Metadata-Version: 2.4
Name: crapkit
Version: 0.2.0
Summary: Deterministic CRAP-score framework: per-function complexity x coverage risk, worklists, ratchets, refactor verification
Author: Jean-Francois Gagne
License: MIT
Project-URL: Repository, https://github.com/JeanFrancoisGagne/crapkit
Keywords: crap,code-quality,complexity,coverage,ratchet,technical-debt
Classifier: Development Status :: 4 - Beta
Classifier: Environment :: Console
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: MIT License
Classifier: Operating System :: OS Independent
Classifier: Programming Language :: Python :: 3.11
Classifier: Programming Language :: Python :: 3.12
Classifier: Programming Language :: Python :: 3.13
Classifier: Topic :: Software Development :: Quality Assurance
Requires-Python: >=3.11
Description-Content-Type: text/markdown
License-File: LICENSE
Requires-Dist: lizard>=1.24.0
Provides-Extra: dev
Requires-Dist: pytest>=8; extra == "dev"
Requires-Dist: pytest-cov>=5; extra == "dev"
Dynamic: license-file

# crapkit

crapkit scores every function in your repo on complexity times uncovered risk, ranks the
worst ones by how often the file changes, and blocks commits that add more. It reads
TypeScript, TSX, JavaScript and Python through [lizard](https://github.com/terryyin/lizard),
and joins per-function branch coverage from istanbul or coverage.py artifacts your own test
command already produces. Every read-side command speaks JSON with a pinned schema, because
half the callers are coding agents.

```
CRAP = ccn^2 * (1 - cov)^3 + ccn
```

`ccn` is the smaller of standard and modified cyclomatic complexity, both read off one lizard pass.
`cov` is branch coverage inside the function's span; with no branches it falls back to
statement coverage, and with no statements to invoked-or-not, so a half-executed
straight-line function never reads as fully covered.

**Above the ceiling, coverage cannot save you. Decompose.** At the default target of 6, a
function at ccn 7 with 100% coverage still scores 7 and still fails the gate. The only move
that clears it is splitting the function.

crapkit scores **git-tracked files only**. Source you have not `git add`ed is invisible to it.

---

## Install

```
pip install git+https://github.com/JeanFrancoisGagne/crapkit.git
```

From a clone of this repo, run at the clone root:

```
pip install .
```

Either install pulls one dependency, `lizard`. The `pip install -e ".[dev]"` under
[Development](#development) is a different thing: it adds the test extra and is for people
changing crapkit.

Once the PyPI release lands, plain `pip install crapkit` will work too.

Requires Python 3.11 or newer. The one runtime dependency is `lizard>=1.24.0`, which comes
from PyPI as a normal wheel, so a PyPI-only or offline-mirror environment installs fine and
no `git` binary is needed for the dependency itself.

Check the install:

```
$ crapkit --version
crapkit 0.2.0
```

`python -m crapkit` works identically to the `crapkit` console script, and is what to use
from a source checkout. Every subcommand accepts `--repo PATH` (default: the current
directory), so you never have to `cd` into the repo you are scoring. The flag goes after
the subcommand; [Subcommands](#subcommands) shows both orders.

---

## Quickstart: Python

A repo with `calc/grade.py`, `tests/test_grade.py`, and a `pyproject.toml`. Commit first;
crapkit reads `git ls-files`.

**This is the step that stops most Python users:** the lane `crapkit init` writes runs
`pytest --cov`, and the `--cov` flags come from the `pytest-cov` package. Install it first:

```
pip install pytest-cov
```

### 1. Scaffold the config

```
$ crapkit init
wrote crapkit.toml with 1 scope(s): calc
detected 1 lane(s) from this repo's own files: py — next: run `crapkit coverage`
added to .gitignore: .crapkit/, .coverage, __pycache__/
```

`init` sniffs tracked source into one scope per top-level source directory, and detects a
coverage lane from what the repo already has: a pytest marker file (`pyproject.toml`,
`pytest.ini`, `setup.cfg`) writes a live `[[lane]]`, and so does a `test` script or
`vitest`/`jest` in `package.json`. Whatever it detects, it also leaves commented templates
for the runners it did not find.

Every lane it writes reports into `.crapkit/cov/`, so the only `.gitignore` lines it needs
are `.crapkit/` and what the runner drops elsewhere in the tree (a pytest lane's
`.coverage` and `__pycache__/`). Point the JUnit report and any lane you add by hand at
`.crapkit/` too: see [Where artifacts live](docs/lanes.md#where-artifacts-live).

The generated `crapkit.toml`:

```toml
[crapkit]
target = 6

[[scope]]
name = "calc"
paths = ["calc"]
languages = ["python"]

[exclude]
globs = ["**/node_modules/**", "**/dist/**", "**/build/**", "**/vendor/**", "**/*.test.*", "**/*.spec.*", "**/test_*.py", "**/*_test.py", "**/conftest.py", "*.config.ts", "*.config.js", "*.config.mts", "**/*.config.ts", "**/*.config.js", "**/*.config.mts"]

[[lane]]
name = "py"
command = "python -m pytest --cov --cov-branch --cov-report=json:.crapkit/cov/py.json"
artifact = ".crapkit/cov/py.json"
parser = "coveragepy"
scopes = ["calc"]

# Declare one [[lane]] per coverage command, then run `crapkit coverage`.
# [[lane]]
# name = "js"
# command = "npx vitest run --coverage --coverage.reportsDirectory=.crapkit/cov/js"
# artifact = ".crapkit/cov/js/coverage-final.json"
# parser = "istanbul"
# scopes = ["<your-scope>"]

# `crapkit test-scoped FILES` runs one command per scope, with {files}
# replaced by that scope's files, each quoted.
[crapkit.scoped_tests]
calc = "python -m pytest {files} -q -p no:cacheprovider"
```

