diff --git a/.github/workflows/bazel_arm64_macos.yml b/.github/workflows/bazel_arm64_macos.yml
index 1d0adf3b..f9799bd7 100644
--- a/.github/workflows/bazel_arm64_macos.yml
+++ b/.github/workflows/bazel_arm64_macos.yml
@@ -36,23 +36,46 @@ jobs:
         USE_BAZEL_VERSION: 9.0.0
       steps:
         - uses: actions/checkout@v6
+        # We use actions/cache for the disk cache rather than setup-bazel's
+        # built-in disk-cache feature because setup-bazel includes a hash of
+        # all BUILD files in the cache key.  Since Bazel's disk cache is
+        # already content-addressed, this is redundant and causes the entire
+        # cache (~1.7 GB on Windows) to be re-uploaded whenever any BUILD
+        # file changes, quickly hitting GitHub's 10 GB limit.
+        #
+        # actions/cache entries are immutable (write-once), so we include the
+        # ISO week number to rotate the cache weekly.  On a miss the
+        # restore-keys prefix match restores the previous week's cache,
+        # avoiding a fully cold build.
+        #
+        # See: https://github.com/bazel-contrib/setup-bazel/issues/18
+        - name: Get current week
+          id: week
+          run: echo "week=$(date +%Y-W%V)" >> "$GITHUB_OUTPUT"
+        - name: Cache Bazel disk cache
+          uses: actions/cache@v4
+          with:
+            path: ~/.cache/bazel-disk
+            key: bazel-disk-cache-${{ runner.os }}-${{ github.base_ref || github.ref }}-${{ steps.week.outputs.week }}
+            restore-keys: |
+              bazel-disk-cache-${{ runner.os }}-${{ github.base_ref || github.ref }}-
+              bazel-disk-cache-${{ runner.os }}-main-
+              bazel-disk-cache-${{ runner.os }}-
         - name: Setup Bazel
           uses: bazel-contrib/setup-bazel@c5acdfb288317d0b5c0bbd7a396a3dc868bb0f86 # 0.19.0
           with:
             # Avoid downloading Bazel every time.
             bazelisk-cache: true
-            # Store build cache per workflow.
-            disk-cache: ${{github.workflow}}
             # Share repository cache between workflows.
             repository-cache: true
         - name: Check Bazelisk
           run: bazelisk --version
         - name: Build
           run: |
-            bazelisk build --config=dev -c fastbuild //...
+            bazelisk build --config=dev --disk_cache=~/.cache/bazel-disk -c fastbuild //...
         - name: Test
           run: >-
-            bazelisk test --config=dev -c fastbuild
+            bazelisk test --config=dev --disk_cache=~/.cache/bazel-disk -c fastbuild
             --test_size_filters=-enormous
             --test_output=errors
             --test_filter="-PywrapFstTest.testRandGen"
diff --git a/.github/workflows/bazel_x64_linux.yml b/.github/workflows/bazel_x64_linux.yml
index 16025060..a2600f86 100644
--- a/.github/workflows/bazel_x64_linux.yml
+++ b/.github/workflows/bazel_x64_linux.yml
@@ -36,22 +36,45 @@ jobs:
         USE_BAZEL_VERSION: 9.0.0
       steps:
         - uses: actions/checkout@v6
+        # We use actions/cache for the disk cache rather than setup-bazel's
+        # built-in disk-cache feature because setup-bazel includes a hash of
+        # all BUILD files in the cache key.  Since Bazel's disk cache is
+        # already content-addressed, this is redundant and causes the entire
+        # cache (~1.7 GB on Windows) to be re-uploaded whenever any BUILD
+        # file changes, quickly hitting GitHub's 10 GB limit.
+        #
+        # actions/cache entries are immutable (write-once), so we include the
+        # ISO week number to rotate the cache weekly.  On a miss the
+        # restore-keys prefix match restores the previous week's cache,
+        # avoiding a fully cold build.
+        #
+        # See: https://github.com/bazel-contrib/setup-bazel/issues/18
+        - name: Get current week
+          id: week
+          run: echo "week=$(date +%Y-W%V)" >> "$GITHUB_OUTPUT"
+        - name: Cache Bazel disk cache
+          uses: actions/cache@v4
+          with:
+            path: ~/.cache/bazel-disk
+            key: bazel-disk-cache-${{ runner.os }}-${{ github.base_ref || github.ref }}-${{ steps.week.outputs.week }}
+            restore-keys: |
+              bazel-disk-cache-${{ runner.os }}-${{ github.base_ref || github.ref }}-
+              bazel-disk-cache-${{ runner.os }}-main-
+              bazel-disk-cache-${{ runner.os }}-
         - name: Setup Bazel
           uses: bazel-contrib/setup-bazel@c5acdfb288317d0b5c0bbd7a396a3dc868bb0f86 # 0.19.0
           with:
             # Avoid downloading Bazel every time.
             bazelisk-cache: true
-            # Store build cache per workflow.
