.gitignore

@@ -30,3 +30,5 @@ web/ui/node_modules/
 
 # Temp
 /tmp/
+akai-fetch.test
+cover.out

AGENTS.md

@@ -16,7 +16,9 @@ mise run serve             # → starts HTTP server, opens browser
 mise run electron-deps     # installs electron + electron-builder
 mise run electron-dev      # runs electron in dev mode
 mise run docker-up         # docker compose up --build
-mise run lint              # go vet ./...
+mise run lint              # golangci-lint run (Go)
+mise run js-lint            # eslint (JS)
+mise run js-test            # node --test (JS)
 mise run check-all         # verify gcc, brew, mise, go, node, docker, colima
 ```
 
@@ -55,7 +57,14 @@ Single binary (`fetch`) with subcommands. No external Go dependencies — pure s
 ```
 main.go        CLI entry, commands (search/list/download/extract/pipeline/serve)
 serve.go       HTTP server + REST API + embedded web UI (embed.FS)
-web/ui/        Static frontend (index.html, style.css, app.js)
+web/ui/        Static frontend
+  ├── index.html              HTML layout
+  ├── style.css               CSS custom properties theme
+  ├── util.js                 shared utility functions
+  ├── app.js                  application logic, event delegation
+  ├── util.test.js            JS tests (node --test)
+  ├── eslint.config.js        ESLint flat config
+  └── package.json            ESLint + test scripts
 electron/      Electron wrapper shell
 scripts/       Bash helpers called via exec
   ├── extract_wavs.sh            batch WAV extraction via akaiutil
@@ -70,8 +79,9 @@ third_party/   Vendored akaiutil C binary (GPLv2)
 - **Flag parsing**: each command creates its own `flag.NewFlagSet` — avoids global flag state
 - **Concurrency**: semaphore channel pattern (`sem := make(chan struct{}, N)`) for bounded parallelism
 - **SSE progress**: `serve.go:handleProgress` — 500ms ticker, EventSource stream, auto-closes when all done
+- **Event delegation**: `app.js` — single click listener on document, dispatches by `[data-action]` attribute (download, list, play)
 - **akaiutil wrapper**: `extract.go` — persistent stdin/stdout pipes, no bash intermediary
-- **Zero-deps web UI**: vanilla JS, no bundler, no framework. API calls use `fetch()` + `EventSource`
+- **Zero-deps web UI**: vanilla JS, no bundler, no framework. API calls use `fetch()` + `EventSource`. Web Audio API for WAV playback.
 - **Embed directive**: `//go:embed web/ui/*` in `serve.go` — frontend baked into the binary
 - **Bind address handling**: `serve.go:37` — `--host` flag defaults to `127.0.0.1` for local dev; set `--host 0.0.0.0` for Docker. When binding to `0.0.0.0`, prints both `localhost` and `<host-ip>` URLs for clarity.
 
@@ -124,12 +134,15 @@ All akaiutil calls use `-r` (read-only) flag. Write operations (S900 compress, p
 
 ## Testing
 
-No test framework yet. Manual verification:
 ```bash
-go build -o /dev/null .        # compile check
+# Go
+go test -cover                  # unit tests (extract, serve, http, download, cli, util)
 go vet ./...                   # static analysis
-golangci-lint run              # comprehensive lint
+golangci-lint run              # comprehensive lint (uses .golangci.yml)
-./akai-fetch serve              # manual smoke test
+
+# JavaScript
+mise run js-test               # node --test (19 tests: esc, sanitize, formatBytes, formatTime)
+mise run js-lint               # eslint (flat config)
 ```
 
 ## Secrets & Tokens

README.md

@@ -110,7 +110,7 @@ See [open issues](https://git.notsosm.art/david/akai-utils/issues).
 | #6 | Direct-to-Disk Take Extraction | todo |
 | #7 | TAR Bulk Import/Export | todo |
 | #8 | Sample Tag Editor | todo |
-| #9 | Audio Preview Player | todo |
+| #9 | Audio Preview Player | done |
 
 ## License
 

web/ui/app.js

@@ -200,42 +200,85 @@ let animationFrame = null;
 
 document.getElementById('wav-browse-btn').addEventListener('click', browseWavs);
 
