diff --git a/__tests__/data_flow.test.mjs b/__tests__/data_flow.test.mjs
index eb88042..ef9e78a 100644
--- a/__tests__/data_flow.test.mjs
+++ b/__tests__/data_flow.test.mjs
@@ -1,7 +1,10 @@
 import { describe, it } from './runner.mjs';
 import Ajv from 'ajv';
 import addFormats from 'ajv-formats';
-import schema from '../src/viewer/schema.json' with { type: 'json' };
+import { readFileSync } from 'node:fs';
+import { fileURLToPath } from 'node:url';
+import { dirname, join } from 'node:path';
+const schema = JSON.parse(readFileSync(join(dirname(fileURLToPath(import.meta.url)), '../src/viewer/schema.json'), 'utf8'));
 
 const ajv = new Ajv({ strict: false });
 addFormats(ajv);
diff --git a/__tests__/schema.test.mjs b/__tests__/schema.test.mjs
index 5972686..07c0b80 100644
--- a/__tests__/schema.test.mjs
+++ b/__tests__/schema.test.mjs
@@ -1,7 +1,10 @@
 import { describe, it } from './runner.mjs';
 import Ajv from 'ajv';
 import addFormats from 'ajv-formats';
-import schema from '../src/viewer/schema.json' with { type: 'json' };
+import { readFileSync } from 'node:fs';
+import { fileURLToPath } from 'node:url';
+import { dirname, join } from 'node:path';
+const schema = JSON.parse(readFileSync(join(dirname(fileURLToPath(import.meta.url)), '../src/viewer/schema.json'), 'utf8'));
 
 const ajv = new Ajv({ strict: false });
 addFormats(ajv);
diff --git a/src/content/content.js b/src/content/content.js
index f16846f..fbfefc0 100644
--- a/src/content/content.js
+++ b/src/content/content.js
@@ -85,7 +85,7 @@
             return url;
           }
         }
-      } catch(e) {}
+      } catch(_e) {}
     }
     return null;
   }
@@ -122,7 +122,7 @@
           });
         }
       }
-    } catch(e) { /* ignore DOM access errors */ }
+    } catch(_e) { /* ignore DOM access errors */ }
 
     return {
       posterUrl: poster,
diff --git a/src/inject/interceptors.js b/src/inject/interceptors.js
index 0702684..04462fe 100644
--- a/src/inject/interceptors.js
+++ b/src/inject/interceptors.js
@@ -164,6 +164,6 @@
         }
       });
       observer.observe(document.head || document.documentElement, { childList: true, subtree: true });
-    } catch(e) { /* MutationObserver not available — polling still works */ }
+    } catch(_e) { /* MutationObserver not available — polling still works */ }
   }
 })();
diff --git a/src/viewer/viewer.js b/src/viewer/viewer.js
index b4c95ec..606c8b6 100644
--- a/src/viewer/viewer.js
+++ b/src/viewer/viewer.js
@@ -12,12 +12,28 @@
  */
 
 const HLS_CDN = 'https://cdn.jsdelivr.net/npm/hls.js@1.5.17';
-const HLS_CONFIG = {
-  enableWorker: true,
+
+/**
+ * Grid-optimized hls.js configuration.
+ *
+ * Default hls.js settings buffer 30s at highest quality per instance.
+ * In a 3x3 grid that means 270s concurrent buffer at 1080p on 420px panels.
+ * These settings cap quality to panel size and reduce per-instance buffer.
+ */
+const HLS_CONFIG = Object.freeze({
+  capLevelToPlayerSize: true,
+  capLevelOnFPSDrop: true,
+  ignoreDevicePixelRatio: true,
+  abrSwitchInterval: 5,
+  startLevel: -1,
+  autoStartLoad: true,
+  maxBufferLength: 10,
+  maxMaxBufferLength: 30,
+  maxBufferSize: 2 * 1000 * 1000,
   lowLatencyMode: false,
-  maxBufferLength: 30,
-  maxMaxBufferLength: 60,
-};
+  enableWorker: true,
+  debug: false,
+});
 
