diff --git a/.github/actions/bootstrap/action.yaml b/.github/actions/bootstrap/action.yaml
index 020bfaed..945d0b78 100644
--- a/.github/actions/bootstrap/action.yaml
+++ b/.github/actions/bootstrap/action.yaml
@@ -31,27 +31,94 @@ inputs:
 
 runs:
   using: "composite"
+  # restore-only caching pattern: PRs (and pushes to fork default branches) read existing
+  # caches but never write back. Only pushes to the upstream repo's default branch refresh
+  # them. This keeps untrusted runs from polluting or evicting trusted cache entries.
   steps:
     - name: Setup node.js
       uses: actions/setup-node@6044e13b5dc448c55e2357c09f80417699197238 # v6.2.0
       if: inputs.node-version != ''
       with:
         node-version: ${{ inputs.node-version }}
-        cache: 'npm'
+        # npm cache is managed below so untrusted runs cannot write back
 
     - uses: astral-sh/setup-uv@eac588ad8def6316056a12d4907a9d4d84ff7a3b # v7.3.0
       if: inputs.python-version != ''
       with:
-        enable-cache: true
+        # uv cache is managed below so untrusted runs cannot write back
+        enable-cache: false
 
     - uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
       if: inputs.python-version != ''
       with:
         python-version: ${{ inputs.python-version }}
 
+    # resolve cache locations so the restore/save steps below stay tool-agnostic
+    - name: Resolve npm cache directory
+      if: inputs.node-version != ''
+      id: npm-cache-dir
+      shell: bash
+      run: echo "dir=$(npm config get cache)" >> "$GITHUB_OUTPUT"
+
+    - name: Resolve uv cache directory
+      if: inputs.python-version != ''
+      id: uv-cache-dir
+      shell: bash
+      run: echo "dir=$(uv cache dir)" >> "$GITHUB_OUTPUT"
+
+    # npm cache: restore-only on non-default branches and forks
+    - name: Restore npm cache
+      if: ${{ inputs.node-version != '' && (github.ref != format('refs/heads/{0}', github.event.repository.default_branch) || github.event.repository.fork == true) }}
+      uses: actions/cache/restore@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
+      with:
+        path: ${{ steps.npm-cache-dir.outputs.dir }}
+        key: ${{ inputs.cache-key-prefix }}-${{ runner.os }}-node-${{ inputs.node-version }}-${{ hashFiles('**/package-lock.json') }}
+        restore-keys: |
+          ${{ inputs.cache-key-prefix }}-${{ runner.os }}-node-${{ inputs.node-version }}-
+
+    # npm cache: restore + save on the upstream default branch only
+    - name: Restore and save npm cache
+      if: ${{ inputs.node-version != '' && github.ref == format('refs/heads/{0}', github.event.repository.default_branch) && github.event.repository.fork == false }}
+      uses: actions/cache@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
+      with:
+        path: ${{ steps.npm-cache-dir.outputs.dir }}
+        key: ${{ inputs.cache-key-prefix }}-${{ runner.os }}-node-${{ inputs.node-version }}-${{ hashFiles('**/package-lock.json') }}
+        restore-keys: |
+          ${{ inputs.cache-key-prefix }}-${{ runner.os }}-node-${{ inputs.node-version }}-
+
+    # uv cache: restore-only on non-default branches and forks
+    - name: Restore uv cache
+      if: ${{ inputs.python-version != '' && (github.ref != format('refs/heads/{0}', github.event.repository.default_branch) || github.event.repository.fork == true) }}
+      uses: actions/cache/restore@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
+      with:
+        path: ${{ steps.uv-cache-dir.outputs.dir }}
+        key: ${{ inputs.cache-key-prefix }}-${{ runner.os }}-uv-${{ inputs.uv-version }}-${{ hashFiles('uv.lock', 'pyproject.toml') }}
+        restore-keys: |
+          ${{ inputs.cache-key-prefix }}-${{ runner.os }}-uv-${{ inputs.uv-version }}-
+
+    # uv cache: restore + save on the upstream default branch only
+    - name: Restore and save uv cache
+      if: ${{ inputs.python-version != '' && github.ref == format('refs/heads/{0}', github.event.repository.default_branch) && github.event.repository.fork == false }}
+      uses: actions/cache@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
+      with:
+        path: ${{ steps.uv-cache-dir.outputs.dir }}
+        key: ${{ inputs.cache-key-prefix }}-${{ runner.os }}-uv-${{ inputs.uv-version }}-${{ hashFiles('uv.lock', 'pyproject.toml') }}
+        restore-keys: |
+          ${{ inputs.cache-key-prefix }}-${{ runner.os }}-uv-${{ inputs.uv-version }}-
+
+    # tool cache: restore-only on non-default branches and forks
     - name: Restore tool cache
-      if: inputs.tools == 'true'
+      if: ${{ inputs.tools == 'true' && (github.ref != format('refs/heads/{0}', github.event.repository.default_branch) || github.event.repository.fork == true) }}
       id: tool-cache
+      uses: actions/cache/restore@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
+      with:
+        path: ${{ github.workspace }}/.tool
+        key: ${{ inputs.cache-key-prefix }}-${{ runner.os }}-tool-${{ hashFiles('.binny.yaml') }}
+
+    # tool cache: restore + save on the upstream default branch only
+    - name: Restore and save tool cache
+      if: ${{ inputs.tools == 'true' && github.ref == format('refs/heads/{0}', github.event.repository.default_branch) && github.event.repository.fork == false }}
+      id: tool-cache-rw
       uses: actions/cache@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
       with:
         path: ${{ github.workspace }}/.tool
@@ -76,8 +143,17 @@ runs:
         IFS=' ' read -ra packages <<< "$APT_PACKAGES"
         DEBIAN_FRONTEND=noninteractive sudo apt update && sudo -E apt install -y "${packages[@]}"
 
