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). A requirement written once can be taken by reference in other folders and repositories (use).

$ 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

Give your coding agent this prompt to install Reqfile and wire it into your project's workflow:

set up https://reqfile.dev/SKILL.md

Read the agent skill or visit reqfile.dev.

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

# mise.toml
[tools]
"github:arkadia-so/reqfile" = "0.3"

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, tar (for requirements taken from other repositories), and the tools your Reqfiles' commands call.

Security

Reqfiles, configs and requirements taken with use are executable code:

• A command check runs its shell command on your machine or CI runner, with your environment.
• A config chooses the Jev endpoint and the environment variable whose value is sent to it as the API key.
• Decision checks send the code they select to the configured provider.
• Taking a requirement from another repository (use: owner/repo@ref) means running that repository's commands in your CI. Pin it to a commit or a tag you trust, and read what reqfile add prints before adding it.

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

  - { id: DECOMPLECT, use: acme/reqs@v1.2.0 }

• The file is named exactly Reqfile.yaml and has a reqfile: 1 version key.
• Requirements are listed under product (what users get), code (how the code is built) or process (how the project is run, such as its CI).
• A block with use is a use block, taking its requirement by reference (below); any other block is a definition. A definition 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, code or process key, so a CI workflow named reqfile.yml is fine.

Macro and micro

A requirement is a macro: one durable promise, in one or two sentences, that would get a bug filed if it broke six months from now. Its details are micro: tests named after the sentence they prove, in the files its checks run. Implementation decisions, such as a chunk size or a library choice, stay in specs and pull requests. Keep each Reqfile to at most 10 product requirements; past that, merge requirements into broader promises, or split the folder into subfolders with their own Reqfiles.

Scope

Any folder can hold a Reqfile.yaml. For a file and an id, the block that applies is the one in the nearest Reqfile at or above the file's folder; blocks with that id in farther Reqfiles do not apply to it. A definition id appears once in a repository, and an id at most once in a Reqfile, so a nearer block with the same id is always a use block. Each code unit is judged at most once per id in a run.

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

Command checks

Field	Required	Meaning
run	yes	Shell command, run from the folder of its Reqfile
fix_hint	yes	One line telling how to fix a violation
files	no	Glob relative to that folder; the command runs only if a target file matches
pass_files	no	Append the matching files as arguments (default false)
format	no	exit (default), sarif or junit
violation_codes	no	Exit codes meaning "violations found" (default [1]; [101] for cargo test)
timeout	no	Seconds, default 60
fast	no	Quick enough for reqfile check --fast, such as in an edit hook (default false)
thresholds	no	{ violation_above, pass_below } for SARIF results carrying a probability (default 0.8 and 0.2)

A command without files always runs. With pass_files, the files are appended at the end of the whole command, so a pipeline such as tool "$@" | filter receives nothing; put pipelines in a script.

Commands reach the files of their requirement through $REQFILE_ASSETS, the absolute path of its .reqfile/<ID>/ folder, as in run: $REQFILE_ASSETS/check.sh. $REQFILE is the reqfile executable running the check, for commands that inspect the requirements themselves, such as $REQFILE list --format json.

With format: exit, exit 0 passes and a code listed in violation_codes reports one violation carrying the last 50 lines of output.

With format: sarif, the report is parsed on both exit 0 and a listed violation code. Each kind: fail result is a violation; an absent kind defaults to fail. Other kinds and suppressed results are ignored. A suppression with no status or status: accepted suppresses the result; rejected and underReview do not. An empty suppressions array does not suppress anything. This catches findings from pipelines such as clippy | clippy-sarif even when the final command exits 0.

A SARIF result may carry properties.probability, the probability that it is a violation, so heuristics and models speak the same protocol as linters. Such a result is judged by it, whatever its kind: above violation_above a violation, below pass_below nothing, and between an uncertain finding, always advisory. A probability outside 0 to 1 is a tool error. A checker can report every file it judged, with low probabilities for the fine ones.

With format: junit, the command prints a JUnit XML report, as cargo-nextest, pytest, vitest, bun and gotestsum write: each failed or errored test case is a violation named after the test (test output::names_conflicts failed: …), located by its file and line attributes when the runner gives them. A report with no test case, or a violation code with no failed test, is a tool error.

A checker is any program. When a requirement is shared, its command fetches the checker with its ecosystem's runner at an exact version, such as bunx @scope/reqfile-colocation@0.1.1, uvx tool==1.2.0 or go run example.com/tool@v1.2.0, so nothing needs installing and reqfile manages no packages.

Invalid SARIF (including on exit 0), a violation code with no SARIF results, any unexpected exit code, a signal or a timeout is a tool error. A report containing only ignored results passes on exit 0 or a listed violation code.