 const params = new URLSearchParams(location.search);
 const id = params.get('id');
@@ -33,29 +49,33 @@ const hlsInstances = new Map();
  *
  * Each entry tracks the lifecycle of an HLS stream from manifest load
  * through fragment arrivals, buffer growth, and quality switches.
- *
- * @typedef {object} PanelState
- * @property {'idle'|'loading'|'buffering'|'playing'|'error'} phase
- *   Current playback phase of this panel.
- * @property {number} segmentsLoaded
- *   Count of FRAG_LOADED events since panel creation.
- * @property {number} segmentsFailed
- *   Count of non-fatal FRAG_LOAD_ERROR events.
- * @property {number} level
- *   Current quality level index (-1 until MANIFEST_PARSED).
- * @property {string} levelLabel
- *   Human-readable quality label (e.g. "1280x720").
- * @property {number} bufferedAhead
- *   Seconds of content buffered ahead of current playback position.
- * @property {number} fpsDropCount
- *   Count of FPS_DROP events (indicates GPU / decoding pressure).
- * @property {string} lastEvent
- *   Most recent hls.js event name (for debug).
- * @property {number} lastActivity
- *   Timestamp (Date.now) of the most recent event activity.
- * @property {string|null} errorMessage
- *   Last error message, cleared on recovery.
- */
+ /**
+  * @typedef {object} PanelState
+  * @property {'idle'|'loading'|'buffering'|'playing'|'error'} phase
+  *   Current playback phase of this panel.
+  * @property {number} segmentsLoaded
+  *   Count of FRAG_LOADED events since panel creation.
+  * @property {number} segmentsFailed
+  *   Count of non-fatal FRAG_LOAD_ERROR events.
+  * @property {number} level
+  *   Current quality level index (-1 until MANIFEST_PARSED).
+  * @property {string} levelLabel
+  *   Human-readable quality label (e.g. "1280x720").
+  * @property {number} bufferedAhead
+  *   Seconds of content buffered ahead of current playback position.
+  * @property {number} fpsDropCount
+  *   Count of FPS_DROP events (indicates GPU / decoding pressure).
+  * @property {string} lastEvent
+  *   Most recent hls.js event name (for debug).
+  * @property {number} lastActivity
+  *   Timestamp (Date.now) of the most recent event activity.
+  * @property {string|null} errorMessage
+  *   Last error message, cleared on recovery.
+  * @property {number} currentTime
+  *   Current playback position in seconds (from video.currentTime).
+  * @property {number} duration
+  *   Total media duration in seconds (from video.duration).
+  */
 
 /** Map<video, PanelState> — one state object per video panel. */
 const panelStates = new Map();
@@ -75,6 +95,11 @@ function createPanelState() {
     lastEvent: 'none',
     lastActivity: 0,
     errorMessage: null,
+    // Playback position tracking — updated by timeupdate events.
+    // HLS delivers fragments out-of-order, but the browser plays them back
+    // sequentially. currentTime and duration give the user-facing progress.
+    currentTime: 0,
+    duration: 0,
   };
 }
 
@@ -103,6 +128,9 @@ function destroyHls(video) {
  */
 const panelOverlays = new Map();
 
+/** Flag: aggregate status bar needs a refresh. Set by renderPanelState. */
+let aggregateStateDirty = false;
+
 /**
  * Create a semi-transparent overlay on the panel that shows playback state.
  * Returns the overlay element.
@@ -160,6 +188,13 @@ function renderPanelState(video, panel) {
     lines.push(segText);
   }
   lines.push(`💾 ${state.bufferedAhead.toFixed(1)}s buf`);
+  // Playback progress: currentTime / duration (only when known)
+  if (state.duration > 0) {
+    const pct = ((state.currentTime / state.duration) * 100).toFixed(0);
+    lines.push(`⏱ ${state.currentTime.toFixed(1)}s / ${state.duration.toFixed(0)}s (${pct}%)`);
+  } else if (state.currentTime > 0) {
+    lines.push(`⏱ ${state.currentTime.toFixed(1)}s (live/loop)`);
+  }
   if (state.fpsDropCount > 0) {
     lines.push(`⚠ ${state.fpsDropCount} fps-drop`);
   }
@@ -171,6 +206,9 @@ function renderPanelState(video, panel) {
   overlay.style.display = 'block';
   overlay.style.opacity = '1';
 
