ci: move PR analysis and Linux unit tests to Blacksmith (#29362)

* ci: report final PR checks outside the shared runner queue

* ci: fix inherited mobile test file size failure

* ci: move PR analysis and ARM test shards to Blacksmith

* Qualify x64 Blacksmith capacity and reject incompatible runner images early

* Keep extracted mobile test adapters within the test-only lint scope

* Identify the runner profile overriding shell fixture homes

* Preserve fixture HOME through the Blacksmith login profile

* Make cache invalidation fixtures observable within one filesystem clock tick

* Scope Blacksmith system-profile preparation to Linux runners

* Wait for observable ctime in daemon hash cache fixtures

* Use the mobile test lint scope already merged on main

* Stabilize metadata and timer fixtures on fast CI runners

---------

Co-authored-by: OrcaWin <293788423+OrcaWin@users.noreply.github.com>

.github/workflows/ci-cache-warmup-platform-jobs.yml

@@ -7,12 +7,16 @@ permissions:
   contents: read
 
 jobs:
-  warm-linux-arm:
+  warm-linux-runtime:
     if: github.event_name != 'pull_request'
     concurrency:
-      group: ci-cache-warmup-linux-arm-${{ github.event.pull_request.number || github.ref }}
+      group: ci-cache-warmup-linux-runtime-${{ matrix.runner }}-${{ github.event.pull_request.number || github.ref }}
       cancel-in-progress: ${{ github.event_name != 'schedule' }}
-    runs-on: ubuntu-24.04-arm
+    strategy:
+      fail-fast: false
+      matrix:
+        runner: [ubuntu-24.04-arm, blacksmith-4vcpu-ubuntu-2404]
+    runs-on: ${{ matrix.runner }}
     timeout-minutes: 10
     env:
       ORCA_BACKGROUND_LAUNCH: '1'

.github/workflows/pr.yml

@@ -25,8 +25,8 @@ jobs:
   # inputs are unchanged; empty diffs fail closed and run everything.
   code_paths:
     name: detect changes and check repository guards
-    # Reuse one lightweight checkout for detection and the always-required guards.
-    runs-on: ubuntu-slim
+    # Start routing without waiting behind the GitHub-hosted test queue.
+    runs-on: blacksmith-2vcpu-ubuntu-2404
     timeout-minutes: 5
     permissions:
       contents: read
@@ -175,11 +175,8 @@ jobs:
     name: static analysis and typecheck
     needs: [code_paths]
     if: needs.code_paths.outputs.static_analysis == 'true' || needs.code_paths.outputs.typecheck == 'true'
-    # Why ARM: measured 128s against 172s on ubuntu-latest, with every compute step faster --
-    # type-aware 24s->15s, anti-slop 28->19s, localization extraction 67->46s, the orcad smoke
-    # 39->14s. Both lint engines ship linux-arm64 and the Bun target follows process.arch, so
-    # the whole toolchain resolves. Free for public repositories.
-    runs-on: ubuntu-24.04-arm
+    # Leave headroom for typechecking and overlapping checks.
+    runs-on: blacksmith-8vcpu-ubuntu-2404
     outputs:
       shards: ${{ steps.unit-plan.outputs.shards }}
       managed_hook_node18: ${{ steps.managed_hook_node18.outcome }}
@@ -896,7 +893,7 @@ jobs:
     uses: ./.github/workflows/unit-tests.yml
     with:
       node_versions: '["24"]'
-      runner: ubuntu-24.04-arm
+      runner: blacksmith-4vcpu-ubuntu-2404
       shards: ${{ needs.preflight.outputs.shards }}
       run_shards: ${{ needs.code_paths.outputs.mobile_ci_tools != 'true' }}
       browser_contract: ${{ needs.code_paths.outputs.orcad_browser == 'true' }}

.github/workflows/unit-tests.yml

@@ -91,6 +91,36 @@ jobs:
       - name: Install Electron package binary for tests
         run: node config/scripts/install-electron-package-binary.mjs
 
+      # The image resets HOME during login; shell fixtures intentionally use temporary homes.
+      - name: Preserve explicit login-shell homes on Blacksmith
+        if: runner.os == 'Linux' && startsWith(inputs.runner, 'blacksmith-')
+        run: |
+          sudo python3 - <<'PYTHON'
+          from pathlib import Path
+          profile = Path('/etc/profile.d/blacksmith.sh')
+          if profile.exists():
+              original = profile.read_text()
+              updated = original.replace('export HOME="$RUNNER_HOME"', 'export HOME="${HOME:-$RUNNER_HOME}"')
+              if updated != original:
+                  profile.write_text(updated)
+          PYTHON
+
+      - name: Verify Blacksmith unit runner environment
+        if: runner.os == 'Linux' && startsWith(inputs.runner, 'blacksmith-')
+        run: |
+          ELECTRON_RUN_AS_NODE=1 "$(node -p "require('electron')")" --version
+          fixture_home="$(mktemp -d)"
+          trap 'rm -rf "$fixture_home"' EXIT
+          printf 'export ORCA_CI_PROFILE_LOADED=1\n' > "$fixture_home/.bash_profile"
+          HOME="$fixture_home" ORCA_CI_FIXTURE_HOME="$fixture_home" /bin/bash -lc '
+            test "$HOME" = "$ORCA_CI_FIXTURE_HOME" && test "$ORCA_CI_PROFILE_LOADED" = 1
+          ' || {
+            echo '::error::Runner login profile overrides fixture HOME'
+            grep -nH 'HOME' /etc/profile /etc/profile.d/*.sh || true
+            HOME="$fixture_home" /bin/bash -lc 'printf "Observed HOME=%s\n" "$HOME"'
+            exit 1
+          }
+
       - uses: oven-sh/setup-bun@0c5077e51419868618aeaa5fe8019c62421857d6 # v2.2.0
         with:
           bun-version-file: config/.bun-version
@@ -145,7 +175,7 @@ jobs:
           export ORCA_SHARD_SOURCE_SHA
           node config/scripts/run-vitest.mjs run --config config/vitest.config.ts \
             --shard=${{ matrix.shard.index }}/${{ matrix.shard.count }} \
-            ${{ inputs.runner == 'ubuntu-24.04-arm' && '--maxWorkers=4' || '' }}
+            ${{ (runner.arch == 'ARM64' || inputs.runner == 'blacksmith-4vcpu-ubuntu-2404') && '--maxWorkers=4' || '' }}
 
       - name: Seal unit module cache
         id: module-cache-seal