-            disk-cache: ${{github.workflow}}
             # Share repository cache between workflows.
             repository-cache: true
         - name: Check Bazelisk
           run: bazelisk --version
         - name: Build
           run: |
-            bazelisk build --config=dev -c fastbuild //...
+            bazelisk build --config=dev --disk_cache=~/.cache/bazel-disk -c fastbuild //...
         - name: Test
           run: >-
-            bazelisk test --config=dev -c fastbuild
+            bazelisk test --config=dev --disk_cache=~/.cache/bazel-disk -c fastbuild
             --test_size_filters=-enormous --test_output=errors
             //...
diff --git a/.github/workflows/bazel_x64_windows.yml b/.github/workflows/bazel_x64_windows.yml
index e7941ca4..63451366 100644
--- a/.github/workflows/bazel_x64_windows.yml
+++ b/.github/workflows/bazel_x64_windows.yml
@@ -39,24 +39,48 @@ jobs:
         USE_BAZEL_VERSION: 9.0.0
       steps:
         - uses: actions/checkout@v6
+        # We use actions/cache for the disk cache rather than setup-bazel's
+        # built-in disk-cache feature because setup-bazel includes a hash of
+        # all BUILD files in the cache key.  Since Bazel's disk cache is
+        # already content-addressed, this is redundant and causes the entire
+        # cache (~1.7 GB on Windows) to be re-uploaded whenever any BUILD
+        # file changes, quickly hitting GitHub's 10 GB limit.
+        #
+        # actions/cache entries are immutable (write-once), so we include the
+        # ISO week number to rotate the cache weekly.  On a miss the
+        # restore-keys prefix match restores the previous week's cache,
+        # avoiding a fully cold build.
+        #
+        # See: https://github.com/bazel-contrib/setup-bazel/issues/18
+        - name: Get current week
+          id: week
+          shell: bash
+          run: echo "week=$(date +%Y-W%V)" >> "$GITHUB_OUTPUT"
+        - name: Cache Bazel disk cache
+          uses: actions/cache@v4
+          with:
+            path: ~/.cache/bazel-disk
+            key: bazel-disk-cache-${{ runner.os }}-${{ github.base_ref || github.ref }}-${{ steps.week.outputs.week }}
+            restore-keys: |
+              bazel-disk-cache-${{ runner.os }}-${{ github.base_ref || github.ref }}-
+              bazel-disk-cache-${{ runner.os }}-main-
+              bazel-disk-cache-${{ runner.os }}-
         - name: Setup Bazel
           uses: bazel-contrib/setup-bazel@c5acdfb288317d0b5c0bbd7a396a3dc868bb0f86 # 0.19.0
           with:
             # Avoid downloading Bazel every time.
             bazelisk-cache: true
-            # Store build cache per workflow.
-            disk-cache: ${{github.workflow}}
             # Share repository cache between workflows.
             repository-cache: true
         - name: Check Bazelisk
           run: bazelisk --version
         - name: Build
           run: |
-            bazelisk build -c fastbuild //...
+            bazelisk build -c fastbuild --disk_cache=~/.cache/bazel-disk //...
         - name: Test
           shell: bash  # Avoid default PowerShell syntax headaches.
           run: >-
-            bazelisk test -c fastbuild
+            bazelisk test -c fastbuild --disk_cache=~/.cache/bazel-disk
             --test_size_filters=-enormous
             --test_output=errors
             --test_tag_filters=-no_windows_msvc
diff --git a/.github/workflows/cmake_arm64_macos.yml b/.github/workflows/cmake_arm64_macos.yml
index 18fa0a33..575953bc 100644
--- a/.github/workflows/cmake_arm64_macos.yml
+++ b/.github/workflows/cmake_arm64_macos.yml
@@ -50,6 +50,7 @@ jobs:
           uses: hendrikmuhs/ccache-action@1bbbcda0748b3e340dee71a314fa68ffcbd6df79 # v1.2.21
           with:
             key: cmake-cache-${{env.cache-name}}
+            # Compressed cache is ~125MB; default 500MB max-size is sufficient.
         - name: Configure
           run: >-
             cmake -S . -B build
diff --git a/.github/workflows/cmake_x64_linux.yml b/.github/workflows/cmake_x64_linux.yml
index 7f43ffea..edf75ef6 100644
--- a/.github/workflows/cmake_x64_linux.yml
+++ b/.github/workflows/cmake_x64_linux.yml
@@ -50,6 +50,7 @@ jobs:
           uses: hendrikmuhs/ccache-action@1bbbcda0748b3e340dee71a314fa68ffcbd6df79 # v1.2.21
           with:
             key: cmake-cache-${{env.cache-name}}
+            # Compressed cache is ~156MB; default 500MB max-size is sufficient.
         - name: Configure
           run: >-
             cmake -S . -B build