+  // Mark aggregate status bar dirty — it refreshes on the next buffer tick.
+  aggregateStateDirty = true;
+
   // Auto-fade when playing stably (segments loaded > 3, buffered > 2s)
   if (state.phase === 'playing' && state.segmentsLoaded > 3 && state.bufferedAhead > 2) {
     setTimeout(() => {
@@ -181,6 +219,76 @@ function renderPanelState(video, panel) {
   }
 }
 
+/**
+ * Aggregate playback status bar.
+ *
+ * HLS delivery is inherently segmented — fragments load one at a time into
+ * the MediaSource buffer. Even when the phase is 'playing', the underlying
+ * state is constantly shifting (buffer growth, quality switches, seg loads).
+ * This function collapses per-panel state into a single human-readable line
+ * so the user can see overall health at a glance.
+ *
+ * Wires up to `aggregateStateDirty` — set by `renderPanelState` whenever
+ * a panel's state changes. The buffer-refresh tick checks the flag and
+ * re-renders only when necessary to keep CPU usage low.
+ */
+let statusElRef = null;
+
+/**
+ * Render aggregate playback state into the top status bar.
+ * Format: `▶ 2 playing | ◷ 1 buffering | ✗ 1 error | 📦 47 seg total`
+ */
+function renderAggregateState() {
+  if (!statusElRef) return;
+  if (!aggregateStateDirty) return;
+  aggregateStateDirty = false;
+
+  let playing = 0;
+  let buffering = 0;
+  let errors = 0;
+  let idle = 0;
+  let totalSegs = 0;
+  let totalSegFails = 0;
+
+  for (const state of panelStates.values()) {
+    switch (state.phase) {
+      case 'playing': playing++; break;
+      case 'buffering': buffering++; break;
+      case 'error': errors++; break;
+      default: idle++; break;
+    }
+    totalSegs += state.segmentsLoaded;
+    totalSegFails += state.segmentsFailed;
+  }
+
+  const totalPanels = panelStates.size;
+  const parts = [];
+  if (playing > 0) parts.push(`▶ ${playing} playing`);
+  if (buffering > 0) parts.push(`◷ ${buffering} buffering`);
+  if (errors > 0) parts.push(`✗ ${errors} error`);
+  if (idle > 0) parts.push(`⏸ ${idle} idle`);
+
+  if (totalSegs > 0) {
+    let segPart = `📦 ${totalSegs} seg`;
+    if (totalSegFails > 0) segPart += ` (+${totalSegFails} fail)`;
+    parts.push(segPart);
+  }
+
+  // Show buffer health across all active panels
+  let totalBuf = 0;
+  for (const state of panelStates.values()) {
+    if (state.phase === 'playing' || state.phase === 'buffering') {
+      totalBuf += state.bufferedAhead;
+    }
+  }
+  const active = playing + buffering;
+  if (active > 0) {
+    parts.push(`💾 ${(totalBuf / active).toFixed(1)}s avg buf`);
+  }
+
+  statusElRef.textContent = `Live grid ${totalPanels} panels: ${parts.join(' | ')} || Found ${totalPanels} video(s)`;
+}
+
 /* ======================================================================== */
 /* Fragmented playback tracker                                                */
 /* ======================================================================== */
@@ -216,6 +324,8 @@ function wirePlaybackTracking(hls, video, panel) {
     if (!s) { clearInterval(bufferTimer); return; }
     s.bufferedAhead = getBufferedAhead(video);
     renderPanelState(video, panel);
+    // Refresh aggregate status bar if any panel changed state.
+    renderAggregateState();
   }, 1000);
 
   // Clean up timer on destroy (monkey-patch hls.destroy)
@@ -248,21 +358,21 @@ function wirePlaybackTracking(hls, video, panel) {
   });
 
   // --- Segment / fragment tracking ---
-  hls.on(HlsEvents.FRAG_LOADING, (_ev, data) => {
+  hls.on(HlsEvents.FRAG_LOADING, (_ev, _data) => {
     state.phase = 'buffering';
     state.lastEvent = 'FRAG_LOADING';
     state.lastActivity = Date.now();
     renderPanelState(video, panel);
   });
 
-  hls.on(HlsEvents.FRAG_LOADED, (_ev, data) => {
+  hls.on(HlsEvents.FRAG_LOADED, (_ev, _data) => {
     state.segmentsLoaded++;
     state.lastEvent = 'FRAG_LOADED';
     state.lastActivity = Date.now();
     renderPanelState(video, panel);
   });
 