+function renderSampleCards(samples) {
+  return samples.map(s => `
+    <div class="sample-card" data-action="play" data-wav="${esc(s.fullPath)}">
+      <span class="sample-name" title="${esc(s.name)}">${esc(s.name)}</span>
+    </div>
+  `).join('');
+}
+
+function renderPrograms(programs) {
+  const progNames = Object.keys(programs).sort();
+  return progNames.map(prog => {
+    const samples = programs[prog];
+    return `
+      <div class="program-card">
+        <div class="program-header">
+          <h4>${esc(cleanName(prog))}</h4>
+          <span class="prog-meta">${samples.length} samples</span>
+        </div>
+        <div class="program-samples">
+          ${renderSampleCards(samples)}
+        </div>
+      </div>`;
+  }).join('');
+}
+
+function renderLibraries(libs) {
+  const libNames = Object.keys(libs).sort();
+  return libNames.map(lib => {
+    const programs = libs[lib];
+    const progCount = Object.keys(programs).length;
+    const sampleCount = Object.values(programs).reduce((sum, s) => sum + s.length, 0);
+    return `
+      <div class="library-card">
+        <div class="library-header" onclick="this.parentNode.classList.toggle('collapsed')">
+          <h3>${esc(cleanName(lib))}<span class="lib-toggle">▾</span></h3>
+          <span class="lib-meta">${progCount} programs · ${sampleCount} samples</span>
+        </div>
+        <div class="library-programs">
+          ${renderPrograms(programs)}
+        </div>
+      </div>`;
+  }).join('');
+}
+
 async function browseWavs() {
   const dir = document.getElementById('wav-dir').value;
+  const results = document.getElementById('wav-results');
+  const summary = document.getElementById('wav-summary');
   const list = document.getElementById('wav-list');
   list.innerHTML = 'Loading...';
-  console.log('browseWavs: dir =', dir);
 
   try {
     const url = `${API}/list-wavs?dir=${encodeURIComponent(dir)}`;
-    console.log('browseWavs: fetching', url);
     const resp = await fetch(url);
-    console.log('browseWavs: response status', resp.status, 'ok', resp.ok);
 
     if (!resp.ok) {
       list.innerHTML = '<span class="no-files">HTTP ' + resp.status + '</span>';
+      results.style.display = 'block';
       return;
     }
     const data = await resp.json();
-    console.log('browseWavs: parsed data', data, 'type', typeof data, 'isArray', Array.isArray(data));
     if (!data || data.error) {
       list.innerHTML = '<span class="no-files">Error: ' + (data && data.error ? data.error : 'server error') + '</span>';
+      results.style.display = 'block';
       return;
     }
     if (!Array.isArray(data) || data.length === 0) {
       list.innerHTML = '<span class="no-files">No WAV files found</span>';
+      results.style.display = 'block';
       return;
     }
-    console.log('browseWavs: found', data.length, 'wavs');
+    const libs = groupWavs(data);
-    list.innerHTML = data.map(f => `
+    const libCount = Object.keys(libs).length;
-      <div class="wav-item" data-file="${esc(f)}">
+    summary.textContent = libCount + ' librar' + (libCount === 1 ? 'y' : 'ies') + ' · ' + data.length + ' samples';
-        <span class="wav-name" title="${esc(f)}">${esc(f)}</span>
+    list.innerHTML = renderLibraries(libs);
-        <button class="wav-play-btn" data-action="play" data-wav="${esc(f)}">Play</button>
+    results.style.display = 'block';
-      </div>
-    `).join('');
   } catch (e) {
-    console.error('browseWavs: error', e);
     list.innerHTML = 'Failed: ' + e.message;
+    results.style.display = 'block';
   }
 }
 
@@ -255,8 +298,11 @@ async function playWav(filename) {
     animationFrame = null;
   }
 
+  const name = filename.split('/').pop().replace(/\.wav$/i, '');
+  const player = document.getElementById('wav-player');
   const nowPlaying = document.getElementById('wav-now-playing');
-  nowPlaying.textContent = 'Loading: ' + filename;
+  player.style.display = 'block';
+  nowPlaying.textContent = 'Loading: ' + name;
 
   try {
     const resp = await fetch(`/wavs/${encodeURIComponent(filename)}`);
@@ -276,6 +322,7 @@ async function playWav(filename) {
         document.getElementById('wav-progress-fill').style.width = '0%';
         document.getElementById('wav-time').textContent = formatTime(0);
         clearActiveItem();
+        player.style.display = 'none';
       }
     };
 
