feat: loudness walk (U/I) keeps its own cursor, independent of J/K

The clip bar had one shared cursor, so pressing U/I re-derived the
loudness rank from wherever you currently were. A J/K detour to review
clips around an interesting spot therefore hijacked the loudness walk:
returning to U/I continued from the J/K position, not from where the
ranking left off.

Add a separate scoreCursor that only U/I (and "highlights only" auto-
advance) move; J/K never touches it. So: U/I to a loud moment, J/K to
review the time-adjacent clips, U/I again resumes the ranking exactly
where you left it. scoreCursor resets to -1 on every explicit jump /
queue re-arm (hideClipBar, chip clicks, day-highlights arm) so the next
U/I re-anchors on the selected section.

Also label the position count "by time" (J/K) or "by loudness" (U/I) so
the blind user can hear which dimension the count is in — the two looked
identical before and switched meaning silently when changing keys.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

CLAUDE.md

@@ -38,10 +38,10 @@ Dependencies: `requests` (streams), `numpy` + `soundfile` (FLAC output and FLAC
 - Serving: `_stream()` (Range support), `_copy_to_response()`, `_safe_path()` (path traversal guard).
 
 `webui.html` (one `<script>` block):
-- Clip review: `clipQueue`/`clipCursor` globals, `playClip()`, `playFileSection()`, `hideClipBar()`; markup is the `#clip-bar` div.
-- Day review: `dayHighlights()` builds `dayActiveSections` (chronological); `jumpToDaySection()` arms the queue.
-- J/K/U/I: single document-level `keydown` listener — clip queue takes priority, in-player `currentTime` stepping is the fallback when no queue is armed. U/I (and the `#clip-hl-only` checkbox, which also affects J/K, Prev/Next, and auto-advance) restrict stepping to highlights: the top `#clip-top` (default 50) sections by score, computed on demand by `topScoreSet()`; `stepClip()` is the shared queue-stepping path.
-- Analysis: `fetchAnalysis()` (session `analysisCache`), `analyse()` (per-row render), `cachedParamsMatch()` (autoload guard).
+- Clip review: `clipQueue`/`clipCursor`/`scoreCursor` globals, `playClip()`, `playFileSection()`, `hideClipBar()`; markup is the `#clip-bar` div. The clip label shows wall-clock occurrence time + dB prominence + position (`17:09:56 to 17:09:57 · +30 dB (30 / 426 by time)`): queue entries carry `absStart` (epoch s), derived from `fileStartEpoch(f.date)` — the filename clock — with in-file offsets as fallback for non-standard names; only the filename/in-file offset lives in the tooltip now. **`playClip()` builds one `text` string used for both `label.textContent` and the `announce()` aria-live message** — they must never diverge (a past bug had the announcement read `Clip N of M: …` while the label read the wall-clock form). **Two cursors, deliberately independent:** `clipCursor` is the time-order position and follows every play; `scoreCursor` is the loudness walk's own position in `scoreOrder()` and is moved *only* by U/I (and "highlights only" auto-advance) in `stepClip`'s by-score branch — J/K must never touch it, so a J/K detour to review nearby clips leaves the loudness walk's place intact and the next U/I resumes the ranking where it left off. `scoreCursor` resets to `-1` on every explicit jump / queue (re-)arm (`hideClipBar`, `playFileSection`, `jumpToDaySection`, both day-highlights arm points), so the next U/I re-anchors on `clipCursor` (the section just selected) else the loudest. `playClip(i, byScore)`: when `byScore` the count shows `scoreCursor` (rank, suffix "by loudness"), else `i` (time-order index, suffix "by time") — the suffix tells the blind user which dimension the count is in. `stepClip`'s by-score branch passes `byScore=true`; every other caller (chip click, J/K, Prev/Next) leaves it false.
+- Day review: `dayHighlights()` builds `dayActiveSections` (chronological); `jumpToDaySection()` arms the queue. Section `absStart` comes from `fileStartEpoch(f.date)` (filename clock), mtime−duration only as fallback. **The user is blind and uses a screen reader — there is deliberately no day-timeline SVG** (one existed and was removed on request as useless); the highlights panel is linear text/buttons: summary line → key-hint note → chips toggle → chips. Do not add decorative visualizations; any future graphic must be aria-hidden and must not be the only carrier of information. Chip lists longer than 12 are collapsed behind an `aria-expanded` toggle button (the `.chips[hidden]{display:none}` rule is required — the author-level `display:flex` on `.chips` would otherwise override the UA `[hidden]` rule). Group `aria-label`s stay short ("Day loud sections") — the J/K/U/I key explanation lives only in the visible note, per user feedback against repeating info text in labels. The Highlights button is a collapse/expand toggle (`setHlExpanded()` keeps arrow + `aria-expanded` in sync, also from the day-collapse path): a built panel is kept and re-armed from `dayHlSections` instead of recomputing, keyed by `hlRow.dataset.loaded = hlParams()` (margin|gap|minDur string) so changed params force a re-run. The `#dayhls-<dayId>` "· analysed" suffix appears when every file's `cached_analysis` passes `cachedParamsMatch()`; `fetchAnalysis()` updates `f.cached_analysis` client-side so the marker survives re-renders without refetching `/api/files`. **`aria-label` on a button replaces its visible content for screen readers** — any status text rendered inside a labelled button (like the analysed suffix) must be mirrored into the label (render path + the end of `dayHighlights()`), or the blind user never hears it. Likewise, the accessible text of a button built as `aria-hidden arrow span + text node` must not start the text node with a space (the hidden arrow drops out and the leading space reads as an indent) — keep separator spaces inside the aria-hidden span.
+- J/K/U/I/O: single document-level `keydown` listener — clip queue takes priority, in-player `currentTime` stepping is the fallback when no queue is armed; O calls `openClipInFile()` (shared with the "Open in file" button). J/K (and Prev/Next) always step in time order; U/I walk the loudest-first ranking from `scoreOrder()` — no top-N cutoff (the `#clip-top` input and `#clip-hl-only` checkbox were removed deliberately; J/K must never be affected by an auto-advance/highlights setting). Auto-advance is the `input[name="clip-adv"]` radio (off / next in time / next by loudness), read by `advanceMode()`; `stepClip(dir, byScore)` is the shared queue-stepping path. In-player U/I anchor the ranking on the section under the playhead, else start at the loudest.
+- Analysis: `fetchAnalysis()` (session `analysisCache`), `analyse()` (per-row render: meta line with section count + params, then chips — no waveform SVG, see day-review note on the blind user), `cachedParamsMatch()` (autoload guard).
 
