# Agent rules for the `linker` repo (reddit → spotify/bandcamp)

A Firefox extension + a tiny Node resolver that turn artist/band names in reddit
comments into Spotify/Bandcamp links. This file is the repo-local doctrine; the work
is tracked in the **towl** work-item store under project **`reddit-spotify-linker`**.

## Stack & layout

- `service/` — zero-dependency Node resolver (Node 18+, built-in `fetch`/`http`).
  `resolver.js` = the HTTP server; `lib.js` = pure, side-effect-free logic (the
  artist-match precision lever) so it's unit-testable; `lib.test.js` = `node:test`.
- `extension/` — Firefox **MV2** content script (`content.js` + `manifest.json` +
  `styles.css`). No build step.
- `scripts/check.sh` — the local check gate.

## How work lands (IMPORTANT — this is NOT the towl repo)

`linker` is hosted at **git.yapplesauce.com/paul/linker**, a **plain repo**: there is
**no PR pipeline and no branch protection**. You **push to `main` directly** (via the
user's PAT). Do **not** use `towl-orchestrate` / worktree+PR here.

1. Make a small, reversible change.
2. Run the gate: `bash scripts/check.sh` (must print `ALL CHECKS PASSED`).
3. Commit citing the towl ref (e.g. `(task/odesli-direct-links)`), push `main`.
4. Stamp the SHA on the towl item: `stamp_commit { ref, sha, repo: "linker" }`.
5. Close the towl item.

**NEVER touch the `towl` or `stickball` repos from work scoped to this project.**

## Testing (zero-dep)

`node --test` over `service/*.test.js` exercises `lib.js` (norm + the exact-name match
+ link builders). Keep pure logic in `lib.js` (not `resolver.js`, which has the
server side effect) so it stays testable without opening a port. **Add/extend a test
with every logic change.** The extension's in-browser behavior is **not** headlessly
testable in this environment — validate `content.js` with `node --check` and a
documented manual check on a real reddit thread (`about:debugging` → load temporary
add-on).

## Code stewards (towl plans under objective/linker-stewardship)

Standing, language-appropriate stewards (adapted from towl's SCOUT→FILE doctrine; run
them like any other steward — e.g. via a `/loop`). Each files findings into towl and
fixes small things directly.

- **quality** (`plan/steward-linker-quality`) — correctness + regressions; **owns and
  maintains `scripts/check.sh` and the `node:test` suite**.
- **design** (`plan/steward-linker-design`) — detection precision/recall, the
  injected-link UX, README accuracy, reddit-DOM drift.
- **security** (`plan/steward-linker-security`) — DOM injection (build nodes via
  `createElement`/`textContent`, **never `innerHTML`**; http(s) hrefs only), minimal
  extension permissions, bounded external API calls (no SSRF), secrets never
  logged/committed (`.env` is gitignored).

## Standing decisions

- Firefox **MV2** stays — Mozilla has no deprecation timeline; do not migrate to MV3
  speculatively.
- **No ML/NER** in the resolver — keep it zero-dep; improve detection with cheap
  heuristics + the API exact-match filter.
- Detection precision lever: a candidate links **only** when a music API returns an
  artist whose name matches it case-insensitively.