The last block is the one an agent loop needs: `crapkit test-scoped` exits 3 for a file
whose scope declares no template, and [AGENTS.md](AGENTS.md#4-run-the-owning-scopes-tests)
makes it step 4 of the burn-down loop. init writes the entry live when it detected the
runner (a pytest marker proves the python command); a scope whose runner init could not
confirm gets a commented template to fill in, and `doctor` warns while it stays empty.

Every key is in [docs/configuration.md](docs/configuration.md).

### 2. Check the config against the repo

```
$ crapkit doctor
ok   config keys all recognized
ok   scope 'calc': 1 files
ok   every tracked source file belongs to a scope
ok   1 lane(s) declared
ok   lizard 1.24.0
doctor: no problems found
```

`doctor` exits 1 only on a `FAIL` line. `WARN` and `note` report and exit 0.

### 3. Score the repo

```
$ crapkit coverage
run 1 @ fae4db93108: 2 functions scored — 2 measured / 0 untested / 0 no-lane / 0 cc-only, 1 over target 6, CRAP load 41.0, grade F
```

`coverage` runs the lane commands, parses their artifacts, joins coverage onto a fresh
complexity inventory, and writes a scored run into `.crapkit/crap.sqlite`.

### 4. Read the queue

```
$ crapkit worklist
worklist @ fae4db93108 (run 1, floor ccn>=5, churn 12mo) — 1 active, 0 dormant
  risk      0.0  ccn  14 ( 14 std)    1c/1a w   0.00  calc/grade.py:7  classify( score , attempts , late , bonus )
```

Columns: `risk`, then `ccn` with the standard-only ccn in parentheses, then
`<commits>c/<authors>a` in the churn window and `w<weight>`, then `path:line` and the
function's long name, and last a marker on rows the burn-down queue will not hand out:
`ok` for a function already at or under its ceiling, `no-lane` for one no lane measures.

`floor ccn>=5` in the header orders the list; it never withholds debt. A function whose
CRAP is over its ceiling is listed whatever its ccn, so an empty `worklist` on a repo
`coverage` just graded `F` is not a thing crapkit can print.

**`worklist` is the risk map, not a to-do list.** It ranks every function it admits,
finished ones included, so it does not empty when the burn-down finishes — the `ok`
markers are what a done repo looks like here. `next-item` is the other view: same run,
same admission floor, but it drops the `no-lane` rows and ranks by `crap` descending
instead of by risk. Its `empty: true` is the stop condition; the worklist has none.

**Every risk is 0.0 here because this repo has one commit**: the churn
weight is recency-weighted against the log's own span, and a log with no span has no
recency to weight. Ranking then falls back to ccn order. It takes a second commit at a
different second to end that, not days of history: see
[Risk](#risk-what-ranks-the-worklist).

### 5. Take the top item

```
$ crapkit next-item
{"commit": "fae4db93108b4841a00959f9117430679e7250ca", "empty": false, "item": {"authors": 1, "ccn": 14, "ccn_std": 14, "cognitive": 13, "commits": 1, "cov": 0.5, "crap": 38.5, "end": 28, "est_splits": 3, "est_uncovered_paths": 7, "flag": "measured", "function": "classify( score , attempts , late , bonus )", "nesting": 8, "nloc": 22, "path": "calc/grade.py", "remedy": "decompose", "scope": "calc", "start": 7, "target": 6, "uncovered_lines": [9, 11, 15, 17, 19, 24, 25, 26, 27, 28]}, "run_id": 1, "schema": 1, "skipped_no_lane": 0}
```

`remedy: "decompose"`, `est_splits: 3` (this needs roughly three pieces to fit under 6), and
`uncovered_lines` naming the ten lines no test walks. Every field is in
[docs/agent-json.md](docs/agent-json.md).

### 6. Seed the ratchet

Arm the debt gate before fixing anything: `ratchet seed` records every over-target
function at its current score, and from then on nothing may get worse.

```
$ crapkit ratchet seed
crapkit-ratchet.tsv: added 1, tightened 0 — 1 mark(s) vs run 1 (fae4db93108)

$ git add crapkit.toml crapkit-ratchet.tsv .gitignore && git commit -m "adopt crapkit"
```

### 7. Fix it and verify

Extract until every piece sits at or under the ceiling. Here `classify` became
`_validate`, `_adjusted`, `_band` and a `classify` that only sequences them, with the
table of cases pushed into parametrized tests. Commit the fix, then:

```
$ crapkit verify
verify OK @ 8d10c13303d vs baseline fae4db93108 (5 changed files)
```

A passing verify tightens `crapkit-ratchet.tsv` in place (the repaid mark leaves the file),
so follow up with `git commit -am "ratchet: classify repaid"` — or amend, if the fix commit
is still unpushed. The full mark lifecycle is in [docs/ratchet.md](docs/ratchet.md).