 ## Verifying changes
 
@@ -61,7 +61,7 @@ Dependencies: `requests` (streams), `numpy` + `soundfile` (FLAC output and FLAC
 - **Loud-section detection is adaptive — do not regress it to an absolute threshold.** Per-window dB is compared against a rolling noise floor (`NOISE_PERCENTILE`-th percentile per `NOISE_BLOCK_SECONDS` block, min-smoothed over ±2 blocks so events can't raise their own floor; clamped to ≥ `MIN_RMS`). A section needs `margin` dB of prominence and carries a `score` used for ranking: peak dB above floor, **capped by the sharpest rise within `ONSET_SECONDS` (0.5 s)** — so a short (~10 s) swell that outruns the 30 s floor blocks still flags but scores ≈ 0 and sinks in the U/I highlight ranking, while sharp events keep their full prominence. A section starting in the first 0.5 s of a file is scored against the floor instead (events cut off by a file split must not be punished as swells). Do not regress the scoring to raw peak, and do not fight swells with a higher margin. If flagging itself (not just ranking) ever needs improving, the next step is a spectral filter or optional Silero VAD over candidate sections. Sections shorter than `min_duration` (default 0.5 s, after `min_gap` merging) are discarded — without this, isolated 100 ms pops (clicks, single raindrops) produced thousands of zero-length sections per day. The original fixed RMS threshold flagged every ambience change (passing cars, rain) and produced ~600 useless sections/day — that is why it was replaced. Tests in `tests/test_web.py`.
 - **Analysis params are coupled in five places.** CLI `--margin`/`--min-gap`/`--min-duration` → `/api/config` → UI inputs `#margin-input`/`#min-gap-input`/`#min-duration-input` → `/api/analyze` query params → cache JSON head keys. Renaming or adding a param means touching all five plus `cachedParamsMatch()` and the `_cached_analysis_params()` regex (see the threshold→margin change `c84b7d8` and the min_duration addition).
 - **Analysis cache:** results stored as `<analyses-dir>/<file>.analysis.json` keyed by margin+min_gap+min_duration; orphans pruned at web startup. In Docker the recordings mount is **read-only** for the web container, so docker-compose layers a read-write `./recordings/analyses` bind mount over it. The `detector`, `margin`, `min_gap`, and `min_duration` keys MUST stay first in the cache JSON — `_cached_analysis_params()` reads only the first 256 bytes to avoid parsing the large embedded result. `detector` is `DETECTOR_VERSION`: bump it whenever detection/scoring changes make old cached results wrong (e.g. v2 = onset-capped scores); caches with another version (or missing keys) never match and get overwritten on the next analyse.
-- **Analyze responses:** `/api/analyze` returns `rms_display` (~800 points), never the full per-window RMS list — the UI doesn't use it and it is ~45x larger.
+- **Analyze responses:** `/api/analyze` returns only `sections`, `duration`, `window` — no RMS data of any kind. `rms_display` (~800-point waveform preview) and the full per-window list were dropped when the waveform SVGs were removed (user is blind, see webui notes). Old caches that embed `rms`/`rms_display` are still valid; both keys are popped when serving from cache, so no DETECTOR_VERSION bump was needed.
 - **Section playback uses clips, not seeks:** `/api/clip?file&start&end` decodes the slice server-side (wave/soundfile) and returns a standalone 16-bit WAV with exact Content-Length (capped at `CLIP_MAX_SECONDS`), `Cache-Control: private` so re-listening is free. The UI plays chips/J-K through the bottom clip bar (`clipQueue` in webui.html); seeking the full file only happens via "Open in file". Rationale (finding): libsndfile writes FLAC **without a SEEKTABLE**, so a browser seek bisects the whole multi-hundred-MB file with Range requests — seeking big FLACs in `<audio>` is inherently slow and must not be reintroduced as the primary navigation. Server-side `sf.SoundFile.seek()` on local disk is fast and frame-accurate.
 - **HTTP/1.1 keep-alive:** `_Handler.protocol_version = 'HTTP/1.1'`; every response path must set an accurate `Content-Length`. `_copy_to_response()` force-closes the connection if it under-delivers (file truncated mid-serve).
 - **Live playback:** for files listed in status.json, `/stream/` patches the header on the fly so the browser sees the duration recorded so far and can seek; responses get `Cache-Control: no-store`. WAV: `_live_wav_header` derives sizes from the byte count. FLAC: `_live_flac_header` parses the sample count out of the last frame header in the file tail (CRC-8-verified to reject false sync matches) and rewrites STREAMINFO total_samples — duration is NOT derivable from byte size for FLAC.

README.md

@@ -154,25 +154,25 @@ The browser UI (HTML/CSS/JS) lives in `webui.html`, which `web.py` loads at star
 Shows recordings grouped by day with collapsible sections. Features:
 
