diff --git a/.github/actions/npm-audit-pr-comment/action.yml b/.github/actions/npm-audit-pr-comment/action.yml
new file mode 100644
index 00000000..1e2023f0
--- /dev/null
+++ b/.github/actions/npm-audit-pr-comment/action.yml
@@ -0,0 +1,104 @@
+name: npm audit PR comment
+description: >
+  Posts or updates a PR comment with pre-existing npm audit findings.
+  Informational only — never fails. Pair with dependency-review-action for gating.
+
+inputs:
+  working-directory:
+    description: Directory containing package.json / package-lock.json
+    required: true
+  audit-flags:
+    description: Extra flags forwarded to npm audit (e.g. --omit=dev)
+    required: false
+    default: ''
+  min-severity:
+    description: Minimum severity to include in the report (info, low, moderate, high, critical)
+    required: false
+    default: high
+  label:
+    description: Short label shown in the comment header (e.g. "website", "extension")
+    required: true
+
+runs:
+  using: composite
+  steps:
+    - name: Collect audit findings and post PR comment
+      uses: actions/github-script@v7
+      env:
+        AUDIT_FLAGS: ${{ inputs.audit-flags }}
+        MIN_SEVERITY: ${{ inputs.min-severity }}
+        WORK_DIR: ${{ inputs.working-directory }}
+        LABEL: ${{ inputs.label }}
+      with:
+        script: |
+          const { execSync } = require('child_process')
+
+          let auditOutput
+          try {
+            auditOutput = execSync(
+              `npm audit --json ${process.env.AUDIT_FLAGS}`,
+              { cwd: process.env.WORK_DIR, stdio: ['pipe', 'pipe', 'pipe'] }
+            ).toString()
+          } catch (e) {
+            auditOutput = e.stdout?.toString() ?? '{}'
+          }
+
+          const SEVERITY_RANK = ['info', 'low', 'moderate', 'high', 'critical']
+          const minSeverity = (process.env.MIN_SEVERITY || 'high').toLowerCase()
+          const minRank = Math.max(0, SEVERITY_RANK.indexOf(minSeverity))
+
+          let report
+          try {
+            const json = JSON.parse(auditOutput)
+            const advisories = new Map(
+              Object.values(json.vulnerabilities ?? {})
+                .flatMap(v => (Array.isArray(v.via) ? v.via : [v.via]))
+                .filter(v => v && typeof v === 'object' && v.url && SEVERITY_RANK.indexOf(v.severity) >= minRank)
+                .map(v => [v.url, v])
+            )
+
+            const rows = [...advisories.values()].map(a =>
+              `| ${a.severity} | [${a.title}](${a.url}) | \`${a.module_name ?? a.name}\` |`
+            )
+
+            report = rows.length === 0
+              ? `✅ No vulnerabilities found (severity ≥ ${minSeverity}).`
+              : [
+                  `⚠️ **Pre-existing vulnerabilities in \`${process.env.LABEL}\` (severity ≥ ${minSeverity})** — not introduced by this PR, informational only.`,
+                  '',
+                  `| Severity | Advisory | Package |`,
+                  `|----------|----------|---------|`,
+                  ...rows,
+                  '',
+                  `> These were already present on the base branch. Use \`npm audit fix\` or upgrade dependencies to resolve them.`,
+                ].join('\n')
+          } catch (_) {
+            report = `⚠️ Could not parse audit output for \`${process.env.LABEL}\`.`
+          }
+
+          const marker = `<!-- npm-audit-comment:${process.env.LABEL} -->`
+          const body = `${marker}\n### npm audit — \`${process.env.LABEL}\`\n\n${report}`
+
+          const comments = await github.paginate(github.rest.issues.listComments, {
+            owner: context.repo.owner,
+            repo: context.repo.repo,
+            issue_number: context.issue.number,
+            per_page: 100,
+          })
+
+          const existing = comments.find(c => c.body.includes(marker))
+          if (existing) {
+            await github.rest.issues.updateComment({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              comment_id: existing.id,
+              body,
+            })
+          } else {
+            await github.rest.issues.createComment({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body,
+            })
+          }
diff --git a/.github/workflows/dependency-review.yml b/.github/workflows/dependency-review.yml
new file mode 100644
index 00000000..9811f37f
--- /dev/null
+++ b/.github/workflows/dependency-review.yml
@@ -0,0 +1,36 @@
+name: Dependency Review
+
+# Single repo-wide gate for newly-introduced vulnerabilities.
+# dependency-review-action diffs the PR's dependency graph (base -> head), so it
+# only flags dependencies CHANGED by this PR — per-package scoping comes for free.
+# Pre-existing vulnerabilities are reported separately (non-blocking) by the
+# npm-audit-pr-comment action in each package's CI workflow.
+on:
+  pull_request:
+    branches: [main]
+    paths:
+      - '**/package.json'
+      - '**/package-lock.json'
+
+jobs:
+  dependency-review:
+    name: Dependency Review (fail on new vulnerabilities)
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      pull-requests: write
+    steps:
+      - name: Harden Runner
+        uses: step-security/harden-runner@v2
+        with:
+          egress-policy: audit
+
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Dependency Review
+        uses: actions/dependency-review-action@v4
+        with:
+          fail-on-severity: moderate
+          vulnerability-check: true
+          comment-summary-in-pr: on-failure
diff --git a/.github/workflows/docs.yml b/.github/workflows/docs.yml
index 68bacbab..4207312e 100644
--- a/.github/workflows/docs.yml
+++ b/.github/workflows/docs.yml
@@ -26,6 +26,9 @@ jobs:
   build:
     name: Build Documentation
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      pull-requests: write
     steps:
       - name: Harden Runner
         uses: step-security/harden-runner@v2
@@ -46,9 +49,13 @@ jobs:
         working-directory: website
         run: npm ci
 
