feat: persist analyses on reload, add re-analyse button and metadata, trim highlights tally

- _api_files: read each file's analysis cache and return cached_analysis
  {threshold, min_gap} so the client knows upfront which files are cached
- On page load: files with a cached analysis auto-fetch and render their
  waveform immediately instead of showing an idle Analyse button
- After any analysis: show threshold/gap/cached metadata line below the
  waveform and a Re-analyse button inside the waveform box; old button
  no longer disappears on success
- Error path now always re-adds an actionable Analyse button to the cell
- dayHighlights progress: remove the redundant intermediate "N analysed"
  tally (16/22 counter already conveys progress); done message now says
  "N files (N from cache)" when relevant
- Threshold hint updated to show dBFS equivalent (0.05 ≈ −26 dBFS)
- CSS: remove unused .prog-tally and .cached-badge; add .analysis-meta
  and .reanalyse-btn

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web.py

@@ -324,8 +324,24 @@ class _Handler(BaseHTTPRequestHandler):
         self._send(200, _HTML.encode('utf-8'), 'text/html; charset=utf-8')
 
     def _api_files(self):
-        data = json.dumps(list_files(self.recordings_dir)).encode('utf-8')
+        files = list_files(self.recordings_dir)
-        self._send(200, data, 'application/json')
+        recordings_base = Path(self.recordings_dir).resolve()
+        analyses_base   = Path(self.analyses_dir).resolve()
+        for f in files:
+            if f.get('ext') in ('wav', 'flac') and not f.get('recording'):
+                cache_path = _analysis_cache_path(
+                    analyses_base, recordings_base, recordings_base / f['name'])
+                try:
+                    cached = json.loads(cache_path.read_text('utf-8'))
+                    f['cached_analysis'] = {
+                        'threshold': cached['threshold'],
+                        'min_gap':   cached['min_gap'],
+                    }
+                except Exception:
+                    f['cached_analysis'] = None
+            else:
+                f['cached_analysis'] = None
+        self._send(200, json.dumps(files).encode('utf-8'), 'application/json')
 
     def _api_analyze(self, qs):
         filename = qs.get('file', [None])[0]
@@ -712,8 +728,9 @@ button.chip:focus-visible{outline:2px solid var(--accent);outline-offset:2px}
 .prog-bar{height:3px;background:var(--brd);border-radius:2px;margin:6px 0 4px;overflow:hidden}
 .prog-fill{height:100%;background:var(--accent);border-radius:2px;transition:width 0.15s ease}
 .prog-file{font-size:12px;color:var(--muted);font-style:italic;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;max-width:100%}
-.prog-tally{font-size:11px;color:var(--muted);margin-top:3px}
+.analysis-meta{font-size:10px;color:var(--muted);margin-top:5px;font-style:italic}
-.cached-badge{font-size:10px;color:var(--muted);background:var(--surf);border:1px solid var(--brd);border-radius:3px;padding:1px 5px;margin-left:6px;vertical-align:middle;font-style:normal}
+button.reanalyse-btn{font-size:10px;padding:2px 7px;margin-top:6px;color:var(--muted);border-color:var(--brd);background:transparent}
+button.reanalyse-btn:hover:not(:disabled){background:var(--surf);color:var(--txt)}
 .empty{text-align:center;padding:60px;color:var(--muted)}
 /* player row */
 .player-row td{padding:0 10px 10px;background:var(--bg);border-bottom:1px solid var(--brd)}
@@ -772,7 +789,7 @@ svg.day-timeline{display:block;width:100%;height:22px}
   <label for="threshold-input">Analysis threshold:</label>
   <input type="number" id="threshold-input" min="0" max="1" step="0.005" value="0.05"
     aria-describedby="threshold-hint">
-  <span id="threshold-hint" class="controls-hint">RMS 0–1 · sections above this value are marked loud</span>
+  <span id="threshold-hint" class="controls-hint">RMS amplitude 0–1 (linear; 0.05 ≈ −26 dBFS) · sections above this are marked loud</span>
   <label for="preroll-input" style="margin-left:16px">Pre-roll:</label>
   <input type="number" id="preroll-input" min="0" max="30" step="0.5" value="3"
     aria-describedby="preroll-hint">
@@ -954,6 +971,11 @@ async function analyse(idx, filename, cell, btn) {
   cell.innerHTML = '<div class="spin" aria-live="polite" aria-busy="true">Analysing…</div>';
   const threshold = document.getElementById('threshold-input').value || '0.05';
   const minGap    = document.getElementById('min-gap-input').value || '2';
+  const restoreBtn = () => {
+    btn.textContent = 'Analyse'; btn.disabled = false;
+    btn.onclick = () => analyse(idx, filename, cell, btn);
+    if (!cell.contains(btn)) cell.appendChild(btn);
+  };
   try {
     const r = await fetch('/api/analyze?file='+encodeURIComponent(filename)
       +'&threshold='+encodeURIComponent(threshold)
@@ -961,17 +983,14 @@ async function analyse(idx, filename, cell, btn) {
     const d = await r.json();
     if (d.error) {
       cell.innerHTML = `<div class="spin" role="alert">Error: ${esc(d.error)}</div>`;
-      btn.disabled = false; btn.textContent = 'Analyse';
+      restoreBtn(); return;
-      return;
     }
     const box = document.createElement('div'); box.className='wbox';
     box.appendChild(drawWave(d.rms_display||[], d.sections||[], d.duration||0, filename));
-    if (d.cached) {
+
-      const badge = document.createElement('span');
+    const meta = document.createElement('div'); meta.className='analysis-meta';
-      badge.className = 'cached-badge'; badge.textContent = 'cached';
+    meta.textContent = `threshold: ${threshold} · gap: ${minGap}s${d.cached ? ' · cached' : ''}`;
-      badge.title = 'Result loaded from cache — change threshold/gap and re-analyse to recompute';
+    box.appendChild(meta);
-      box.firstChild.after(badge);
-    }
 