`verify` reruns the lanes and checks three things against the trusted baseline: every
function the diff touched sits at or under its ceiling, no marked function got worse, and no
test that passed in the baseline fails now. Exit 0 advances the baseline and tightens the
ratchet.

```
$ crapkit coverage
run 3 @ 8d10c13303d: 5 functions scored — 5 measured / 0 untested / 0 no-lane / 0 cc-only, 0 over target 6, CRAP load 19.0, grade A+
```

CRAP load 41.0 to 19.0, grade F to A+, and the queue is empty:

```
$ crapkit next-item
{"commit": "8d10c13303dfd9ef4172d9f736582ff4ffa96e60", "empty": true, "reasons": {"all_remaining_at_or_under_target": 4, "below_floor": 1, "churn_window_months": 12, "excluded_by_flag": 0, "no_churn_in_window": 0, "no_lane": 0, "no_lane_over_target": 0}, "run_id": 3, "schema": 1, "skipped_no_lane": 0}
```

`empty: true` is most of the stop condition: nothing the queue admits is over target, and
`all_remaining_at_or_under_target: 4` says the queue emptied because the work is done
rather than because a filter ate it. Two siblings finish the rule.
`no_lane_over_target: 0` says no scope is holding debt no lane measures, and
`skipped_claimed` is absent, which is how the payload says no claim hid a row.
[AGENTS.md](AGENTS.md#the-termination-rule) states the whole condition and reads the rest
of `reasons`.

---

## Quickstart: TypeScript

A vitest repo with `src/grade.ts` and `test/grade.test.ts`.

### 1. Scaffold the config

```
$ crapkit init
wrote crapkit.toml with 1 scope(s): src
detected 1 lane(s) from this repo's own files: js — next: run `crapkit coverage`
added to .gitignore: .crapkit/
```

The lane `init` wrote is
`npm run test -- --coverage --coverage.reportsDirectory=.crapkit/cov/js`. It reads
vitest's `json` reporter from `.crapkit/cov/js/coverage-final.json`; the
`reportsDirectory` flag is what keeps that report out of your root. Anything that produces
an istanbul `coverage-final.json` works; see [docs/lanes.md](docs/lanes.md) for jest,
pytest, monorepo and per-package recipes.

### 2. Install a coverage provider

**This is the step that stops most TypeScript users.** vitest ships no coverage provider by
default. Without one, `init` and `doctor` are both happy and `coverage` dies:

```
$ crapkit coverage
crapkit: lane 'js' FAILED: lane 'js' produced no artifact at .crapkit/cov/js/coverage-final.json (command exit 1); last output: $ npm run test -- --coverage --coverage.reportsDirectory=.crapkit/cov/js

> tsproj@0.1.0 test
> vitest run --coverage --coverage.reportsDirectory=.crapkit/cov/js

 MISSING DEPENDENCY  Cannot find dependency '@vitest/coverage-v8'

(exit 1)
crapkit: every lane failed: ...
```

Exit 5. Install the provider, pinned to your vitest major or npm refuses the peer
dependency (on vitest 2: `npm i -D "@vitest/coverage-v8@2"`):

```
npm i -D @vitest/coverage-v8
```

Three things about that package:

| Question | Answer |
|---|---|
| Which provider? | Either works. `@vitest/coverage-v8` is vitest's default and needs no config. `@vitest/coverage-istanbul` also works and needs `coverage.provider = "istanbul"` in your vitest config. |
| Which crapkit parser? | Both feed `parser = "istanbul"`. The provider name and the parser name are unrelated: v8 output is remapped to the istanbul JSON schema before it is written. |
| Which version? | It must match your vitest major. npm refuses the install otherwise (`peer vitest@"4.x" from @vitest/coverage-v8@4.x`). On vitest 2, `npm i -D "@vitest/coverage-v8@2"`. |

The artifact crapkit wants is `coverage-final.json`, written by vitest's `json` coverage
reporter, which is on by default. If your vitest config sets `coverage.reporter`
explicitly, keep `"json"` in the list. The lane's `--coverage.reportsDirectory` flag
decides where the report lands, and `init` points it at `.crapkit/cov/js/`.

One more vitest default worth flipping now: it writes **no coverage report at all when the
run fails**, so a single red test becomes a missing artifact and a lane failure. Set
`coverage.reportOnFailure = true`. Details and the full config block are in
[docs/lanes.md](docs/lanes.md#reportonfailure).

### 3. Score the repo

```
$ crapkit coverage
run 1 @ 8bfbe613fcd: 2 functions scored — 2 measured / 0 untested / 0 no-lane / 0 cc-only, 1 over target 6, CRAP load 56.68, grade F

$ crapkit worklist
worklist @ 8bfbe613fcd (run 1, floor ccn>=5, churn 12mo) — 1 active, 0 dormant
  risk      0.0  ccn  15 ( 15 std)    1c/1a w   0.00  src/grade.ts:8  classify ( row Row )
```

`classify` is ccn 15 against a ceiling of 6: one function holding the late-and-retry
penalty, the letter bands, the demotion rule and the null case.