-      - name: Audit for vulnerabilities
-        working-directory: website
-        run: npm audit --audit-level=high
+      - name: Report pre-existing vulnerabilities on PR
+        if: github.event_name == 'pull_request'
+        uses: ./.github/actions/npm-audit-pr-comment
+        with:
+          working-directory: ${{ github.workspace }}/website
+          min-severity: high
+          label: website
 
       - name: Build documentation
         working-directory: website
diff --git a/.github/workflows/lib-collection-scripts-ci.yml b/.github/workflows/lib-collection-scripts-ci.yml
index 23b1eff9..71677677 100644
--- a/.github/workflows/lib-collection-scripts-ci.yml
+++ b/.github/workflows/lib-collection-scripts-ci.yml
@@ -33,11 +33,27 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: read
+      security-events: write
 
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
 
+      - name: Run Trivy vulnerability scanner
+        uses: aquasecurity/trivy-action@master
+        with:
+          scan-type: "fs"
+          scan-ref: lib
+          format: "sarif"
+          output: "trivy-lib-results.sarif"
+
+      - name: Upload Trivy scan results to GitHub Security tab
+        uses: github/codeql-action/upload-sarif@v4
+        if: always()
+        with:
+          sarif_file: "trivy-lib-results.sarif"
+          category: lib
+
       - name: Setup Node.js
         uses: actions/setup-node@v4
         with:
@@ -56,10 +72,6 @@ jobs:
         working-directory: lib
         run: npm run lint
 
-      - name: Audit for vulnerabilities
-        working-directory: lib
-        run: npm audit --audit-level=high
-
       - name: Run tests
         working-directory: lib
         run: npm test
diff --git a/.github/workflows/vscode-extension-secure-ci.yml b/.github/workflows/vscode-extension-secure-ci.yml
index ac1ef64c..6b00e05c 100644
--- a/.github/workflows/vscode-extension-secure-ci.yml
+++ b/.github/workflows/vscode-extension-secure-ci.yml
@@ -33,7 +33,9 @@ jobs:
     name: Security Analysis & Vulnerability Scanning
     runs-on: ubuntu-latest
     permissions:
+      contents: read
       security-events: write
+      pull-requests: write
 
     steps:
       - name: Harden Runner
@@ -62,12 +64,19 @@ jobs:
           npm ci --fund=false
           npm run build
 
-      - name: Install dependencies with audit
+      - name: Install dependencies
         working-directory: ${{ env.EXTENSION_DIR }}
         shell: bash
-        run: |
-          npm ci --audit --fund=false
-          npm audit --omit=dev --audit-level=moderate
+        run: npm ci --fund=false
+
+      - name: Report pre-existing vulnerabilities on PR
+        if: github.event_name == 'pull_request'
+        uses: ./.github/actions/npm-audit-pr-comment
+        with:
+          working-directory: ${{ github.workspace }}
+          audit-flags: --omit=dev
+          min-severity: moderate
+          label: extension
 
       - name: Run Trivy vulnerability scanner
         uses: aquasecurity/trivy-action@master