flex items-center gap-1 transition-colors duration-150 ease-in text-secondary hover:text-link"
-          onClick={handleReset}>
+          onClick={handleReset}
+        >
           <RefreshIcon className="w-5 h-5" />
           <p className="hidden sm:block">Reset</p>
         </button>
@@ -69,7 +70,8 @@ export default function Header(): JSX.Element {
           aria-label="Copy sharable URL"
           className="flex items-center gap-1 transition-colors duration-150 ease-in text-secondary hover:text-link"
           onClick={handleShare}
-          disabled={showCheck}>
+          disabled={showCheck}
+        >
           {!showCheck ? (
             <ShareIcon className="w-5 h-5" />
           ) : (
@@ -82,7 +84,8 @@ export default function Header(): JSX.Element {
           target="_blank"
           rel="noreferrer noopener"
           aria-label="Open on GitHub"
-          className="flex items-center gap-1 transition-colors duration-150 ease-in text-secondary hover:text-link">
+          className="flex items-center gap-1 transition-colors duration-150 ease-in text-secondary hover:text-link"
+        >
           <IconGitHub />
         </Link>
       </div>

compiler/apps/playground/components/Icons/IconGitHub.tsx

@@ -5,9 +5,9 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {memo} from 'react';
+import { memo } from "react";
 
-export const IconGitHub = memo<JSX.IntrinsicElements['svg']>(
+export const IconGitHub = memo<JSX.IntrinsicElements["svg"]>(
   function IconGitHub(props) {
     return (
       <svg
@@ -16,9 +16,10 @@ export const IconGitHub = memo<JSX.IntrinsicElements['svg']>(
         height="1.5em"
         viewBox="0 -2 24 24"
         fill="currentColor"
-        {...props}>
+        {...props}
+      >
         <path d="M10 0a10 10 0 0 0-3.16 19.49c.5.1.68-.22.68-.48l-.01-1.7c-2.78.6-3.37-1.34-3.37-1.34-.46-1.16-1.11-1.47-1.11-1.47-.9-.62.07-.6.07-.6 1 .07 1.53 1.03 1.53 1.03.9 1.52 2.34 1.08 2.91.83.1-.65.35-1.09.63-1.34-2.22-.25-4.55-1.11-4.55-4.94 0-1.1.39-1.99 1.03-2.69a3.6 3.6 0 0 1 .1-2.64s.84-.27 2.75 1.02a9.58 9.58 0 0 1 5 0c1.91-1.3 2.75-1.02 2.75-1.02.55 1.37.2 2.4.1 2.64.64.7 1.03 1.6 1.03 2.69 0 3.84-2.34 4.68-4.57 4.93.36.31.68.92.68 1.85l-.01 2.75c0 .26.18.58.69.48A10 10 0 0 0 10 0"></path>
       </svg>
     );
-  },
+  }
 );

compiler/apps/playground/components/Logo.tsx

@@ -7,13 +7,14 @@
 
 // https://github.com/reactjs/reactjs.org/blob/main/beta/src/components/Logo.tsx
 
-export default function Logo(props: JSX.IntrinsicElements['svg']): JSX.Element {
+export default function Logo(props: JSX.IntrinsicElements["svg"]) {
   return (
     <svg
       viewBox="0 0 410 369"
       fill="none"
       xmlns="http://www.w3.org/2000/svg"
-      {...props}>
+      {...props}
+    >
       <path
         d="M204.995 224.552C226.56 224.552 244.042 207.07 244.042 185.506C244.042 163.941 226.56 146.459 204.995 146.459C183.43 146.459 165.948 163.941 165.948 185.506C165.948 207.07 183.43 224.552 204.995 224.552Z"
         fill="currentColor"

compiler/apps/playground/components/Message.tsx

@@ -10,13 +10,13 @@ import {
   ExclamationIcon,
   InformationCircleIcon,
   XIcon,
-} from '@heroicons/react/solid';
-import {CustomContentProps, SnackbarContent, useSnackbar} from 'notistack';
-import {forwardRef} from 'react';
-import {MessageLevel, MessageSource} from '../lib/stores';
+} from "@heroicons/react/solid";
+import { CustomContentProps, SnackbarContent, useSnackbar } from "notistack";
+import { forwardRef } from "react";
+import { MessageLevel, MessageSource } from "../lib/stores";
 