### 4. Seed the ratchet and commit

`ratchet seed` records every over-target function at the score it has today, so nothing can
get worse while you burn this one down.

```
$ crapkit ratchet seed
crapkit-ratchet.tsv: added 1, tightened 0 — 1 mark(s) vs run 1 (8bfbe613fcd)

$ git add crapkit.toml crapkit-ratchet.tsv .gitignore && git commit -m "adopt crapkit"
```

### 5. Fix it

Above the ceiling, coverage cannot help, so `classify` gets split rather than tested.
`penalty`, `band` and `demote` come out as their own exported functions, and `classify`
keeps the null case and the bonus:

```ts
export function classify(row: Row): string {
  if (row.score === null) {
    return "N/A";
  }
  let score = row.score - penalty(row.attempts, row.late);
  if (row.bonus && score < 90) {
    score += 3;
  }
  return demote(band(score), row);
}
```

`rescore --gate` judges that edit on complexity alone, before the slow step:

```
$ crapkit rescore src/grade.ts --gate
rescore vs run 1 @ 8bfbe613fcd (coverage STALE, complexity fresh)
   ccn   cov     crap  remedy     function
     5    0%     30.0  add-tests  src/grade.ts:22  band ( score )
     5    0%     30.0  add-tests  src/grade.ts:38  demote ( letter , row Row )
     4    0%     20.0  add-tests  src/grade.ts:8  penalty ( attempts , late )
     4   45%      6.7  add-tests  src/grade.ts:48  classify ( row Row )
     4   75%      4.2  ok         src/grade.ts:59  average ( scores Array )
```

Exit 0: every piece is at or under 6. The `crap` column is loud because its coverage half
is still run 1's, from before three of those functions existed, and `add-tests` is the
literal instruction for step 6.

### 6. Cover the new pieces

`rescore --gate` passed on complexity, not on coverage. `penalty`, `band` and `demote` are
three functions no test has ever called, so each gets a table test:

```ts
describe("band", () => {
  it.each([
    [95, "A"],
    [85, "B"],
    [75, "C"],
    [65, "D"],
    [10, "F"],
  ])("scores %i as %s", (score, expected) => {
    expect(band(score)).toBe(expected);
  });
});
```

Run the suite once before the slow step:

```
$ npx vitest run
 ✓ test/grade.test.ts (21 tests) 2ms

 Test Files  1 passed (1)
      Tests  21 passed (21)
```

Skip this step and step 7 fails rather than passes. Run on a copy of this repo with step 6
left out, `verify` reruns the lanes against the real tree and three functions the old suite
never called come back over the ceiling:

```
$ crapkit verify
verify FAILED @ 0296156ff21 vs baseline 0e646697946 (1 changed files)
  GATE  crap     17.8  ccn   5 cov 20%  src/grade.ts:38  demote ( letter , row Row )  -> add-tests
  GATE  crap     12.4  ccn   5 cov 33%  src/grade.ts:22  band ( score )  -> add-tests
  GATE  crap     10.8  ccn   4 cov 25%  src/grade.ts:8  penalty ( attempts , late )  -> add-tests
```

### 7. Verify

```
$ crapkit verify
verify OK @ 2af3433d979 vs baseline 8bfbe613fcd (3 changed files)

$ crapkit coverage
run 3 @ 2af3433d979: 5 functions scored — 5 measured / 0 untested / 0 no-lane / 0 cc-only, 0 over target 6, CRAP load 22.0, grade A+
```

CRAP load 56.68 to 22.0, grade F to A+, and the mark seeded in step 4 is gone: `verify`
dropped it once `classify` scored under the ceiling, rewriting the tracked
`crapkit-ratchet.tsv` in place — commit it with your change. Marks only ever fall.

A verify may also print `warning: N changed line(s) have no coverage` above its verdict;
that block is advisory unless `diff_uncovered_max` is set
([docs/configuration.md](docs/configuration.md)).

---

## Installing the gate

`crapkit hook-precommit` reads every staged blob in one `git cat-file --batch`, analyzes it
without touching the repo-wide cache, and refuses the commit when a staged function exceeds
its scope ceiling. It needs no coverage data and no snapshot, so it costs the size of the
commit, not the size of the repo.

Two limits to know. The gate judges files a `[[scope]]` claims; a staged source file no
scope claims is not gated, and the hook says so on stderr (`N staged file(s) belong to no
scope and were not gated`) so the hole is visible the moment a new top-level directory
appears. And git runs hooks outside your shell's activated venv: bare `python` must resolve
to an interpreter that has crapkit installed, or use the absolute form
(`exec /path/to/venv/Scripts/python -m crapkit hook-precommit`).

### Route 1: `.git/hooks/pre-commit` (local, not committed)

```sh
cat > .git/hooks/pre-commit <<'EOF'
#!/bin/sh
exec python -m crapkit hook-precommit
EOF
chmod +x .git/hooks/pre-commit
```

### Route 2: a committed hooks directory

The whole route, from a repo that has no `githooks/` yet:

```sh
mkdir -p githooks
cat > githooks/pre-commit <<'EOF'
#!/bin/sh
exec python -m crapkit hook-precommit
EOF
chmod +x githooks/pre-commit
printf 'githooks/pre-commit text eol=lf\n' >> .gitattributes
git add .gitattributes githooks/pre-commit
git update-index --chmod=+x githooks/pre-commit
git commit -m "add crapkit gate hook"
git config core.hooksPath githooks
```

**The `--chmod` goes between the `add` and the `commit`.** It writes the executable bit to
the index, so a commit that already happened does not carry it: run it after and `git
ls-tree HEAD` still says `100644`, which is a hook Unix checkouts silently skip. The
`.gitattributes` line is the harder half of the same failure — under Windows' default
`core.autocrlf` the hook checks out CRLF and `#!/bin/sh\r` dies on Linux and macOS with a
bad-interpreter error. `crapkit doctor` warns when a file under `core.hooksPath` is not
`100755` in the index and prints the `update-index` line for it.

