reqfile

Check that a codebase meets its requirements, so agents and humans get concrete, fixable violations instead of vague advice.

Requirements live in Reqfile.yaml files next to the code. Each one says what must hold, why, for whom, and how it is checked: with an existing tool when the rule is mechanical (command), or with Jev, a decision model returning calibrated probabilities, when it needs judgment (decision).

$ reqfile check
FAIL_FAST  services/api/handler.py:42  Do not use bare `except` (E722)
  fix: Catch the specific expected error and handle it visibly, or let it propagate.
advisory  DECOMPLECT  services/sync/worker.ts:88  p=0.91  It mixes several jobs.
  fix: Split the I/O from the logic into two functions.

14 checks run, 2 with nothing to check, 212 code units judged. 1 violation, 1 advisory finding, 0 errors.

Install

With mise, from the prebuilt binaries (macOS and Linux):

# mise.toml
[tools]
"github:arkadia-so/reqfile" = "0.1"

Or with the install script, cargo binstall reqfile, or from source with cargo install reqfile --locked (Rust 1.90 or later):

curl -LsSf https://github.com/arkadia-so/reqfile/releases/latest/download/reqfile-installer.sh | sh

reqfile needs git, sh, and the tools your Reqfiles' commands call.

Reqfile.yaml

# Requirements for this folder, checked by reqfile (https://reqfile.dev)
reqfile: 1

code:
  - id: FAIL_FAST
    ref: Shore, "Fail Fast"
    must: No silent fallbacks, no swallowed errors, no default values that hide a failure.
    why: A swallowed error is an invariant violation nobody sees.
    who: Anyone debugging production.
    checks:
      - command:
          run: ruff check --isolated --select E722,BLE001,S110 --output-format sarif
          files: "**/*.py"
          pass_files: true
          format: sarif
          fix_hint: Catch the specific expected error and handle it visibly, or let it propagate.
      - decision

• The file is named exactly Reqfile.yaml and has a reqfile: 1 version key.
• Requirements are listed under product (what users get) or code (how the code is built). Each has an id in SCREAMING_SNAKE_CASE, must, why and at least one check, and optionally who and ref.
• Unknown keys, missing fields and near-miss file names (reqfile.yaml, Reqfile.yml) are errors naming the file and line. A near-miss name is only an error when the file has a top-level reqfile, product or code key, so a CI workflow named reqfile.yml is fine.

Cascade

Any folder can hold a Reqfile.yaml. The requirements that apply to a file are those of every Reqfile from its folder up to the repository root, and a requirement only checks files under its own folder. Ids are unique across the repository.

Target files come from git (tracked and untracked, never ignored), minus .reqfile/ folders and the exclude globs of the configs above them.

Command checks

Exit 0 passes. An exit code listed in violation_codes means violations: one per SARIF result with format: sarif, otherwise one violation carrying the last 50 lines of output. Any other exit code, a signal or a timeout is a tool error.

Decision checks

A decision check (or decision: { mode: blocking }) reads .reqfile/<ID>/decision.yaml next to its Reqfile:

units:                      # ast-grep rules selecting the code to ask about
  - { language: typescript, rule: { kind: catch_clause } }
  - { language: python, rule: { kind: except_clause } }
  - { language: rust, rule: { pattern: $X.unwrap_or_default() } }
context: enclosing          # optional: also send the enclosing function
question: Does this error handler hide the failure?
violation_when: It discards the error, only logs it, or replaces it with a default value, and execution continues as if nothing failed.
ok_when: It rethrows, returns an explicit error, or handles a specific expected error in a way the caller can observe.
fix_hint: Rethrow, return an explicit error, or narrow the handler to the expected error and handle it visibly.
thresholds: { violation_above: 0.8, pass_below: 0.2 }

Units accept ast-grep's rule, constraints and utils, plus files and ignores globs (relative to the Reqfile's folder). For each unit, reqfile asks Jev the question with the language, path, unit source and, with context: enclosing, the enclosing function. Each unit is sent once, with the questions of every decision check that selects it: Jev charges input tokens and reads the state once per request, so several checks on the same code cost little more than one. Answers are cached in a local file in the git folder (.git/reqfile/jev-cache), so checking never modifies tracked files. An answer is reused while the unit, the question and the exact model behind latest are unchanged, and a full run drops answers no unit uses any more. In CI, keep that file between runs (for example with actions/cache). A probability above violation_above is a violation, below pass_below a pass, and anything in between an uncertain finding.

Decision checks are advisory unless mode: blocking; uncertain findings are always advisory. Label a few dozen units of your codebase and adjust the thresholds before making a check blocking.

