feat: day-collapsed-by-default, cross-file highlights navigation

- All days collapsed by default; only today auto-expands
- Day Highlights chips now show absolute HH:MM:SS timestamps and are
  clickable — jumps to the right file's player, auto-opening it and
  closing the previous one when switching files
- J/K keys navigate across all files in the highlighted day (day-level
  mode) instead of staying within a single file; falls back to per-file
  mode when no day highlights are active
- Collapsing a day clears its cross-file section state

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

web.py

@@ -790,6 +790,10 @@ let activePlayerIdx = null;
 let allFiles = [];
 // dayId -> boolean, persists expanded state across re-renders
 const dayExpanded = new Map();
+// cross-file day section navigation (populated by ★ Highlights)
+let dayActiveSections = [];
+let dayActiveSectionCursor = -1;
+let dayActiveId = null;
 
 function groupByDay(files) {
   const map = new Map();
@@ -941,6 +945,24 @@ async function analyse(idx, filename, cell, btn) {
 // J = previous section, K = next section (only when focus is not in an input)
 document.addEventListener('keydown', e => {
   if (e.target.tagName === 'INPUT' || e.target.tagName === 'TEXTAREA') return;
+  if (e.key !== 'j' && e.key !== 'J' && e.key !== 'k' && e.key !== 'K') return;
+  e.preventDefault();
+
+  // Day-level cross-file navigation when Highlights have been loaded
+  if (dayActiveSections.length) {
+    if (e.key === 'j' || e.key === 'J') {
+      const ni = dayActiveSectionCursor > 0 ? dayActiveSectionCursor - 1 : -1;
+      if (ni >= 0) jumpToDaySection(ni);
+      else announce('Beginning of day sections');
+    } else {
+      const ni = dayActiveSectionCursor + 1;
+      if (ni < dayActiveSections.length) jumpToDaySection(ni);
+      else announce('End of day sections');
+    }
+    return;
+  }
+
+  // Per-file section navigation
   if (activePlayerIdx === null) return;
   const sections = sectionMap.get(activePlayerIdx) || [];
   if (!sections.length) return;
@@ -949,7 +971,6 @@ document.addEventListener('keydown', e => {
   const preroll = getPreroll();
 
   if (e.key === 'j' || e.key === 'J') {
-    e.preventDefault();
     const cur = audio.currentTime;
     let targetIdx = -1;
     for (let i = sections.length - 1; i >= 0; i--) {
@@ -963,8 +984,7 @@ document.addEventListener('keydown', e => {
     } else {
       announce('Beginning of sections');
     }
-  } else if (e.key === 'k' || e.key === 'K') {
+  } else {
-    e.preventDefault();
     const cur = audio.currentTime;
     let jumped = false;
     for (let i = 0; i < sections.length; i++) {
@@ -1077,13 +1097,12 @@ function renderFiles(files) {
   document.getElementById('empty').style.display = visible ? 'none' : '';
 
   const days = groupByDay(files);
-  let isFirst = true;
+  const today = new Date().toISOString().slice(0, 10);
 
   days.forEach((dayFiles, day) => {
     const dayId = 'day-' + day.replace(/-/g, '');
-    if (!dayExpanded.has(dayId)) dayExpanded.set(dayId, isFirst);
+    if (!dayExpanded.has(dayId)) dayExpanded.set(dayId, day === today);
     const expanded = dayExpanded.get(dayId);
-    isFirst = false;
 
     const totalSize = dayFiles.reduce((a, f) => a + f.size, 0);
     const totalDur  = dayFiles.reduce((a, f) => a + (f.duration || 0), 0);
@@ -1218,6 +1237,11 @@ function renderFiles(files) {
           }
         });
         document.getElementById('dayhl-' + dayId).hidden = true;
+        if (dayActiveId === dayId) {
+          dayActiveSections = [];
+          dayActiveSectionCursor = -1;
+          dayActiveId = null;
+        }
       }
     });
 