Decision checks

A decision check (or decision: { mode: blocking }) reads $REQFILE_ASSETS/decision.yaml, the .reqfile/<ID>/decision.yaml of its requirement:

units:                      # ast-grep rules selecting the code to ask about
  - { language: typescript, rule: { kind: catch_clause } }
  - { language: tsx, 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). A unit rule selects files of exactly its language: a typescript rule never selects .tsx files, so TSX needs its own tsx rules. 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), shared by every worktree, so checking never modifies tracked files. An answer is reused while the unit, the requirement's question and the exact model behind latest are unchanged, and a full run drops answers no unit uses any more; pruning changes cost, never results. 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. A blocking decision check needs a pinned model (an exact version, such as typesafe/jev-1.13-20260917, set in .reqfile/config.yaml), so its thresholds stay tied to the version they were measured with. Label a few dozen units of your codebase and adjust the thresholds before making a check blocking.

Imports: use

A use block takes a requirement defined elsewhere:

code:
  - { id: FAIL_FAST, use: ./std }                                                    # a folder of this repository
  - { id: COLOCATION, use: gabsn/reqfile-colocation@d0ba113c4ca2882d8c86329049359e02ae9625b6 }  # v0.1.1
  - id: CONTRACTS
    use: acme/reqs@3f2a9c1e0b7d4c6a8e5f1b2d3c4a5e6f7a8b9c0d   # v1.2.0
    why: The billing core must never reach an invalid state.

Any repository or folder whose Reqfile.yaml defines a requirement, with its checks and labeled examples under .reqfile/<ID>/, is a package: the same format as a local requirement, nothing more.

• Locations. A folder, relative to the folder of the use block's Reqfile (./std, ../shared), or owner/repo@<commit>, fetched from https://github.com/owner/repo ($REQFILE_GIT_BASE/owner/repo when that variable is set, for a mirror). The use block resolves to the unique definition with its id among the Reqfiles at or under that location, discovered like a repository of its own, with its exclusions. Use blocks are never resolution targets, so chains cannot form.
• Pins. A Reqfile pins a repository to a full 40-character commit id; the tag it came from goes in a comment. A tag, a branch, a short id or HEAD is an error: the rules of a repository must not change under it. Nobody types the commit: reqfile add writes the line and reqfile update moves it.
• Cache. A commit never changes, so it is fetched once into the user's cache ($REQFILE_CACHE, else $XDG_CACHE_HOME/reqfile, else ~/.cache/reqfile), shared by every repository and worktree, and checked offline from then on. CI can keep that folder between runs.
• Types. Only code and process requirements can be taken: a product requirement describes its own repository's product. The section of the use block must match its definition's.
• What can be set locally. A use block takes must, ref and its type from its definition. It may set why and who, and checks, which then replace the definition's checks entirely. Setting must is an error.
• Where checks run. The checks of a use block run in the folder of its Reqfile, with its globs relative to that folder, and the settings of that folder in the repository being checked. A source's configs are only used to discover its definitions.
• $REQFILE_ASSETS is one .reqfile/<ID>/ folder, never a merge: the definition's for inherited checks, the use block's own for checks it sets. With inherited checks, the use block's own .reqfile/<ID>/ may only hold examples/, where you add your own examples of a shared requirement.

reqfile add <location> [IDS] writes the use blocks into the Reqfile of the current folder, under their sections, a repository pinned to the commit its tag points to (resolved through refs/tags/<name>, never a branch), and says what their checks run; --dry-run only shows them. Without ids, it takes every code and process requirement there. reqfile update moves every pin to the commit of its repository's latest release tag (vX.Y.Z); the diff is the review.

To try requirements before adopting them, reqfile check --use <location> and reqfile eval --use <location> add them for one run, without writing any Reqfile; --only narrows them. A tag is welcome there: it is resolved on each run and the summary names the commit it resolved to, or the last one cached when the remote cannot be reached.

Use blocks need a reqfile of version 0.2 or later, and commit pins 0.3: 0.1 reports use as an unknown key, naming its line, so it never skips one silently.

Evals: reqfile eval

Checks approximate requirements, so each one is measured on labeled examples, the eval of the requirement. An example is a folder under .reqfile/<ID>/examples/:

.reqfile/COLOCATION/examples/distant-test/
  example.yaml   # what the checks should say
  files/         # the case, the only part the checks see
    src/checkout/discount.ts
    test/unit/checkout/discount.test.ts

expected: violation                          # violation | ok
findings: [test/unit/checkout/discount.test.ts]   # optional: where the checks must flag
rationale: The test sits in a mirror tree while its sibling tests are colocated.
origin: authored                             # or real:<commit>, for a case met in real use
known: miss                                  # optional: a failure tracked without failing

reqfile eval puts each case's files/ alone in a fresh repository and runs the requirement's effective checks on it with $REQFILE_ASSETS and the Jev settings of its folder. The label stays outside, so no check can read its answer. A violation flagged elsewhere than its findings counts as missed. known: miss (a violation) or known: false_alarm (an ok example) records a failure the checks are known to have, reported without failing, until the checks improve and the eval says to remove it. A requirement taken with use is measured on its definition's examples and its own. Examples double as the requirement's documentation: a violation and an ok case side by side say what the must means.

Checks become precise over time when their failures become evidence: reqfile example add <ID> <name> --expected violation|ok [--finding FILE]... [--rationale TEXT] FILES... copies files of the repository into a new example, with the commit it came from, and reqfile eval reports it as missed or a false alarm until the check is improved.