 - **Day groups** — recordings are grouped under a collapsible day heading showing date, file count, total duration, and total size. The most recent day is expanded by default; older days start collapsed. Expanded state is preserved across filter changes.
-- **Day highlights** — click **Highlights** on any day heading to run loudness analysis across all WAV/FLAC files in that day and display a combined activity timeline SVG. Orange segments show when loud sections occurred relative to the day's time span; blue shows the file extents. Labels show the start, midpoint, and end times. When a day has more sections than fit as chips, the chips show the top 50 by score (loudest-above-background first) so the most promising events are reviewed first; J/K still steps through all sections in time order, and U/I steps through only the top-scored highlights.
+- **Day highlights** — click **Highlights** on any day heading to run loudness analysis across all WAV/FLAC files in that day. The button is a toggle: clicking again collapses the panel, and re-expanding it reuses the already-computed results (they are only recomputed when the analysis parameters change). A **· analysed** suffix on the button marks days where every file already has a cached analysis for the current parameters, i.e. highlights open instantly. The panel is plain text and buttons in linear reading order (screen-reader friendly): files-analysed/section totals, a key hint, then the section chips. When a day has more sections than fit as chips, the chips are the top 50 by score (loudest-above-background first) so the most promising events are reviewed first; long chip lists are collapsed behind a toggle button so the panel stays compact. J/K still steps through all sections in time order, and U/I steps through them by loudness. Holding **Shift** jumps straight to an extreme: **Shift+J**/**Shift+K** to the first/last section in time, **Shift+U**/**Shift+I** to the loudest/quietest.
 - **Inline playback** — collapsible `Play` button per row; audio loads lazily via a seekable `/stream/` endpoint with HTTP Range support. Metadata is fetched immediately so the duration is visible without pressing play.
-- **Waveform analysis** — on demand per file; computes RMS per 100 ms window and marks sections that stand out above the background. Detection is **adaptive**: a rolling noise floor (20th percentile per 30 s block) is estimated across the file, and a section is flagged when the level rises at least *margin* dB (default 12) above that floor. Slow ambience changes — rain setting in, day/night traffic hum — move the floor instead of producing false positives. Each section gets a **score** used to rank it: its peak dB above the floor, capped by the sharpest rise within 0.5 s. Abrupt events — voices, impacts, barks — rise fast, so their score is their full prominence; a gradual swell (a gust, a distant approaching car) that drifts up faster than the floor can track still gets flagged, but scores near zero and sinks to the bottom of the highlight ranking. Supported for WAV and FLAC (FLAC requires `numpy` + `soundfile`). Pure-Python fallback for WAV when numpy is absent. Results are cached in `recordings/analyses/<filename>.analysis.json`; subsequent requests at the same margin, min-gap, and min-duration settings return instantly without re-reading the audio. The cache file is deleted automatically when the audio file is deleted. Orphaned cache files (audio deleted outside the UI) are pruned on startup.
+- **Loudness analysis** — on demand per file; computes RMS per 100 ms window and lists sections that stand out above the background as clickable chips (no visual waveform — the UI is built for screen-reader use). Detection is **adaptive**: a rolling noise floor (20th percentile per 30 s block) is estimated across the file, and a section is flagged when the level rises at least *margin* dB (default 12) above that floor. Slow ambience changes — rain setting in, day/night traffic hum — move the floor instead of producing false positives. Each section gets a **score** used to rank it: its peak dB above the floor, capped by the sharpest rise within 0.5 s. Abrupt events — voices, impacts, barks — rise fast, so their score is their full prominence; a gradual swell (a gust, a distant approaching car) that drifts up faster than the floor can track still gets flagged, but scores near zero and sinks to the bottom of the highlight ranking. Supported for WAV and FLAC (FLAC requires `numpy` + `soundfile`). Pure-Python fallback for WAV when numpy is absent. Results are cached in `recordings/analyses/<filename>.analysis.json`; subsequent requests at the same margin, min-gap, and min-duration settings return instantly without re-reading the audio. The cache file is deleted automatically when the audio file is deleted. Orphaned cache files (audio deleted outside the UI) are pruned on startup.
 - **Grace period** — configurable in the controls bar (default 2 s). Loud sections separated by less than this gap are merged into one. Raise this (e.g. to 15–30 s) when a single event generates many timestamps due to brief quiet gaps within it.
 - **Min duration** — configurable in the controls bar (default 0.5 s). Loud sections shorter than this (after grace-period merging) are discarded, so isolated sub-second pops — a click, a single raindrop — don't flood a day with thousands of near-zero-length sections. Set to 0 to disable.
-- **Clip playback** — clicking a loud-section chip plays a short server-rendered WAV clip (`/api/clip`, pre-roll included) in a player bar at the bottom of the page. Playback starts instantly even for sections deep inside multi-hundred-MB FLACs, because the browser never has to seek the full file. **J** / **K** (or the **Prev** / **Next** buttons) step through the queued sections — one file's, or a whole day's after **Highlights** — and **Auto-advance** plays the next section when one ends, turning a day's detections into a continuous review reel. **U** / **I** step through *highlights only*: the top-scored sections of the queue (count set by the **Top** input in the player bar, default 50). Ticking **Highlights only** makes J/K, Prev/Next, and Auto-advance skip non-highlights too, so a day with thousands of detections can be reviewed as a short reel of just the loudest events. The same keys work during full-file playback, seeking the open recording between (highlight) sections. **Open in file** switches to the full recording at the same position for context; each chip click also pre-fills the cut panel.
+- **Clip playback** — clicking a loud-section chip plays a short server-rendered WAV clip (`/api/clip`, pre-roll included) in a player bar at the bottom of the page. Playback starts instantly even for sections deep inside multi-hundred-MB FLACs, because the browser never has to seek the full file. The player bar labels each clip with the wall-clock time it occurred (derived from the recording's filename), its loudness above the background, and its position in the queue, e.g. `17:09:56 to 17:09:57 · +30 dB (30 / 426 by time)` — and the exact same text is announced to screen readers, so the spoken and visible labels never differ. The filename and in-file offset are in the label's hover tooltip. **J** / **K** (or the **Prev** / **Next** buttons) always step through the queued sections in time order — one file's, or a whole day's after **Highlights** — and the count is then the chronological index, labelled **by time** (e.g. `30 / 426 by time` is the 30th section in time). **U** / **I** step through the same queue by loudness instead: **I** plays the next-loudest section, **U** goes back up the ranking, and the count becomes the rank in that loudness order, labelled **by loudness** (`1 / 426 by loudness` is the loudest of all reachable sections, `2 / 426 by loudness` the next-loudest, and so on) — the denominator stays the full count because U/I reaches every section, with no top-N cutoff; the chip list shown on screen is capped only for display. So a day with thousands of detections is reviewed loudest-first for as long as it stays interesting — just stop when it gets boring. The loudness walk keeps its own position **independently** of J/K: find a loud moment with **U** / **I**, press **J** / **K** to review the clips immediately before and after it in time, and pressing **U** / **I** again resumes the loudness ranking exactly where you left it — the J/K detour never moves your place in the loudest-first walk. (Clicking a chip is an explicit jump, so it re-anchors the next U / I there.) The auto-advance radio in the player bar picks what happens when a clip ends: **Don't auto-advance**, **Auto-advance** (next section in time), or **Auto-advance highlights only** (next section by loudness) — it never changes what J/K do. Holding **Shift** with any of these jumps to the extreme in that direction — **Shift+J**/**Shift+K** to the first/last section in time, **Shift+U**/**Shift+I** to the loudest/quietest. The same keys work during full-file playback, seeking the open recording to the next section in time (J/K) or by loudness (U/I). **Open in file** (or the **O** key) switches to the full recording at the same position for context; each chip click also pre-fills the cut panel.
 - **Cut & download** — `Cut` button opens the player row and reveals a cut panel. Enter start and end times in `m:ss` or `h:mm:ss` format and click **Download cut** to receive an ffmpeg-trimmed copy without re-encoding. Requires ffmpeg (included in the Docker image). The cut is named with the real wall-clock span it covers — `<YYYYMMDD>_<HH-MM-SS>_<HH-MM-SS>.<ext>`, e.g. a 22:31:30→22:32:30 slice of a recording started at 22:00:00 becomes `20260523_22-31-30_22-32-30.flac`.
 - **Filters** — live filename search and from/to date pickers above the table; applied client-side with no additional requests. Shows `N of M shown` when a filter is active.
 - **Delete** — `Delete` button per row with confirmation prompt; disabled for files currently being recorded; sends `DELETE /api/files/<name>` and re-renders the table.
 - **Live REC badge** — files currently being written by `isr.py` show an animated REC indicator, polled every 5 seconds via `/api/status`. Duration for in-progress files shows `—` in the table (header is unfinalized until recording stops). The file list refreshes automatically when a recording starts, stops, or rolls over to a new split file (unless audio is playing).
 - **Listen while recording** — in-progress files are playable and seekable. For WAV and FLAC the server patches the (still unfinalized) header on the fly so the browser sees the real duration-so-far — for FLAC the exact sample count is parsed from the last frame header in the file tail. Reopening the player reloads the source to pick up newly recorded audio. Live responses are sent with `Cache-Control: no-store`.
-- **Fast loading** — analysis results are cached server-side on disk and client-side per session; cached waveforms load only for expanded day groups, and collapsed days fetch nothing until opened.
-- **WCAG-compliant** — skip link, `aria-expanded`/`aria-controls` on the player toggle, `aria-live` status, focus management, `role=img` on SVG waveforms.
+- **Fast loading** — analysis results are cached server-side on disk and client-side per session; cached analyses load only for expanded day groups, and collapsed days fetch nothing until opened.
+- **WCAG-compliant** — skip link, `aria-expanded`/`aria-controls` on the player toggle, `aria-live` status, focus management; all information is plain text and buttons in linear reading order, with no visual-only elements.
 
 ### Too many sections per day?
 
 The detector is purely energy-based: anything that rises *margin* dB above the rolling background floor for at least *min duration* seconds is flagged. In a quiet environment the floor sits very low, so even modest sounds — a gust, a distant car, rustling — clear the margin, and an outdoor day can easily produce over a thousand sections. What to adjust, in rough order of preference:
 
-1. **Review by rank instead of thinning the list** — tick **Highlights only** (or use **U**/**I**) to step through just the top-scored sections. Scores favour sharp onsets, so slow ambience swells sort themselves to the bottom automatically. Nothing is discarded — quieter events are still there if the top of the list comes up empty.
+1. **Review by rank instead of thinning the list** — use **U**/**I** (or **Auto-advance highlights only**) to step through the sections loudest-first. Scores favour sharp onsets, so slow ambience swells sort themselves to the bottom automatically. Nothing is discarded and there is no cutoff — just stop when the events stop being interesting.
 2. **Raise the grace period** (2 → 15–30 s) — merges clusters of related noise (a rain burst, one long conversation) into a single section. Cuts the count heavily without dropping any audio from review.
 3. **Raise the margin** (12 → 15–18 dB) — demands more prominence above the background. The quietest events disappear first, so move in small steps.
 4. **Raise min duration** (0.5 → 1–2 s) — drops short rustles and pops, but beware: single bangs or knocks are themselves short.
@@ -186,7 +186,7 @@ Everything the UI does goes through these endpoints, so they can also be scripte
 | Endpoint | Description |
 |----------|-------------|
 | `GET /api/files` | File listing with size, mtime, duration, recording state, cached-analysis params |
-| `GET /api/analyze?file=&margin=&min_gap=&min_duration=` | Loud-section analysis: `rms_display` (~800-point waveform), scored `sections`, `duration` |
+| `GET /api/analyze?file=&margin=&min_gap=&min_duration=` | Loud-section analysis: scored `sections`, `duration` |
 | `GET /api/clip?file=&start=&end=` | Section of a WAV/FLAC decoded server-side, returned as a standalone WAV (max 600 s) |
 | `GET /api/cut?file=&start=&end=` | ffmpeg-trimmed copy of the file as a download |
 | `GET /stream/<name>` | Inline playback with HTTP Range support; live files get an on-the-fly patched header |

web.py

@@ -402,16 +402,9 @@ def _package_result(rms_values: list, framerate: int, n_frames: int,
     window_dur = window_samples / framerate
     duration   = n_frames / framerate
 
