tracer-bullets

name	tracer-bullets
description	Codemap feature layers and worked tracer-bullet examples — vertical slices for new source extensions, SQLite schema changes, and CLI flags. Use when planning a feature as a tracer bullet and deciding slice boundaries across CLI/parser/db/test/docs layers.
disable-model-invocation	true

Tracer bullets — codemap feature layers and examples

Always-on rule: .agents/rules/tracer-bullets.md (the 5 rules + lite-harden). This skill carries the codemap layer map and worked examples.

Feature layers in this project

A typical vertical slice for codemap touches these layers top-to-bottom:

1. CLI / orchestration — src/cli/ (bootstrap.ts, main.ts, lazy cmd-* chunks; entry src/index.ts)
2. Workers / parsing — src/parse-worker.ts / parse-worker-node.ts, parse-worker-core.ts, src/parser.ts, src/css-parser.ts, src/adapters/
3. Persistence — src/db.ts (schema, inserts, SCHEMA_VERSION)
4. Config / runtime — src/config.ts, src/runtime.ts, resolver
5. Tests — src/*.test.ts
6. Docs — docs/*.md when behavior is user-visible

Example 1: Support a new source extension

Bad — building in layers:

• Update every glob, parser, and docs in one giant change
• Hope CI and the index agree

Good — tracer bullet:

1. constants + adapter — LANG_MAP + builtin adapter extensions + extractFileData — commit, bun run check, small test parsing a one-line file
2. Resolver — resolver extensions if needed — commit, validate
3. Docs — docs/architecture.md table row — commit, validate

Example 2: Add a new SQLite column or table

Bad — schema + all call sites + benchmarks in one unreviewable diff.

Good — tracer bullet:

1. Schema + insert path — db.ts + one write path exercised by a test or CLI run — commit, validate
2. Readers / query UX — expose in query or docs — commit, validate
3. Benchmark / fixtures — if numbers matter — separate commit

Example 3: New CLI flag

Bad — flag parsing, help text, config, and tests all speculative.

Good — tracer bullet:

1. Parse flag + minimal behavior — e.g. --dry-run that only logs — commit, test
2. Wire to real work — connect to indexer — commit, validate
3. Document — README / docs/architecture.md — commit

Commit cadence

Each commit should represent a functional, describable milestone — not a placeholder. Every tracer bullet is a shippable slice that works end-to-end, even if the feature isn't complete yet. Small commits get validated by the pre-commit hook and are easier to review and revert.

Before opening a PR, run harden-pr in full mode on origin/main...HEAD (or accept the offer when the plan checklist is complete).