Git will not read a hooks path out of a committed file, so that `git config` line belongs in
your CONTRIBUTING setup steps. Every clone arms the gate with it.

### Route 3: the pre-commit framework

crapkit ships a `.pre-commit-hooks.yaml` declaring `id: crapkit-gate`. In your
`.pre-commit-config.yaml`:

```yaml
repos:
  - repo: https://github.com/JeanFrancoisGagne/crapkit
    rev: 5ffd6361605469a4e7e1212876ab19177354b37b
    hooks:
      - id: crapkit-gate
```

`rev` is a git ref pre-commit resolves against that remote, and the repo carries no tags
yet, so pin a commit sha. The first release will ship a `v0.1.0` tag; pin that instead once
it exists, since `pre-commit autoupdate` only moves between tags.

### What a refusal looks like

```
$ git commit -m "add route"
crapkit gate: 1 staged function(s) exceed the complexity ceiling of 6:
  ccn   7  app/m.py:9  route( a , b , c , d )
decompose before committing (coverage cannot save a function above the target).
```

Run directly, `crapkit hook-precommit` exits 6 on a violation and 0 otherwise.

### Route 4: CI

A CI job runs on a fresh clone, which has no `.crapkit/` store, so bare `crapkit verify`
exits 1 — and running `coverage` first would make the PR's own tree the baseline, a gate
that can never fail. The portable baseline is the mechanism:

```
# on the default branch, after a passing verify — commit this file
crapkit verify --emit-baseline crapkit-baseline.tsv

# in the PR job, against the committed baseline
crapkit verify --baseline-tsv crapkit-baseline.tsv --github
```

`--github` emits `::error file=...` annotations that land on the PR diff; `--sarif PATH`
writes SARIF 2.1.0 for code-scanning upload. Refresh the committed baseline whenever the
default branch's verify passes.

`CRAPKIT_OVERRIDE_REASON` is not a bypass. Setting it routes the commit through the full
three-record audit: an alert line through `alert_command`, a ratchet entry staged into the
commit, and a row in the override log. All three land or nothing does, and an unset
`alert_command` refuses the override outright. See
[docs/ratchet.md](docs/ratchet.md#overrides-and-the-audit-trail).

---

## Reading the output

### Flags: why a coverage number is missing

| Flag | Meaning | Scored |
|---|---|---|
| `measured` | A lane artifact spoke about this function. | Real `cov`. |
| `untested` | A lane covers the scope, but its artifact is silent on this function, which normally means no test imports the file. | `cov = 0`. A testing gap, and `uncovered_lines` comes back `null` because no artifact can name lines it never saw. |
| `no-lane` | No lane's `scopes` list names this function's scope. | `cov = 0`. A tooling gap, not a testing gap. `next-item` never hands one out and counts them in `skipped_no_lane`; `worklist` ranks them and marks the row `no-lane`, because a wiring gap is a risk you have to see. |
| `cc-only` | The scope sets `coverage_optional = true`, so no coverage number can exist. | `crap = ccn`, and `remedy` can only be `ok` or `decompose`. `uncovered_lines` comes back `null` with a note naming that setting. |

The coverage summary counts all four as `measured` / `untested` / `no_lane` / `cc_only`.

### Remedy: what to do about it

| Remedy | Condition | Action |
|---|---|---|
| `decompose` | `ccn > ceiling` | Split it. No amount of coverage clears this. |
| `add-tests` | `ccn <= ceiling` and `crap > ceiling` | Cover the branches. |
| `ok` | `crap <= ceiling` | Nothing. |

### Grade: over-target density

A letter for the fraction of functions over their ceiling. `A+` is reserved for zero.

| Grade | Over-target share |
|---|---|
| `A+` | exactly 0 |
| `A` | under 2% |
| `B` | 2% to under 5% |
| `C` | 5% to under 10% |
| `D` | 10% to under 20% |
| `F` | 20% or more |

`crap_load` beside it is the plain sum of every function's CRAP score, so it moves when a
function gets better even if the grade does not.

### Risk: what ranks the worklist

`risk = ccn * churn weight`. The weight is a time-weighted sum over the file's commits in
the churn window: each commit contributes a logistic weight rising to 0.5 for the newest
commit in the log and falling to near zero for the oldest, so five edits last month outrank
fifty from two years ago. The window anchors on the newest commit, never on the wall clock,
so a fixed tree ranks identically forever.

Age is not the input, position in the log is. A file only the oldest commit ever touched
reads 0.0, and a log whose commits all share one timestamp reads 0.0 everywhere. Commits
minutes apart already rank. This repo was eight commits old, all of them made the same day:

```
$ crapkit worklist --scope util
worklist @ a7c5c85ac37 (run 1, floor ccn>=5, churn 12mo) — 3 active, 0 dormant
  risk      5.4  ccn   5 (  5 std)    5c/1a w   1.08  util/stats.py:1  bucket( value , low , high )
  risk      4.5  ccn   9 (  9 std)    1c/1a w   0.50  util/curve.py:1  curve( scores , mode , floor , ceiling , skip_none )
  risk      4.3  ccn   4 (  4 std)    5c/1a w   1.08  util/stats.py:13  spread( values , cap )  ok
```

`bucket` at ccn 5 outranks `curve` at ccn 9 because five commits touched it and one touched
`curve`. That is the whole point of weighting by churn. `spread` carries the `ok` marker:
it is already at or under its ceiling, and the risk map lists it anyway — `next-item`
would not hand it out.

