CI: a main push the merge queue already tested runs only repository checks (#1860)

The merge queue runs the full suite on exactly the commit it then puts on
main, and main's push run then ran the full suite again on the same files.
Select checks now asks the Actions API whether a passing merge_group CI run
exists for the pushed commit; if so the push runs only the repository checks.
A push that skipped the queue, or an API that cannot answer, still runs
everything. The nightly still runs the whole suite.

Pull requests also run less: the reference tests only when solidcraft-cli (or
anything it depends on) is affected, and doc tests only for the affected
packages that have a library. The ci check requires the reference tests only
when they were selected.


Claude-Session: https://claude.ai/code/session_01LGeCa5jWWdroMWvXxN3LLM

Co-authored-by: jyviko <[email protected]>
Co-authored-by: Claude Opus 5.5 <[email protected]>

.github/workflows/ci.yml

@@ -10,6 +10,10 @@
 # and app startup) run on pull requests only when what they test changes (the GPU crate, the app,
 # the viewport's GPU glue, the graphics dependencies, their scripts or this file); main and
 # nightly always run them. Only main saves the build caches; pull requests restore them.
+# The merge queue runs the full suite on exactly the commit it then puts on main, so a push to
+# main that a passing merge-queue run already tested runs only the repository checks; a push
+# that skipped the queue still runs everything. Pull requests run the reference tests when the
+# command line (or anything it depends on) changes, and doc tests for the affected packages.
 # Cross-compilation is opt-in through Run workflow; release builds remain in release.yml.
 # Pushes to main and merge-queue groups use both pools: Clippy, the doc tests and test shards
 # 1-2 run on the self-hosted runner (`self-hosted-fast`, warm build directories via
@@ -64,12 +68,17 @@ jobs:
   changes:
     name: Select checks
     runs-on: ubuntu-24.04
+    permissions:
+      contents: read
+      # To ask whether the merge queue already tested a commit pushed to main.
+      actions: read
     outputs:
       native: ${{ steps.paths.outputs.native }}
       kernel: ${{ steps.paths.outputs.kernel }}
       windows: ${{ steps.paths.outputs.windows }}
       full: ${{ steps.paths.outputs.full }}
       packages: ${{ steps.paths.outputs.packages }}
+      oracle: ${{ steps.paths.outputs.oracle }}
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
@@ -80,13 +89,30 @@ jobs:
           EVENT_NAME: ${{ github.event_name }}
           BASE_SHA: ${{ github.event.pull_request.base.sha }}
           HEAD_SHA: ${{ github.event.pull_request.head.sha }}
+          PUSH_SHA: ${{ github.sha }}
+          REPO: ${{ github.repository }}
+          GH_TOKEN: ${{ github.token }}
         run: |
           native=false
           kernel=false
           windows=false
           full=true
           packages=
-          if [ "$EVENT_NAME" != pull_request ]; then
+          if [ "$EVENT_NAME" = push ]; then
+            # The queue lands the very commit its merge_group run tested. If that run passed,
+            # testing the push again proves nothing new; otherwise (a merge that skipped the
+            # queue, or the API cannot answer) test everything.
+            # curl and grep only: Select checks of a push runs on the self-hosted runner.
+            tested=$(curl -fsS -H "Authorization: Bearer $GH_TOKEN" -H "Accept: application/vnd.github+json" \
+              "https://api.github.com/repos/$REPO/actions/workflows/ci.yml/runs?event=merge_group&head_sha=$PUSH_SHA&status=success&per_page=1" \
+              | grep -o '"total_count": *[0-9]*' | grep -o '[0-9]*$' || echo 0)
+            if [ "${tested:-0}" -gt 0 ]; then
+              echo "The merge queue already tested $PUSH_SHA: repository checks only."
+            else
+              native=true
+              windows=true
+            fi
+          elif [ "$EVENT_NAME" != pull_request ]; then
             native=true
             windows=true
           else
@@ -121,10 +147,17 @@ jobs:
             # Code changed but nothing was selected: be safe and test everything.
             if [ "$native" = true ] && [ "$full" != true ] && [ -z "$packages" ]; then full=true; fi
           fi
+          # The reference tests replay recipes through solidcraft-cli: needed when it, or anything
+          # it depends on, is selected.
+          oracle=$native
+          if [ "$EVENT_NAME" = pull_request ] && [ "$full" != true ]; then
+            case " $packages " in *" solidcraft-cli "*) ;; *) oracle=false ;; esac
+          fi
           {
             echo "native=$native"
             echo "kernel=$kernel"
             echo "windows=$windows"
+            echo "oracle=$oracle"
             echo "full=$full"
             echo "packages=$packages"
           } >> "$GITHUB_OUTPUT"
@@ -416,12 +449,32 @@ jobs:
         with:
           version: v0.16.0
       # nextest does not run doc tests.
-      - run: cargo test --workspace --profile ci --locked --doc
+      - name: Doc tests
+        env:
+          FULL: ${{ needs.changes.outputs.full }}
+          PACKAGES: ${{ needs.changes.outputs.packages }}
+        run: |
+          # Pull requests test the affected packages that have a library (only libraries have doc
+          # tests); everything else, the whole workspace.
+          scope=(--workspace)
+          if [ "$FULL" != true ]; then
+            scope=()
+            libs=$(cargo metadata --no-deps --format-version 1 --locked \
+              | python3 -I -c 'import json, sys; print(" ".join(p["name"] for p in json.load(sys.stdin)["packages"] if any("lib" in t["kind"] for t in p["targets"])))')
+            for p in $PACKAGES; do
+              case " $libs " in *" $p "*) scope+=(-p "$p") ;; esac
+            done
+          fi
+          if [ ${#scope[@]} -eq 0 ]; then
+            echo "No affected package has a library: no doc tests to run."
+            exit 0
+          fi
+          cargo test "${scope[@]}" --profile ci --locked --doc
 
   oracle:
     name: Reference tests
     needs: changes
-    if: needs.changes.outputs.native == 'true'
+    if: needs.changes.outputs.oracle == 'true'
     runs-on: ubuntu-24.04
     timeout-minutes: 60
     env:
@@ -520,6 +573,7 @@ jobs:
           CHECKS: ${{ needs.checks.result }}
           NATIVE: ${{ needs.changes.outputs.native }}
           WINDOWS: ${{ needs.changes.outputs.windows }}
+          ORACLE_RUN: ${{ needs.changes.outputs.oracle }}
           CLIPPY: ${{ needs.clippy.result }}
           BUILD: ${{ needs.build-tests.result }}
           TESTS: ${{ needs.tests.result }}
@@ -535,6 +589,8 @@ jobs:
             test "$BUILD" = success
             test "$TESTS" = success
             test "$DOCS" = success
+          fi
+          if [ "$ORACLE_RUN" = true ]; then
             test "$ORACLE" = success
           fi
           if [ "$WINDOWS" = true ]; then