+    # ecosystem tool cache: restore-only on non-default branches and forks
     - name: Restore ecosystem tool cache
-      if: inputs.tools == 'true'
+      if: ${{ inputs.tools == 'true' && (github.ref != format('refs/heads/{0}', github.event.repository.default_branch) || github.event.repository.fork == true) }}
+      uses: actions/cache/restore@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
+      with:
+        path: ${{ github.workspace }}/.cache
+        key: ${{ inputs.cache-key-prefix }}-${{ runner.os }}-ecosystem-tool
+
+    # ecosystem tool cache: restore + save on the upstream default branch only
+    - name: Restore and save ecosystem tool cache
+      if: ${{ inputs.tools == 'true' && github.ref == format('refs/heads/{0}', github.event.repository.default_branch) && github.event.repository.fork == false }}
       uses: actions/cache@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
       with:
         path: ${{ github.workspace }}/.cache
diff --git a/.github/dependabot.yml b/.github/dependabot.yml
index 9d68fe08..5ec89b31 100644
--- a/.github/dependabot.yml
+++ b/.github/dependabot.yml
@@ -1,6 +1,19 @@
 version: 2
 updates:
-  # Enable version updates for npm
+
+  - package-ecosystem: gomod
+    directories:
+      - "/"
+      - "/.make"
+    cooldown:
+      default-days: 7
+    schedule:
+      interval: "weekly"
+      day: "friday"
+    open-pull-requests-limit: 10
+    labels:
+      - "dependencies"
+
   - package-ecosystem: "npm"
     directories:
       - "/"
@@ -8,6 +21,7 @@ updates:
       default-days: 7
     schedule:
       interval: "weekly"
+      day: "friday"
     open-pull-requests-limit: 5
     commit-message:
       prefix: "npm"
@@ -21,6 +35,7 @@ updates:
       default-days: 7
     schedule:
       interval: "weekly"
+      day: "friday"
     open-pull-requests-limit: 10
     labels:
       - "dependencies"
diff --git a/.github/workflows/validations.yaml b/.github/workflows/validations.yaml
index b3e2c587..a1c64e1a 100644
--- a/.github/workflows/validations.yaml
+++ b/.github/workflows/validations.yaml
@@ -26,7 +26,17 @@ jobs:
       - name: Bootstrap environment
         uses: ./.github/actions/bootstrap
 
+      # restore-only on non-default branches and forks
       - name: Restore link check cache
+        if: ${{ github.ref != format('refs/heads/{0}', github.event.repository.default_branch) || github.event.repository.fork == true }}
+        uses: actions/cache/restore@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
+        with:
+          path: .cache/lychee
+          key: cache-lychee
+
+      # restore + save on the upstream default branch only
+      - name: Restore and save link check cache
+        if: ${{ github.ref == format('refs/heads/{0}', github.event.repository.default_branch) && github.event.repository.fork == false }}
         uses: actions/cache@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
         with:
           path: .cache/lychee