`worklist` splits its output in two: **active** (files with commits in the window) and
**dormant** (zero churn, kept out of the queue but counted). Two rules reach under the
`worklist_floor`. A file whose churn weight sits in the top 10% is promoted down to ccn 3,
so heavily edited simple code cannot hide under the floor: that is why `spread` is in the
list above at ccn 4, under the floor of 5. And a function scoring over its ceiling is
admitted whatever its ccn, so the floor can never hold back debt.

### The trusted baseline

Every `verify` measures the working tree against one earlier run, the **trusted
baseline**. Three rules decide which run that is, and one escape overrides them.
`crapkit runs list` marks the answer.

**Which runs qualify.** A `coverage` run, or a `verify` run that passed. A failed
`verify` never qualifies, and neither does a `partial` run (a lane failed, so some scope
fell back to `no-lane`) nor a `hook` override record, which carries no scored rows at all.
In `runs list`, `verdict=-` marks a run that produces no verdict rather than one that
failed: only `verify` renders a verdict.

**What advances it.** Any qualifying run. `coverage` writes one wherever HEAD is, so a
dashboard cron advances the baseline exactly as CI does. A passing `verify` advances it
too, and tightens the ratchet on the way.

**The taint rule.** A failed `verify` recorded findings against a tree. Until some
`verify` passes, runs made after that failure do not become the baseline: choosing one
would move the comparison point past the findings, the flagged function would stop
counting as touched, and nothing would ever look at it again. `verify` says which run it
refused and falls back to the newest run in front of the failure.

```
$ crapkit runs list
run   1 @ 88012a148f6 2026-08-23T09:27:46Z coverage  verdict=-      lanes=py  baseline
run   2 @ 803bdde8556 2026-08-23T09:27:53Z verify    verdict=FAILED lanes=py
run   3 @ 803bdde8556 2026-08-23T09:28:02Z coverage  verdict=-      lanes=py

$ crapkit verify
warning: run 3 is not the baseline: verify run 2 FAILED with 1 finding(s) and no passing verify has cleared it since — measuring against run 1 @ 88012a148f6 instead, so those findings stay visible. Fix them, or pass `--baseline 3` to accept the newer run deliberately.
verify FAILED @ d89068de7f3 vs baseline 88012a148f6 (2 changed files)
  GATE  crap     72.0  ccn   8 cov 0%  calc/legacy.py:7  legacy_router( a , b , c , d , e )  -> decompose
  findings: 1 committed / 0 dirty (uncommitted tracked edits)
```

Run 3 is a `coverage` run somebody took on the tree run 2 refused, and it scores the same
ccn-8 function. Without the rule it would have become the baseline, `legacy_router` would
have stopped being a touched function, and that gate line would never print again.

**The escape, twice.** Fix the findings and let a `verify` pass, which clears the taint
for good. Or accept the newer run on purpose with `verify --baseline 3`: an explicit id
bypasses the rule, and the run history records which run the verdict used. Nothing here
touches a repo that has never run `verify` — with no failure to protect, `coverage` alone
always advances the baseline.

---

## Exit codes

| Code | Meaning |
|---|---|
| 0 | OK. For `verify` and `hook-precommit`: the gate passed. |
| 1 | **Overloaded.** Three unrelated things, listed below the table. |
| 2 | Usage error from argparse: unknown flag, missing positional. Raised before crapkit's own error handling. |
| 3 | Config error: `crapkit.toml` missing or unparseable, an unknown language or parser, a ratchet metric-stamp mismatch, a `test-scoped` file under no scope or under a scope with no template. |
| 4 | Git error: not a repository, a baseline commit rewritten out of the history. |
| 5 | Tool error: lizard not importable, a lane produced no artifact, a lane timed out past its retries, an override alert command failed. |
| 6 | Gate violation. A function the diff touched is over its ceiling, or `rescore --gate` found one, or `hook-precommit` did. |
| 7 | Ratchet regression. A marked function scores worse than its recorded high-water mark, touched or not. |
| 8 | New test failures against the baseline run. Failures the baseline already had do not count. |
| 9 | Diff-coverage ceiling breached: `diff_uncovered_max` is set and more changed lines than that never ran. |

### Exit 1 means one of three things

CI cannot tell a crash from a clean policy verdict on the code alone. Which one you got
depends on the command:

| Command | What exit 1 means |
|---|---|
| `doctor` | A **`FAIL` finding**. This is a verdict, not a crash. A `WARN` (an unmeasured directory, or a lane writing its artifact at the repo root) and a `note` (a file over `max_file_bytes`, or no lanes declared) both exit 0. |
| `ratchet report --enforce` | The **debt policy was breached**. Also a verdict. |
| anything else | An unexpected error: "no snapshot yet, run `crapkit coverage` first", a `brief` name that matches no function, a `test-scoped` runner that exited non-zero. |

### Precedence

`verify` reports the **first** of 6, 7, 8, 9 that fires, in that order. A gate violation and
a ratchet regression together report 6. A run that takes any of them fails, so it neither
advances the baseline nor tightens the ratchet, exit 9 included.