-    if len(rms_values) > 800:
-        step = len(rms_values) / 800
-        rms_display = [rms_values[int(i * step)] for i in range(800)]
-    else:
-        rms_display = rms_values
-
-    # Note: the full per-window RMS list is deliberately NOT returned — the UI
-    # only renders rms_display (~800 points), and the full list is ~45x larger.
+    # Note: no RMS data is returned — the UI is screen-reader oriented and
+    # draws no waveform, so sections + duration is all it needs.
     return {
-        'rms_display': rms_display,
         'sections':    _loud_sections(rms_values, window_dur, duration, margin_db, min_gap, min_duration),
         'duration':    round(duration, 2),
         'window':      round(window_dur, 4),
@@ -690,7 +683,9 @@ class _Handler(BaseHTTPRequestHandler):
                     and cached.get('margin') == margin and cached.get('min_gap') == min_gap
                     and cached.get('min_duration') == min_duration):
                 payload = dict(cached['result'])
-                payload.pop('rms', None)  # caches written before the full-RMS field was dropped
+                # strip fields that older cache versions embedded
+                payload.pop('rms', None)          # full per-window RMS list
+                payload.pop('rms_display', None)  # ~800-point waveform preview
                 payload['cached'] = True
                 self._send(200, json.dumps(payload).encode('utf-8'), 'application/json')
                 return

webui.html

@@ -63,8 +63,8 @@ button.del{color:var(--red);border-color:#7f1d1d}
 button.del:hover:not(:disabled){background:#2d0808}
 /* waveform */
 .wbox{background:var(--surf);border:1px solid var(--brd);border-radius:6px;padding:10px 12px}
-svg.wave{display:block;width:100%;height:56px}
 .chips{display:flex;flex-wrap:wrap;gap:5px;margin-top:8px}
+.chips[hidden]{display:none}
 .chip{background:#431407;color:var(--orange);border:1px solid #7c2d12;border-radius:4px;
   padding:2px 8px;font-size:11px;font-family:ui-monospace,monospace}
 button.chip{cursor:pointer}
@@ -115,22 +115,24 @@ button.cut:hover:not(:disabled){background:#1e3a8a}
 button.day-hl{color:var(--green);border-color:#166534;background:#052e16;font-size:11px}
 button.day-hl:hover:not(:disabled){background:#0a3d1f}
 button.day-hl:disabled{opacity:.5;cursor:default}
+button.day-hl .day-arrow{font-size:9px}
+.day-hl-status{opacity:.75;font-weight:400}
 h2.day-heading{margin:0;font-size:inherit;font-weight:inherit;line-height:inherit;flex:1 1 auto}
 .day-hl-container{background:var(--bg);border:1px solid var(--brd);border-top:none;padding:8px 12px 12px}
 table.day-table{width:100%;border-collapse:collapse;border:1px solid var(--brd);border-top:none}
-svg.day-timeline{display:block;width:100%;height:22px}
-.day-tl-labels{display:flex;justify-content:space-between;font-size:10px;
-  color:var(--muted);font-family:ui-monospace,monospace;margin-top:2px}
 /* clip player bar */
 #clip-bar{position:fixed;bottom:0;left:0;right:0;z-index:20;background:var(--surf);
   border-top:1px solid var(--brd);padding:8px 28px;display:flex;align-items:center;
   gap:10px;flex-wrap:wrap}
+/* display:flex above beats the UA's [hidden]{display:none} — restate it, or
+   the bar is visible from page load and the close button looks dead */
+#clip-bar[hidden]{display:none}
 #clip-bar audio{flex:1 1 240px;min-width:180px;height:32px}
 #clip-label{font-size:12px;color:var(--muted);font-family:ui-monospace,monospace;
   white-space:nowrap;overflow:hidden;text-overflow:ellipsis;max-width:38%}
-#clip-auto-label,#clip-hl-label,#clip-top-label{font-size:12px;color:var(--muted);
+#clip-adv{display:flex;align-items:center;gap:10px}
+#clip-adv label{font-size:12px;color:var(--muted);
   display:flex;align-items:center;gap:4px;white-space:nowrap;cursor:pointer}
-#clip-top{width:52px}
 body.clip-open{padding-bottom:70px}
 </style>
 </head>
@@ -179,10 +181,12 @@ body.clip-open{padding-bottom:70px}
   <button id="clip-next" aria-label="Next section (K)">Next</button>
   <span id="clip-label"></span>
   <audio id="clip-audio" controls preload="auto" aria-label="Section clip playback"></audio>
-  <label id="clip-auto-label"><input type="checkbox" id="clip-auto" checked> Auto-advance</label>
-  <label id="clip-hl-label" title="J/K, Prev/Next and auto-advance skip everything outside the top sections"><input type="checkbox" id="clip-hl-only"> Highlights only</label>
-  <label id="clip-top-label" title="How many top-scored sections count as highlights">Top <input type="number" id="clip-top" min="1" step="1" value="50" aria-label="Number of top-scored sections treated as highlights"></label>
-  <button id="clip-context" title="Open the full recording at this position">Open in file</button>
+  <span id="clip-adv" role="radiogroup" aria-label="Auto-advance mode">
+    <label><input type="radio" name="clip-adv" value="off"> Don't auto-advance</label>
+    <label><input type="radio" name="clip-adv" value="all" checked> Auto-advance</label>
+    <label title="When a clip ends, play the next-loudest section instead of the next in time"><input type="radio" name="clip-adv" value="hl"> Auto-advance highlights only</label>
+  </span>
+  <button id="clip-context" title="Open the full recording at this position (O)" aria-label="Open in file (O)">Open in file</button>
   <button id="clip-close" aria-label="Close clip player">&times;</button>
 </div>
 <script>
@@ -202,6 +206,17 @@ const fmtSize = b => {
   return (b/(1<<30)).toFixed(2)+' GB';
 };
 const pad = n => String(n).padStart(2,'0');
+// Epoch seconds -> local wall-clock "HH:MM:SS"
+const fmtClock = ts => {
+  const d = new Date(ts * 1000);
+  return pad(d.getHours()) + ':' + pad(d.getMinutes()) + ':' + pad(d.getSeconds());
+};
+// Listing `date` ("YYYY-MM-DD HH:MM:SS", the recording start parsed out of
+// the filename server-side) -> epoch seconds, or null for unparseable values
+const fileStartEpoch = date => {
+  const t = Date.parse(String(date).replace(' ', 'T'));
+  return isNaN(t) ? null : t / 1000;
+};
 
 function announce(msg) {
   const el = document.getElementById('sr-announce');
@@ -232,6 +247,23 @@ const dayExpanded = new Map();
 // cross-file day section list (populated by the day Highlights button)
 let dayActiveSections = [];
 let dayActiveId = null;
+// dayId -> section list of an already-built highlights panel, so collapsing
+// and re-expanding it re-arms J/K without recomputing
+const dayHlSections = new Map();
+
+// Current analysis params as one string; a highlights panel built with other
+// values is stale and gets recomputed on the next expand
+const hlParams = () =>
+  ['margin-input', 'min-gap-input', 'min-duration-input']
+    .map(id => document.getElementById(id).value).join('|');
+
+function setHlExpanded(dayId, exp) {
+  const btn = document.getElementById('dayhln-' + dayId);
+  if (!btn) return;
+  btn.setAttribute('aria-expanded', exp);
+  const arrow = btn.querySelector('.day-arrow');
+  if (arrow) arrow.textContent = exp ? '▾' : '▸';
+}
 
 function groupByDay(files) {
   const map = new Map();
@@ -284,42 +316,6 @@ function togglePlayer(idx, filename) {
   audio.focus();
 }
 