     const chips = document.createElement('div');
     chips.className='chips';
@@ -995,10 +1014,16 @@ async function analyse(idx, filename, cell, btn) {
       chips.appendChild(q);
     }
     box.appendChild(chips);
+
+    const rebtn = document.createElement('button');
+    rebtn.className='reanalyse-btn'; rebtn.textContent='Re-analyse';
+    rebtn.onclick = () => analyse(idx, filename, cell, rebtn);
+    box.appendChild(rebtn);
+
     cell.innerHTML=''; cell.appendChild(box);
   } catch(e) {
     cell.innerHTML = `<div class="spin" role="alert">Error: ${esc(e.message)}</div>`;
-    btn.disabled = false; btn.textContent = 'Analyse';
+    restoreBtn();
   }
 }
 
@@ -1102,15 +1127,21 @@ function _attachFileRowHandlers(f, isRec, expanded, dayId) {
   if (canAnalyse) {
     const cell = document.getElementById('wave-'+i);
     const abtn = document.createElement('button');
-    abtn.textContent = 'Analyse';
     abtn.setAttribute('aria-label', `Analyse loudness of ${f.name}`);
     if (isRec) {
+      abtn.textContent = 'Analyse';
       abtn.disabled = true;
       abtn.title = 'Recording in progress — analyse after recording stops';
-    } else {
-      abtn.addEventListener('click', () => analyse(i, f.name, cell, abtn));
-    }
       cell.appendChild(abtn);
+    } else if (f.cached_analysis) {
+      abtn.textContent = 'Re-analyse';
+      cell.innerHTML = '<div class="spin">Loading…</div>';
+      analyse(i, f.name, cell, abtn);
+    } else {
+      abtn.textContent = 'Analyse';
+      abtn.onclick = () => analyse(i, f.name, cell, abtn);
+      cell.appendChild(abtn);
+    }
   }
 
   document.getElementById('pbtn-'+i)
@@ -1349,8 +1380,7 @@ async function dayHighlights(dayId, analyzableFiles) {
   const progFill = document.createElement('div'); progFill.className = 'prog-fill'; progFill.style.width = '0%';
   progBar.appendChild(progFill);
   const progFile  = document.createElement('div'); progFile.className  = 'prog-file';
-  const progTally = document.createElement('div'); progTally.className = 'prog-tally';
+  progWrap.appendChild(progBar); progWrap.appendChild(progFile);
-  progWrap.appendChild(progBar); progWrap.appendChild(progFile); progWrap.appendChild(progTally);
   contentEl.innerHTML = ''; contentEl.appendChild(progWrap);
 
   const threshold = document.getElementById('threshold-input').value || '0.05';
@@ -1362,10 +1392,6 @@ async function dayHighlights(dayId, analyzableFiles) {
     const f = analyzableFiles[i];
     progFile.textContent  = `${i + 1} / ${n} — ${f.name}`;
     progFill.style.width  = `${(i / n) * 100}%`;
-    const tallyParts = [];
-    if (nCached) tallyParts.push(`${nCached} cached`);
-    if (nLive)   tallyParts.push(`${nLive} analysed`);
-    progTally.textContent = tallyParts.join(' · ');
     try {
       const r = await fetch('/api/analyze?file=' + encodeURIComponent(f.name)
         + '&threshold=' + encodeURIComponent(threshold)
@@ -1375,8 +1401,8 @@ async function dayHighlights(dayId, analyzableFiles) {
     } catch(e) {}
   }
   progFill.style.width = '100%';
-  progFile.textContent  = `Done — ${n} file${n!==1?'s':''} (${nCached} cached, ${nLive} analysed)`;
+  const doneExtra = nCached ? ` (${nCached} from cache)` : '';
-  progTally.textContent = '';
+  progFile.textContent = `Done — ${n} file${n!==1?'s':''}${doneExtra}`;
 
   if (!results.length) {
     contentEl.innerHTML = '<div class="quiet">No analysable results.</div>';