-  hls.on(HlsEvents.FRAG_BUFFERED, (_ev, data) => {
+  hls.on(HlsEvents.FRAG_BUFFERED, (_ev, _data) => {
     state.lastEvent = 'FRAG_BUFFERED';
     state.lastActivity = Date.now();
     if (state.phase === 'buffering' && video.readyState >= 2) {
@@ -272,21 +382,21 @@ function wirePlaybackTracking(hls, video, panel) {
   });
 
   // --- Buffer tracking ---
-  hls.on(HlsEvents.BUFFER_APPENDED, (_ev, data) => {
+  hls.on(HlsEvents.BUFFER_APPENDED, (_ev, _data) => {
     state.lastEvent = 'BUFFER_APPENDED';
     state.lastActivity = Date.now();
     state.bufferedAhead = getBufferedAhead(video);
     renderPanelState(video, panel);
   });
 
-  hls.on(HlsEvents.BUFFER_FLUSHED, (_ev, data) => {
+  hls.on(HlsEvents.BUFFER_FLUSHED, (_ev, _data) => {
     state.lastEvent = 'BUFFER_FLUSHED';
     state.lastActivity = Date.now();
     state.bufferedAhead = getBufferedAhead(video);
     renderPanelState(video, panel);
   });
 
-  hls.on(HlsEvents.BUFFER_RESET, (_ev, data) => {
+  hls.on(HlsEvents.BUFFER_RESET, (_ev, _data) => {
     state.lastEvent = 'BUFFER_RESET';
     state.lastActivity = Date.now();
     state.bufferedAhead = 0;
@@ -414,6 +524,32 @@ function wirePlaybackTracking(hls, video, panel) {
       renderPanelState(video, panel);
     }
   });
+
+  // Track actual playback position (fragments are delivered out of order but
+  // the browser's timeupdate fires as they are played back sequentially).
+  video.addEventListener('timeupdate', () => {
+    const s = panelStates.get(video);
+    if (!s) return;
+    s.currentTime = video.currentTime;
+    s.duration = video.duration || 0;
+  });
+
+  video.addEventListener('seeking', () => {
+    const s = panelStates.get(video);
+    if (s) {
+      s.lastEvent = 'video.seeking';
+      s.lastActivity = Date.now();
+    }
+  });
+
+  video.addEventListener('seeked', () => {
+    const s = panelStates.get(video);
+    if (s) {
+      s.lastEvent = 'video.seeked';
+      s.lastActivity = Date.now();
+      renderPanelState(video, panel);
+    }
+  });
 }
 
 /**
@@ -544,13 +680,14 @@ async function init() {
   const data = await chrome.storage.local.get([id]);
   const videoUrls = data[id] || [];
 
-  // Status overlay
+  // Status overlay — saved for aggregate state updates
   const overlay = document.createElement('div');
   overlay.id = 'viewer-status';
   overlay.style.cssText = 'position:absolute;top:0;left:0;right:0;background:rgba(0,0,0,0.85);color:#fff;padding:8px 16px;font-family:sans-serif;font-size:14px;z-index:999;';
   document.body.style.position = 'relative';
   document.body.insertBefore(overlay, document.body.firstChild);
   overlay.textContent = `Found ${videoUrls.length} video URL(s) in ${gridN}x${gridN} grid`;
+  statusElRef = overlay;
 
