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Bewaker AI

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Building Cryptographic Guardrails for AI-Assisted Coding

#vscode #security #ai #opensource

Bewaker: local-first cryptographic guardrails for critical code (VS Code + git hooks)

AI coding assistants are great! That is until a tiny diff lands in the wrong place. For things like infrastructure-as-code, authorization paths, or payment logic, even subtle changes can carry real risk.

Bewaker is an open-source, local-first tool that helps you lock down the sensitive parts of your repo and prove they weren’t changed without an explicit unlock. It runs inside VS Code and enforces integrity with git pre-commit/pre-push hooks. No backend, no telemetry; keys and audit stay on your machine. Apache-2.0.

What it does

  • Policy-driven protection — define a simple YAML policy that lists what to protect.
  • Cryptographic lockfile — Bewaker writes a Merkle-rooted, Ed25519-signed lock that represents the expected state.
  • Editor + hooks enforcement — VS Code surfaces guardrails as you edit; pre-commit/pre-push hooks block unapproved changes.
  • Tamper-evident audit — events are chained locally so you have a verifiable trail.

Works alongside Copilot/Cursor—goal is secure AI-assisted dev, not blocking AI.

Quickstart (90 seconds)

  1. Install the VS Code extension

    Marketplace: https://marketplace.visualstudio.com/items?itemName=BewakerAI.Bewaker

  2. Create a policy

    In VS Code, open the Command Palette and run "Bewaker: Recommend Policy" (or create .guardpolicy.yml).

    # .guardpolicy.yml (minimal example)
protect:
  - path: "infra/**"
  - path: "src/auth/**"
  - path: ".github/workflows/**"

  3. Lock the repository

    Command Palette → "Bewaker: Lock Repository"

    This writes .guardlock (Merkle + Ed25519) to represent the expected state.

  4. Install git hooks

    Command Palette → "Bewaker: Install Git Hooks"

    This adds pre-commit / pre-push verification.

  5. Try it

    Edit a protected file and attempt a commit. The hook will block it until you explicitly unlock in the extension.

How it works

  • Policy → .guardpolicy.yml tells Bewaker which files/paths are considered sensitive.
  • Lockfile → .guardlock stores a Merkle root and signature so drift is detectable and the lock itself is tamper-evident.
  • Hooks → pre-commit / pre-push recompute hashes for protected paths and compare against the lockfile before a commit/push is allowed.
  • Audit → local JSONL keeps an append-only, tamper-evident record of locks/unlocks/verification events.

Local-first by design: no server, no telemetry, keys stay on your machine.

How this differs from CODEOWNERS

CODEOWNERS is great for review workflows, but it triggers during PR, after a commit exists.

Bewaker focuses on pre-commit, on the developer’s machine. It’s a guardrail while editing, not just during review.

Use both: CODEOWNERS for review gates; Bewaker for local cryptographic integrity.

Threat model & limitations

  • Local enforcement: disables “it was the bot” surprises; hooks still run even if the editor is bypassed.
  • No network: reduces data exfil/telemetry risks.
  • Language-agnostic: path/policy-based across text files.

Known gaps / roadmap:

  • Heuristics are intentionally simple today; “adaptive/ML-ready” risk scoring is in progress.
  • Org-wide controls (e.g., server-side pre-receive checks) and multi-approver unlocks are part of a future Team Edition.

Call for feedback

  • Does the UX make sense?
  • Any obvious bypasses or threat-model blind spots?
  • What policy shapes would make this easier to adopt in monorepos?

If this scratches an itch for your team, I’d love to hear how you’d extend it.

Appendix: tiny policy + what happens 

# .guardpolicy.yml
protect:
  - path: "infra/**"
  - path: "src/auth/**"
  - path: ".github/workflows/**"
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  • Save the file, Lock Repository, Install Git Hooks.
  • Change infra/terraform.tf and try git commit.
  • The pre-commit hook verifies the hash against .guardlock and rejects the commit until you unlock in VS Code (events show up in the local audit).

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