diff --git a/.github/workflows/ql3-ci.yml b/.github/workflows/ql3-ci.yml
index faa49477..6d62f596 100644
--- a/.github/workflows/ql3-ci.yml
+++ b/.github/workflows/ql3-ci.yml
@@ -1788,9 +1788,14 @@ jobs:
     runs-on: ubuntu-24.04
     steps:
       - uses: actions/checkout@v6
+      - uses: pnpm/action-setup@v6
       - uses: actions/setup-node@v6
         with:
           node-version: '24.18.0'
+          cache: pnpm
+          cache-dependency-path: pnpm-lock.yaml
+      - name: Install workspace dependencies without lifecycle scripts
+        run: pnpm install --frozen-lockfile --ignore-scripts
       - name: Download the exact control amd64 Cluster Alpha bundle
         uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
@@ -1894,9 +1899,14 @@ jobs:
     runs-on: ubuntu-24.04
     steps:
       - uses: actions/checkout@v6
+      - uses: pnpm/action-setup@v6
       - uses: actions/setup-node@v6
         with:
           node-version: '24.18.0'
+          cache: pnpm
+          cache-dependency-path: pnpm-lock.yaml
+      - name: Install workspace dependencies without lifecycle scripts
+        run: pnpm install --frozen-lockfile --ignore-scripts
       - name: Download the exact amd64 Local Alpha trial kit
         uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
@@ -1948,9 +1958,14 @@ jobs:
     runs-on: ubuntu-24.04
     steps:
       - uses: actions/checkout@v6
+      - uses: pnpm/action-setup@v6
       - uses: actions/setup-node@v6
         with:
           node-version: '24.18.0'
+          cache: pnpm
+          cache-dependency-path: pnpm-lock.yaml
+      - name: Install workspace dependencies without lifecycle scripts
+        run: pnpm install --frozen-lockfile --ignore-scripts
       - name: Download the closed Local Alpha milestone
         uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
diff --git a/scripts/ql3-alpha-stage-index.cjs b/scripts/ql3-alpha-stage-index.cjs
index 6ba3e5d5..a6bbe854 100644
--- a/scripts/ql3-alpha-stage-index.cjs
+++ b/scripts/ql3-alpha-stage-index.cjs
@@ -559,6 +559,9 @@ function auditAlphaStageIndexWorkflow(root = DEFAULT_ROOT) {
     `if: ${condition}`,
     '      - local-alpha-milestone\n',
     '      - cluster-alpha-milestone\n',
+    'pnpm/action-setup@v6',
+    'cache-dependency-path: pnpm-lock.yaml',
+    'pnpm install --frozen-lockfile --ignore-scripts',
     `name: ql3-alpha-${'${{ github.sha }}'}-local-${'${{ inputs.local_alpha_variant }}'}-milestone`,
     `name: ql3-alpha-${'${{ github.sha }}'}-cluster-milestone`,
     'scripts/ql3-alpha-stage-index.cjs',
@@ -571,11 +574,15 @@ function auditAlphaStageIndexWorkflow(root = DEFAULT_ROOT) {
   if (!stage || tokens.some((token) => !stage.includes(token))) {
     findings.push('ALPHA_STAGE_INDEX_FINALIZER_CONTRACT_DRIFT');
   }
+  const dependencyInstallIndex = stage.indexOf(
+    'pnpm install --frozen-lockfile --ignore-scripts',
+  );
   const finalizeIndex = stage.indexOf('--mode=finalize');
   const auditIndex = stage.indexOf('--mode=audit');
   const uploadIndex = stage.indexOf('actions/upload-artifact@');
   if (
-    finalizeIndex < 0 ||
+    dependencyInstallIndex < 0 ||
+    finalizeIndex <= dependencyInstallIndex ||
     auditIndex <= finalizeIndex ||
     uploadIndex <= auditIndex
   ) {
diff --git a/scripts/ql3-cluster-alpha-milestone.cjs b/scripts/ql3-cluster-alpha-milestone.cjs
index 0d8c612a..59b32397 100644
--- a/scripts/ql3-cluster-alpha-milestone.cjs
+++ b/scripts/ql3-cluster-alpha-milestone.cjs
@@ -494,6 +494,9 @@ function auditClusterAlphaMilestoneWorkflow(root = DEFAULT_ROOT) {
