Feature: Show Tile Cache size in menu

docs/data-storage.md

@@ -2,14 +2,18 @@
 
 All data storage is cross-browser (Chrome, Firefox, Safari) — none depends on the service worker.
 
-| Storage | What it stores | Purpose | Cross-browser |
-|---|---|---|---|
-| **IndexedDB** | Photo objects (full-size base64 image + thumbnail + all metadata), album objects, geo caches | Primary data store — the app reads from here on every load | Yes |
-| **Disk (matrix-data.json)** | JSON dump of all IndexedDB content | Backup that survives browser data clearing; auto-saved by `serve.py` | Yes |
-| **Disk (matrix-photos/)** | Individual image files (`{id}.jpg`, `{id}_thumb.jpg`) extracted from base64 | Used by the export flow (avoids embedding huge base64 in JSON) and for lightbox display after import | Yes |
+| Storage | What it stores | Purpose |
+|---|---|---|
+| **matrix-photos/** | Full-size images (`{id}.jpg`) and thumbnails (`{id}_thumb.jpg`) | Source of truth for image data — written on upload, served directly for display |
+| **IndexedDB** | Photo metadata (coords, date, camera, notes) + file path references to `matrix-photos/`, album objects | Source of truth for metadata — the app reads from here on every load |
+| **matrix-data.json** | JSON backup of metadata, albums, and geo caches (file paths, not image data) | Backup that survives browser data clearing; auto-saved by `serve.py` |
 
-**IndexedDB** is the source of truth during normal use. `matrix-data.json` and `matrix-photos/` are redundant backups maintained by `serve.py`. If you clear browser data, the app offers to restore from `matrix-data.json` on next load.
+## How it works
 
-## Scalability note
+**Image data** lives on disk in `matrix-photos/`. IndexedDB stores only metadata and a path reference (e.g. `matrix-photos/p_123.jpg`), keeping the database lean (~50KB/photo vs ~4MB with embedded base64). This lets the app handle tens of thousands of photos without bloating browser storage.
 
-IndexedDB currently stores full-size images as base64 inside each photo record. At scale (thousands of large photos), this can cause high memory usage at startup since all records are loaded into memory. A future refactor will move full-size images to `matrix-photos/` only, keeping IndexedDB lean (metadata + thumbnails). See the [planned refactor](../plans/reactive-bubbling-creek.md) for details.
+**On upload**, `processFiles()` saves the full-size image to disk via `POST /api/photos/{id}`, verifies the file is servable, then stores the file path in IndexedDB.
+
+**On load**, the app reads metadata from IndexedDB and references images by their disk paths. If IndexedDB is empty (e.g. after clearing browser data), the app offers to restore metadata from `matrix-data.json`. The image files in `matrix-photos/` remain intact regardless.
+
+**Auto-save** (`scheduleAutoSave()`) writes metadata to `matrix-data.json` via `POST /api/data` after any data-modifying action. This file contains file paths — not image data — so it stays small.

index.html

@@ -35,7 +35,7 @@
         </div>
         <div class="settings-item" onclick="emptyTileCache()">
           <span class="settings-item-icon">🗺</span>
-          <div><div class="settings-item-label">Empty Map Cache</div><div class="settings-item-sub">Clear cached map tiles from disk</div></div>
+          <div><div class="settings-item-label">Empty Map Cache</div><div class="settings-item-sub" id="cache-size-status">Clear cached map tiles from disk</div></div>
         </div>
       </div>
     </div>

js/data.js

@@ -122,6 +122,15 @@ function toggleSettingsMenu(e) {
   const dd = document.getElementById('settings-dropdown');
   dd.classList.toggle('open');
   updateAutoSaveIndicator();
+  if (dd.classList.contains('open')) updateCacheSizeStatus();
+}
+
+function updateCacheSizeStatus() {
+  fetch('/api/tiles/size').then(r => r.json()).then(d => {
+    const mb = (d.bytes / (1024 * 1024)).toFixed(0);
+    const el = document.getElementById('cache-size-status');
+    if (el) el.textContent = `${mb} MB used (${d.limitMB} MB limit)`;
+  }).catch(() => {});
 }
 document.addEventListener('click', e => {
   if (!e.target.closest('.settings-btn') && !e.target.closest('.settings-dropdown')) {
@@ -161,6 +170,7 @@ async function emptyTileCache() {
       const tileCacheName = cacheNames.find(n => n.endsWith('-tiles'));
       if (tileCacheName) await caches.delete(tileCacheName);
       showToast(`Map cache cleared — ${d.removed} file${d.removed !== 1 ? 's' : ''} removed`, 'success');
+      updateCacheSizeStatus();
     } else {
       showToast('Failed to clear map cache', 'error');
     }

serve.py

@@ -290,6 +290,8 @@ def do_GET(self):
         try:
             if self.path == "/api/data":
                 self._serve_data()
+            elif self.path == "/api/tiles/size":
+                self._tile_cache_size()
             elif self.path.startswith("/api/tiles/proxy?"):
                 self._proxy_tile()
             elif self.path.startswith("/api/video/download?"):
@@ -632,6 +634,24 @@ def _video_abort(self):
         self.end_headers()
         self.wfile.write(b'{"ok":true}')
 
+    def _tile_cache_size(self):
+        total = 0
+        count = 0
+        if os.path.isdir(TILES_DIR):
+            for root, _, fnames in os.walk(TILES_DIR):
+                for fn in fnames:
+                    if fn.startswith('.'):
+                        continue
+                    try:
+                        total += os.stat(os.path.join(root, fn)).st_size
+                        count += 1
+                    except OSError:
+                        pass
+        self.send_response(200)
+        self.send_header('Content-Type', 'application/json')
+        self.end_headers()
+        self.wfile.write(json.dumps({'bytes': total, 'files': count, 'limitMB': MAX_TILES_MB}).encode())
+
     def _clear_tile_cache(self):
         """Wipe the entire matrix-tiles directory and recreate it empty for a clean state."""
         try: