coverage-tools

name	coverage-tools
description	Aggregates Vitest v8/Istanbul coverage across Tachi workspaces via tachi-coverage-tools (manifest, CLI, optional programmatic API). Use when measuring test coverage, reviewing coverage after changes, adding CI gates, registering a new Vitest package, or when the user mentions coverage reports, coverage-final.json, or just coverage-report.

Coverage tools (tachi-coverage-tools)

When to use

• After running tests with coverage, to see totals and cold areas.
• When adding a new workspace that runs Vitest with --coverage.
• To gate CI on minimum line coverage (--min-lines + --strict).

Prerequisite

Coverage JSON is produced by Vitest v8 with --coverage (e.g. just test-typescript). Output is under each package’s coverage/ directory (gitignored). If reports are missing, run tests with coverage first.

Commands (repo root)

Command	Purpose
just coverage-report	Table: lines, statements, functions, branches per registered package
just coverage-report --by-dir	Same plus top-level src/* buckets (server/bot)
just coverage-report --json	Machine-readable CoverageReport on stdout
just coverage-report --packages server	Filter by manifest id (comma-separated)
just coverage-report --min-lines 80 --strict	Exit non-zero if files missing or line % below floor

Implementation: workspace package typescript/coverage-tools (bun run --filter tachi-coverage-tools report).

Registering a new Vitest package

Edit typescript/coverage-tools/src/manifest.ts: add a CoverageSource with:

• id - short name for --packages
• packageRoot - e.g. typescript/my-pkg
• coverageFinal - path to coverage/coverage-final.json relative to repo root (Vitest default unless coverage.reportsDirectory overrides)

Programmatic use

import { buildReport, COVERAGE_SOURCES } from "tachi-coverage-tools";

buildReport({ repoRoot, packageIds, byDir }) returns CoverageReport (see typescript/coverage-tools/src/report-coverage.ts).

Related files

• typescript/coverage-tools/src/manifest.ts - source registry
• typescript/coverage-tools/src/report-coverage.ts - CLI flags and buildReport
• Justfile-test - coverage-report recipe