ci(js-tests): split check into parallel matrix shards per workspace (#70252)

Every npm workspace package now defines check:* scripts (check:unit,
check:lint, check:bundle, check:typecheck, etc.) that fan out to
separate matrix runners in CI. The check umbrella script chains all
shards for local dev.

The matrix discovery in the workspaces job queries npm workspaces,
finds check:* scripts (in package.json insertion order), falls back to
check when none exist, and emits an include matrix. No hardcoded
package names — the workflow is fully auto-derived from workspace
metadata.

Previously every package ran a single check script on one worker, and
the fix step (lint:fix + prettier) ran as a separate CI step with
special-cased run_fix gating to avoid running on every shard. Now that
lint is just another check:lint shard, the run_fix field and the fix
step are gone entirely — lint runs in its own runner like everything
else.

.github/workflows/js-tests.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 20
     outputs:
-      packages: ${{ steps.set-matrix.outputs.packages }}
+      checks: ${{ steps.set-matrix.outputs.checks }}
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
       - uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4
@@ -22,21 +22,40 @@ jobs:
           command: npm ci --ignore-scripts
       - id: set-matrix
         run: |
-          PACKAGES=$(npm query .workspace | jq -c '[.[].location]')
-          if [ "$PACKAGES" = "[]" ] || [ -z "$PACKAGES" ]; then
-            echo "::error::Workspace discovery produced an empty package list — refusing to emit a zero-length matrix (would skip all JS/TS checks silently)."
-            exit 1
-          fi
-          echo "packages=$PACKAGES" >> "$GITHUB_OUTPUT"
+          node -e '
+          const { execSync } = require("child_process");
+          const pkgs = JSON.parse(execSync("npm query .workspace", { encoding: "utf-8" }));
+          if (pkgs.length === 0) {
+            console.error("::error::Workspace discovery produced an empty package list — refusing to emit a zero-length matrix (would skip all JS/TS checks silently).");
+            process.exit(1);
+          }
+          const checks = [];
+          for (const pkg of pkgs) {
+            const scripts = pkg.scripts || {};
+            const subs = Object.keys(scripts).filter(s => /^check:.+$/.test(s));
+            if (subs.length > 0) {
+              for (const script of subs) {
+                checks.push({ package: pkg.location, script });
+              }
+            } else if (scripts.check) {
+              checks.push({ package: pkg.location, script: "check" });
+            }
+          }
+          if (checks.length === 0) {
+            console.error("::error::No check scripts found in any workspace package.");
+            process.exit(1);
+          }
+          process.stdout.write("checks=" + JSON.stringify(checks) + "\n");
+          ' >> "$GITHUB_OUTPUT"
 
   check:
-    name: Typecheck & Test
+    name: ${{ matrix.package }} / ${{ matrix.script }}
     needs: workspaces
     runs-on: ubuntu-latest
     timeout-minutes: 20
     strategy:
       matrix:
-        package: ${{ fromJson(needs.workspaces.outputs.packages) }}
+        include: ${{ fromJson(needs.workspaces.outputs.checks) }}
       fail-fast: false # report all failures, not just the first one
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -47,5 +66,4 @@ jobs:
       - uses: ./.github/actions/retry
         with:
           command: npm ci
-      - run: npm run --prefix ${{ matrix.package }} check
-      - run: npm run --prefix ${{ matrix.package }} fix
+      - run: npm run --prefix ${{ matrix.package }} ${{ matrix.script }}