fix(sidebar): make the repaint-skip opt-in, not the default

familiar-workspace/static/workspace.js

@@ -1751,12 +1751,39 @@
     // Refresh sidebar children for all currently-expanded categories.
     // Called when titles change or docs are created/deleted so the
     // sidebar list stays current without a page refresh.
-    async function refreshSidebarChildren() {
+    // force=true (default): always repaint. force=false: skip the repaint
+    // when neither the fetched category data NOR the expanded set changed —
+    // used ONLY by the autosave-driven sidebarRefresh path to stop the rail
+    // flashing on every 500ms debounce.
+    //
+    // Safe-by-default is deliberate. The first cut inverted this: it diffed
+    // the category data and skipped on a match, which silently suppressed a
+    // caret toggle (expansion state lives outside that data) and a
+    // created/deleted page (page trees live in sidebarWikiPagesCache, also
+    // outside it). Any mutation path — notesChanged clearing the cache, a
+    // caret toggle, a drag — must force the repaint; only the pure autosave
+    // signal opts out.
+    async function refreshSidebarChildren(force = true) {
         for (const category of sidebarCatState.expanded) {
             const childList = document.querySelector('.sidebar-children[data-category="' + category + '"]');
             if (!childList) continue;
             const items = await fetchCategoryChildren(category);
-            sidebarCatState.cache[category] = items;
+            if (!force) {
+                const expandedSet = sidebarTreeExpanded.get(category);
+                const expandedSig = expandedSet ? Array.from(expandedSet).sort().join(",") : "";
+                const sig = JSON.stringify(items) + "|" + expandedSig;
+                if (!sidebarCatState.renderSig) sidebarCatState.renderSig = {};
+                const same = sidebarCatState.renderSig[category] === sig;
+                sidebarCatState.renderSig[category] = sig;
+                sidebarCatState.cache[category] = items;
+                if (same) continue;
+            } else {
+                sidebarCatState.cache[category] = items;
+                // Invalidate the skip-cache so the NEXT autosave refresh, if it
+                // fetches this same data, still repaints once to reflect this
+                // forced change before it starts skipping again.
+                if (sidebarCatState.renderSig) delete sidebarCatState.renderSig[category];
+            }
             renderCategoryChildren(childList, category, items);
         }
     }
@@ -1941,7 +1968,7 @@
     });
 
     // Listen for sidebar refresh requests from surface modules.
-    window.addEventListener("familiar:sidebarRefresh", refreshSidebarChildren);
+    window.addEventListener("familiar:sidebarRefresh", () => refreshSidebarChildren(false));
 
     // AI tool calls that mutate notes / pages dispatch
     // familiar:notesChanged via chat.js when the gateway emits the