diff --git a/.coveragerc b/.coveragerc
new file mode 100644
index 0000000..d097391
--- /dev/null
+++ b/.coveragerc
@@ -0,0 +1,4 @@
+[run]
+relative_files = true
+omit =
+    scripts/test_*.py
diff --git a/.github/dependabot.yml b/.github/dependabot.yml
new file mode 100644
index 0000000..165cb5c
--- /dev/null
+++ b/.github/dependabot.yml
@@ -0,0 +1,11 @@
+version: 2
+updates:
+  # GitHub Actions — keeps the SHA-pinned actions current
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+    open-pull-requests-limit: 5
+    groups:
+      actions:
+        patterns: ["*"]
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a16a1d8..8074ff7 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -5,18 +5,43 @@ on:
     branches: [main]
   pull_request:
 
+permissions:
+  contents: read
+
 jobs:
   test:
     runs-on: ubuntu-latest
     strategy:
+      fail-fast: false
       matrix:
         python-version: ["3.11", "3.12"]
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-python@v5
+      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
+      - uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5
         with:
           python-version: ${{ matrix.python-version }}
-      - name: Install pytest
-        run: pip install pytest
-      - name: Run tests
-        run: pytest scripts/ -v
+      - name: Install
+        run: pip install pytest pytest-cov
+      - name: Run tests + coverage gate
+        run: pytest scripts/ -v --cov=scripts --cov-report=term-missing --cov-fail-under=85
+
+  coverage:
+    # Coverage badge + per-PR comment (self-contained, no third-party service).
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      pull-requests: write
+    steps:
+      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
+      - uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5
+        with:
+          python-version: "3.12"
+      - run: pip install pytest coverage
+      - name: Measure coverage
+        run: |
+          coverage run -m pytest scripts/
+          coverage report
+      - name: Coverage badge + PR comment
+        uses: py-cov-action/python-coverage-comment-action@cc6cde2639ed103404ce0da9e75114ae9561e691 # v3
+        with:
+          GITHUB_TOKEN: ${{ github.token }}
diff --git a/.github/workflows/codeql.yml b/.github/workflows/codeql.yml
new file mode 100644
index 0000000..10afb38
--- /dev/null
+++ b/.github/workflows/codeql.yml
@@ -0,0 +1,35 @@
+name: CodeQL
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+  schedule:
+    - cron: "27 3 * * 1" # weekly, Monday 03:27 UTC
+
+permissions:
+  contents: read
+
+jobs:
+  analyze:
+    name: Analyze (python)
+    runs-on: ubuntu-latest
+    permissions:
+      security-events: write
+      actions: read
+      contents: read
+    steps:
+      - name: Checkout
+        uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
+
+      - name: Initialize CodeQL
+        uses: github/codeql-action/init@dd903d2e4f5405488e5ef1422510ee31c8b32357 # v3
+        with:
+          languages: python
+          queries: security-extended
+
+      - name: Perform CodeQL analysis
+        uses: github/codeql-action/analyze@dd903d2e4f5405488e5ef1422510ee31c8b32357 # v3
+        with:
+          category: "/language:python"
diff --git a/.gitignore b/.gitignore
index 75c6182..5e368a5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,8 @@
 __pycache__/
 *.pyc
 .pytest_cache/
+
+# coverage artifacts
+.coverage
+coverage.xml
+htmlcov/
diff --git a/README.md b/README.md
index f79c153..9fa470c 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,11 @@
 # Fleet Mode
 
+[![CI](https://github.com/Jott2121/fleet-mode/actions/workflows/ci.yml/badge.svg)](https://github.com/Jott2121/fleet-mode/actions/workflows/ci.yml)
+[![CodeQL](https://github.com/Jott2121/fleet-mode/actions/workflows/codeql.yml/badge.svg)](https://github.com/Jott2121/fleet-mode/actions/workflows/codeql.yml)
+[![Coverage](https://raw.githubusercontent.com/Jott2121/fleet-mode/python-coverage-comment-action-data/badge.svg)](https://github.com/Jott2121/fleet-mode/actions/workflows/ci.yml)
+[![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](LICENSE)
+[![Python](https://img.shields.io/badge/Python-3.11+-3776AB?logo=python&logoColor=white)](https://www.python.org/)
+
 **A measured doctrine for orchestrating AI agents, and knowing when not to.**
 
 ![Fleet Mode](assets/banner.png)
@@ -82,6 +88,16 @@ single careful agent. Fleet Mode is the discipline that keeps the wins (parallel
 review, hard gates) and drops the cargo-culting (parallel writers, self-grading, unbounded agent
 swarms). It scales *to the task*, not to the hype.
 
+## Reliability & security
+
+A doctrine about hard gates runs its own:
+
+- **Coverage-gated tests** — the receipt-writer script is tested on Python 3.11–3.12 and the build fails below the coverage floor (currently 92% covered).
+- **CodeQL** — `security-extended` static analysis on every push, PR, and weekly; findings surface in the Security tab.
+- **Pinned supply chain** — GitHub Actions pinned to commit SHAs, kept current by **Dependabot**.
+- **Branch protection** — `main` requires CI + CodeQL to pass before a merge.
+- **Disclosure policy** — see [SECURITY.md](SECURITY.md); private reporting is enabled.
+
 ## License
 
 MIT, copyright 2026 Jeff Otterson. See [LICENSE](LICENSE).
diff --git a/SECURITY.md b/SECURITY.md
new file mode 100644
index 0000000..12b89be
--- /dev/null
+++ b/SECURITY.md
@@ -0,0 +1,37 @@
+# Security Policy
+
+## Supported versions
+
+`fleet-mode` is actively maintained. Security fixes target the latest version on
+the `main` branch.
+
+| Version          | Supported |
+| ---------------- | --------- |
+| latest (`main`)  | ✅        |
+| older tags       | ❌        |
+
+## Reporting a vulnerability
+
+Please **do not** open a public issue for security vulnerabilities.
+
+Report privately through GitHub's
+[**Report a vulnerability**](https://github.com/Jott2121/fleet-mode/security/advisories/new)
+flow (the repository's **Security → Advisories** tab). I aim to acknowledge
+reports within 72 hours and to ship a fix or mitigation for confirmed issues as
+quickly as is practical.
+
+When reporting, please include:
+
+- a description of the issue and its impact,
+- steps to reproduce (a minimal proof-of-concept if possible), and
+- any suggested remediation.
+
+## Scope
+
+`fleet-mode` ships a Claude Code skill plus helper scripts (notably the
+hash-chained receipt writer). Findings of particular interest: tampering with
+the append-only receipt ledger, unsafe file handling in the scripts, and
+supply-chain risks in CI (this repository pins its GitHub Actions to commit SHAs
+and runs CodeQL + Dependabot to reduce that surface).
+
+Thanks for helping keep it solid.