// Entry point for the changed-line coverage gate (#1418):

// `pnpm check:coverage-changed [--base <ref>]`.

//

// Reuses the lcov report that `pnpm test:coverage` already produced (never runs

// coverage a second time), joins it with the changed-lines diff against <base>

// (`readChangedLinesDiff`, which pairs renames so a moved file owes only the

// hunks that differ from its source), and fails when changed-line coverage is

// below the threshold. A PR carrying the `coverage-waiver` label skips the

// failure but still prints every number.

// The same markdown report goes to stdout and to the GitHub job summary; it

// includes changed-branch coverage and the count of changed executable lines

// excluded from coverage, both non-gating.

//

// The report is only scored when the stamp beside it proves this checkout

// wrote it: no stamp, a stamp from another commit or another working tree, or

// a narrowed run all refuse with the reason instead of a verdict, the same as

// the CRAP gate. A report whose records name files outside this checkout is

// refused the same way — the stamp cannot catch two checkouts of one commit,

// which share HEAD and bytes. Instrumentation is selected from the verified

// stamp's include/exclude, so the gate and the CRAP gate answer from one

// declaration of what the run measured.

import fs from 'node:fs';

import path from 'node:path';

import { pathToFileURL } from 'node:url';

import { runCmdSync } from '@agent-device/host-kit/command';

import { parseScriptArgs } from '../lib/cli-args.ts';

import { parseUnifiedDiff, readChangedLinesDiff } from '../lib/repo-git.ts';

import { computeChangedCoverage, parseLcov, type ChangedCoverageResult } from './model.ts';

import { describeStampMismatch, verifyCoverageStamp } from '../coverage-crap/stamp.ts';

const USAGE = 'Usage: pnpm check:coverage-changed [--base <ref>]\n';

const COVERAGE_DIR = 'coverage';

const LCOV_PATH = 'coverage/lcov.info';

function fmtPct(pct: number | null): string {

return pct === null ? 'n/a' : `${pct.toFixed(2)}%`;

}

function render(result: ChangedCoverageResult): string {

const verdict = result.waived

? 'WAIVED (`coverage-waiver` label)'

: result.passed

? 'PASS'

: 'FAIL';

const lines = [

`## Changed-line coverage gate: ${verdict}`,

'',

'| Metric | Value |',

'| --- | --- |',

`| Changed-line coverage (gating, threshold ${result.threshold}%) | ${result.coveredLines}/${result.totalLines} (${fmtPct(result.pct)}) |`,

`| Changed-branch coverage (non-gating) | ${result.branch.covered}/${result.branch.total} (${fmtPct(result.branch.pct)}) |`,

`| Changed executable lines excluded (non-gating) | ${result.excluded.totalLines} |`,

];

for (const file of result.excluded.files) {

lines.push(`- excluded \`${file.path}\` [${file.reason}]: ${file.lines.join(', ')}`);

}

if (result.offenders.length > 0) {

lines.push('', 'Uncovered changed lines:');

for (const file of result.offenders) {

lines.push(`- \`${file.path}\`: ${file.uncoveredLines.join(', ')}`);

}

}

return `${lines.join('\n')}\n`;

}

export function run(argv: readonly string[], cwd?: string): number {

const values = parseScriptArgs(argv, USAGE, {

base: { type: 'string', default: 'origin/main' },

});

const base = values.base ?? 'origin/main';

// The `coverage-waiver` PR label sets this env var in CI (and locally).

const waived = /^(1|true)$/i.test(process.env.AGENT_DEVICE_COVERAGE_WAIVER ?? '');

const root = cwd ?? runCmdSync('git', ['rev-parse', '--show-toplevel']).stdout.trim();

const coverageDir = path.resolve(root, COVERAGE_DIR);

const lcovPath = path.resolve(root, LCOV_PATH);

if (!fs.existsSync(lcovPath)) {

process.stderr.write(

`check:coverage-changed: no lcov report at ${lcovPath}. Run \`pnpm test:coverage\` first.\n`,

);

return 1;

}

const coverage = parseLcov(fs.readFileSync(lcovPath, 'utf8'), root);

// lcov writes its paths absolute, so a report from another root relativizes

// outside this one and can join none of its files. That must not read as "no

// file was measured", and the stamp cannot catch it: two checkouts of one

// commit carry the same HEAD and the same bytes.

const outside = [...coverage.keys()].find((file) => file.startsWith('../'));

if (outside !== undefined) {

return refuse(

`${lcovPath} records files outside this checkout, for example ${outside}. ` +

'It was written by a run in another root; run `pnpm test:coverage` here.',

);

}

// A verdict computed from an unreadable or unattributable report would read

// as "no findings", which is indistinguishable from a clean branch, so those

// cases stop here — before the waiver is consulted, which skips a failure

// rather than blessing a report with no numbers to print.

const verified = verifyCoverageStamp(coverageDir, root);

if ('mismatch' in verified) return refuse(describeStampMismatch(verified.mismatch));

const diff = readChangedLinesDiff(root, base);

const result = computeChangedCoverage({

diffs: parseUnifiedDiff(diff),

coverage,

stamp: verified.stamp,

waived,

fileLines: (relPath) => {

const abs = path.join(root, relPath);

return fs.existsSync(abs) ? fs.readFileSync(abs, 'utf8').split('\n') : null;

},

});

const report = render(result);

process.stdout.write(report);

const summaryPath = process.env.GITHUB_STEP_SUMMARY;

if (summaryPath) fs.appendFileSync(summaryPath, report);

return result.passed ? 0 : 1;

}

/**

* Says out loud that no verdict was reached. These cases exit before a report exists, so they go to

* stderr rather than heading a table of nothing, which would read as a clean result in the logs.

*/

function refuse(reason: string): number {

process.stderr.write(`check:coverage-changed: no trustworthy verdict — ${reason}\n`);

return 1;

}

if (import.meta.url === pathToFileURL(process.argv[1] ?? '').href) {

try {

process.exitCode = run(process.argv.slice(2));

} catch (error: unknown) {

process.stderr.write(

`check:coverage-changed: ${error instanceof Error ? error.message : String(error)}\n`,

);

process.exitCode = 1;

}

}