diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index cc479dc..9d37c4c 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -155,3 +155,25 @@ jobs:
         if: always()
         working-directory: infra/compose
         run: docker compose down -v
+
+  dependency-audit:
+    runs-on: ubuntu-latest
+    # E10: fail on high/critical production advisories only. Policy:
+    # docs/ops/dependency-audit.md
+    steps:
+      - uses: actions/checkout@v7
+
+      - uses: pnpm/action-setup@v6
+        with:
+          version: 9.15.0
+
+      - uses: actions/setup-node@v7
+        with:
+          node-version: "20"
+          cache: "pnpm"
+
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+
+      - name: pnpm audit (prod, high+)
+        run: pnpm audit:ci
diff --git a/.github/workflows/codeql.yml b/.github/workflows/codeql.yml
new file mode 100644
index 0000000..dae629d
--- /dev/null
+++ b/.github/workflows/codeql.yml
@@ -0,0 +1,51 @@
+name: CodeQL
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+  schedule:
+    # Weekly Monday 06:30 UTC
+    - cron: "30 6 * * 1"
+
+concurrency:
+  group: codeql-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  analyze:
+    name: Analyze JavaScript / TypeScript
+    runs-on: ubuntu-latest
+    permissions:
+      actions: read
+      contents: read
+      # Required once GitHub code scanning is enabled on the repo (Settings →
+      # Code security). Until then we keep upload:never so analysis still gates CI.
+      security-events: write
+
+    steps:
+      - uses: actions/checkout@v7
+
+      - name: Initialize CodeQL
+        uses: github/codeql-action/init@v4
+        with:
+          languages: javascript-typescript
+          build-mode: none
+
+      - name: Perform CodeQL Analysis
+        uses: github/codeql-action/analyze@v4
+        with:
+          category: "/language:javascript-typescript"
+          # Private repos without Code Scanning / GHAS cannot upload SARIF to
+          # the Security tab. Analysis still runs and fails the job on query
+          # errors. Enable code scanning in repo settings to switch to upload.
+          upload: never
+
+      - name: Upload SARIF artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: codeql-javascript-typescript
+          path: ${{ runner.temp }}/codeql/javascript/results/*.sarif
+          if-no-files-found: ignore
+          retention-days: 14
diff --git a/docs/ops/codeql.md b/docs/ops/codeql.md
new file mode 100644
index 0000000..a1f9b9a
--- /dev/null
+++ b/docs/ops/codeql.md
@@ -0,0 +1,20 @@
+# CodeQL (E10)
+
+Workflow: `.github/workflows/codeql.yml` — runs on `main` PRs/pushes + weekly.
+
+## Behavior
+
+- Analyzes JavaScript/TypeScript (`build-mode: none`).
+- **Upload to GitHub Code Scanning** is `never` until code scanning is enabled on this private repository (Settings → Code security and analysis → Code scanning). Without that, SARIF upload fails the job even when analysis succeeds.
+- SARIF is retained as a workflow artifact (`codeql-javascript-typescript`) for 14 days.
+
+## Enabling Security-tab upload
+
+1. Repo **Settings → Code security** → enable **Code scanning**.
+2. Change `upload: never` → `upload: always` (or remove the `upload` key) in `.github/workflows/codeql.yml`.
+3. Keep `permissions.security-events: write`.
+
+## Related
+
+- Dependency audit gate: [`dependency-audit.md`](./dependency-audit.md)
+- Dependabot: `.github/dependabot.yml`
diff --git a/docs/ops/dependency-audit.md b/docs/ops/dependency-audit.md
new file mode 100644
index 0000000..dfca636
--- /dev/null
+++ b/docs/ops/dependency-audit.md
@@ -0,0 +1,45 @@
+# Dependency audit policy (E10)
+
+**Goal:** catch high/critical production advisories in CI without papering over real risk.
+
+## CI gate
+
+| Command | When | Fail on |
+|---------|------|---------|
+| `pnpm audit:ci` → `pnpm audit --prod --audit-level=high` | Every PR (`ci.yml` job `dependency-audit`) | **high** and **critical** only |
+
+Moderate / low findings are **visible** in local `pnpm audit --prod` but do not fail the gate. Prefer fixing them via Dependabot (already weekly) rather than ignoring.
+
+## Allowlist (carefully)
+
+If a high/critical advisory cannot be fixed immediately (no patch, or only via a breaking major):
+
+1. Prefer `pnpm.overrides` / dependency bump that removes the vulnerable path.
+2. Only if blocked: add the **CVE / GHSA id** under `pnpm.auditConfig.ignoreCves` in the **root** `package.json`, with an inline comment in `docs/ops/dependency-audit.md` stating:
+   - advisory id + package
+   - why production risk is accepted (or not reachable)
+   - owner + review-by date
+3. Never ignore an advisory “to make CI green” without that note.
+4. Revisit allowlisted entries every Dependabot cycle; delete when fixed.
+
+Empty allowlist is the default. Do **not** copy npm’s `--force` / blanket ignore.
+
+Example shape (comments belong in this doc, not in `package.json`):
+
+```json
+{
+  "pnpm": {
+    "auditConfig": {
+      "ignoreCves": ["CVE-YYYY-NNNNN"]
+    }
+  }
+}
+```
+
+Document each ignored id in this file with package, rationale, owner, and review-by date.
+
+## Related
+
+- Dependabot: `.github/dependabot.yml` (weekly npm + Actions minors/patches)
+- CodeQL: `.github/workflows/codeql.yml` (SAST on default branch + PRs) — see [`codeql.md`](./codeql.md)
+- Local: `pnpm audit --prod` (all severities)
diff --git a/infra/ci/README.md b/infra/ci/README.md
index 525ac17..b0173f8 100644
--- a/infra/ci/README.md
+++ b/infra/ci/README.md
@@ -17,8 +17,11 @@ This folder is reserved for reusable CI helper scripts if they outgrow the workf
 | `compose-smoke-test` | Infra startup | Compose Postgres + Redis + Qdrant healthy |
 | `integration-test` | Product path (D5.4 e2e) | `pnpm build` → migrate → `pnpm test:integration` |
 | | Golden eval (D5.2) | `pnpm test:eval` (hit@3 ≥80%, citation 100%) |
+| `dependency-audit` | E10 supply-chain | `pnpm audit:ci` (prod, fail on high/critical) — see [`docs/ops/dependency-audit.md`](../../docs/ops/dependency-audit.md) |
 
