perf(ci): parallelize the test suite and split out Rust checks (#7286)

Co-authored-by: Codesmith <codesmith-bot@users.noreply.github.com>

Author: t3dotgg

.github/workflows/ci.yml

@@ -31,11 +31,6 @@ jobs:
           cache: true
           run-install: true
 
-      - name: Setup Rust
-        uses: dtolnay/rust-toolchain@stable
-        with:
-          components: rustfmt
-
       - name: Ensure Electron runtime is installed
         run: vp run --filter @t3tools/desktop ensure:electron
 
@@ -45,9 +40,6 @@ jobs:
       - name: Typecheck
         run: vpr typecheck
 
-      - name: Check resource monitor formatting
-        run: cargo fmt --manifest-path native/resource-monitor/Cargo.toml -- --check
-
       - name: Build desktop pipeline
         run: vp run build:desktop
 
@@ -57,6 +49,11 @@ jobs:
           grep -nE "desktopBridge|getLocalEnvironmentBootstrap|PICK_FOLDER_CHANNEL|wsUrl" apps/desktop/dist-electron/preload.cjs
           grep -n "__clerk_internal_electron_passkeys" apps/desktop/dist-electron/preload.cjs
 
+  # Everything except `t3` (apps/server). `--parallel` drops the package
+  # dependency ordering that `vp run` applies by default: these `test` tasks
+  # declare no `dependsOn` and resolve workspace deps from source, so ordering
+  # only bought us idle runners between dependency layers. The concurrency
+  # limit stays at the default 4 so peak load per runner is unchanged.
   test:
     name: Test
     runs-on: blacksmith-8vcpu-ubuntu-2404
@@ -77,20 +74,65 @@ jobs:
           cache: true
           run-install: true
 
-      - name: Setup Rust
-        uses: dtolnay/rust-toolchain@stable
-
       - name: Ensure Electron runtime is installed
         run: vp run --filter @t3tools/desktop ensure:electron
 
+      - name: Test
+        run: vp run --parallel --concurrency-limit 4 --filter '!t3' --filter '!@t3tools/monorepo' test
+
+  # apps/server sets `fileParallelism: false`, so its 239 files run strictly
+  # one at a time. Sharding spreads them over separate runners instead of
+  # separate workers, so no two server test files ever share a machine and the
+  # isolation that flag buys is preserved exactly.
+  test_server:
+    name: Test Server ${{ matrix.shard }}
+    runs-on: blacksmith-8vcpu-ubuntu-2404
+    timeout-minutes: 10
+    strategy:
+      fail-fast: false
+      matrix:
+        shard: [1, 2, 3]
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v6
+        with:
+          sparse-checkout: |
+            /*
+            !/.repos/
+          sparse-checkout-cone-mode: false
+
+      - name: Setup Vite+
+        uses: voidzero-dev/setup-vp@v1
+        with:
+          node-version-file: package.json
+          cache: true
+          run-install: true
+
+      # No Electron setup here: `t3` (apps/server) has no Electron dependency
+      # and none of its tests touch the runtime. Only the non-server `test`
+      # job, which covers @t3tools/desktop, needs the download.
       - name: Test
         env:
           T3CODE_TRANSFER_BUDGET_REPORT_PATH: ${{ runner.temp }}/t3code-transfer-budget.md
           T3CODE_TRANSFER_BUDGET_RESULT_PATH: ${{ runner.temp }}/thread-transfer-result.json
-        run: vp run test
+        run: vp run --filter t3 test --shard ${{ matrix.shard }}/${{ strategy.job-total }}
+
+      # src/server.test.ts writes the budget report, so exactly one shard
+      # produces these files. Gating the upload on their presence keeps a
+      # single `thread-transfer-results` artifact per run, which is the name
+      # thread-transfer-report.yml resolves.
+      - name: Detect transfer budget report
+        id: transfer_budget
+        if: always()
+        run: |
+          if test -f "${{ runner.temp }}/thread-transfer-result.json"; then
+            echo "present=true" >> "$GITHUB_OUTPUT"
+          else
+            echo "present=false" >> "$GITHUB_OUTPUT"
+          fi
 
       - name: Publish transfer budget report
-        if: always()
+        if: always() && steps.transfer_budget.outputs.present == 'true'
         run: |
           if test -f "${{ runner.temp }}/t3code-transfer-budget.md"; then
             tee -a "$GITHUB_STEP_SUMMARY" < "${{ runner.temp }}/t3code-transfer-budget.md"
@@ -99,14 +141,37 @@ jobs:
           fi
 
       - name: Upload thread transfer result
-        if: always()
+        if: always() && steps.transfer_budget.outputs.present == 'true'
         uses: actions/upload-artifact@v7
         with:
           name: thread-transfer-results
           path: ${{ runner.temp }}/thread-transfer-result.json
           if-no-files-found: ignore
           retention-days: 30
 
+  # Split out of Check and Test: both paid ~7-9s to install a Rust toolchain
+  # for checks that take under 3s, on the critical path of every PR.
+  rust:
+    name: Rust
+    runs-on: blacksmith-4vcpu-ubuntu-2404
+    timeout-minutes: 10
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v6
+        with:
+          sparse-checkout: |
+            /*
+            !/.repos/
+          sparse-checkout-cone-mode: false
+
+      - name: Setup Rust
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          components: rustfmt
+
+      - name: Check resource monitor formatting
+        run: cargo fmt --manifest-path native/resource-monitor/Cargo.toml -- --check
+
       - name: Test resource monitor
         run: cargo test --locked --manifest-path native/resource-monitor/Cargo.toml