 // https://notistack.com/examples/advanced/custom-component#custom-variant-(typescript)
-declare module 'notistack' {
+declare module "notistack" {
   interface VariantOverrides {
     message: {
       title: string;
@@ -34,14 +34,15 @@ interface MessageProps extends CustomContentProps {
 }
 
 const Message = forwardRef<HTMLDivElement, MessageProps>(
-  ({id, title, level, source, codeframe}, ref) => {
-    const {closeSnackbar} = useSnackbar();
+  ({ id, title, level, source, codeframe }, ref) => {
+    const { closeSnackbar } = useSnackbar();
     const isDismissible = source !== MessageSource.Playground;
 
     return (
       <SnackbarContent
         ref={ref}
-        className="flex items-start justify-between gap-3 px-4 py-3 text-sm bg-white border rounded-md shadow w-toast">
+        className="flex items-start justify-between gap-3 px-4 py-3 text-sm bg-white border rounded-md shadow w-toast"
+      >
         <div className="flex gap-3 w-toast-body">
           {level === MessageLevel.Warning ? (
             <div className="flex items-center justify-center flex-none rounded-md w-7 h-7 bg-amber-100">
@@ -68,15 +69,16 @@ const Message = forwardRef<HTMLDivElement, MessageProps>(
         {isDismissible ? (
           <button
             className="flex items-center justify-center flex-none transition-colors duration-150 ease-in rounded-md justify-self-end group w-7 h-7 hover:bg-gray-200"
-            onClick={() => closeSnackbar(id)}>
+            onClick={() => closeSnackbar(id)}
+          >
             <XIcon className="w-5 h-5 fill-gray-500 group-hover:fill-gray-800" />
           </button>
         ) : null}
       </SnackbarContent>
     );
-  },
+  }
 );
 
-Message.displayName = 'MessageComponent';
+Message.displayName = "MessageComponent";
 
 export default Message;

compiler/apps/playground/components/StoreContext.tsx

@@ -5,11 +5,12 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import type {Dispatch, ReactNode} from 'react';
-import {useEffect, useReducer} from 'react';
-import createContext from '../lib/createContext';
-import {emptyStore} from '../lib/defaultStore';
-import {saveStore, type Store} from '../lib/stores';
+import type { Dispatch, ReactNode } from "react";
+import { useReducer } from "react";
+import createContext from "../lib/createContext";
+import { emptyStore } from "../lib/defaultStore";
+import type { Store } from "../lib/stores";
+import { saveStore } from "../lib/stores";
 
 const StoreContext = createContext<Store>();
 
@@ -28,13 +29,8 @@ export const useStoreDispatch = StoreDispatchContext.useContext;
 /**
  * Make Store and dispatch function available to all sub-components in children.
  */
-export function StoreProvider({children}: {children: ReactNode}): JSX.Element {
+export function StoreProvider({ children }: { children: ReactNode }) {
   const [store, dispatch] = useReducer(storeReducer, emptyStore);
-  useEffect(() => {
-    if (store !== emptyStore) {
-      saveStore(store);
-    }
-  }, [store]);
 
   return (
     <StoreContext.Provider value={store}>
@@ -47,13 +43,13 @@ export function StoreProvider({children}: {children: ReactNode}): JSX.Element {
 
 type ReducerAction =
   | {
-      type: 'setStore';
+      type: "setStore";
       payload: {
         store: Store;
       };
     }
   | {
-      type: 'updateFile';
+      type: "updateFile";
       payload: {
         source: string;
       };
@@ -61,16 +57,21 @@ type ReducerAction =
 
 function storeReducer(store: Store, action: ReducerAction): Store {
   switch (action.type) {
-    case 'setStore': {
+    case "setStore": {
       const newStore = action.payload.store;
+
+      saveStore(newStore);
       return newStore;
     }
-    case 'updateFile': {
-      const {source} = action.payload;
+    case "updateFile": {
+      const { source } = action.payload;
+
       const newStore = {
         ...store,
         source,
       };
+
+      saveStore(newStore);
       return newStore;
     }
   }

compiler/apps/playground/components/TabbedWindow.tsx

@@ -5,8 +5,8 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {Resizable} from 're-resizable';
-import React, {useCallback} from 'react';
+import { Resizable } from "re-resizable";
+import React, { useCallback } from "react";
 
 type TabsRecord = Map<string, React.ReactNode>;
 