-function drawWave(rms, sections, duration, filename) {
-  const ns  = 'http://www.w3.org/2000/svg';
-  const svg = document.createElementNS(ns,'svg');
-  svg.setAttribute('class','wave');
-  svg.setAttribute('viewBox',`0 0 ${rms.length} 1`);
-  svg.setAttribute('preserveAspectRatio','none');
-  svg.setAttribute('role','img');
-  const nSec = sections ? sections.length : 0;
-  svg.setAttribute('aria-label',
-    `Waveform for ${filename}: duration ${fmtDur(duration)}, ${nSec} loud section${nSec!==1?'s':''}`);
-
-  if (duration > 0 && sections) {
-    sections.forEach(s => {
-      const r = document.createElementNS(ns,'rect');
-      r.setAttribute('x', (s.start/duration)*rms.length);
-      r.setAttribute('y', 0);
-      r.setAttribute('width', ((s.end-s.start)/duration)*rms.length);
-      r.setAttribute('height', 1);
-      r.setAttribute('fill','rgba(249,115,22,0.22)');
-      r.setAttribute('aria-hidden','true');
-      svg.appendChild(r);
-    });
-  }
-  const maxV = Math.max(...rms, 0.001);
-  rms.forEach((v,i) => {
-    const h = v/maxV;
-    const r = document.createElementNS(ns,'rect');
-    r.setAttribute('x',i); r.setAttribute('y',1-h);
-    r.setAttribute('width',1); r.setAttribute('height',h);
-    r.setAttribute('fill','#4f9cf9');
-    r.setAttribute('aria-hidden','true');
-    svg.appendChild(r);
-  });
-  return svg;
-}
-
 function parseTime(s) {
   if (!s || !s.trim()) return null;
   const parts = s.trim().split(':').map(v => parseFloat(v));
@@ -350,12 +346,24 @@ function seekToSection(idx, filename, startSec, endSec, sectionIdx) {
 // Sections play as small server-rendered WAV clips (/api/clip) in the bottom
 // bar instead of seeking the full recording, which is slow for big FLACs.
 // clipQueue holds the active review list (one file's sections, or a whole
-// day's); J/K and the Prev/Next buttons step through it, U/I (or the
-// "Highlights only" toggle) restrict stepping to the top-N entries by score.
+// day's); J/K and the Prev/Next buttons step through it in time order, U/I
+// step through the loudest-first ranking. The auto-advance radio picks what
+// plays when a clip ends: nothing, the next in time, or the next by loudness.
+//
+// Two cursors, deliberately independent. clipCursor is the time-order position
+// and follows every play (chip click, J/K, U/I). scoreCursor is the loudness
+// walk's own position in scoreOrder(): only U/I (and "highlights only" auto-
+// advance) move it; J/K detours to review nearby clips leave it alone, so
+// coming back to U/I resumes the ranking exactly where you left it. An explicit
+// jump (chip click, new queue) resets it to -1 so the next U/I re-anchors there.
 let clipQueue = [];
 let clipCursor = -1;
+let scoreCursor = -1;
 
-function playClip(i) {
+// byScore: this play is part of a loudness walk (U/I or "highlights only"
+// auto-advance), so the position shown is scoreCursor — the rank in the
+// loudest-first ranking, labelled "by loudness" — not the time-order index.
+function playClip(i, byScore) {
   if (i < 0 || i >= clipQueue.length) return;
   clipCursor = i;
   const c  = clipQueue[i];
@@ -365,13 +373,25 @@ function playClip(i) {
   a.src = '/api/clip?file=' + encodeURIComponent(c.filename)
         + '&start=' + cs.toFixed(1) + '&end=' + ce.toFixed(1);
   a.play().catch(() => {});
-  document.getElementById('clip-label').textContent =
-    `${i + 1}/${clipQueue.length} · ${c.filename} @ ${fmtDur(c.start)}–${fmtDur(c.end)}`
-    + (c.score != null ? ` · +${Math.round(c.score)} dB` : '');
+  // Label = wall-clock time of occurrence (absStart from the filename clock);
+  // falls back to in-file offsets for non-standard filenames. The visible
+  // label and the screen-reader announcement use one identical string:
+  // "17:09:56 to 17:09:57 · +30 dB (30 / 426 by time)" — the count is the
+  // time-order index "by time" (J/K) or the loudness rank "by loudness" (U/I).
+  const when = c.absStart != null
+    ? `${fmtClock(c.absStart)} to ${fmtClock(c.absStart + (c.end - c.start))}`
+    : `${fmtDur(c.start)} to ${fmtDur(c.end)}`;
+  const score = c.score != null ? ` · +${Math.round(c.score)} dB` : '';
+  const pos   = byScore ? scoreCursor : i;
+  const dim   = byScore ? 'by loudness' : 'by time';
+  const text  = `${when}${score} (${pos + 1} / ${clipQueue.length} ${dim})`;
+  const label = document.getElementById('clip-label');
+  label.textContent = text;
+  label.title = `${c.filename} @ ${fmtDur(c.start)}–${fmtDur(c.end)}`;
   document.getElementById('clip-bar').hidden = false;
   document.body.classList.add('clip-open');
   setCutFields(c.fileIdx, c.start, c.end);
-  announce(`Clip ${i + 1} of ${clipQueue.length}: ${fmtDur(c.start)} to ${fmtDur(c.end)} in ${c.filename}`);
+  announce(text);
 }
 
 function hideClipBar() {
@@ -382,47 +402,70 @@ function hideClipBar() {
   document.body.classList.remove('clip-open');
   clipQueue = [];
   clipCursor = -1;
+  scoreCursor = -1;
 }
 
 function playFileSection(idx, filename, si) {
   const secs  = sectionMap.get(idx) || [];
-  clipQueue = secs.map(s => ({fileIdx: idx, filename, start: s.start, end: s.end, score: s.score}));
+  const f     = allFiles.find(f => f._idx === idx);
+  const epoch = f ? fileStartEpoch(f.date) : null;
+  clipQueue = secs.map(s => ({fileIdx: idx, filename, start: s.start, end: s.end, score: s.score,
+                              absStart: epoch != null ? epoch + s.start : null}));
+  scoreCursor = -1;                 // explicit jump: next U/I re-anchors here
   playClip(si);
 }
 
-// Highlights = the top-N entries of a section list by score (N from the
-// clip-bar "Top" input). Returns the indices into the original list.
-function topScoreSet(secs) {
-  const n = Math.max(1, parseInt(document.getElementById('clip-top').value, 10) || 50);
-  return new Set(secs.map((s, i) => ({i, score: s.score || 0}))
+// Highlight order = section indices sorted loudest-first. U/I (and
+// auto-advance in "highlights only" mode) walk this ranking, so a review
+// runs from the most to the least interesting event until the user stops —
+// no top-N cutoff.
+function scoreOrder(secs) {
+  return secs.map((s, i) => ({i, score: s.score || 0}))
     .sort((a, b) => b.score - a.score)
-    .slice(0, n)
-    .map(r => r.i));
+    .map(r => r.i);
 }
 
-function highlightsOnly() {
-  return document.getElementById('clip-hl-only').checked;
-}
+const advanceMode = () =>
+  document.querySelector('input[name="clip-adv"]:checked')?.value || 'off';
 
