# klasp

[![ci](https://github.com/klasp-dev/klasp/actions/workflows/ci.yml/badge.svg)](https://github.com/klasp-dev/klasp/actions/workflows/ci.yml)

[**klasp.dev**](https://klasp.dev) · [crates.io](https://crates.io/crates/klasp) · [npm](https://www.npmjs.com/package/@klasp-dev/klasp) · [PyPI](https://pypi.org/project/klasp/) · [GitHub](https://github.com/klasp-dev/klasp)

> Block AI coding agents (Claude Code, Codex, and Aider) on the same quality gates your humans hit at `git commit`.

## What klasp does

You write one `klasp.toml`. You run `klasp install`. Every AI agent on the repo (Claude Code today, more coming) is now blocked on the same `pre-commit`, `cargo clippy`, `pytest`, or any-shell-command gate your humans see at `git commit`. The agent gets a structured "blocked, here's why" reply at its tool-call surface (Claude Code's `PreToolUse` hook) so it self-corrects rather than retrying with `--no-verify`. That retry path is the failure mode burning every team running agents at scale.

## Why klasp

### 1. Stops the `--no-verify` escape hatch

Your agent runs the test suite, sees a red, decides the failure is "unrelated to my task", and commits with `--no-verify` (or amends past the hook). The bad path lands on `main`, CI catches it a few minutes later, and you're the one cleaning up.

klasp blocks at the Claude Code `PreToolUse` surface, before the agent's `Bash` call ever runs `git commit`. Failure detail is returned inline so the agent retries against the gate instead of around it.

### 2. CI parity at the agent surface

Agent ships a green-locally PR. CI runs the team's pre-commit, linter, and type-check. PR turns red 30 seconds later and you triage.

One `klasp.toml` declares the same checks. Pass-locally now means pass-CI.

```toml
# Typed recipe form (v0.2 W4) — preferred for pre-commit setups.
[[checks]]
name = "pre-commit"
triggers = [{ on = ["commit"] }]
[checks.source]
type = "pre_commit"           # optional: hook_stage, config_path
```

The typed `type = "pre_commit"` recipe handles the `--hook-stage`, `--from-ref`, `--to-ref` flags internally and parses pre-commit's per-hook output into structured findings the agent can act on. The v0.1 shell form still works:

```toml
[[checks]]
name = "pre-commit"
triggers = [{ on = ["commit"] }]
[checks.source]
type = "shell"
command = "pre-commit run --from-ref $KLASP_BASE_REF --to-ref HEAD"
```

### 3. Diff-scoped checks on big repos

Agent edits one file. The full test suite kicks off. 90 seconds later the agent has lost the thread and you're paying for tokens spent waiting.

Every shell check sees `KLASP_BASE_REF`, set to the merge-base of `HEAD` against the upstream tracking branch. Scope linters, formatters, and audits to the diff:

```toml
[[checks]]
name = "fallow-audit"
triggers = [{ on = ["commit", "push"] }]
[checks.source]
type = "shell"
command = "fallow audit --base $KLASP_BASE_REF"
```

### 4. Protected-path guards

Agent debugs a flaky test by reverting your schema migration. Or your i18n bundle. Or the generated API client. The PR looks clean and the regression surfaces in prod a week later.

Add a check that fails when a staged file lives in a path the agent shouldn't have touched without sign-off:

```toml
[[checks]]
name = "no-migration-edits-without-marker"
triggers = [{ on = ["commit"] }]
[checks.source]
type = "shell"
command = '''
  if git diff --cached --name-only | grep -q "^migrations/"; then
    test -f .agent-migration-allowed && exit 0
    echo "Migration files staged. If intentional, drop a .agent-migration-allowed marker and re-stage."
    exit 1
  fi
'''
```

### 5. Polyglot stacks

Agent onboards a repo with a TS frontend, Go API, and Python ML pipeline. Three test runners, three lint configs, three formatters. Agent guesses wrong and someone has to walk back its commits.

`klasp.toml` declares each surface once:

```toml
[[checks]]
name = "frontend"
triggers = [{ on = ["commit"] }]
[checks.source]
type = "shell"
command = "cd web && pnpm typecheck && pnpm lint"

[[checks]]
name = "api"
triggers = [{ on = ["commit"] }]
[checks.source]
type = "shell"
command = "cd api && go test ./... && go vet ./..."

[[checks]]
name = "ml"
triggers = [{ on = ["commit"] }]
[checks.source]
type = "shell"
command = "cd ml && uv run pytest && uv run ruff check"
```

Worked configs for pre-commit, fallow, pytest, cargo, ESLint/Biome, and ruff live in [`docs/recipes.md`](./docs/recipes.md).

