Verify what a linter cannot.

Codelight turns the architectural rules you repeat in code review into focused checks for every diff. Each verifier asks one model one yes-or-no question about the files its path globs match.

- id: no-silent-except
  paths: ["**/*.py"]
  severity: warn
  assert: >
    No exception handler discards an exception without either logging it or
    re-raising.

$ codelight
uncommitted changes - 2 changed file(s)

  → no-silent-except [warn]
      app/ingest/worker.py

judging 1 verifier(s) with claude-opus-5

[WARN] no-silent-except
      The added handler at app/ingest/worker.py:88 catches OSError and its body
      is `pass`, so a failed fetch leaves no record.
      → app/ingest/worker.py

Why Codelight

Tests tell you if code works. Linters enforce rules that a program can decide. Neither can tell you if a change follows the local design choices that make your codebase coherent:

• handlers do not swallow exceptions;
• new endpoints declare a timeout;
• migrations are reversible;
• logs never contain credential values.

These rules often live only in the heads of experienced maintainers. That does not scale when agents write and merge more code.

Codelight gives each rule a small, readable check. Path globs select the right diffs. One assertion stays easier to predict than a broad review prompt with many competing priorities.

Need	Best tool
Formatting, types, fixed lists, or exact structure	Linter, type checker, or test
One contextual convention on a diff	Codelight verifier
Broad review of a risky change	Agentic code review

Codelight does not replace deterministic checks or human judgment. A verifier is a model judgment, not a proof. Test every verifier in both directions before you trust it.

Quick start

Install the CLI:

go install github.com/oliverwehrens/codelight/cmd/codelight@latest

Ask your coding agent to create rules grounded in your repository:

Read the output of codelight --spec in full, then propose verifiers for this repository. Ground every verifier in a convention this codebase already holds. Test each verifier in both directions, three runs each.

Review the generated files in .codelight/verifiers/, then check that their globs match real files without making a model call:

codelight --audit

Run Codelight against uncommitted changes:

codelight

It can also judge staged changes or a whole branch:

codelight --staged
codelight --base main

Requires Go 1.25+. Developed and tested on Linux and macOS. Windows is not supported.

Learn more

• Getting started — install, create, test, and run a verifier
• Writing verifiers — the full authoring guide, also available through codelight --spec
• CLI reference — flags, exit codes, costs, and verifier fields
• Provider configuration — Anthropic, Claude CLI, Codex CLI, OpenAI, local models, and custom prompts
• Development — build, test, and understand the repository
• Examples — starter rules and examples for common stacks

License

Apache License 2.0. See LICENSE and NOTICE.

Claude, Codex, and Matt Pocock's skills were used to develop Codelight.