---

## Subcommands

Every subcommand takes `--repo PATH` (default `.`), and the flag goes **after** the
subcommand:

```
$ crapkit worklist --repo /path/to/repo --scope util --top 1
worklist @ a7c5c85ac37 (run 1, floor ccn>=5, churn 12mo) — 1 active, 0 dormant
  risk      5.4  ccn   5 (  5 std)    5c/1a w   1.08  util/stats.py:1  bucket( value , low , high )
```

Before it, argparse reads the path as the subcommand name and exits 2 without ever
mentioning `--repo`:

```
$ crapkit --repo /path/to/repo worklist --top 1
crapkit: error: argument command: invalid choice: '/path/to/repo' (choose from 'inventory', 'coverage', ...)
```

`--json` prints one sorted-keys JSON object on stdout, always carrying a `schema` field.

| Command | What it does |
|---|---|
| `init` | Sniffs tracked source into per-directory scopes, writes a self-validated starter `crapkit.toml` whose lanes report into `.crapkit/cov/`, and appends `.crapkit/` plus each runner's own droppings to `.gitignore`. Writes a live `[[lane]]` when it can detect the test runner, otherwise a commented template. Refuses to clobber an existing config. |
| `doctor [--show-files] [--json] [--tune]` | Checks the config still describes the repo: unknown keys (with the accepted spellings), zero-file scopes, tracked source no scope claims, scopes no lane covers, lane cwds and commands that no longer resolve, lizard importable, oversized files, lanes writing their artifacts at the repo root instead of under `.crapkit/` (WARN), committed hooks under `core.hooksPath` that are not executable in the index (WARN), directories whose functions are all `untested` while their tests exist (WARN), and scopes a lane measures with no `[crapkit.scoped_tests]` template behind them (WARN), which is the loop's step 4 with nothing to run. `--tune` prints suggested parallelism knobs and writes nothing. See [docs/agent-json.md](docs/agent-json.md#doctor---json). |
| `inventory [--db PATH] [--export PATH] [--json]` | Two lizard passes over every in-scope file into a SQLite snapshot run, cached by content hash. `--db` is the only way to point crapkit at a store outside `.crapkit/`, and only this command accepts it. |
| `coverage [--lane NAME] [--reuse-artifacts] [--reuse-unchanged] [--export PATH] [--sarif PATH] [--github] [--json]` | Runs the lanes, joins branch coverage onto a fresh inventory, writes a scored run. A failed lane is recorded, not fatal: its scopes fall back to `no-lane` and the run is typed `partial`, so it can never serve as a baseline. See [docs/lanes.md](docs/lanes.md). |
| `verify [--baseline ID \| --base REF \| --baseline-tsv PATH] [--emit-baseline PATH] [--override REASON] [--reuse-artifacts] [--reuse-unchanged] [--sarif PATH] [--github] [--json]` | The full verdict against the trusted baseline: gate on touched functions, ratchet, no new test failures, optional diff-coverage ceiling. The three baseline selectors are mutually exclusive; `--baseline ID` also bypasses the taint rule ([The trusted baseline](#the-trusted-baseline)), and `--baseline-tsv` reads a commit-stamped file so a fresh clone verifies with no store. Findings a dirty tree produced are tagged `dirty` and counted apart. |
| `worklist [--top N] [--scope NAME] [--batches N] [--json]` | The risk map: every admitted function ranked by `ccn * churn weight`, floored by `worklist_floor`, with hot simple code and anything over its ceiling admitted past that floor. It ranks finished rows and `no-lane` rows too, marked `ok` and `no-lane`, so it never empties; `next-item` carries the stop condition. `--scope NAME` (repeatable) is exact, not a substring. `--batches N` **adds** a `batches[]` view cutting the active list into at most N file-disjoint batches with co-changing files kept together; the normal keys stay. |
| `next-item [--top N] [--exclude FRAG] [--scope NAME] [--claim]` | The actionable queue as JSON, with churn, budget estimates and uncovered lines. Same run and same admission floor as `worklist`, a different view of it: `no-lane` rows are skipped and counted in `skipped_no_lane`, and what is left is ranked by `crap` descending rather than by risk, so the item it hands out is often not the worklist's first row. `--exclude FRAG` (repeatable) skips items whose path or function name contains FRAG; `--scope NAME` (repeatable) is exact, not a substring. `--claim` holds what it hands out so a second session skips it. `stale` is true when the ranked run's commit is not HEAD, the same field `worklist` carries. Every item carries a `handle`: the bare identifier, or `(anonymous)#N` for a function with no name, which is the name form that survives the edit the item asks for. |
| `claims [list \| release PATH NAME \| release --all] [--json]` | The open claims, and the way to hand one back without waiting for a verify. `release` takes the bare identifier, the whole long name, or the `handle` the claim was taken under, which is the only one that picks out a single `(anonymous)` claim. |
| `brief FILE NAME [--batch N] [--json]` | The start-editing packet for one function: its own `source` text, every function in the file, the scored row and the scope ceiling, the ratchet mark and what the gate will bind on, uncovered lines, duplication twins, file churn, coupling partners, the config's notes, and the literal commands for the rest of the loop. Plus `handle`, `remedy` and the same `est_splits` / `est_uncovered_paths` the queue prints, and a `commands.refresh` that writes a run (`refresh_writes_run`) rather than re-reading the stale one. `NAME` takes the bare identifier, the long name `next-item` printed, the function's start line, or `(anonymous)#N` for a function printed `(anonymous)`, counting the file's anonymous functions from the top. `--batch N` drops the positionals and emits `packets[]` instead: the top N of the queue, built from one read of the store. |
| `explain FILE NAME [--history] [--tests] [--json]` | A function's score across runs plus its mark. `--history` adds the commits that touched it (`git log -L`), each carrying its message `body`, `--tests` the tests that covered it, which needs coverage.py contexts turned on ([recipe](docs/lanes.md#test-attribution-for-explain---tests)). `--json` emits the same content as one `schema` 1 object. |
| `rescore FILE ... [--gate] [--json]` | Fresh complexity for named files over the latest run's stale coverage, joined by name. Advisory: it writes no run. `--gate` applies the pre-commit hook's policy to the same selection the hook uses (functions the tree changed since HEAD), minus functions a ratchet mark already covers, and exits 6. |
| `ratchet seed \| prune \| merge \| move \| report [--enforce] [--json]` | The mark lifecycle: seed new debt, prune gone code (a mark whose file git renamed follows it), merge as a git driver, move re-paths marks, report reads burn-down from the file's own git history. See [docs/ratchet.md](docs/ratchet.md). |
| `runs [list \| prune [--keep N]] [--json]` | Run history, and retention. `list` marks the run `verify` compares against today `baseline`, and prints `verdict=-` for a run that produces no verdict rather than one that failed. See [The trusted baseline](#the-trusted-baseline). `--keep` (default 5) is a floor on the newest trusted runs, not a cap: the digest pair, every passing verify baseline, every run an override names, and the newest non-hook run are kept too. `prune` VACUUMs afterwards. |
| `overrides [--json]` | The override audit trail: who granted what, when, and why. |
| `trend [--json]` | Totals per trusted run: functions, over-target count, CRAP load, average, per-scope rollup. |
| `digest [--alert]` | The delta between the two newest runs with identical lane sets. Silent when nothing changed. `--alert` pipes the body to `alert_command` on stdin. Plain lines, never JSON. |
| `duplication [--min-lines N] [--similarity F] [--top N] [--json]` | Near-duplicate functions by normalized line shingles with containment scoring. Defaults: `--min-lines 8`, `--similarity 0.8`, `--top 50`. `--top` truncates the list. |
| `coupling [--min-support N] [--min-confidence F] [--top N] [--json]` | File pairs that keep landing in the same commits. Defaults: `--min-support 5` shared commits, `--min-confidence 0.5` max-direction ratio, `--top 50`. Bulk commits never couple pairs, and a young repo returns nothing at the default support. |
| `mutate [--files F ...] [--max-mutants N] [--json]` | Diff-scoped mutation testing: flips comparisons, boundary shifts, boolean connectives and boolean literals on changed lines, runs `mutation_command` per mutant, lists survivors. `--files` replaces diff scope with the whole file. `--max-mutants` (default 100) caps the run and the cap warning goes to stderr only, so `mutants` in `--json` is the capped count. |
| `test-scoped FILE ...` | Runs each owning scope's `[crapkit.scoped_tests]` template on the files (quoted, longest-prefix scope wins). A template with no `{files}` runs as written, which is how a scope whose tests live outside its own paths runs its whole suite. Exit code only; a nonzero runner exits 1. |
| `hook-precommit` | The cc-only gate on staged blobs. No coverage, no snapshot, no repo-wide cache. Exit 6 on a violation. |
| `watch [--interval SECONDS] [--cycles N]` | Rescores tracked files as they change (mtime polling, default 2s, subprocess-isolated so a half-saved syntax error never kills the watcher). `--cycles N` polls exactly N times and exits 0; without it the loop runs until ctrl-c. |
| `mcp` | A dependency-free stdio MCP server (newline JSON-RPC 2.0) exposing nine read-only tools. See [docs/agent-json.md](docs/agent-json.md#mcp-server). |