## Install

Pick the package manager that matches your primary stack. All three ship the same binary:

```bash
cargo install klasp                        # Rust (also the right pick for x86 Macs — no prebuilt wheel)
npm i -g @klasp-dev/klasp                  # JS / TS (biome-style platform shim)
pip install klasp                          # Python (maturin wheel)
```

Prebuilt binaries cover `darwin-arm64`, `linux-x64-gnu`, `linux-arm64-gnu`, and `win32-x64`. On x86 Macs and other unsupported targets, `cargo install klasp` builds from source.

### Set up a repo

```bash
cd your-project
klasp init                                 # writes klasp.toml at repo root
$EDITOR klasp.toml                         # add your checks (see below)

# For Claude Code
klasp install --agent claude_code          # writes .claude/hooks/klasp-gate.sh + merges .claude/settings.json

# For Codex
klasp install --agent codex               # writes .codex/git-hooks/<gate>.sh

# For Aider
klasp install --agent aider               # edits .aider.conf.yml commit-cmd-pre

# Or all three at once
klasp install --agent all                 # installs Claude Code + Codex + Aider in one step

klasp doctor                               # verify the install is healthy
```

### Uninstall

```bash
klasp uninstall --agent claude_code        # removes the hook + settings entry, preserves siblings
klasp uninstall --agent aider              # removes commit-cmd-pre entry from .aider.conf.yml
```

### Migration from v0.2.x

After upgrading the binary to v0.2.5 (`cargo install klasp`, `npm i -g @klasp-dev/klasp`, or `pip install -U klasp`), re-run `klasp install` in each enrolled repo so the hook shim picks up `KLASP_GATE_SCHEMA=2`. Old shims fail open — they print a schema-mismatch notice and let the commit proceed — so there is no silent breakage, but the gate is inactive until the hook is regenerated. Configs written for v0.2 with no `parallel` or `policy` field continue working unchanged.

```bash
klasp install --agent all                  # regenerates the shim(s) with KLASP_GATE_SCHEMA=2
```

## What works today

| Feature | Status |
|---|---|
| Claude Code agent gate (`PreToolUse`) | Shipped in v0.1 |
| Shell-command checks via `klasp.toml` | Shipped in v0.1 |
| `klasp init` / `install` / `uninstall` / `gate` / `doctor` | Shipped in v0.1 |
| `KLASP_BASE_REF` env var for diff-aware checks | Shipped in v0.1 |
| Four-platform binary distribution (cargo / npm / PyPI) | Shipped in v0.1 (live post-tag); darwin-arm64, linux-x64-gnu, linux-arm64-gnu, win-x64. x86 mac → `cargo install klasp` from source. |
| Codex via `AGENTS.md` + git hooks | v0.2 (W1-W3 shipped) |
| Named recipe: `type = "pre_commit"` | Shipped in v0.2 W4 |
| Named recipe: `type = "fallow"` | Shipped in v0.2 W5 |
| Named recipes: `type = "pytest"` / `"cargo"` | Shipped in v0.2 W6 |
| Per-surface contract (`install_with_warnings` + `doctor_check`) | v0.2.5 (#55) |
| Gate noop when cwd is outside the project root | v0.2.5 (#65) |
| Monorepo config discovery (nearest `klasp.toml` wins) | v0.2.5 (#38) |
| Aider as the third agent surface alongside Claude + Codex | **v0.3** (#46) — `klasp install --agent aider` |
| Plugin protocol for third-party `klasp-plugin-*` binaries (experimental) | **v0.3** (#41, #43) — see [`docs/plugins.md`](./docs/plugins.md) |
| [Agent surface conformance matrix](./docs/conformance-matrix.md) | **v0.3** (#46, #68) — Claude, Codex, Aider all-green; Cursor documented NO-GO |
| Cursor surface | NO-GO for v0.3 (#44) — see [`docs/cursor-assessment.md`](./docs/cursor-assessment.md) |
| Parallel check execution | v0.2.5+ (#34) |

v0.3 ships the third agent surface (Aider), the plugin extensibility protocol, and a
[public conformance matrix](./docs/conformance-matrix.md) so "klasp supports agent X"
means the same thing for every X. See [`docs/roadmap.md`](./docs/roadmap.md) for the full milestone plan.

