Harden CI against transient Bazelisk setup failures

.github/actions/setup-bazelisk/action.yml

@@ -0,0 +1,41 @@
+name: Setup Bazelisk
+description: Install Bazelisk with one retry, then verify it is on PATH
+inputs:
+  bazelisk-version:
+    description: Bazelisk version to install
+    required: false
+    default: "1.29.0"
+runs:
+  using: composite
+  steps:
+    - name: Setup Bazelisk (attempt 1)
+      id: setup_bazelisk_1
+      continue-on-error: true
+      uses: bazel-contrib/setup-bazel@0.19.0
+      with:
+        bazelisk-version: ${{ inputs.bazelisk-version }}
+
+    - name: Setup Bazelisk (attempt 2)
+      id: setup_bazelisk_2
+      if: steps.setup_bazelisk_1.outcome != 'success'
+      continue-on-error: false
+      uses: bazel-contrib/setup-bazel@0.19.0
+      with:
+        bazelisk-version: ${{ inputs.bazelisk-version }}
+
+    # Composite run steps need an explicit shell. Use bash on Linux/macOS (pwsh
+    # is not always present after free-disk-space) and pwsh on Windows.
+    - name: Verify Bazelisk installation
+      if: runner.os != 'Windows'
+      shell: bash
+      run: bazelisk version || (echo "Failed to install Bazelisk after two setup attempts, or Bazelisk is not available on PATH." && exit 1)
+
+    - name: Verify Bazelisk installation
+      if: runner.os == 'Windows'
+      shell: pwsh
+      run: |
+        bazelisk version
+        if ($LASTEXITCODE -ne 0) {
+          Write-Error "Failed to install Bazelisk after two setup attempts, or Bazelisk is not available on PATH."
+          exit 1
+        }

.github/workflows/ci_linux.yml

@@ -28,9 +28,7 @@ jobs:
 
       # 3️⃣ Install Bazelisk (recommended Bazel launcher)
       - name: Setup Bazelisk
-        uses: bazel-contrib/setup-bazel@0.19.0
-        with:
-          bazelisk-version: "1.29.0"
+        uses: ./.github/actions/setup-bazelisk
 
       # 4️⃣ (Optional) Install Doxygen for documentation generation
       - name: Install Doxygen
@@ -87,9 +85,7 @@ jobs:
           swap-storage: false
 
       - name: Setup Bazelisk
-        uses: bazel-contrib/setup-bazel@0.19.0
-        with:
-          bazelisk-version: "1.29.0"
+        uses: ./.github/actions/setup-bazelisk
 
       - name: Prefetch external repos
         run: |
@@ -135,9 +131,7 @@ jobs:
           swap-storage: false
 
       - name: Setup Bazelisk
-        uses: bazel-contrib/setup-bazel@0.19.0
-        with:
-          bazelisk-version: "1.29.0"
+        uses: ./.github/actions/setup-bazelisk
 
       - name: Prefetch external repos
         run: |

.github/workflows/ci_macos.yml

@@ -16,9 +16,7 @@ jobs:
 
       # Install Bazelisk (recommended Bazel launcher)
       - name: Setup Bazelisk
-        uses: bazel-contrib/setup-bazel@0.19.0
-        with:
-          bazelisk-version: "1.29.0"
+        uses: ./.github/actions/setup-bazelisk
 
       # Install Doxygen, to generate documentation
       - name: Install Doxygen
@@ -65,9 +63,7 @@ jobs:
         uses: actions/checkout@v6
 
       - name: Setup Bazelisk
-        uses: bazel-contrib/setup-bazel@0.19.0
-        with:
-          bazelisk-version: "1.29.0"
+        uses: ./.github/actions/setup-bazelisk
 
       - name: Prefetch external repos
         run: |

.github/workflows/ci_wasm.yml

@@ -30,9 +30,7 @@ jobs:
 
       # 3️⃣ Install Bazelisk (recommended Bazel launcher)
       - name: Setup Bazelisk
-        uses: bazel-contrib/setup-bazel@0.19.0
-        with:
-          bazelisk-version: "1.29.0"
+        uses: ./.github/actions/setup-bazelisk
 
       # 4️⃣ Prefetch emsdk / toolchain archives (retry transient network timeouts)
       - name: Prefetch external repos

.github/workflows/ci_windows.yml

@@ -16,9 +16,7 @@ jobs:
 
       # Install Bazelisk (recommended Bazel launcher)
       - name: Setup Bazelisk
-        uses: bazel-contrib/setup-bazel@0.19.0
-        with:
-          bazelisk-version: "1.29.0"
+        uses: ./.github/actions/setup-bazelisk
 
       # Warm external deps (emsdk, LLVM, …); retry transient network fetch failures
       - name: Prefetch external repos