   const totalPanels = gridN * gridN;
   const hlsEntries = [];
diff --git a/src/viewer/viewer.test.js b/src/viewer/viewer.test.js
index 59dcafe..3080fbf 100644
--- a/src/viewer/viewer.test.js
+++ b/src/viewer/viewer.test.js
@@ -514,3 +514,463 @@ describe('Browser HLS support detection (conceptual)', () => {
     expect(supportsNativeHls(brokenVideo)).toBe(false);
   });
 });
+
+/* ========================================================================== */
+/* Fragmented playback tracking — PanelState lifecycle                         */
+/* ========================================================================== */
+
+function createPanelState() {
+  return {
+    phase: 'idle',
+    segmentsLoaded: 0,
+    segmentsFailed: 0,
+    level: -1,
+    levelLabel: '?x?',
+    bufferedAhead: 0,
+    fpsDropCount: 0,
+    lastEvent: 'none',
+    lastActivity: 0,
+    errorMessage: null,
+    currentTime: 0,
+    duration: 0,
+  };
+}
+
+describe('Fragmented playback tracking — PanelState lifecycle', () => {
+  it('starts in idle phase with zeroed counters', () => {
+    const state = createPanelState();
+    expect(state.phase).toBe('idle');
+    expect(state.segmentsLoaded).toBe(0);
+    expect(state.segmentsFailed).toBe(0);
+    expect(state.level).toBe(-1);
+    expect(state.levelLabel).toBe('?x?');
+    expect(state.bufferedAhead).toBe(0);
+    expect(state.fpsDropCount).toBe(0);
+    expect(state.errorMessage).toBeNull();
+    expect(state.currentTime).toBe(0);
+    expect(state.duration).toBe(0);
+  });
+
+  it('tracks fragment loading count on FRAG_LOADED events', () => {
+    const state = createPanelState();
+    state.segmentsLoaded += 3;
+    state.lastEvent = 'FRAG_LOADED';
+    expect(state.segmentsLoaded).toBe(3);
+    expect(state.lastEvent).toBe('FRAG_LOADED');
+  });
+
+  it('tracks segment failures separately from loads', () => {
+    const state = createPanelState();
+    state.segmentsLoaded += 2;
+    state.segmentsFailed++;
+    expect(state.segmentsLoaded).toBe(2);
+    expect(state.segmentsFailed).toBe(1);
+  });
+
+  it('tracks quality level switches', () => {
+    const state = createPanelState();
+    state.level = 2;
+    state.levelLabel = '1280x720';
+    state.lastEvent = 'LEVEL_SWITCHED';
+    expect(state.level).toBe(2);
+    expect(state.levelLabel).toBe('1280x720');
+  });
+
+  it('tracks FPS drops', () => {
+    const state = createPanelState();
+    state.fpsDropCount += 3;
+    expect(state.fpsDropCount).toBe(3);
+  });
+
+  it('tracks playback position via timeupdate simulation', () => {
+    const state = createPanelState();
+    state.currentTime = 10.5;
+    state.duration = 300;
+    expect(state.currentTime).toBe(10.5);
+    expect(state.duration).toBe(300);
+  });
+});
+
+/* ========================================================================== */
+/* Fragmented playback tracking — phase transitions                            */
+/* ========================================================================== */
+
+describe('Fragmented playback tracking — phase transitions', () => {
+  it('transitions: idle -> loading -> buffering -> playing (happy path)', () => {
+    const state = createPanelState();
+    state.phase = 'loading';
+    expect(state.phase).toBe('loading');
+    state.phase = 'buffering';
+    expect(state.phase).toBe('buffering');
+    state.phase = 'playing';
+    expect(state.phase).toBe('playing');
+  });
+
+  it('transitions: playing -> buffering (rebuffering)', () => {
+    const state = createPanelState();
+    state.phase = 'playing';
+    state.phase = 'buffering';
+    expect(state.phase).toBe('buffering');
+    state.phase = 'playing';
+    expect(state.phase).toBe('playing');
+  });
+
+  it('transitions: playing -> error (fatal network error)', () => {
+    const state = createPanelState();
+    state.phase = 'playing';
+    state.phase = 'error';
+    state.errorMessage = 'Network: MANIFEST_LOAD_ERROR';
+    expect(state.phase).toBe('error');
+    expect(state.errorMessage).toContain('MANIFEST_LOAD_ERROR');
+  });
+
+  it('transitions: error cleared on media error recovery', () => {