## Example `klasp.toml`

This is klasp's own dogfood config (also at [`/klasp.toml`](./klasp.toml)):

```toml
version = 1

[gate]
agents = ["claude_code"]
policy = "any_fail"

# Fast type/borrow check on every commit attempt.
[[checks]]
name = "cargo-check"
triggers = [{ on = ["commit", "push"] }]
timeout_secs = 60
[checks.source]
type = "shell"
command = "cargo check --all-targets --workspace"

# Lint with -D warnings on commit and push.
[[checks]]
name = "cargo-clippy"
triggers = [{ on = ["commit", "push"] }]
timeout_secs = 180
[checks.source]
type = "shell"
command = "cargo clippy --all-targets --workspace -- -D warnings"

# Full workspace tests on push only (slower than clippy).
[[checks]]
name = "cargo-test"
triggers = [{ on = ["push"] }]
timeout_secs = 300
[checks.source]
type = "shell"
command = "cargo test --workspace"
```

Every shell check sees `KLASP_BASE_REF` in its environment, set to the merge-base of `HEAD` against the upstream tracking branch (falling back to `origin/main`, `origin/master`, then `HEAD~1`). Diff-aware tools (`pre-commit run --from-ref`, `fallow audit --base`) can scope themselves to the diff without an agent-side wrapper. See [`docs/recipes.md`](./docs/recipes.md) for worked examples in pre-commit, fallow, pytest, ESLint/Biome, ruff.

## Parallel check execution (v0.2.5+)

By default, klasp runs checks sequentially. When individual checks are long-running and independent (test runners, type-checkers), you can enable rayon-based parallel execution by adding `parallel = true` to the `[gate]` section:

```toml
[gate]
agents = ["claude_code"]
parallel = true
```

With `parallel = true`, all triggered checks for a gate run concurrently via rayon's work-stealing thread pool. A 5-check workload that takes 25 seconds sequentially completes in ~5 seconds in parallel mode.

**Important contract:** checks must be stateless when parallel mode is enabled. Reading shared input (source files, config) is fine. Writing to shared output — the same temp file, the same database row, process-global state — will race and produce non-deterministic results. klasp does not detect or prevent this. The default remains `false` so existing v0.2 configs continue working unchanged.

## Verdict policies

The `[gate].policy` field controls how multiple check results are combined into
a single gate outcome. Three values are available:

| Policy | Blocks when | Use when |
|---|---|---|
| `"any_fail"` | Any single check returned `Fail` (default) | Standard strict quality gates — one red check is enough to block. |
| `"all_fail"` | Every non-`Warn` check returned `Fail` and no check returned `Pass` | Experimental: block only when every participating check agrees the change is bad. Mixed `Pass`+`Fail` downgrades to `Warn` so the agent is informed but not blocked. |
| `"majority_fail"` | Strictly more than half the non-`Warn` checks returned `Fail` | Weighted consensus: useful when you have several independent checks and want partial failures to surface as warnings rather than hard blocks. Ties (e.g. 2 pass + 2 fail) are not a majority — they downgrade to `Warn`. |

`Warn` verdicts are never counted in the decisive majority or unanimity tests —
they pass through as informational noise regardless of the policy.

See [`docs/recipes.md`](./docs/recipes.md#verdict-policies) for selection guidance.

## Documentation

- [`docs/design.md`](./docs/design.md) — v0.1 architecture, abstractions, and rationale
- [`docs/recipes.md`](./docs/recipes.md) — worked `klasp.toml` examples for pre-commit, fallow, pytest, cargo, ESLint/Biome, ruff; verdict policy guidance
- [`docs/plugins.md`](./docs/plugins.md) — plugin authoring guide; fork `examples/klasp-plugin-pre-commit/`
- [`docs/plugin-protocol.md`](./docs/plugin-protocol.md) — plugin wire-format specification
- [`docs/conformance-matrix.md`](./docs/conformance-matrix.md) — per-surface support matrix (Claude, Codex, Aider all-green; Cursor NO-GO)
- [`docs/roadmap.md`](./docs/roadmap.md) — milestones from v0.1 → v1.0
- [`CHANGELOG.md`](./CHANGELOG.md) — release notes

## Repository layout

| Path | Purpose |
|---|---|
| `klasp-core/` | Library crate — public traits, types, gate protocol |
| `klasp-agents-claude/` | `AgentSurface` impl for Claude Code |
| `klasp-agents-codex/` | `AgentSurface` impl for Codex CLI |
| `klasp-agents-aider/` | `AgentSurface` impl for Aider (v0.3) |
| `klasp/` | Binary crate — the CLI |
| `examples/klasp-plugin-pre-commit/` | Reference plugin — fork this to build your own |
| `npm/` | Biome-style npm distribution shim |
| `pypi/` | maturin-based PyPI distribution wrapper |
| `docs/` | Architecture docs, recipes, roadmap, conformance matrix, plugin guide |
| `klasp.toml` | klasp's own dogfood config (the canonical example) |

## License

Apache-2.0. See [`LICENSE`](./LICENSE).