@@ -1327,6 +1351,23 @@ async function dayHighlights(dayId, analyzableFiles) {
     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 = [];
+  positioned.forEach(({ f, data, fileStart }) => {
+    (data.sections || []).forEach(s => {
+      dayActiveSections.push({
+        fileIdx: f._idx,
+        filename: f.name,
+        start: s.start,
+        end: s.end,
+        absStart: fileStart + s.start,
+      });
+    });
+  });
+  dayActiveSections.sort((a, b) => a.absStart - b.absStart);
+  dayActiveSectionCursor = -1;
+  dayActiveId = dayId;
+
   const box = document.createElement('div');
   box.className = 'wbox';
   box.style.marginBottom = '4px';
@@ -1337,6 +1378,27 @@ async function dayHighlights(dayId, analyzableFiles) {
   labels.innerHTML = `<span>${esc(fmtHM(minT))}</span><span>${esc(fmtHM((minT+maxT)/2))}</span><span>${esc(fmtHM(maxT))}</span>`;
   box.appendChild(labels);
 
+  if (dayActiveSections.length) {
+    const chips = document.createElement('div');
+    chips.className = 'chips';
+    chips.setAttribute('role', 'list');
+    chips.setAttribute('aria-label', 'Day loud sections — click to jump, J/K to step across files');
+    dayActiveSections.forEach((sec, si) => {
+      const c = document.createElement('button');
+      c.className = 'chip';
+      c.setAttribute('role', 'listitem');
+      c.title = sec.filename + ' @ ' + fmtT(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;
+      c.addEventListener('click', () => jumpToDaySection(si));
+      chips.appendChild(c);
+    });
+    box.appendChild(chips);
+  }
+
   const summary = document.createElement('div');
   summary.className = 'quiet';
   summary.style.marginTop = '4px';
@@ -1348,6 +1410,43 @@ async function dayHighlights(dayId, analyzableFiles) {
   if (btn) btn.disabled = false;
 }
 
+function jumpToDaySection(si) {
+  if (si < 0 || si >= dayActiveSections.length) return;
+  dayActiveSectionCursor = si;
+  const sec = dayActiveSections[si];
+  const { fileIdx, filename, start, end } = sec;
+
+  // Close the previous player if switching to a different file
+  if (activePlayerIdx !== null && activePlayerIdx !== fileIdx) {
+    const prevProw = document.getElementById('prow-' + activePlayerIdx);
+    if (prevProw && !prevProw.hidden) {
+      document.getElementById('aud-' + activePlayerIdx)?.pause();
+      prevProw.hidden = true;
+      const prevPbtn = document.getElementById('pbtn-' + activePlayerIdx);
+      if (prevPbtn) {
+        prevPbtn.setAttribute('aria-expanded', 'false');
+        prevPbtn.textContent = '▶ Play';
+        prevPbtn.setAttribute('aria-label', 'Play ' + (recMap.get(activePlayerIdx) || ''));
+      }
+    }
+  }
+
+  // Open this file's player
+  const pbtn = document.getElementById('pbtn-' + fileIdx);
+  if (pbtn && pbtn.getAttribute('aria-expanded') !== 'true') togglePlayer(fileIdx, filename);
+  activePlayerIdx = fileIdx;
+
+  const audio = document.getElementById('aud-' + fileIdx);
+  if (!audio) return;
+  const seekTo = Math.max(0, start - getPreroll());
+  const doSeek = () => { audio.currentTime = seekTo; };
+  if (audio.readyState >= 1) doSeek();
+  else audio.addEventListener('loadedmetadata', doSeek, { once: true });
+
+  setCutFields(fileIdx, start, end);
+  announce(`Day section ${si + 1} of ${dayActiveSections.length}: ${fmtT(start)}–${fmtT(end)} in ${filename}`);
+}
+
 function applyFilters() {
   const nameQ = document.getElementById('filter-name').value.toLowerCase().trim();
   const fromD = document.getElementById('filter-from').value;