feat: reddit -> spotify/bandcamp artist linker MVP (extension + resolver service)

Firefox MV2 content script that detects artist/band names in reddit comment threads and rewrites them inline into Spotify + Bandcamp links, backed by a tiny zero-dependency Node resolver that confirms each candidate against the Spotify Web API (direct links) or MusicBrainz (zero-setup, search links). Includes build + install instructions in the README. Source: project/reddit-spotify-linker (user 2026-06-12) + user message 2026-06-14 "Full vibe code, small service, minimal code." Closes task/resolver-service, closes task/firefox-extension, closes task/docs-and-publish (plan/mvp-build, objective/ship-mvp-linker). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-06-14 21:33:33 +00:00
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+# Reddit → Spotify / Bandcamp linker
+
+A Firefox extension that, while you browse a Reddit thread, finds **artist / band
+names** in the comments (and the post body) and turns them into inline links to
+**Spotify** and **Bandcamp** — so a recommendation thread like
+[this one](https://www.reddit.com/r/SlamDeathMetal/comments/1txh2r1/) becomes a
+list of clickable artists instead of names you have to copy-paste into search.
+
+The hard part is *"which words are artists and which aren't?"*. Rather than guess
+with client-side rules, the extension hands candidate names to a tiny local
+**resolver service** that checks each one against a real music database and only
+links the names that actually match an artist.
+
+```
+ reddit page                 content script                 resolver service
+ ───────────                 ──────────────                 ────────────────
+ comment text  ──extract──>  candidate names  ──POST /resolve──>  Spotify API  (direct links)
+                                                                     or
+ <a> links     <──rewrite──  confirmed links  <─────────────────  MusicBrainz  (zero-setup)
+```
+
+## Layout
+
+```
+service/      tiny Node.js resolver (one file, zero npm deps)
+  resolver.js
+  package.json
+  .env.example
+extension/    Firefox MV2 extension (content script only)
+  manifest.json
+  content.js
+  styles.css
+```
+
+## 1. Run the resolver service
+
+Requirements: **Node 18+** (uses the built-in `fetch`). No `npm install` needed —
+there are no dependencies.
+
+```sh
+cd service
+node resolver.js
+# resolver listening on http://localhost:8787  (provider: musicbrainz)
+```
+
+That's it. With no configuration the resolver validates names against
+**MusicBrainz** (no account required) and links to Spotify/Bandcamp **search**
+pages.
+
+### Optional: direct Spotify links
+
+For **direct artist links** (instead of Spotify search), give the service Spotify
+API credentials:
+
+1. Create a free app at <https://developer.spotify.com/dashboard> and copy its
+   **Client ID** and **Client Secret**.
+2. `cp .env.example .env` and fill them in (the `.env` file is gitignored):
+
+   ```
+   SPOTIFY_CLIENT_ID=your_id
+   SPOTIFY_CLIENT_SECRET=your_secret
+   ```
+3. Restart the service. It will report `provider: spotify` on startup.
+
+(Bandcamp has no public API, so Bandcamp links are always a search URL.)
+
+Quick check that it works:
+
+```sh
+curl -s localhost:8787/resolve \
+  -H 'content-type: application/json' \
+  -d '{"candidates":["Cerebral Bore","Devourment","Notarealband Xyzzy"]}'
+# {"Cerebral Bore":{...},"Devourment":{...},"Notarealband Xyzzy":null}
+```
+
+## 2. Install the extension in Firefox
+
+The extension is unpacked / unsigned, so load it as a **temporary add-on**:
+
+1. Open `about:debugging#/runtime/this-firefox`.
+2. **Load Temporary Add-on…**
+3. Select `extension/manifest.json`.
+
+It's now active until you restart Firefox. (To keep it permanently you'd sign it
+via [AMO](https://addons.mozilla.org/developers/) or use Firefox Developer/ESR
+with `xpinstall.signatures.required = false`.)
+
+## 3. Use it
+
+1. Make sure the resolver service is running.
+2. Open any Reddit comments thread (a URL with `/comments/` in it).
+3. Artist names in the comments become links: the name links to **Spotify**, with
+   a small superscript **`bc`** link to **Bandcamp** beside it. New comments loaded
+   as you scroll are linked automatically.
+
+## Configuration
+
+The resolver URL is the constant `RESOLVER_URL` at the top of
+`extension/content.js` (default `http://localhost:8787`). If you change the host
+or port, update **both** that constant **and** the matching entry in
+`extension/manifest.json` → `permissions` (Firefox needs the host listed there to
+let the content script reach it).
+
+## Limitations (MVP)
+
+- **Detection is capitalization-based.** Names written in lowercase, or split
+  across formatting (e.g. **bold** in the middle of a name), can be missed. The
+  resolver's exact-name match keeps false *positives* low; the trade-off is some
+  false *negatives*.
+- **Bandcamp links are searches**, not direct artist pages (no public API).
+- The resolver caches results in memory; it resets when you restart it.
+- Without Spotify credentials the MusicBrainz path is rate-limited to ~1 lookup/
+  second, so the first scan of a large thread fills in gradually (cached after).
+- Built and tested as a Firefox MV2 extension.
+
+## License
+
+Personal project — do as you like.