-All of the above use the checked-in sample-repo fixture + fake OpenAI-compatible provider — **no** GitHub/Ollama/cloud network on the required path (₹0 / offline CI).
+**Also on PRs / main (separate workflow):** CodeQL JavaScript/TypeScript — `.github/workflows/codeql.yml`.
+
+All product-path jobs above use the checked-in sample-repo fixture + fake OpenAI-compatible provider — **no** GitHub/Ollama/cloud network on that path (₹0 / offline CI). Dependency audit and CodeQL need network for the advisory DB / CodeQL pack download.
 
 **Not in CI:** `codeoracle replay` against a product/dogfood index (needs a ready repo + real embeddings). That is an ops gate — see [`test/replay/README.md`](../../test/replay/README.md) and [`infra/dogfood/README.md`](../dogfood/README.md).
 
diff --git a/package.json b/package.json
index 1eebfe1..435e93e 100644
--- a/package.json
+++ b/package.json
@@ -23,6 +23,7 @@
     "test:golden": "vitest run --config test/golden-queries/vitest.config.ts",
     "test:eval": "INTEGRATION_TEST=1 vitest run --config test/golden-queries/eval.vitest.config.ts",
     "test:retrieval-gates": "pnpm --filter @codeoracle/core-domain test -- test/absolute-score-floor.test.ts test/secret-path-class.test.ts && pnpm --filter @codeoracle/retrieval exec vitest run test/search-codebase.test.ts test/find-decision.test.ts test/explain-file.test.ts && pnpm --filter @codeoracle/cli test -- src/replay/score.test.ts",
+    "audit:ci": "pnpm audit --prod --audit-level=high",
     "typecheck:e2e": "tsc -p test/e2e/tsconfig.json",
     "typecheck:golden": "tsc -p test/golden-queries/tsconfig.json",
     "fixture:sample-repo:tree": "pnpm --filter @codeoracle/worker exec tsx ../../test/fixtures/sample-repo/write-tree-cli.ts",