@@ -21,14 +21,15 @@ export default function TabbedWindow(props: {
     return (
       <div
         className="flex items-center justify-center"
-        style={{width: 'calc(100vw - 650px)'}}>
+        style={{ width: "calc(100vw - 650px)" }}
+      >
         No compiler output detected, see errors below
       </div>
     );
   }
   return (
     <div className="flex flex-row">
-      {Array.from(props.tabs.keys()).map(name => {
+      {Array.from(props.tabs.keys()).map((name) => {
         return (
           <TabbedWindowItem
             name={name}
@@ -69,21 +70,19 @@ function TabbedWindowItem({
     setTabsOpen(nextState);
   }, [tabsOpen, name, setTabsOpen]);
 
-  // Replace spaces with non-breaking spaces
-  const displayName = name.replace(/ /g, '\u00A0');
-
   return (
     <div key={name} className="flex flex-row">
       {isShow ? (
-        <Resizable className="border-r" minWidth={550} enable={{right: true}}>
+        <Resizable className="border-r" minWidth={550} enable={{ right: true }}>
           <h2
             title="Minimize tab"
             aria-label="Minimize tab"
             onClick={toggleTabs}
             className={`p-4 duration-150 ease-in border-b cursor-pointer border-grey-200 ${
-              hasChanged ? 'font-bold' : 'font-light'
-            } text-secondary hover:text-link`}>
-            - {displayName}
+              hasChanged ? "font-bold" : "font-light"
+            } text-secondary hover:text-link`}
+          >
+            - {name}
           </h2>
           {tabs.get(name) ?? <div>No output for {name}</div>}
         </Resizable>
@@ -92,12 +91,13 @@ function TabbedWindowItem({
           <button
             title={`Expand compiler tab: ${name}`}
             aria-label={`Expand compiler tab: ${name}`}
-            style={{transform: 'rotate(90deg) translate(-50%)'}}
+            style={{ transform: "rotate(90deg) translate(-50%)" }}
             onClick={toggleTabs}
             className={`flex-grow-0 w-5 transition-colors duration-150 ease-in ${
-              hasChanged ? 'font-bold' : 'font-light'
-            } text-secondary hover:text-link`}>
-            {displayName}
+              hasChanged ? "font-bold" : "font-light"
+            } text-secondary hover:text-link`}
+          >
+            {name}
           </button>
         </div>
       )}

compiler/apps/playground/components/index.ts

@@ -5,6 +5,6 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-export {default as Editor} from './Editor';
-export {default as Header} from './Header';
-export {StoreProvider} from './StoreContext';
+export { default as Editor } from "./Editor";
+export { default as Header } from "./Header";
+export { StoreProvider } from "./StoreContext";

compiler/apps/playground/hooks/index.ts

@@ -5,4 +5,4 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-export {default as useMountEffect} from './useMountEffect';
+export { default as useMountEffect } from "./useMountEffect";

compiler/apps/playground/hooks/useMountEffect.ts

@@ -5,8 +5,8 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import type {EffectCallback} from 'react';
-import {useEffect} from 'react';
+import type { EffectCallback } from "react";
+import { useEffect } from "react";
 
 export default function useMountEffect(effect: EffectCallback) {
   return useEffect(effect, []);

compiler/apps/playground/lib/createContext.ts

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import React from 'react';
+import React from "react";
 
 /**
  * Replacement to React.createContext.
@@ -23,18 +23,15 @@ import React from 'react';
  * Instead, it throws an error when `useContext` is not called within a
  * Provider with a value.
  */
-export default function createContext<T>(): {
-  useContext: () => NonNullable<T>;
-  Provider: React.Provider<T | null>;
-} {
+export default function createContext<T>() {
   const context = React.createContext<T | null>(null);
 