   const milestone = jobBlock(workflow, 'cluster-alpha-milestone');
   const tokens = [
     'name: Finalize the Cluster Alpha integration milestone',
+    'pnpm/action-setup@v6',
+    'cache-dependency-path: pnpm-lock.yaml',
+    'pnpm install --frozen-lockfile --ignore-scripts',
     'actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c',
     'scripts/ql3-cluster-alpha-milestone.cjs',
     '--mode=finalize',
@@ -517,11 +520,15 @@ function auditClusterAlphaMilestoneWorkflow(root = DEFAULT_ROOT) {
   ) {
     findings.push('CLUSTER_MILESTONE_FINALIZER_CONTRACT_DRIFT');
   }
+  const dependencyInstallIndex = milestone.indexOf(
+    'pnpm install --frozen-lockfile --ignore-scripts',
+  );
   const finalizerIndex = milestone.indexOf('--mode=finalize');
   const auditIndex = milestone.indexOf('--mode=audit');
   const uploadIndex = milestone.indexOf('actions/upload-artifact@');
   if (
-    finalizerIndex < 0 ||
+    dependencyInstallIndex < 0 ||
+    finalizerIndex <= dependencyInstallIndex ||
     auditIndex <= finalizerIndex ||
     uploadIndex <= auditIndex
   ) {
diff --git a/scripts/ql3-local-alpha-milestone.cjs b/scripts/ql3-local-alpha-milestone.cjs
index dca62a73..634eb20e 100644
--- a/scripts/ql3-local-alpha-milestone.cjs
+++ b/scripts/ql3-local-alpha-milestone.cjs
@@ -527,6 +527,9 @@ function auditLocalAlphaMilestoneWorkflow(root = DEFAULT_ROOT) {
   const milestoneTokens = [
     '    name: Finalize the Local Alpha milestone',
     '    needs:',
+    'pnpm/action-setup@v6',
+    'cache-dependency-path: pnpm-lock.yaml',
+    'pnpm install --frozen-lockfile --ignore-scripts',
     'actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c',
     `name: ql3-alpha-${'${{ github.sha }}'}-local-${'${{ inputs.local_alpha_variant }}'}-amd64`,
     `name: ql3-alpha-${'${{ github.sha }}'}-local-${'${{ inputs.local_alpha_variant }}'}-arm64`,
@@ -547,11 +550,15 @@ function auditLocalAlphaMilestoneWorkflow(root = DEFAULT_ROOT) {
   ) {
     findings.push('MILESTONE_FINALIZER_CONTRACT_DRIFT');
   }
+  const dependencyInstallIndex = milestone.indexOf(
+    'pnpm install --frozen-lockfile --ignore-scripts',
+  );
   const finalizerIndex = milestone.indexOf('--mode=finalize');
   const auditIndex = milestone.indexOf('--mode=audit');
   const uploadIndex = milestone.lastIndexOf('actions/upload-artifact@');
   if (
-    finalizerIndex < 0 ||
+    dependencyInstallIndex < 0 ||
+    finalizerIndex <= dependencyInstallIndex ||
     auditIndex <= finalizerIndex ||
     uploadIndex <= auditIndex
   ) {
diff --git a/test/back/ql3AlphaStageIndex.test.cjs b/test/back/ql3AlphaStageIndex.test.cjs
index 1bc0888b..41ce187d 100644
--- a/test/back/ql3AlphaStageIndex.test.cjs
+++ b/test/back/ql3AlphaStageIndex.test.cjs
@@ -327,6 +327,34 @@ test('workflow audit rejects a partial or prematurely uploaded stage index', (t)
   );
 });
 
+test('workflow audit rejects a stage finalizer without installed dependencies', (t) => {
+  const fixtureRoot = fs.realpathSync(
+    fs.mkdtempSync(path.join(os.tmpdir(), 'ql3-alpha-stage-dependencies-')),
+  );
+  t.after(() => fs.rmSync(fixtureRoot, { recursive: true, force: true }));
+  fs.mkdirSync(path.join(fixtureRoot, '.github/workflows'), {
+    recursive: true,
+  });
+  const source = fs.readFileSync(
+    path.join(root, '.github/workflows/ql3-ci.yml'),
+    'utf8',
+  );
+  const marker = '\n  alpha-stage-index:\n';
+  const markerIndex = source.indexOf(marker);
+  const workflow = `${source.slice(0, markerIndex)}${source
+    .slice(markerIndex)
