diff --git a/.github/workflows/codeql.yml b/.github/workflows/codeql.yml
new file mode 100644
index 00000000..8698a55e
--- /dev/null
+++ b/.github/workflows/codeql.yml
@@ -0,0 +1,63 @@
+# SPDX-FileCopyrightText: 2026 soundminds.ai
+#
+# SPDX-License-Identifier: Apache-2.0
+
+# CodeQL — GitHub's first-party static analysis (SAST). Closes the OSSF
+# Scorecard "SAST tool is not run on all commits" finding and, more importantly,
+# surfaces real code-level security bugs on every PR. Scans both languages in
+# the repo: Python (backend) and JavaScript/TypeScript (ui). Both use
+# build-mode `none` — CodeQL extracts interpreted-language source directly, so
+# no compile step is needed (and no engine/cluster service containers).
+#
+# Action refs are pinned to commit SHAs to match the repo's pinned-dependencies
+# posture (chore_scorecard_pin_deps_postcss); Dependabot's github-actions
+# ecosystem keeps the SHAs fresh.
+name: CodeQL
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+  schedule:
+    # Mondays 04:31 UTC — offset from scorecard.yml's 04:27 to spread load.
+    - cron: "31 4 * * 1"
+
+# Least-privilege default; the analyze job widens to security-events: write.
+permissions:
+  contents: read
+
+concurrency:
+  group: codeql-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  analyze:
+    name: Analyze (${{ matrix.language }})
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
+    permissions:
+      contents: read
+      security-events: write # upload CodeQL SARIF to the Security tab
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - language: python
+            build-mode: none
+          - language: javascript-typescript
+            build-mode: none
+    steps:
+      - name: Checkout
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+
+      - name: Initialize CodeQL
+        uses: github/codeql-action/init@87557b9c84dde89fdd9b10e88954ac2f4248e463 # v4
+        with:
+          languages: ${{ matrix.language }}
+          build-mode: ${{ matrix.build-mode }}
+
+      - name: Perform CodeQL Analysis
+        uses: github/codeql-action/analyze@87557b9c84dde89fdd9b10e88954ac2f4248e463 # v4
+        with:
+          category: "/language:${{ matrix.language }}"
diff --git a/Dockerfile b/Dockerfile
index f6f5a00a..abd6aebf 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -12,16 +12,17 @@
 # Per docs/01_architecture/deployment.md §"MVP1 deployment shape" + the
 # implementation_plan.md Story 4.1 "Decision rationale".
 
-# Single digest-pinned base image (PinnedDependencies / OSSF Scorecard).
-# tag + digest in one ARG so an override (`--build-arg BASE_IMAGE=...`) is
-# unambiguous — a separate version/digest pair would let the digest silently
-# win over a changed tag. Dependabot's docker ecosystem keeps this fresh.
-ARG BASE_IMAGE=python:3.14-slim@sha256:c845af9399020c7e562969a13689e929074a10fd057acd1b1fad06a2fb068e97
-
 # ---------------------------------------------------------------------------
 # Stage 1 — base: Python + uv + system deps for healthcheck (curl)
 # ---------------------------------------------------------------------------
-FROM ${BASE_IMAGE} AS base
+# python:3.14-slim, digest-pinned (PinnedDependencies / OSSF Scorecard). The
+# digest is written literally on the FROM (not via an ARG) because Scorecard's
+# static parser only credits a pin it can see inline as `image@sha256:…`; an
+# ARG-indirected digest reads as "unpinned". Writing the tag + digest together
+# also removes the override footgun of a separate version/digest pair (the
+# digest would silently win over a changed tag). Dependabot's docker ecosystem
+# bumps the tag + digest together; refresh both when bumping Python.
+FROM python:3.14-slim@sha256:c845af9399020c7e562969a13689e929074a10fd057acd1b1fad06a2fb068e97 AS base
 
 ENV PYTHONUNBUFFERED=1 \
     PYTHONDONTWRITEBYTECODE=1 \
diff --git a/ui/Dockerfile b/ui/Dockerfile
index 204f7a9a..af2454ce 100644
--- a/ui/Dockerfile
+++ b/ui/Dockerfile
@@ -16,27 +16,28 @@
 # Node 26 to use the latest engine features without waiting for the
 # October LTS transition.
 
-# Single digest-pinned base image (PinnedDependencies / OSSF Scorecard),
-# declared once and reused by every stage. Dependabot's docker ecosystem
-# keeps the digest fresh.
-ARG BASE_IMAGE=node:26-bookworm-slim@sha256:79723b41edbedf595f62e943a9f8b0ba9af5b1e61045c5f8f59c2c02c1212a16
-
-FROM ${BASE_IMAGE} AS deps
+# node:26-bookworm-slim, digest-pinned (PinnedDependencies / OSSF Scorecard).
+# The digest is written literally on every FROM (not via an ARG) because
+# Scorecard's static parser only credits a pin it can see inline as
+# `image@sha256:…`; an ARG-indirected digest reads as "unpinned". Dependabot's
+# docker ecosystem bumps every occurrence in lockstep, so the repetition is not
+# a sync hazard.
+FROM node:26-bookworm-slim@sha256:79723b41edbedf595f62e943a9f8b0ba9af5b1e61045c5f8f59c2c02c1212a16 AS deps
 WORKDIR /app
 RUN npm install -g pnpm@9
 COPY pnpm-lock.yaml package.json ./
 RUN pnpm install --frozen-lockfile
 
-FROM ${BASE_IMAGE} AS builder
-WORKDIR /app
-RUN npm install -g pnpm@9
-COPY --from=deps /app/node_modules ./node_modules
+# Inherit from `deps` — pnpm, WORKDIR, and node_modules are already in place,
+# so no redundant install/copy (and one fewer digest occurrence). A stage ref
+# to a digest-pinned stage is still credited as pinned by Scorecard.
+FROM deps AS builder
 COPY . .
 ARG NEXT_PUBLIC_API_BASE_URL=http://localhost:8000
 ENV NEXT_PUBLIC_API_BASE_URL=$NEXT_PUBLIC_API_BASE_URL
 RUN pnpm build
 
-FROM ${BASE_IMAGE} AS runner
+FROM node:26-bookworm-slim@sha256:79723b41edbedf595f62e943a9f8b0ba9af5b1e61045c5f8f59c2c02c1212a16 AS runner
 WORKDIR /app
 ENV NODE_ENV=production
 ENV PORT=3000