-  function useContext(): NonNullable<T> {
+  function useContext() {
     const c = React.useContext(context);
     if (!c)
-      throw new Error('useContext must be within a Provider with a value');
+      throw new Error("useContext must be within a Provider with a value");
     return c;
   }
 
-  return {useContext, Provider: context.Provider};
+  return { useContext, Provider: context.Provider };
 }

compiler/apps/playground/lib/defaultStore.ts

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import type {Store} from './stores';
+import type { Store } from "./stores";
 
 const index = `\
 export default function MyApp() {
@@ -18,5 +18,5 @@ export const defaultStore: Store = {
 };
 
 export const emptyStore: Store = {
-  source: '',
+  source: "",
 };

compiler/apps/playground/lib/reactCompilerMonacoDiagnostics.ts

@@ -5,16 +5,16 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {Monaco} from '@monaco-editor/react';
+import { Monaco } from "@monaco-editor/react";
 import {
   CompilerErrorDetail,
   ErrorSeverity,
-} from 'babel-plugin-react-compiler/src';
-import {MarkerSeverity, type editor} from 'monaco-editor';
+} from "babel-plugin-react-compiler/src";
+import { MarkerSeverity, type editor } from "monaco-editor";
 
 function mapReactCompilerSeverityToMonaco(
   level: ErrorSeverity,
-  monaco: Monaco,
+  monaco: Monaco
 ): MarkerSeverity {
   switch (level) {
     case ErrorSeverity.Todo:
@@ -26,9 +26,9 @@ function mapReactCompilerSeverityToMonaco(
 
 function mapReactCompilerDiagnosticToMonacoMarker(
   detail: CompilerErrorDetail,
-  monaco: Monaco,
+  monaco: Monaco
 ): editor.IMarkerData | null {
-  if (detail.loc == null || typeof detail.loc === 'symbol') {
+  if (detail.loc == null || typeof detail.loc === "symbol") {
     return null;
   }
   const severity = mapReactCompilerSeverityToMonaco(detail.severity, monaco);
@@ -46,9 +46,9 @@ function mapReactCompilerDiagnosticToMonacoMarker(
 type ReactCompilerMarkerConfig = {
   monaco: Monaco;
   model: editor.ITextModel;
-  details: Array<CompilerErrorDetail>;
+  details: CompilerErrorDetail[];
 };
-let decorations: Array<string> = [];
+let decorations: string[] = [];
 export function renderReactCompilerMarkers({
   monaco,
   model,
@@ -63,27 +63,27 @@ export function renderReactCompilerMarkers({
     markers.push(marker);
   }
   if (markers.length > 0) {
-    monaco.editor.setModelMarkers(model, 'owner', markers);
-    const newDecorations = markers.map(marker => {
+    monaco.editor.setModelMarkers(model, "owner", markers);
+    const newDecorations = markers.map((marker) => {
       return {
         range: new monaco.Range(
           marker.startLineNumber,
           marker.startColumn,
           marker.endLineNumber,
-          marker.endColumn,
+          marker.endColumn
         ),
         options: {
           isWholeLine: true,
-          glyphMarginClassName: 'bg-red-300',
+          glyphMarginClassName: "bg-red-300",
         },
       };
     });
     decorations = model.deltaDecorations(decorations, newDecorations);
   } else {
-    monaco.editor.setModelMarkers(model, 'owner', []);
+    monaco.editor.setModelMarkers(model, "owner", []);
     decorations = model.deltaDecorations(
-      model.getAllDecorations().map(d => d.id),
-      [],
+      model.getAllDecorations().map((d) => d.id),
+      []
     );
   }
 }

compiler/apps/playground/lib/stores/index.ts

@@ -5,5 +5,5 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-export * from './messages';
-export * from './store';
+export * from "./messages";
+export * from "./store";