+    .replace('pnpm install --frozen-lockfile --ignore-scripts', 'true')}`;
+  fs.writeFileSync(
+    path.join(fixtureRoot, '.github/workflows/ql3-ci.yml'),
+    workflow,
+  );
+  const report = auditAlphaStageIndexWorkflow(fixtureRoot);
+  assert.equal(report.compatible, false);
+  assert.ok(
+    report.findings.includes('ALPHA_STAGE_INDEX_FINALIZER_CONTRACT_DRIFT'),
+  );
+});
+
 test('CLI grammar keeps cross-index audit explicit', () => {
   assert.deepEqual(
     parseArguments([
diff --git a/test/back/ql3ClusterAlphaMilestone.test.cjs b/test/back/ql3ClusterAlphaMilestone.test.cjs
index 4fed389f..d410ad97 100644
--- a/test/back/ql3ClusterAlphaMilestone.test.cjs
+++ b/test/back/ql3ClusterAlphaMilestone.test.cjs
@@ -216,3 +216,27 @@ test('workflow audit rejects missing final offline audit', (t) => {
     report.findings.includes('CLUSTER_MILESTONE_FINALIZER_CONTRACT_DRIFT'),
   );
 });
+
+test('workflow audit rejects a finalizer without installed dependencies', (t) => {
+  const fixtureRoot = fs.mkdtempSync(
+    path.join(os.tmpdir(), 'ql3-cluster-alpha-dependencies-'),
+  );
+  t.after(() => fs.rmSync(fixtureRoot, { recursive: true, force: true }));
+  const workflowDirectory = path.join(fixtureRoot, '.github/workflows');
+  fs.mkdirSync(workflowDirectory, { recursive: true });
+  const source = fs.readFileSync(
+    path.join(root, '.github/workflows/ql3-ci.yml'),
+    'utf8',
+  );
+  const marker = '\n  cluster-alpha-milestone:\n';
+  const markerIndex = source.indexOf(marker);
+  const workflow = `${source.slice(0, markerIndex)}${source
+    .slice(markerIndex)
+    .replace('pnpm install --frozen-lockfile --ignore-scripts', 'true')}`;
+  fs.writeFileSync(path.join(workflowDirectory, 'ql3-ci.yml'), workflow);
+  const report = auditClusterAlphaMilestoneWorkflow(fixtureRoot);
+  assert.equal(report.compatible, false);
+  assert.ok(
+    report.findings.includes('CLUSTER_MILESTONE_FINALIZER_CONTRACT_DRIFT'),
+  );
+});
diff --git a/test/back/ql3LocalAlphaMilestone.test.cjs b/test/back/ql3LocalAlphaMilestone.test.cjs
index 9716337d..d5998954 100644
--- a/test/back/ql3LocalAlphaMilestone.test.cjs
+++ b/test/back/ql3LocalAlphaMilestone.test.cjs
@@ -325,6 +325,35 @@ test('workflow audit rejects a partial milestone finalizer', (t) => {
   );
 });
 
+test('workflow audit rejects a finalizer without installed dependencies', (t) => {
+  const fixtureRoot = fs.realpathSync(
+    fs.mkdtempSync(path.join(os.tmpdir(), 'ql3-local-alpha-dependencies-')),
+  );
+  t.after(() => fs.rmSync(fixtureRoot, { recursive: true, force: true }));
+  fs.mkdirSync(path.join(fixtureRoot, '.github/workflows'), {
+    recursive: true,
+  });
+  const source = fs.readFileSync(
+    path.join(root, '.github/workflows/ql3-ci.yml'),
+    'utf8',
+  );
+  const marker = '\n  local-alpha-milestone:\n';
+  const markerIndex = source.indexOf(marker);
+  const workflow = `${source.slice(0, markerIndex)}${source
+    .slice(markerIndex)
+    .replace('pnpm install --frozen-lockfile --ignore-scripts', 'true')}`;
+  fs.writeFileSync(
+    path.join(fixtureRoot, '.github/workflows/ql3-ci.yml'),
+    workflow,
+  );
+  const report = auditLocalAlphaMilestoneWorkflow(fixtureRoot);
+  assert.equal(report.compatible, false);
+  assert.equal(
+    report.findings.includes('MILESTONE_FINALIZER_CONTRACT_DRIFT'),
+    true,
+  );
+});
+
 test('CLI grammar separates finalization, index audit and workflow audit', () => {
   assert.deepEqual(
     parseArguments(['--mode=audit', '--milestone=/tmp/ql3-alpha-milestone']),