mp3-com-meta-browser/AGENTS.md

This repository contains a static web app for searching a large music metadata database (no server/API calls). It uses:

• Bulma (bulma.min.css) for UI (https://bulma.io/documentation/)
• A single HTML file (index.html)
• A single JS file (script.js)
• A client-side SQLite database (WASM) fetched as a static asset (paged with HTTP Range if available)

Keep implementation details minimal; this file orients agents to project structure, constraints, and the data model.

---

Goals (for agents)

• Provide a responsive search UI over a large SQLite metadata DB entirely in-browser.
• No server-side code; all queries run client-side.
• Fast startup, predictable UX, minimal dependencies.

Non-Goals

• Hosting or streaming audio files.
• Write access to the DB.
• Complex build systems or frameworks.

---

Repository Layout (expected)

/
+- index.html        # Single-page app shell
+- bulma.min.css     # Bulma CSS (pinned)
+- script.js         # All app logic
+- /assets/
¦   +- mp3com-meta.sqlite   # Metadata DB (read-only)
+- AGENTS.md

• If subfolders are added later (icons, fonts), prefer /assets/....
• Do not introduce bundlers unless requested.

---

UI/UX Conventions

• Use Bulma components (containers, navbar, form controls, tables, pagination).
• Default to semantic HTML + Bulma classes; avoid inline styles.
• Accessibility: ensure focus states, label–input associations, and ARIA for dynamic content.

---

Data Access (Client-Side)

• Use SQLite compiled to WebAssembly in the browser.
• Prefer an HTTP VFS (range requests) to avoid fetching the entire DB up front.
• Queries should be read-only; no schema migrations/run-time writes.

Minimal runtime expectations

• One network fetch for the WASM runtime.
• The DB file (/assets/mp3com-meta.sqlite) fetched lazily by page(s) as needed.

---

Database Schema (authoritative)

PRAGMA foreign_keys=ON;

CREATE TABLE IF NOT EXISTS artists(
  id   INTEGER PRIMARY KEY,
  name TEXT NOT NULL COLLATE NOCASE UNIQUE
);

CREATE TABLE IF NOT EXISTS albums(
  id        INTEGER PRIMARY KEY,
  artist_id INTEGER NOT NULL REFERENCES artists(id),
  title     TEXT COLLATE NOCASE,
  year      INTEGER,
  UNIQUE(artist_id, title, year)
);

CREATE TABLE IF NOT EXISTS tracks(
  id             INTEGER PRIMARY KEY,
  artist_id      INTEGER NOT NULL REFERENCES artists(id),
  album_id       INTEGER REFERENCES albums(id),
  title          TEXT NOT NULL COLLATE NOCASE,
  track_no       INTEGER,
  year           INTEGER,
  genre          TEXT,
  duration_sec   INTEGER,
  bitrate_kbps   INTEGER,
  samplerate_hz  INTEGER,
  channels       INTEGER,
  filesize_bytes INTEGER,
  sha1           TEXT,   -- optional; may be NULL
  relpath        TEXT NOT NULL
);

-- External-content FTS5 (search over key text fields)
CREATE VIRTUAL TABLE IF NOT EXISTS fts_tracks USING fts5(
  title, artist, album, genre,
  content='tracks', content_rowid='id',
  tokenize = 'unicode61 remove_diacritics 2',
  prefix='2 3 4'
);

-- Keep FTS index in sync
CREATE TRIGGER IF NOT EXISTS tracks_ai AFTER INSERT ON tracks BEGIN
  INSERT INTO fts_tracks(rowid,title,artist,album,genre)
  VALUES (new.id,
          new.title,
          (SELECT name FROM artists WHERE id=new.artist_id),
          (SELECT title FROM albums WHERE id=new.album_id),
          new.genre);
END;

CREATE TRIGGER IF NOT EXISTS tracks_ad AFTER DELETE ON tracks BEGIN
  INSERT INTO fts_tracks(fts_tracks, rowid) VALUES('delete', old.id);
END;

CREATE TRIGGER IF NOT EXISTS tracks_au AFTER UPDATE ON tracks BEGIN
  INSERT INTO fts_tracks(fts_tracks, rowid) VALUES('delete', old.id);
  INSERT INTO fts_tracks(rowid,title,artist,album,genre)
  VALUES (new.id,
          new.title,
          (SELECT name FROM artists WHERE id=new.artist_id),
          (SELECT title FROM albums WHERE id=new.album_id),
          new.genre);
END;

CREATE INDEX IF NOT EXISTS idx_tracks_artist_id ON tracks(artist_id);
CREATE INDEX IF NOT EXISTS idx_tracks_album_id  ON tracks(album_id);
CREATE INDEX IF NOT EXISTS idx_tracks_year      ON tracks(year);

Notes

• Text search should use fts_tracks MATCH ? and join back to tracks for details.
• Sorting for display can use ORDER BY rank (FTS) or artist,title,year.

---

Example Queries (for agents)

• Free text:

  SELECT t.id, a.name AS artist, t.title, IFNULL(al.title,'') AS album, t.year, t.genre
  FROM fts_tracks f
  JOIN tracks t ON t.id=f.rowid
  JOIN artists a ON a.id=t.artist_id
  LEFT JOIN albums al ON al.id=t.album_id
  WHERE f MATCH ?            -- e.g., 'queen "bohemian rhapsody"'
  ORDER BY rank LIMIT 50;
  

• By artist prefix (fast via FTS prefix):

  WHERE f MATCH 'artist:beatl*'
  

• Count by year:

  SELECT year, COUNT(*) FROM tracks GROUP BY year ORDER BY year;
  

---

Local Development

• Serve statically (to enable range requests and avoid file:// issues):

  • Python: python3 -m http.server 8000
  • Node: npx http-server -p 8000

• Open http://localhost:8000/

• Ensure the server sends Accept-Ranges: bytes for /assets/mp3com-meta.sqlite.

---

Performance Guidance

• Keep initial DOM minimal; render results incrementally (virtualized list if needed).
• Debounce search input (e.g., 200–300 ms).
• Use LIMIT/pagination; avoid SELECT * on large result sets.
• Cache prepared statements in JS if the WASM wrapper allows.

---

Quality Bar

• No console errors.
• Basic keyboard navigation works.
• Layout adapts from mobile ? desktop via Bulma columns.
• Reasonable query latency for common searches (<300ms after warm-up).

---

Security & Privacy

• No third-party trackers.
• Only static file loads; no credentials.
• If adding analytics, prefer privacy-preserving, self-hosted options and document them.

---

How to Extend (if requested later)

• Autocomplete table (prebuilt) for artists/albums.
• Sharded DBs by initial letter with a tiny manifest.
• Export results (CSV) client-side.

---

Agent Etiquette

• Do not introduce new build steps or frameworks unless explicitly asked.
• Keep diffs small and focused.
• When editing index.html/script.js, include inline comments explaining assumptions.
• Verify changes against the schema above.