-// Step the clip queue by dir (±1); with hlOnly, skip non-highlight entries.
-function stepClip(dir, hlOnly) {
+// Step the clip queue by dir (±1): in time order, or with byScore down/up
+// the loudest-first ranking (next = next quieter). With jump=true, go straight
+// to the extreme in that direction (first/last section, or loudest/quietest).
+function stepClip(dir, byScore, jump) {
   if (!clipQueue.length) return;
-  const hs = hlOnly ? topScoreSet(clipQueue) : null;
-  const word = hlOnly ? 'highlights' : 'sections';
-  for (let i = clipCursor + dir; i >= 0 && i < clipQueue.length; i += dir) {
-    if (!hs || hs.has(i)) { playClip(i); return; }
+  if (byScore) {
+    // Walk scoreCursor, not the shared clipCursor: a J/K detour never moved
+    // it, so we resume the ranking where we left off. scoreCursor === -1 means
+    // the walk hasn't started since the queue was armed or an explicit jump —
+    // anchor on the section currently selected (clipCursor), else the loudest.
+    const order = scoreOrder(clipQueue);
+    let next;
+    if (jump) next = dir > 0 ? order.length - 1 : 0;
+    else if (scoreCursor !== -1) next = scoreCursor + dir;
+    else {
+      const anchor = clipCursor >= 0 ? order.indexOf(clipCursor) : -1;
+      next = anchor === -1 ? (dir > 0 ? 0 : -1) : anchor + dir;
     }
-  announce(dir < 0 ? `Beginning of ${word}` : `End of ${word}`);
+    if (next >= 0 && next < order.length) { scoreCursor = next; playClip(order[next], true); }
+    else announce(dir < 0 ? 'Loudest highlight reached' : 'End of highlights');
+    return;
+  }
+  // J/K (time order) deliberately does NOT touch scoreCursor.
+  const i = jump ? (dir > 0 ? clipQueue.length - 1 : 0) : clipCursor + dir;
+  if (i >= 0 && i < clipQueue.length) playClip(i);
+  else announce(dir < 0 ? 'Beginning of sections' : 'End of sections');
 }
 
-document.getElementById('clip-prev').addEventListener('click', () => stepClip(-1, highlightsOnly()));
-document.getElementById('clip-next').addEventListener('click', () => stepClip(1, highlightsOnly()));
+document.getElementById('clip-prev').addEventListener('click', () => stepClip(-1, false));
+document.getElementById('clip-next').addEventListener('click', () => stepClip(1, false));
 document.getElementById('clip-close').addEventListener('click', hideClipBar);
 document.getElementById('clip-audio').addEventListener('ended', () => {
-  if (document.getElementById('clip-auto').checked)
-    stepClip(1, highlightsOnly());
+  const mode = advanceMode();
+  if (mode !== 'off') stepClip(1, mode === 'hl');
 });
-document.getElementById('clip-context').addEventListener('click', () => {
+// "Open in file": switch from the current clip to the full recording at the
+// same position. Bound to the clip-bar button and the O key.
+function openClipInFile() {
   const c = clipQueue[clipCursor];
   if (!c) return;
   document.getElementById('clip-audio').pause();
@@ -434,7 +477,8 @@ document.getElementById('clip-context').addEventListener('click', () => {
     row.scrollIntoView({block: 'center'});
   }
   seekToSection(c.fileIdx, c.filename, c.start, c.end, null);
-});
+}
+document.getElementById('clip-context').addEventListener('click', openClipInFile);
 
 // filename|margin|gap|minDur -> analysis result, so re-renders (filtering,
 // refresh) never refetch what this session already has
@@ -448,7 +492,13 @@ async function fetchAnalysis(filename, margin, minGap, minDur, force = false) {
     +'&min_gap='+encodeURIComponent(minGap)
     +'&min_duration='+encodeURIComponent(minDur));
   const d = await r.json();
-  if (!d.error) analysisCache.set(key, d);
+  if (!d.error) {
+    analysisCache.set(key, d);
+    // Keep the listing's cache info current so re-renders (filtering) still
+    // know the file is analysed without refetching /api/files
+    const f = allFiles.find(f => f.name === filename);
+    if (f) f.cached_analysis = {margin, min_gap: minGap, min_duration: minDur};
+  }
   return d;
 }
 
@@ -471,16 +521,16 @@ async function analyse(idx, filename, cell, btn, force = false) {
       restoreBtn(); return;
     }
     const box = document.createElement('div'); box.className='wbox';
-    box.appendChild(drawWave(d.rms_display||[], d.sections||[], d.duration||0, filename));
-
+    const nSec = (d.sections || []).length;
     const meta = document.createElement('div'); meta.className='analysis-meta';
-    meta.textContent = `margin: ${margin} dB · gap: ${minGap}s · min: ${minDur}s${d.cached ? ' · cached' : ''}`;
+    meta.textContent = `${nSec} loud section${nSec!==1?'s':''}`
+      + ` · margin: ${margin} dB · gap: ${minGap}s · min: ${minDur}s${d.cached ? ' · cached' : ''}`;
     box.appendChild(meta);
 
     const chips = document.createElement('div');
     chips.className='chips';
     chips.setAttribute('role','group');
-    chips.setAttribute('aria-label','Loud sections — click to jump, J/K to step, U/I for highlights only');
+    chips.setAttribute('aria-label','Loud sections');
     if (d.sections && d.sections.length) {
       sectionMap.set(idx, d.sections);
       d.sections.forEach((s, si) => {
@@ -513,21 +563,24 @@ async function analyse(idx, filename, cell, btn, force = false) {
   }
 }
 
-// J/K = previous/next section, U/I = previous/next highlight (top-N by score).
-// With "Highlights only" checked, J/K behave like U/I.
-// Only when focus is not in an input.
+// J/K = previous/next section in time order, U/I = up/down the loudest-first
+// ranking, O = open the current clip in the full file. Holding Shift jumps to
+// the extreme in that direction: Shift+J/K = first/last section in time,
+// Shift+U/I = loudest/quietest. Only when focus is not in an input.
 document.addEventListener('keydown', e => {
   if (e.target.tagName === 'INPUT' || e.target.tagName === 'TEXTAREA') return;
   if (e.ctrlKey || e.metaKey || e.altKey) return;
   const key = e.key.toLowerCase();
-  if (key !== 'j' && key !== 'k' && key !== 'u' && key !== 'i') return;
+  if (key !== 'j' && key !== 'k' && key !== 'u' && key !== 'i' && key !== 'o') return;
   e.preventDefault();
+  if (key === 'o') { openClipInFile(); return; }
   const dir     = (key === 'j' || key === 'u') ? -1 : 1;
-  const hlOnly = key === 'u' || key === 'i' || highlightsOnly();
+  const byScore = key === 'u' || key === 'i';
+  const jump    = e.shiftKey;
 
   // Clip queue navigation (a chip was clicked or day highlights are loaded)
   if (clipQueue.length) {
-    stepClip(dir, hlOnly);
+    stepClip(dir, byScore, jump);
     return;
   }
 
@@ -537,29 +590,48 @@ document.addEventListener('keydown', e => {
   if (!all.length) return;
   const audio = document.getElementById('aud-'+activePlayerIdx);
   if (!audio) return;
-  const hs = hlOnly ? topScoreSet(all) : null;
-  const sections = all.filter((s, i) => !hs || hs.has(i));
-  if (!sections.length) return;
   const preroll = getPreroll();
   const cur  = audio.currentTime;
-  const word = hlOnly ? 'Highlight' : 'Section';
 