Examples: reqfile test

Each requirement can keep labeled examples in .reqfile/<ID>/examples/: one folder per case, named violation-… or ok-…, holding a small file tree. reqfile test copies each case into a fresh repository with the Reqfile, the requirement's .reqfile/<ID>/ and its Jev settings, and runs the requirement's real checks on it.

UNUSED_CODE  2 examples, 2 as labeled
FAIL_FAST  6 examples, measured: 3 of 4 violations caught (1 missed, 0 not selected, 0 uncertain); 0 of 2 correct examples flagged (0 uncertain)
  violation-rust-ok-discard: missed

Requirements with only command checks must match every label, or reqfile test exits 1. With a decision check, results are measured instead: model judgments vary, and a detector earns its place, or mode: blocking, by the rates it reaches on examples it was not tuned on. Violations no check looked at are reported as "not selected", apart from those it looked at and missed.

Settings: .reqfile/config.yaml

Any folder can hold a .reqfile/config.yaml, with or without a Reqfile.yaml next to it. Nothing is specific to the repository root: the settings of a folder come, key by key, from the nearest config in that folder or its ancestors, and each check uses the settings of its Reqfile's folder. Every key is optional, and most repositories need no config at all.

base: origin/main                      # default base of --changed (default: origin/HEAD)
exclude: ["vendor/**", "tests/fixtures/**"]   # relative to this folder

decision:                              # defaults shown
  model: "~typesafe/jev-latest"        # the latest Jev on OpenRouter
  api_key_env: OPENROUTER_API_KEY
  endpoint: https://openrouter.ai/api/v1
  concurrency: 16

exclude globs add up down the tree, so a nested config cannot re-include what a parent excluded; a config inside an excluded folder is ignored.

Decision checks follow the latest Jev by default. Set model to an exact version (such as typesafe/jev-1.13-20260917) to keep thresholds tied to the version they were chosen with. The endpoint also accepts TypeSafe's own API (https://api.typesafe.ai/v1, model jev-latest).

CLI

reqfile check [--fast] [--changed [BASE]] [--only ID,...] [--format summary|json]
              [--log FILE [--log-tag KEY=VALUE]...]
reqfile explain <PATH>
reqfile test [--only ID,...]

• --changed restricts file-based checks (commands with files, decision units) to files changed since the merge-base of BASE and HEAD, including uncommitted, untracked and deleted files. Commands without files still run. A requirement whose definition changed (its Reqfile, its .reqfile/<ID>/ files, or a config above it) is checked on its whole scope.
• --fast runs only decision checks and the commands declared fast: true, for edit hooks; the summary counts the checks left for a full run. Without it, every check runs, so a CI running reqfile check never skips checks.
• --only runs only the listed requirements.
• --log FILE appends one JSON line per judged code unit (clean ones included), command check and command finding: run id, git HEAD, requirement, location, the unit's source and fingerprint, the question's fingerprint, probability, verdict, exact model and whether the answer was cached, plus any --log-tag KEY=VALUE. It feeds evaluation and replay without changing results.
• explain lists the requirements that apply to a path, each with its Reqfile.
• list lists every requirement of the repository with its type (product or code) and the types of its checks; --kind product or --kind code keeps one type.
• test runs each requirement's checks on its labeled examples (below).

Exit codes: 0 when every selected check ran and found no blocking violation, 1 on blocking violations, 3 on any config or tool error (which takes precedence). Exit 0 means the checks passed, not that the requirements hold: checks approximate requirements. The summary counts checks run, checks with nothing to check, and code units judged, so a run that looked at nothing shows.

Using it

In CI, as a required check on pull requests:

# .github/workflows/reqfile.yml
name: reqfile
on: pull_request
jobs:
  check:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
      - run: cargo install reqfile --locked
      # Also install the tools the Reqfiles' commands use (ruff, ast-grep, knip, ...).
      - run: reqfile check
        env:
          OPENROUTER_API_KEY: ${{ secrets.OPENROUTER_API_KEY }}

With Claude Code, as a Stop hook that sends violations back to the agent before it finishes:

{
  "hooks": {
    "Stop": [
      { "hooks": [{ "type": "command",
        "command": "jq -e '.stop_hook_active' >/dev/null && exit 0; reqfile check --fast --changed >&2 || exit 2" }] }
    ]
  }
}

The stop_hook_active guard lets the agent stop after one forced retry, which avoids infinite loops but allows finishing with violations left. CI remains the gate.

In AGENTS.md:

Before editing a folder, run `reqfile explain <folder>` to see the requirements that apply.
Before finishing, run `reqfile check --fast --changed` and fix every violation.

License

Licensed under either of Apache License, Version 2.0 or MIT license at your option.

Development

reqfile checks itself: Reqfile.yaml lists its product requirements, each verified by the integration tests in tests/<id in lowercase>.rs. Decision tests call a local fake of Jev, so the suite runs offline.

cargo test
reqfile check