@@ -284,7 +331,7 @@ async function playWav(filename) {
     isPlaying = true;
     pauseOffset = 0;
 
-    nowPlaying.textContent = '▶ ' + filename;
+    nowPlaying.textContent = '▶ ' + name;
     setActiveItem(filename);
     updateProgress();
   } catch (e) {
@@ -308,13 +355,13 @@ function updateProgress() {
 }
 
 function setActiveItem(filename) {
-  document.querySelectorAll('.wav-item').forEach(el => {
+  document.querySelectorAll('.sample-card').forEach(el => {
-    el.classList.toggle('playing', el.dataset.file === filename);
+    el.classList.toggle('playing', el.dataset.wav === filename);
   });
 }
 
 function clearActiveItem() {
-  document.querySelectorAll('.wav-item').forEach(el => {
+  document.querySelectorAll('.sample-card').forEach(el => {
     el.classList.remove('playing');
   });
 }
@@ -335,3 +382,17 @@ document.addEventListener('click', function(e) {
     playWav(btn.dataset.wav);
   }
 });
+
+// Section collapse toggle
+document.querySelectorAll('.section-toggle').forEach(h => {
+  h.addEventListener('click', function () {
+    this.classList.toggle('collapsed');
+    const target = document.getElementById(this.dataset.section);
+    target.style.display = target.style.display === 'none' ? '' : 'none';
+  });
+});
+
+// Collapse all libraries
+document.getElementById('wav-collapse-all').addEventListener('click', function () {
+  document.querySelectorAll('.library-card').forEach(c => c.classList.add('collapsed'));
+});

web/ui/index.html

@@ -40,18 +40,26 @@
   </section>
 
   <section id="wav-section">
-    <h2>WAV Browser</h2>
+    <h2 class="section-toggle" data-section="wav-body">Sample Library <span class="toggle-icon">▾</span></h2>
+    <div id="wav-body">
     <div class="wav-controls">
       <input type="text" id="wav-dir" placeholder="WAV directory" value="./output/wavs">
       <button id="wav-browse-btn">Browse</button>
     </div>
-    <div id="wav-player" class="wav-player">
+    <div id="wav-results" style="display:none">
-      <div id="wav-now-playing" class="now-playing"></div>
+      <div class="wav-summary-row">
-      <div class="audio-bar">
+        <div id="wav-summary" class="wav-summary"></div>
-        <div class="audio-progress"><div id="wav-progress-fill" class="audio-progress-fill"></div></div>
+        <button id="wav-collapse-all" class="collapse-all-btn">Collapse All</button>
-        <span id="wav-time">0:00</span>
       </div>
-      <div id="wav-list" class="wav-list"></div>
+      <div id="wav-player" class="wav-player" style="display:none">
+        <div id="wav-now-playing" class="now-playing"></div>
+        <div class="audio-bar">
+          <div class="audio-progress"><div id="wav-progress-fill" class="audio-progress-fill"></div></div>
+          <span id="wav-time">0:00</span>
+        </div>
+      </div>
+      <div id="wav-list" class="wav-library"></div>
+    </div>
     </div>
   </section>
 

web/ui/style.css

@@ -50,6 +50,23 @@ section {
   margin-bottom: 20px;
 }
 
+/* Section collapse toggle */
+.section-toggle {
+  cursor: pointer;
+  user-select: none;
+  display: flex;
+  align-items: center;
+  gap: 8px;
+}
+.toggle-icon {
+  font-size: 12px;
+  transition: transform 0.2s;
+  display: inline-block;
+}
+.section-toggle.collapsed .toggle-icon {
+  transform: rotate(-90deg);
+}
+
 h2 {
   font-size: 16px;
   color: var(--text2);
@@ -272,42 +289,168 @@ h2 {
   min-width: 40px;
 }
 
-.wav-list {
+.no-files {
-  display: grid;
+  color: var(--text2);
-  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
+  font-size: 13px;
-  gap: 8px;
+  padding: 12px 0;
 }
 
