diff --git a/.github/workflows/go.yml b/.github/workflows/go.yml
index e8dfc2ead3..e1072f8c45 100644
--- a/.github/workflows/go.yml
+++ b/.github/workflows/go.yml
@@ -18,14 +18,25 @@ concurrency:
 
 jobs:
   test:
+    name: test (${{matrix.os}}, ${{matrix.llvm}}, ${{matrix.suite}})
     continue-on-error: true
     timeout-minutes: 60
     strategy:
+      fail-fast: false
+      # Cap how many heavy, llgo-building test packages share one VM:
+      # their concurrent clang/lld bursts were killing 16GB ubuntu
+      # runners and starving mac runners into go-list WaitDelay
+      # expirations. ubuntu (plentiful runners) gets one suite per VM;
+      # macos (scarce runners) gets two balanced groups of at most two
+      # heavy packages each — the pre-backbone peak, which mac handled.
       matrix:
-        os:
-          - macos-latest
-          - ubuntu-latest
-        llvm: [19]
+        include:
+          - { os: ubuntu-latest, llvm: 19, suite: cl }
+          - { os: ubuntu-latest, llvm: 19, suite: ssa }
+          - { os: ubuntu-latest, llvm: 19, suite: testgo }
+          - { os: ubuntu-latest, llvm: 19, suite: rest }
+          - { os: macos-latest, llvm: 19, suite: cl+cabi }
+          - { os: macos-latest, llvm: 19, suite: ssa+testgo+rest }
     runs-on: ${{matrix.os}}
     steps:
       - uses: actions/checkout@v7
@@ -69,20 +80,33 @@ jobs:
       - name: Build
         run: go build -v ./...
 
+      - name: Select suite packages
+        id: suite
+        run: |
+          case "${{matrix.suite}}" in
+            cl)      pkgs="./cl" ;;
+            ssa)     pkgs="./ssa ./internal/cabi" ;;
+            testgo)  pkgs="./test/..." ;;
+            rest)    pkgs=$(go list ./... | grep -v -E '^github.com/goplus/llgo/(cl$|ssa$|internal/cabi$|test/)' | tr '\n' ' ') ;;
+            cl+cabi) pkgs="./cl ./internal/cabi" ;;
+            ssa+testgo+rest) pkgs="./ssa ./test/... $(go list ./... | grep -v -E '^github.com/goplus/llgo/(cl$|ssa$|internal/cabi$|test/)' | tr '\n' ' ')" ;;
+          esac
+          echo "pkgs=$pkgs" >> "$GITHUB_OUTPUT"
+
       # Both platforms upload coverage: OS-specific paths (ELF vs Mach-O
       # emission, per-OS runtime shims) are otherwise invisible to
       # codecov/patch and fail it on lines only the other OS executes.
       - name: Test with coverage
-        # 45m: the caller-info acceptance suite (test/go) legitimately grew
-        # the covered run past the old 30m budget on macOS runners.
-        run: go test -timeout 45m -coverprofile="coverage.txt" -covermode=atomic ./...
+        run: go test -timeout 45m -coverprofile="coverage.txt" -covermode=atomic ${{steps.suite.outputs.pkgs}}
 
       - name: Test with embedded emulator env
+        if: contains(matrix.suite, 'cl')
         env:
           LLGO_EMBED_TESTS: "1"
         run: go test -v -timeout 60m ./cl -run '^TestRunEmbedEmulator$'
 
       - name: Check std symbol coverage
+        if: contains(matrix.suite, 'rest')
         run: bash doc/_readme/scripts/check_std_cover.sh
 
       - name: Upload coverage reports to Codecov