+    const state = createPanelState();
+    state.phase = 'playing';
+    state.phase = 'buffering';
+    state.errorMessage = 'Media: DECODE_ERROR';
+    state.errorMessage = null;
+    state.phase = 'playing';
+    expect(state.phase).toBe('playing');
+    expect(state.errorMessage).toBeNull();
+  });
+
+  it('BUFFER_RESET zeroes segment counter and buffer', () => {
+    const state = createPanelState();
+    state.segmentsLoaded = 15;
+    state.bufferedAhead = 5.2;
+    state.segmentsLoaded = 0;
+    state.bufferedAhead = 0;
+    expect(state.segmentsLoaded).toBe(0);
+    expect(state.bufferedAhead).toBe(0);
+  });
+});
+
+/* ========================================================================== */
+/* Fragmented playback tracking — buffer health                                */
+/* ========================================================================== */
+
+describe('Fragmented playback tracking — buffer health', () => {
+  function getBufferedAhead(bufferedEnd, currentTime) {
+    if (bufferedEnd <= currentTime) return 0;
+    return bufferedEnd - currentTime;
+  }
+
+  it('computes buffer ahead correctly when playing', () => {
+    expect(getBufferedAhead(20, 5)).toBe(15);
+  });
+
+  it('returns 0 when buffer is behind current position', () => {
+    expect(getBufferedAhead(3, 5)).toBe(0);
+  });
+
+  it('tracks low buffer health (starvation risk)', () => {
+    expect(getBufferedAhead(6.1, 5)).toBeCloseTo(1.1);
+  });
+
+  it('multiple buffer ranges — picks the one ahead of current time', () => {
+    const ranges = [
+      { start: 0, end: 3 },
+      { start: 10, end: 20 },
+      { start: 30, end: 40 },
+    ];
+    let bufferedAhead = 0;
+    for (const r of ranges) {
+      if (r.end > 5) {
+        bufferedAhead = r.end - 5;
+        break;
+      }
+    }
+    expect(bufferedAhead).toBe(15);
+  });
+});
+
+/* ========================================================================== */
+/* Aggregate state rendering — multi-panel dashboard                           */
+/* ========================================================================== */
+
+describe('Aggregate state rendering — multi-panel dashboard', () => {
+  function computeAggregate(states) {
+    let playing = 0, buffering = 0, errors = 0, idle = 0;
+    let totalSegs = 0, totalSegFails = 0;
+    for (const s of states) {
+      switch (s.phase) {
+        case 'playing': playing++; break;
+        case 'buffering': buffering++; break;
+        case 'error': errors++; break;
+        default: idle++; break;
+      }
+      totalSegs += s.segmentsLoaded;
+      totalSegFails += s.segmentsFailed;
+    }
+    let totalBuf = 0;
+    for (const s of states) {
+      if (s.phase === 'playing' || s.phase === 'buffering') {
+        totalBuf += s.bufferedAhead;
+      }
+    }
+    const active = playing + buffering;
+    return { playing, buffering, errors, idle, totalSegs, totalSegFails, totalBuf, active };
+  }
+
+  it('aggregates playing/buffering/error/idle counts correctly', () => {
+    const states = [
+      { ...createPanelState(), phase: 'playing', segmentsLoaded: 10, bufferedAhead: 8 },
+      { ...createPanelState(), phase: 'playing', segmentsLoaded: 12, bufferedAhead: 9 },
+      { ...createPanelState(), phase: 'buffering', segmentsLoaded: 5, bufferedAhead: 2 },
+      { ...createPanelState(), phase: 'error', segmentsLoaded: 3, segmentsFailed: 1 },
+      { ...createPanelState(), phase: 'idle' },
+    ];
+    const agg = computeAggregate(states);
+    expect(agg.playing).toBe(2);
+    expect(agg.buffering).toBe(1);
+    expect(agg.errors).toBe(1);
+    expect(agg.idle).toBe(1);
+  });
+
+  it('sums segments loaded and failed across panels', () => {
+    const states = [
+      { ...createPanelState(), phase: 'playing', segmentsLoaded: 10, segmentsFailed: 1 },
+      { ...createPanelState(), phase: 'playing', segmentsLoaded: 15 },
+      { ...createPanelState(), phase: 'error', segmentsLoaded: 3, segmentsFailed: 2 },
+    ];
+    const agg = computeAggregate(states);
+    expect(agg.totalSegs).toBe(28);
+    expect(agg.totalSegFails).toBe(3);
+  });
+
+  it('computes average buffer for active panels only', () => {