compiler/apps/playground/lib/stores/messages.ts

@@ -27,10 +27,10 @@ export interface Message {
 export function createMessage(
   message: string,
   level: MessageLevel,
-  source: MessageSource,
+  source: MessageSource
 ): Message {
-  const [title, ...body] = message.split('\n');
-  const codeframe = body.length > 0 ? body.join('\n') : undefined;
+  const [title, ...body] = message.split("\n");
+  const codeframe = body.length > 0 ? body.join("\n") : undefined;
 
   return {
     source,

compiler/apps/playground/lib/stores/store.ts

@@ -5,12 +5,12 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import invariant from 'invariant';
+import invariant from "invariant";
 import {
   compressToEncodedURIComponent,
   decompressFromEncodedURIComponent,
-} from 'lz-string';
-import {defaultStore} from '../defaultStore';
+} from "lz-string";
+import { defaultStore } from "../defaultStore";
 
 /**
  * Global Store for Playground
@@ -28,10 +28,10 @@ export function decodeStore(hash: string): Store {
 /**
  * Serialize, encode, and save @param store to localStorage and update URL.
  */
-export function saveStore(store: Store): void {
+export function saveStore(store: Store) {
   const hash = encodeStore(store);
-  localStorage.setItem('playgroundStore', hash);
-  history.replaceState({}, '', `#${hash}`);
+  localStorage.setItem("playgroundStore", hash);
+  history.replaceState({}, "", `#${hash}`);
 }
 
 /**
@@ -41,9 +41,9 @@ export function saveStore(store: Store): void {
 function isValidStore(raw: unknown): raw is Store {
   return (
     raw != null &&
-    typeof raw == 'object' &&
-    'source' in raw &&
-    typeof raw['source'] === 'string'
+    typeof raw == "object" &&
+    "source" in raw &&
+    typeof raw["source"] === "string"
   );
 }
 
@@ -53,17 +53,15 @@ function isValidStore(raw: unknown): raw is Store {
  */
 export function initStoreFromUrlOrLocalStorage(): Store {
   const encodedSourceFromUrl = location.hash.slice(1);
-  const encodedSourceFromLocal = localStorage.getItem('playgroundStore');
+  const encodedSourceFromLocal = localStorage.getItem("playgroundStore");
   const encodedSource = encodedSourceFromUrl || encodedSourceFromLocal;
 
-  /**
-   * No data in the URL and no data in the localStorage to fallback to.
-   * Initialize with the default store.
-   */
+  // No data in the URL and no data in the localStorage to fallback to.
+  // Initialize with the default store.
   if (!encodedSource) return defaultStore;
 
   const raw = decodeStore(encodedSource);
 
-  invariant(isValidStore(raw), 'Invalid Store');
+  invariant(isValidStore(raw), "Invalid Store");
   return raw;
 }

compiler/apps/playground/lib/types.d.ts

@@ -1,20 +0,0 @@
-/**
- * Copyright (c) Meta Platforms, Inc. and affiliates.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- */
-
-// v0.17.1
-declare module "hermes-parser" {
-  type HermesParserOptions = {
-    allowReturnOutsideFunction?: boolean;
-    babel?: boolean;
-    flow?: "all" | "detect";
-    enableExperimentalComponentSyntax?: boolean;
-    sourceFilename?: string;
-    sourceType?: "module" | "script" | "unambiguous";
-    tokens?: boolean;
-  };
-  export function parse(code: string, options: Partial<HermesParserOptions>);
-}

compiler/apps/playground/next-env.d.ts

@@ -2,4 +2,4 @@
 /// <reference types="next/image-types/global" />
 
 // NOTE: This file should not be edited
-// see https://nextjs.org/docs/app/api-reference/config/typescript for more information.
+// see https://nextjs.org/docs/basic-features/typescript for more information.

compiler/apps/playground/next.config.js

@@ -5,48 +5,40 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-const MonacoWebpackPlugin = require('monaco-editor-webpack-plugin');
-const path = require('path');
+const MonacoWebpackPlugin = require("monaco-editor-webpack-plugin");
+const path = require("path");
 
 const nextConfig = {
-  experimental: {
-    reactCompiler: true,
-  },
   reactStrictMode: true,
   webpack: (config, options) => {
     // Load *.d.ts files as strings using https://webpack.js.org/guides/asset-modules/#source-assets.
     config.module.rules.push({
       test: /\.d\.ts/,
-      type: 'asset/source',
+      type: "asset/source",
     });
 
