[pull] main from react:main

.github/workflows/runtime_build_and_test.yml

@@ -82,6 +82,38 @@ jobs:
  - run: yarn --cwd compiler install --frozen-lockfile
  if: steps.node_modules.outputs.cache-hit != 'true'
 
+ # ----- BUILD WEIGHTS -----
+ # Pins one weights snapshot for the whole run. A cache restore with
+ # restore-keys returns the newest entry at call time, so 50 workers
+ # restoring individually can disagree when another run saves a new entry
+ # mid-fan-out, which scrambles the shard assignment and drops bundles from
+ # the build.
+ resolve_build_weights:
+ name: Resolve build shard weights
+ runs-on: ubuntu-latest
+ outputs:
+ available: ${{ steps.available.outputs.available }}
+ steps:
+ - name: Restore latest build shard weights
+ id: weights
+ uses: actions/cache/restore@v4
+ with:
+ # Must match the save step's path in process_artifacts_combined
+ # exactly: the cache version is a hash of the path, so a different
+ # path never matches the key.
+ path: build-weights.json
+ key: build-weights-v1-${{ github.run_id }}
+ restore-keys: build-weights-v1-
+ - id: available
+ run: echo "available=${{ steps.weights.outputs.cache-matched-key != '' }}" >> "$GITHUB_OUTPUT"
+ - name: Publish build shard weights for this run
+ if: steps.available.outputs.available == 'true'
+ uses: actions/upload-artifact@v4
+ with:
+ name: build-weights
+ path: build-weights.json
+ if-no-files-found: error
+
  # ----- FLOW -----
  discover_flow_inline_configs:
  name: Discover flow inline configs
@@ -269,7 +301,7 @@ jobs:
  # ----- BUILD -----
  build_and_lint:
  name: yarn build and lint
- needs: [runtime_compiler_node_modules_cache]
+ needs: [runtime_compiler_node_modules_cache, resolve_build_weights]
  runs-on: ubuntu-latest
  strategy:
  fail-fast: false
@@ -307,15 +339,14 @@ jobs:
  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 build shard weights
- uses: actions/cache/restore@v4
+ # Pinned once per run by resolve_build_weights so every worker computes
+ # the same shard assignment. Absent on a cold start; the build then
+ # falls back to round-robin sharding.
+ - name: Download build shard weights
+ if: needs.resolve_build_weights.outputs.available == 'true'
+ uses: actions/download-artifact@v4
  with:
- # Written by process_artifacts_combined on every push. The
- # restore-keys prefix picks up the most recent entry. On a miss the
- # build falls back to round-robin sharding.
- path: build-weights.json
- key: build-weights-v1-${{ github.run_id }}
- restore-keys: build-weights-v1-
+ name: build-weights
  # setup-java's exports (e.g. JAVA_HOME) only apply to steps after this wait.
  - name: Wait for Java setup
  wait: setup_java
@@ -469,7 +500,7 @@ jobs:
 
  process_artifacts_combined:
  name: Process artifacts combined
- needs: [build_and_lint, runtime_node_modules_cache]
+ needs: [build_and_lint, runtime_node_modules_cache, resolve_build_weights]
  permissions:
  # https://github.com/actions/attest-build-provenance
  id-token: write
@@ -505,15 +536,14 @@ jobs:
  - name: Wait for archived build
  wait: download_build
  # Only used to log weight variance; the new measurement is what gets
- # saved, so removed bundles drop out instead of accumulating.
- - name: Restore previous build shard weights
- uses: actions/cache/restore@v4
+ # saved, so removed bundles drop out instead of accumulating. Downloads
+ # the run's pinned snapshot so the diff compares against the weights
+ # that actually drove this run's assignment.
+ - name: Download previous build shard weights
+ if: needs.resolve_build_weights.outputs.available == 'true'
+ uses: actions/download-artifact@v4
  with:
- # Must match the save step's path exactly: the cache version is a
- # hash of the path, so a different path never matches the key.
- path: build-weights.json
- key: build-weights-v1-${{ github.run_id }}
- restore-keys: build-weights-v1-
+ name: build-weights
  - name: Update build shard weights
  run: node scripts/ci/merge-build-weights.js
  - name: Save build shard weights