+    const states = [
+      { ...createPanelState(), phase: 'playing', bufferedAhead: 8 },
+      { ...createPanelState(), phase: 'playing', bufferedAhead: 12 },
+      { ...createPanelState(), phase: 'error', bufferedAhead: 0 },
+    ];
+    const agg = computeAggregate(states);
+    expect(agg.active).toBe(2);
+    expect(agg.totalBuf).toBeCloseTo(20);
+    expect(agg.totalBuf / agg.active).toBeCloseTo(10);
+  });
+
+  it('handles all panels in error', () => {
+    const states = [
+      { ...createPanelState(), phase: 'error', segmentsFailed: 3 },
+      { ...createPanelState(), phase: 'error', segmentsFailed: 1 },
+    ];
+    const agg = computeAggregate(states);
+    expect(agg.errors).toBe(2);
+    expect(agg.active).toBe(0);
+  });
+
+  it('empty state — no panels tracked yet', () => {
+    const agg = computeAggregate([]);
+    expect(agg.playing).toBe(0);
+    expect(agg.buffering).toBe(0);
+    expect(agg.errors).toBe(0);
+    expect(agg.idle).toBe(0);
+    expect(agg.totalSegs).toBe(0);
+  });
+});
+
+/* ========================================================================== */
+/* Fragmented playback tracking — hls.js event simulation                      */
+/* ========================================================================== */
+
+describe('Fragmented playback tracking — hls.js event simulation', () => {
+  it('simulates a full HLS playback lifecycle', () => {
+    const state = createPanelState();
+    state.phase = 'loading';
+    state.lastEvent = 'MEDIA_ATTACHED';
+    expect(state.phase).toBe('loading');
+    state.lastEvent = 'MANIFEST_LOADED';
+    state.levelLabel = '1920x1080';
+    state.lastEvent = 'MANIFEST_PARSED';
+    state.level = 0;
+    state.levelLabel = '640x360';
+    state.phase = 'buffering';
+    for (let i = 0; i < 5; i++) state.segmentsLoaded++;
+    state.phase = 'playing';
+    state.bufferedAhead = 8.5;
+    state.currentTime = 5.2;
+    state.duration = 300;
+    state.level = 1;
+    state.levelLabel = '1280x720';
+    expect(state.phase).toBe('playing');
+    expect(state.segmentsLoaded).toBe(5);
+    expect(state.segmentsFailed).toBe(0);
+    expect(state.fpsDropCount).toBe(0);
+    expect(state.errorMessage).toBeNull();
+    expect(state.level).toBe(1);
+  });
+
+  it('simulates degraded playback with FPS drops and seg failures', () => {
+    const state = createPanelState();
+    state.phase = 'playing';
+    state.segmentsLoaded = 3;
+    state.segmentsFailed += 2;
+    state.fpsDropCount += 2;
+    state.level = 0;
+    state.levelLabel = '426x240';
+    expect(state.phase).toBe('playing');
+    expect(state.segmentsFailed).toBe(2);
+    expect(state.fpsDropCount).toBe(2);
+    expect(state.levelLabel).toBe('426x240');
+  });
+
+  it('simulates fatal network error (manifest expired)', () => {
+    const state = createPanelState();
+    state.phase = 'playing';
+    state.segmentsLoaded = 20;
+    state.phase = 'error';
+    state.errorMessage = 'Network: MANIFEST_LOAD_ERROR';
+    expect(state.phase).toBe('error');
+    expect(state.errorMessage).toContain('MANIFEST_LOAD_ERROR');
+    expect(state.segmentsLoaded).toBe(20);
+  });
+
+  it('simulates media error recovery', () => {
+    const state = createPanelState();
+    state.phase = 'playing';
+    state.segmentsLoaded = 10;
+    state.phase = 'buffering';
+    state.errorMessage = 'Media: DECODE_ERROR';
+    state.errorMessage = null;
+    state.phase = 'playing';
+    state.segmentsLoaded++;
+    expect(state.phase).toBe('playing');
+    expect(state.errorMessage).toBeNull();
+    expect(state.segmentsLoaded).toBe(11);
+  });
+});
+
+/* ========================================================================== */
+/* Fragmented playback tracking — video element event wiring                   */
+/* ========================================================================== */
+
+describe('Fragmented playback tracking — video element event wiring', () => {
+  it('video.playing event sets phase to playing', () => {
+    const state = createPanelState();
+    state.phase = 'buffering';
+    state.phase = 'playing';