     // Monaco Editor
     if (!options.isServer) {
       config.plugins.push(
         new MonacoWebpackPlugin({
-          languages: ['typescript', 'javascript'],
-          filename: 'static/[name].worker.js',
+          languages: ["typescript", "javascript"],
+          filename: "static/[name].worker.js",
         })
       );
     }
 
     config.resolve.alias = {
       ...config.resolve.alias,
-      'react-compiler-runtime': path.resolve(
+      "react-compiler-runtime": path.resolve(
         __dirname,
-        '../../packages/react-compiler-runtime'
+        "../../packages/react-compiler-runtime"
       ),
     };
-    config.resolve.fallback = {
-      fs: false,
-      path: false,
-      os: false,
-    };
 
     return config;
   },
 
-  transpilePackages: ['monaco-editor'],
+  transpilePackages: ["monaco-editor"],
 };
 
 module.exports = nextConfig;

compiler/apps/playground/package.json

@@ -3,57 +3,58 @@
   "version": "0.1.0",
   "private": true,
   "scripts": {
-    "dev": "cd ../.. && concurrently --kill-others -n compiler,runtime,playground \"yarn workspace babel-plugin-react-compiler run watch\" \"yarn workspace react-compiler-runtime run watch\" \"wait-on packages/babel-plugin-react-compiler/dist/index.js && cd apps/playground && NODE_ENV=development next dev\"",
-    "build:compiler": "cd ../.. && concurrently -n compiler,runtime \"yarn workspace babel-plugin-react-compiler run build\" \"yarn workspace react-compiler-runtime run build\"",
-    "build": "yarn build:compiler && next build",
-    "postbuild": "node ./scripts/downloadFonts.js",
-    "preinstall": "cd ../.. && yarn install --frozen-lockfile",
-    "postinstall": "./scripts/link-compiler.sh",
-    "vercel-build": "yarn build",
+    "dev": "NODE_ENV=development next dev",
+    "build": "next build && node ./scripts/downloadFonts.js",
+    "vercel-build": "yarn workspaces run build",
     "start": "next start",
     "lint": "next lint",
-    "test": "playwright test --workers=4"
+    "test": "playwright test"
   },
   "dependencies": {
-    "@babel/core": "^7.18.9",
-    "@babel/generator": "^7.18.9",
-    "@babel/parser": "^7.18.9",
-    "@babel/plugin-syntax-typescript": "^7.18.9",
+    "@babel/core": "^7.19.1",
+    "@babel/parser": "^7.19.1",
+    "@babel/plugin-syntax-typescript": "^7.18.6",
     "@babel/plugin-transform-block-scoping": "^7.18.9",
-    "@babel/plugin-transform-modules-commonjs": "^7.18.9",
-    "@babel/preset-react": "^7.18.9",
-    "@babel/preset-typescript": "^7.26.0",
-    "@babel/traverse": "^7.18.9",
-    "@babel/types": "7.26.3",
+    "@babel/plugin-transform-modules-commonjs": "^7.18.6",
+    "@babel/preset-react": "^7.18.6",
+    "@babel/preset-typescript": "^7.18.6",
+    "@babel/traverse": "^7.19.1",
+    "@babel/types": "^7.19.0",
     "@heroicons/react": "^1.0.6",
     "@monaco-editor/react": "^4.4.6",
     "@playwright/test": "^1.42.1",
     "@use-gesture/react": "^10.2.22",
-    "hermes-eslint": "^0.25.0",
-    "hermes-parser": "^0.25.0",
+    "hermes-eslint": "^0.14.0",
     "invariant": "^2.2.4",
     "lz-string": "^1.5.0",
-    "monaco-editor": "^0.52.0",
-    "next": "^15.2.0-canary.64",
+    "monaco-editor": "^0.34.1",
+    "next": "^13.5.6",
     "notistack": "^3.0.0-alpha.7",
-    "prettier": "^3.3.3",
+    "prettier": "3.0.3",
     "pretty-format": "^29.3.1",
     "re-resizable": "^6.9.16",
-    "react": "^19.0.0",
-    "react-dom": "^19.0.0"
+    "react": "18.2.0",
+    "react-dom": "18.2.0",
+    "react-compiler-runtime": "*"
   },
   "devDependencies": {
     "@types/node": "18.11.9",
-    "@types/react": "^19.0.0",
-    "@types/react-dom": "^19.0.0",
+    "@types/prettier": "^2.7.1",
+    "@types/react": "18.0.25",
+    "@types/react-dom": "18.0.9",
     "autoprefixer": "^10.4.13",
     "clsx": "^1.2.1",
-    "concurrently": "^7.4.0",
     "eslint": "^8.28.0",
-    "eslint-config-next": "^15.0.1",
+    "eslint-config-next": "^13.5.6",
     "monaco-editor-webpack-plugin": "^7.1.0",
     "postcss": "^8.4.31",
-    "tailwindcss": "^3.2.4",
-    "wait-on": "^7.2.0"
+    "tailwindcss": "^3.2.4"
+  },
+  "resolutions": {
+    "./**/@babel/parser": "7.7.4",
+    "./**/@babel/types": "7.7.4",
+    "@babel/core": "7.2.0",
+    "@babel/traverse": "7.1.6",
+    "@babel/generator": "7.2.0"
   }
 }