-  const jumpTo = (s, i) => {
+  const jumpTo = (s, i, n, word) => {
     audio.currentTime = Math.max(0, s.start - preroll);
     setCutFields(activePlayerIdx, s.start, s.end);
-    announce(`${word} ${i + 1} of ${sections.length}: ${fmtDur(s.start)} to ${fmtDur(s.end)}`);
+    announce(`${word} ${i + 1} of ${n}: ${fmtDur(s.start)} to ${fmtDur(s.end)}`);
   };
 
+  if (byScore) {
+    // U/I walk the ranking; the anchor is the section the playhead sits in
+    // (incl. its preroll lead-in). Anywhere else, I starts at the loudest.
+    // Shift jumps straight to the loudest (Shift+U) or quietest (Shift+I).
+    const order  = scoreOrder(all);
+    const curIdx = all.findIndex(s => cur >= s.start - preroll - 0.5 && cur <= s.end + 0.5);
+    const pos    = curIdx === -1 ? -1 : order.indexOf(curIdx);
+    const next   = jump ? (dir > 0 ? order.length - 1 : 0)
+                        : pos === -1 ? (dir > 0 ? 0 : -1) : pos + dir;
+    if (next >= 0 && next < order.length)
+      jumpTo(all[order[next]], next, order.length, 'Highlight');
+    else
+      announce(dir < 0 ? 'Loudest highlight reached' : 'End of highlights');
+    return;
+  }
+
+  // Shift+J/K jump to the first/last section regardless of the playhead.
+  if (jump) {
+    const i = dir < 0 ? 0 : all.length - 1;
+    jumpTo(all[i], i, all.length, 'Section');
+    return;
+  }
+
   if (dir < 0) {
-    for (let i = sections.length - 1; i >= 0; i--) {
-      if (sections[i].start < cur - 1) { jumpTo(sections[i], i); return; }
+    for (let i = all.length - 1; i >= 0; i--) {
+      if (all[i].start < cur - 1) { jumpTo(all[i], i, all.length, 'Section'); return; }
     }
-    announce(`Beginning of ${word.toLowerCase()}s`);
+    announce('Beginning of sections');
   } else {
-    for (let i = 0; i < sections.length; i++) {
-      if (sections[i].start > cur + preroll) { jumpTo(sections[i], i); return; }
+    for (let i = 0; i < all.length; i++) {
+      if (all[i].start > cur + preroll) { jumpTo(all[i], i, all.length, 'Section'); return; }
     }
-    announce(`End of ${word.toLowerCase()}s`);
+    announce('End of sections');
   }
 });
 
@@ -704,7 +776,11 @@ function renderFiles(files) {
 
     const totalSize = dayFiles.reduce((a, f) => a + f.size, 0);
     const totalDur  = dayFiles.reduce((a, f) => a + (f.duration || 0), 0);
-    const canHl     = dayFiles.some(f => (f.ext === 'wav' || f.ext === 'flac') && !f.recording);
+    const hlFiles   = dayFiles.filter(f => (f.ext === 'wav' || f.ext === 'flac') && !f.recording);
+    const canHl     = hlFiles.length > 0;
+    // Every analysable file already has a cached analysis for the current
+    // params -> the day's highlights are available without recomputing
+    const analysed  = canHl && hlFiles.every(f => cachedParamsMatch(f.cached_analysis));
     const durStr    = totalDur > 0 ? ' · ' + fmtDur(Math.round(totalDur)) : '';
     const sizeStr   = ' · ' + fmtSize(totalSize);
     const fileStr   = `${dayFiles.length} file${dayFiles.length !== 1 ? 's' : ''}`;
@@ -729,7 +805,10 @@ function renderFiles(files) {
         </button>
       </h2>
       ${canHl ? `<button class="day-hl" id="dayhln-${dayId}"
-        aria-label="Show day highlights for ${esc(day)}">Highlights</button>` : ''}`;
+        aria-expanded="false" aria-controls="dayhl-${dayId}"
+        aria-label="Day highlights for ${esc(day)}${analysed ? ', analysed' : ''}">
+        <span class="day-arrow" aria-hidden="true">▸</span> Highlights<span
+          class="day-hl-status" id="dayhls-${dayId}"${analysed ? '' : ' hidden'}> · analysed</span></button>` : ''}`;
     section.appendChild(headBar);
 
     // Highlights panel (hidden until button clicked)
@@ -842,6 +921,7 @@ function renderFiles(files) {
       if (!nowExp) {
         dayFiles.forEach(f => closePlayer(f._idx));
         document.getElementById('dayhl-' + dayId).hidden = true;
+        setHlExpanded(dayId, false);
         if (dayActiveId === dayId) {
           dayActiveSections = [];
           dayActiveId = null;
@@ -850,10 +930,26 @@ function renderFiles(files) {
       }
     });
 
-    // Highlights button handler
+    // Highlights button: expand/collapse the panel; only (re)compute when it
+    // has not been built yet this session or the analysis params changed
     if (canHl) {
       document.getElementById('dayhln-' + dayId)?.addEventListener('click', () => {
-        const hlFiles = dayFiles.filter(f => (f.ext === 'wav' || f.ext === 'flac') && !f.recording);
+        const hlRow = document.getElementById('dayhl-' + dayId);
+        if (!hlRow.hidden) {                       // collapse, keep the panel
+          hlRow.hidden = true;
+          setHlExpanded(dayId, false);
+          return;
+        }
+        if (hlRow.dataset.loaded === hlParams()) { // re-open and re-arm J/K
+          hlRow.hidden = false;
+          setHlExpanded(dayId, true);
+          dayActiveSections = dayHlSections.get(dayId) || [];
+          dayActiveId = dayId;
+          clipQueue = dayActiveSections;
+          clipCursor = -1;
+          scoreCursor = -1;
+          return;
+        }
         dayHighlights(dayId, hlFiles);
       });
     }
@@ -866,6 +962,7 @@ async function dayHighlights(dayId, analyzableFiles) {
   const btn      = document.getElementById('dayhln-' + dayId);
 
   hlRow.hidden = false;
+  setHlExpanded(dayId, true);
   const n = analyzableFiles.length;
   if (btn) btn.disabled = true;
 
@@ -904,12 +1001,14 @@ async function dayHighlights(dayId, analyzableFiles) {
     return;
   }
 
-  // Map files onto the day timeline using mtime as file-end, duration for start
+  // Map files onto the day timeline. The filename is the clock: f.date is the
+  // recording start parsed server-side; mtime (≈ file end) is only a fallback
+  // for non-standard names.
   const positioned = results.map(({ f, data }) => {
-    const fileEnd   = f.mtime;
     const fileDur   = data.duration || f.duration || 0;
-    const fileStart = fileEnd - fileDur;
-    return { f, data, fileStart, fileEnd, fileDur };
+    const startEpoch = fileStartEpoch(f.date);
+    const fileStart = startEpoch != null ? startEpoch : f.mtime - fileDur;
+    return { f, data, fileStart, fileEnd: fileStart + fileDur, fileDur };
   }).filter(r => r.fileDur > 0);
 
   if (!positioned.length) {
@@ -918,57 +1017,7 @@ async function dayHighlights(dayId, analyzableFiles) {
     return;
   }
 