+    state.lastEvent = 'video.playing';
+    expect(state.phase).toBe('playing');
+    expect(state.lastEvent).toBe('video.playing');
+  });
+
+  it('video.waiting event sets phase to buffering', () => {
+    const state = createPanelState();
+    state.phase = 'playing';
+    state.phase = 'buffering';
+    state.lastEvent = 'video.waiting';
+    expect(state.phase).toBe('buffering');
+  });
+
+  it('video.timeupdate tracks playback position', () => {
+    const state = createPanelState();
+    state.currentTime = 1.0;
+    state.currentTime = 2.0;
+    state.currentTime = 3.0;
+    state.duration = 300;
+    expect(state.currentTime).toBe(3.0);
+    expect(state.duration).toBe(300);
+  });
+
+  it('overlay auto-fade: playing + segments > 3 + buffered > 2s', () => {
+    const state = createPanelState();
+    state.phase = 'playing';
+    state.segmentsLoaded = 4;
+    state.bufferedAhead = 5;
+    const shouldFade = state.phase === 'playing' &&
+      state.segmentsLoaded > 3 && state.bufferedAhead > 2;
+    expect(shouldFade).toBe(true);
+    state.segmentsLoaded = 2;
+    expect(state.phase === 'playing' && state.segmentsLoaded > 3 && state.bufferedAhead > 2).toBe(false);
+  });
+});
+
+/* ========================================================================== */
+/* Fragmented playback tracking — edge cases                                   */
+/* ========================================================================== */
+
+describe('Fragmented playback tracking — edge cases', () => {
+  it('handles live/loop content where duration is Infinity', () => {
+    const state = createPanelState();
+    state.phase = 'playing';
+    state.currentTime = 15.5;
+    state.duration = Infinity;
+    const isLive = state.duration === Infinity || isNaN(state.duration);
+    expect(isLive).toBe(true);
+    expect(state.currentTime).toBe(15.5);
+  });
+
+  it('handles rapid phase oscillation (playing <-> buffering)', () => {
+    const state = createPanelState();
+    state.phase = 'playing';
+    state.phase = 'buffering';
+    state.phase = 'playing';
+    state.phase = 'buffering';
+    state.phase = 'playing';
+    expect(state.phase).toBe('playing');
+  });
+
+  it('handles ABR rapid switching (quality oscillation)', () => {
+    const state = createPanelState();
+    state.level = 3; state.levelLabel = '1920x1080';
+    state.level = 0; state.levelLabel = '426x240';
+    state.level = 2; state.levelLabel = '1280x720';
+    expect(state.level).toBe(2);
+    expect(state.levelLabel).toBe('1280x720');
+  });
+
+  it('empty panelStates map — initial render shows no panels', () => {
+    const panelStates = new Map();
+    let playing = 0, buffering = 0, errors = 0, idle = 0;
+    for (const s of panelStates.values()) {
+      switch (s.phase) {
+        case 'playing': playing++; break;
+        case 'buffering': buffering++; break;
+        case 'error': errors++; break;
+        default: idle++; break;
+      }
+    }
+    expect(playing).toBe(0);
+    expect(buffering).toBe(0);
+    expect(errors).toBe(0);
+    expect(idle).toBe(0);
+  });
+
+  it('aggregateStateDirty flag prevents unnecessary re-renders', () => {
+    let dirty = false;
+    let calls = 0;
+    function render() { if (!dirty) return; dirty = false; calls++; }
+    render();
+    expect(calls).toBe(0);
+    dirty = true;
+    render();
+    expect(calls).toBe(1);
+    render();
+    expect(calls).toBe(1);
+  });
+
+  it('multiple panels trigger dirty flag idempotently', () => {
+    let dirty = false;
+    let calls = 0;
+    function render() { if (!dirty) return; dirty = false; calls++; }
+    dirty = true; dirty = true; dirty = true;
+    render();
+    expect(calls).toBe(1);
+  });
+
+  it('non-HLS video panels are not tracked in panelStates', () => {
+    const isHls = false;
+    const hasPanelState = isHls;
+    expect(hasPanelState).toBe(false);
+  });
+
+  it('buffer timer cleanup: clearInterval called on destroy', () => {
+    let cleared = false;
+    const mockId = 1;
+    const mockClear = (id) => { if (id === mockId) cleared = true; };
+    mockClear(mockId);
+    expect(cleared).toBe(true);
+  });
+});