-.wav-item {
+.wav-summary {
-  background: var(--bg);
+  font-size: 13px;
+  color: var(--text2);
+  margin-top: 12px;
+  margin-bottom: 12px;
+  min-height: 18px;
+}
+
+/* Library cards */
+.wav-library {
+  display: flex;
+  flex-direction: column;
+  gap: 12px;
+}
+
+.library-card {
+  background: var(--bg2);
   border: 1px solid var(--bg3);
   border-radius: var(--radius);
-  padding: 10px 12px;
+  overflow: hidden;
+  margin-bottom: 8px;
+}
+
+.library-header {
+  padding: 10px 16px;
+  cursor: pointer;
+  user-select: none;
+  background: var(--bg);
+  border-bottom: 1px solid var(--bg3);
+  transition: border-color 0.15s;
   display: flex;
   align-items: center;
-  gap: 8px;
+  gap: 12px;
-  cursor: pointer;
 }
-.wav-item:hover {
+.library-header:hover {
   border-color: var(--accent);
 }
-.wav-item.playing {
+.library-header h3 {
-  border-color: var(--green);
+  font-size: 14px;
-  background: rgba(78, 204, 163, 0.1);
+  font-weight: 600;
+  color: var(--text);
+  margin: 0;
+  text-transform: none;
+  letter-spacing: 0;
+  display: flex;
+  align-items: center;
+  gap: 4px;
 }
-.wav-item .wav-name {
+.library-header .lib-meta {
-  flex: 1;
+  font-size: 11px;
-  font-size: 13px;
+  color: var(--text2);
+  margin-left: auto;
+}
+
+.library-programs {
+  padding: 8px 16px 12px;
+}
+
+/* Program cards */
+.program-card {
+  margin-top: 10px;
+}
+.program-card:first-child {
+  margin-top: 0;
+}
+
+.program-header {
+  cursor: default;
+  user-select: none;
+  margin-bottom: 6px;
+}
+.program-header h4 {
+  font-size: 12px;
+  font-weight: 600;
+  color: var(--accent);
+  margin: 0;
+  text-transform: none;
+  letter-spacing: 0;
+  display: inline;
+}
+.program-header .prog-meta {
+  font-size: 10px;
+  color: var(--text2);
+  margin-left: 6px;
+}
+
+.program-samples {
+  display: grid;
+  grid-template-columns: repeat(auto-fill, minmax(70px, 1fr));
+  gap: 4px;
+}
+
+/* Sample cards */
+.sample-card {
+  background: var(--bg);
+  border: 1px solid var(--bg3);
+  border-radius: 4px;
+  padding: 4px 8px;
+  cursor: pointer;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  min-height: 28px;
+  transition: border-color 0.15s, background 0.15s;
+}
+.sample-card:hover {
+  border-color: var(--accent);
+}
+.sample-card.playing {
+  border-color: var(--green);
+  background: rgba(78, 204, 163, 0.15);
+}
+.sample-card .sample-name {
+  font-size: 10px;
+  color: var(--text);
+  text-align: center;
   overflow: hidden;
   text-overflow: ellipsis;
   white-space: nowrap;
+  max-width: 100%;
 }
-.wav-item .wav-play-btn {
+.sample-card .sample-play-icon {
-  background: var(--accent2);
+  display: none;
-  color: white;
+}
+
+/* Collapse all button */
+.wav-summary-row {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 12px;
+}
+.collapse-all-btn {
+  background: var(--bg3);
+  color: var(--text2);
   border: none;
   border-radius: 4px;
   padding: 4px 10px;
   font-size: 11px;
   cursor: pointer;
+  white-space: nowrap;
+}
+.collapse-all-btn:hover {
+  color: var(--text);
+}
+
+/* Library collapse state */
+.library-card.collapsed .library-programs {
+  display: none;
+}
+.library-header .lib-toggle {
+  font-size: 11px;
+  transition: transform 0.2s;
+  margin-left: 8px;
+  color: var(--text2);
+}
+.library-card.collapsed .lib-toggle {
+  transform: rotate(-90deg);
 }

web/ui/util.js

@@ -24,6 +24,29 @@ function formatTime(secs) {
   return m + ':' + s.toString().padStart(2, '0')
 }
 