compiler/apps/playground/playwright.config.js

@@ -5,8 +5,8 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {defineConfig, devices} from '@playwright/test';
-import path from 'path';
+import { defineConfig, devices } from "@playwright/test";
+import path from "path";
 
 // Use process.env.PORT by default and fallback to port 3000
 const PORT = process.env.PORT || 3000;
@@ -18,30 +18,25 @@ const baseURL = `http://localhost:${PORT}`;
 export default defineConfig({
   // Timeout per test
   timeout: 30 * 1000,
-  // Run all tests in parallel.
-  fullyParallel: true,
   // Test directory
-  testDir: path.join(__dirname, '__tests__/e2e'),
+  testDir: path.join(__dirname, "__tests__/e2e"),
   // If a test fails, retry it additional 2 times
-  retries: 3,
+  retries: 2,
   // Artifacts folder where screenshots, videos, and traces are stored.
-  outputDir: 'test-results/',
+  outputDir: "test-results/",
   // Note: we only use text snapshots, so its safe to omit the host environment name
-  snapshotPathTemplate: '{testDir}/__snapshots__/{testFilePath}/{arg}{ext}',
+  snapshotPathTemplate: "{testDir}/__snapshots__/{testFilePath}/{arg}{ext}",
 
   // Run your local dev server before starting the tests:
   // https://playwright.dev/docs/test-advanced#launching-a-development-web-server-during-the-tests
   webServer: {
-    command: 'yarn dev',
+    command:
+      "yarn workspace babel-plugin-react-compiler build && yarn workspace react-compiler-runtime build && yarn dev",
     url: baseURL,
     timeout: 300 * 1000,
     reuseExistingServer: !process.env.CI,
   },
 
-  // 'github' for GitHub Actions CI to generate annotations, plus a concise 'dot'
-  // default 'list' when running locally
-  reporter: process.env.CI ? 'github' : 'list',
-
   use: {
     // Use baseURL so to make navigations relative.
     // More information: https://playwright.dev/docs/api/class-testoptions#test-options-base-url
@@ -49,7 +44,7 @@ export default defineConfig({
 
     // Retry a test if its failing with enabled tracing. This allows you to analyze the DOM, console logs, network traffic etc.
     // More information: https://playwright.dev/docs/trace-viewer
-    trace: 'retry-with-trace',
+    trace: "retry-with-trace",
 
     // All available context options: https://playwright.dev/docs/api/class-browser#browser-new-context
     // contextOptions: {
@@ -59,8 +54,8 @@ export default defineConfig({
 
   projects: [
     {
-      name: 'chromium',
-      use: {...devices['Desktop Chrome']},
+      name: "chromium",
+      use: { ...devices["Desktop Chrome"] },
     },
     // {
     //   name: 'Desktop Firefox',