-  const minT  = Math.min(...positioned.map(r => r.fileStart));
-  const maxT  = Math.max(...positioned.map(r => r.fileEnd));
-  const spanT = maxT - minT || 1;
-  const W = 800, H = 22;
-  const ns = 'http://www.w3.org/2000/svg';
-
-  const svg = document.createElementNS(ns, 'svg');
-  svg.setAttribute('class', 'wave day-timeline');
-  svg.setAttribute('viewBox', `0 0 ${W} ${H}`);
-  svg.setAttribute('preserveAspectRatio', 'none');
-  svg.setAttribute('role', 'img');
   const totalSecs = positioned.reduce((a, r) => a + r.data.sections.length, 0);
-  svg.setAttribute('aria-label', `Day activity: ${results.length} file${results.length!==1?'s':''}, ${totalSecs} loud section${totalSecs!==1?'s':''}`);
-
-  // Background track
-  const bgR = document.createElementNS(ns, 'rect');
-  bgR.setAttribute('x', 0); bgR.setAttribute('y', 7);
-  bgR.setAttribute('width', W); bgR.setAttribute('height', 8);
-  bgR.setAttribute('fill', '#1e2535');
-  svg.appendChild(bgR);
-
-  positioned.forEach(({ f, data, fileStart, fileEnd, fileDur }) => {
-    const fx = ((fileStart - minT) / spanT) * W;
-    const fw = Math.max(1, ((fileEnd - fileStart) / spanT) * W);
-
-    // File span (dim blue)
-    const fr = document.createElementNS(ns, 'rect');
-    fr.setAttribute('x', fx); fr.setAttribute('y', 8);
-    fr.setAttribute('width', fw); fr.setAttribute('height', 6);
-    fr.setAttribute('fill', '#1e3a5f');
-    fr.setAttribute('aria-hidden', 'true');
-    svg.appendChild(fr);
-
-    // Loud sections (orange)
-    (data.sections || []).forEach(s => {
-      const sx = fx + (s.start / fileDur) * fw;
-      const sw = Math.max(1, ((s.end - s.start) / fileDur) * fw);
-      const sr = document.createElementNS(ns, 'rect');
-      sr.setAttribute('x', sx); sr.setAttribute('y', 4);
-      sr.setAttribute('width', sw); sr.setAttribute('height', 14);
-      sr.setAttribute('fill', '#f97316');
-      sr.setAttribute('rx', '1');
-      sr.setAttribute('aria-hidden', 'true');
-      svg.appendChild(sr);
-    });
-  });
-
-  const fmtHM = ts => {
-    const d = new Date(ts * 1000);
-    return d.getHours().toString().padStart(2,'0') + ':' + d.getMinutes().toString().padStart(2,'0');
-  };
 
   // Build cross-file section list for J/K navigation and chips
   dayActiveSections = [];
@@ -989,18 +1038,26 @@ async function dayHighlights(dayId, analyzableFiles) {
   // Arm the clip queue so J/K steps through the day immediately
   clipQueue = dayActiveSections;
   clipCursor = -1;
+  scoreCursor = -1;
 
   const box = document.createElement('div');
   box.className = 'wbox';
   box.style.marginBottom = '4px';
-  box.appendChild(svg);
 
-  const labels = document.createElement('div');
-  labels.className = 'day-tl-labels';
-  labels.innerHTML = `<span>${esc(fmtHM(minT))}</span><span>${esc(fmtHM((minT+maxT)/2))}</span><span>${esc(fmtHM(maxT))}</span>`;
-  box.appendChild(labels);
+  // Totals first, then the key hint, then the chips: linear reading order
+  const summary = document.createElement('div');
+  summary.className = 'quiet';
+  summary.style.marginTop = '0';
+  summary.textContent = `${results.length} file${results.length!==1?'s':''} analysed · ${totalSecs} loud section${totalSecs!==1?'s':''}`;
+  box.appendChild(summary);
 
   if (dayActiveSections.length) {
+    const note = document.createElement('p');
+    note.className = 'quiet';
+    note.style.marginTop = '6px';
+    note.textContent = 'J / K plays through all sections in time order, U / I by loudness (loudest first). Hold Shift to jump to the first / last section (Shift + J / K) or the loudest / quietest (Shift + U / I)';
+    box.appendChild(note);
+
     const MAX_DAY_CHIPS = 50;
     // When there are too many sections to show them all, show the ones most
     // worth reviewing: the top MAX_DAY_CHIPS by score, loudest first.
@@ -1010,45 +1067,65 @@ async function dayHighlights(dayId, analyzableFiles) {
       chipList = chipList
         .sort((a, b) => (b.sec.score || 0) - (a.sec.score || 0))
         .slice(0, MAX_DAY_CHIPS);
-      const note = document.createElement('p');
-      note.className = 'quiet';
-      note.style.marginTop = '6px';
-      note.textContent = `${dayActiveSections.length} sections — chips show the top ${MAX_DAY_CHIPS} by loudness; J / K steps through all in time order, U / I through highlights only`;
-      box.appendChild(note);
     }
     const chips = document.createElement('div');
     chips.className = 'chips';
     chips.setAttribute('role', 'group');
-    chips.setAttribute('aria-label', 'Day loud sections — click to jump, J/K to step across files, U/I for highlights only');
+    chips.setAttribute('aria-label', 'Day loud sections');
     chipList.forEach(({sec, si}) => {
       const c = document.createElement('button');
       c.className = 'chip';
       c.title = sec.filename + ' @ ' + fmtDur(sec.start);
-      const d = new Date(sec.absStart * 1000);
-      const hms = d.getHours().toString().padStart(2,'0') + ':'
-                + d.getMinutes().toString().padStart(2,'0') + ':'
-                + d.getSeconds().toString().padStart(2,'0');
-      c.textContent = hms + (sec.score != null ? ` · +${Math.round(sec.score)} dB` : '');
+      c.textContent = fmtClock(sec.absStart) + (sec.score != null ? ` · +${Math.round(sec.score)} dB` : '');
       c.addEventListener('click', () => jumpToDaySection(si));
       chips.appendChild(c);
     });
+    // A long chip list is a wall of buttons: collapse it behind a toggle
+    if (chipList.length > 12) {
+      chips.hidden = true;
+      const tog = document.createElement('button');
+      tog.style.marginTop = '8px';
+      tog.setAttribute('aria-expanded', 'false');
+      const arrow = document.createElement('span');
+      arrow.className = 'day-arrow';
+      arrow.setAttribute('aria-hidden', 'true');
+      // the separator space lives inside the aria-hidden arrow: a leading
+      // space in the text node shows up as an indent in screen readers
+      arrow.textContent = '▸ ';
+      tog.appendChild(arrow);
+      tog.appendChild(document.createTextNode(truncated
+        ? `Top ${chipList.length} sections by loudness`
+        : `${chipList.length} sections`));
+      tog.addEventListener('click', () => {
+        const exp = chips.hidden;
+        chips.hidden = !exp;
+        tog.setAttribute('aria-expanded', exp);
+        arrow.textContent = exp ? '▾ ' : '▸ ';
+      });
+      box.appendChild(tog);
+    }
     box.appendChild(chips);
   }
 
-  const summary = document.createElement('div');
-  summary.className = 'quiet';
-  summary.style.marginTop = '4px';
-  summary.textContent = `${results.length} file${results.length!==1?'s':''} analysed · ${totalSecs} loud section${totalSecs!==1?'s':''}`;
-  box.appendChild(summary);
-
   contentEl.innerHTML = '';
   contentEl.appendChild(box);
+  hlRow.dataset.loaded = hlParams();
+  dayHlSections.set(dayId, dayActiveSections);
+  // Every file is now cached with the current params
+  if (results.length === n) {
+    document.getElementById('dayhls-' + dayId)?.removeAttribute('hidden');
+    // aria-label overrides the button content, so the analysed marker has to
+    // be mirrored into it or screen readers never hear it
+    if (btn && !/, analysed$/.test(btn.getAttribute('aria-label') || ''))
+      btn.setAttribute('aria-label', btn.getAttribute('aria-label') + ', analysed');
+  }
   if (btn) btn.disabled = false;
 }
 
 function jumpToDaySection(si) {
   if (si < 0 || si >= dayActiveSections.length) return;
   clipQueue = dayActiveSections;
+  scoreCursor = -1;                 // explicit jump: next U/I re-anchors here
   playClip(si);
 }