UNUSED_CODE  asserted: 2 examples, 2 as labeled
FAIL_FAST  measured, no assertion: 3 of 4 violations caught (1 missed, 0 not selected, 0 uncertain); 0 of 2 correct examples flagged (0 uncertain)
  rust-ok-discard: missed
SIMULATION  no evidence: no labeled examples

3 requirements: 1 asserted, 1 measured, 1 without evidence; 6 examples. 0 failing their labels.

Each requirement falls in one of three classes:

• asserted: deterministic checks only, which must match every label, or reqfile eval exits 1;
• measured: with a decision check, or a command reporting probabilities, results are counted, never asserted: judgments vary, so exit 0 does not mean the check works. A detector earns its place, or mode: blocking, by the rates it reaches on examples it was not tuned on;
• no evidence: no labeled examples, so nothing is known about its checks.

Violations no check looked at are reported as "not selected", apart from those it looked at and missed. A case that cannot run exits 3.

What each step establishes:

Step	Establishes	Does not establish
reqfile eval	How the effective checks classify the labeled examples, in isolation	Anything about your code, the tools in CI, or thresholds on your code
reqfile check	What each check selected (files, units) and found, with your settings and this machine's tools	That the selection covers all relevant code, that no finding means the requirement holds, or that decision thresholds suit your code
reqfile add	Which definitions and commit the blocks resolve to, and what they will run	Anything else: it runs none of them

What stays unverified in every case: code no check looks at, decision precision on your code, the tools installed in CI, and the requirements themselves. Exit 0 means the checks passed, not that the requirements hold.

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.

Advisory 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; blocking decision checks require it. The endpoint also accepts TypeSafe's own API (https://api.typesafe.ai/v1, model jev-latest).

CLI

reqfile check [--fast] [--changed [BASE]] [--only ID,...] [--use LOCATION]...
              [--format summary|json] [--log FILE [--log-tag KEY=VALUE]...]
reqfile eval [--only ID,...] [--use LOCATION]...
reqfile example add <ID> <NAME> --expected violation|ok [--finding FILE]... [--rationale TEXT] <FILE>...
reqfile explain <PATH>
reqfile list [--kind product|code|process] [--format summary|json]
reqfile add <LOCATION> [ID]... [--dry-run]
reqfile update [--dry-run]

• --changed checks everything a change since the merge-base of BASE and HEAD can affect: the changed files (committed, uncommitted, untracked and deleted), and every file whose applicable block is not the same as at the merge-base, because another block now applies to it or because its requirement, its $REQFILE_ASSETS files, its settings or the commit of its source changed. Unchanged files are checked against a redefined requirement, and only files in its scope. Commands without files still run.
• --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: for each, the block that applies, and for a use block its resolved definition and whether its checks are inherited or set in the block.
• list lists every requirement of the repository with its type, the types of its checks and, for a use block, its source; --format json gives the same as data.
• --use adds the requirements of a location for this run (above).
• eval measures each requirement's checks on its labeled examples (above); test is its former name, kept as an alias for one version.
• example add turns files of the repository into a labeled example (above).
• add writes use blocks pinned to a commit, update moves the pins (above).

Every finding of a requirement taken with use names its use block and where its definition was resolved; the summary lists the commit every tag given to --use resolved to.

Requirements will contradict each other. For each violation and advisory finding, reqfile asks Jev whether making the fix it asks for would break another requirement that applies to the same file; each one it would break above 0.7 is listed under the finding (breaks: CORE (p=0.90)), and the summary groups them by pair of requirements as decisions to make:

decide  COLOCATION vs FUNCTIONAL_CORE  p=0.85  fixing COLOCATION in 4 files would break FUNCTIONAL_CORE
    src/core/cache.rs, …
    Reword one of the two requirements, or say which one wins where they meet.

A contradiction is a product decision, not a fix: an agent would undo one fix with the next. JSON marks each finding's conflicts so hooks can send them to a human. Answers share the decision cache and go to the run log; without a Jev key the summary says conflicts were not checked, and failing to ask never changes the exit code.

Exit codes: 0 when every blocking check ran and found no blocking violation, 1 on blocking violations, 3 on any config error or any error in a blocking check (which takes precedence). An advisory check that cannot run, such as a decision check without an API key in a pull request from a fork, is reported as an advisory error without changing the exit code: it could never have blocked. Command checks are always blocking. 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 }}
      - run: reqfile eval

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" }] }
    ]
  }
}

With --fast, only decision checks (advisory unless blocking) and the command checks declared fast: true run, so the hook blocks only on those; declare quick commands fast. 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. When the output holds decide lines, tell the agent not to fix the findings marked breaks: but to ask you: they contradict another requirement.

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 a macro promise checked by the integration tests in tests/, whose names are its micro requirements. Decision tests call a local fake of Jev, and import tests local git repositories, so the suite runs offline.

cargo test
reqfile check
reqfile eval

CI (.github/check.sh, run for every pull request and before every release) compiles the tests with cargo test --no-run --locked before running cargo test --locked, reqfile check and reqfile eval, so cold builds and Cargo's build lock cannot exhaust a check's timeout.