## Documentation

| Page | Covers |
|---|---|
| [docs/handbook.html](docs/handbook.html) | The illustrated handbook: what crapkit is, how every piece works, and where each command earns its keep. Self-contained HTML — open it straight from a clone. |
| [docs/configuration.md](docs/configuration.md) | Every `crapkit.toml` key: type, default, and what it does. |
| [docs/lanes.md](docs/lanes.md) | The lane model, vitest and jest and pytest recipes, artifact reuse, flake retest, containers. |
| [docs/ratchet.md](docs/ratchet.md) | Seeding, pruning, the git merge driver, metric stamps, debt policy, overrides. |
| [docs/agent-json.md](docs/agent-json.md) | The machine surface: `schema`, every payload field, real captured examples. |
| [docs/adoption.md](docs/adoption.md) | The judgment layer over the quickstarts: scope granularity, exclude vs lane, scoped_tests wiring, the first-verify taint hazard. |
| [skills/](skills/) | Agent skills shipped with the repo (`crapkit`, `crapkit-recover`, `crapkit-onboard`) — install by copying to your agent runtime's skills directory. |

[crapkit.schema.json](crapkit.schema.json) is the authority on the config file shape.

## Development

```
pip install -e ".[dev]"
pip install pytest-xdist
git config core.hooksPath git-hooks
python -m pytest -q
```

`pytest-xdist` is not optional: `tests/fixtures/mini_repo` declares a lane that shells out
to `pytest ... -n 2`, and without it that subprocess dies on an unrecognized `-n`. The
`git config` line arms the complexity gate on your own commits. Same steps, with what each
one buys, in [CONTRIBUTING.md](CONTRIBUTING.md).

## License

MIT. See [LICENSE](LICENSE).