+function groupWavs(paths) {
+  const libs = {}
+  for (const p of paths) {
+    const parts = p.split('/')
+    let lib, prog, file
+    if (parts.length === 1) {
+      lib = ''; prog = parts[0]; file = parts[0]
+    } else if (parts.length === 2) {
+      lib = parts[0]; prog = parts[0]; file = parts[1]
+    } else {
+      lib = parts[0]; prog = parts[1]; file = parts[parts.length - 1]
+    }
+    if (!libs[lib]) libs[lib] = {}
+    if (!libs[lib][prog]) libs[lib][prog] = []
+    libs[lib][prog].push({ fullPath: p, name: file.replace(/\.wav$/i, '') })
+  }
+  return libs
+}
+
+function cleanName(name) {
+  return name.replace(/_+/g, ' ').trim()
+}
+
 if (typeof module !== 'undefined' && module.exports) {
-  module.exports = { esc, sanitize, formatBytes, formatTime }
+  module.exports = { esc, sanitize, formatBytes, formatTime, groupWavs, cleanName }
 }

web/ui/util.test.js

@@ -1,6 +1,6 @@
 const { describe, it } = require('node:test')
 const assert = require('node:assert/strict')
-const { esc, sanitize, formatBytes, formatTime } = require('./util.js')
+const { esc, sanitize, formatBytes, formatTime, groupWavs, cleanName } = require('./util.js')
 
 describe('esc', () => {
   it('escapes HTML entities', () => {
@@ -88,4 +88,74 @@ describe('formatTime', () => {
   it('formats large times', () => {
     assert.strictEqual(formatTime(3661), '61:01')
   })
+})
+
+describe('groupWavs', () => {
+  it('groups by library and program', () => {
+    const paths = [
+      'LibA/Prog1/kick.wav',
+      'LibA/Prog1/snare.wav',
+      'LibA/Prog2/hat.wav'
+    ]
+    const result = groupWavs(paths)
+    assert.strictEqual(Object.keys(result).length, 1)
+    assert.strictEqual(Object.keys(result.LibA).length, 2)
+    assert.strictEqual(result.LibA.Prog1.length, 2)
+    assert.strictEqual(result.LibA.Prog2.length, 1)
+  })
+
+  it('handles multiple libraries', () => {
+    const paths = [
+      'LibA/kick.wav',
+      'LibB/snare.wav'
+    ]
+    const result = groupWavs(paths)
+    assert.strictEqual(Object.keys(result).length, 2)
+    assert.strictEqual(result.LibA.LibA[0].name, 'kick')
+    assert.strictEqual(result.LibB.LibB[0].name, 'snare')
+  })
+
+  it('strips .wav extension case-insensitively', () => {
+    const paths = ['Lib/Prog/KICK.WAV']
+    const result = groupWavs(paths)
+    assert.strictEqual(result.Lib.Prog[0].name, 'KICK')
+  })
+
+  it('handles deeply nested paths', () => {
+    const paths = ['A/B/C/D/file.wav']
+    const result = groupWavs(paths)
+    assert.strictEqual(result.A.B.length, 1)
+    assert.strictEqual(result.A.B[0].name, 'file')
+    assert.strictEqual(result.A.B[0].fullPath, 'A/B/C/D/file.wav')
+  })
+
+  it('handles flat paths with no directory', () => {
+    const paths = ['sound.wav']
+    const result = groupWavs(paths)
+    assert.strictEqual(Object.keys(result).length, 1)
+    assert.strictEqual(Object.keys(result['']).length, 1)
+  })
+
+  it('returns empty object for empty input', () => {
+    const result = groupWavs([])
+    assert.strictEqual(Object.keys(result).length, 0)
+  })
+})
+
+describe('cleanName', () => {
+  it('replaces underscores with spaces', () => {
+    assert.strictEqual(cleanName('hello_world'), 'hello world')
+  })
+
+  it('collapses multiple underscores', () => {
+    assert.strictEqual(cleanName('AMG_-_Black__II'), 'AMG - Black II')
+  })
+
+  it('trims leading/trailing spaces from underscores', () => {
+    assert.strictEqual(cleanName('_padded_'), 'padded')
+  })
+
+  it('preserves regular text', () => {
+    assert.strictEqual(cleanName('Kick Drum'), 'Kick Drum')
+  })
 })