Fix re-index timeout: switch to SSE stream + add progress bar

Re-index was using POST /ingest (sync) which times out for large repos
(600+ chunks take several minutes to re-embed). Fix:

Backend:
- Add force=true query param to GET /ingest/stream so it supports
full re-ingestion, not just initial index
- Update contextual_at timestamp when force=true on the stream path

Frontend:
- Rewrite handleReindex to use EventSource (SSE) with force=true,
same as the initial ingest flow — no more timeout failures
- Add per-repo progress % state (reindexPct) mapped from ingest steps:
fetching=10% → filtering=22% → chunking=38% → embedding=75% →
storing=90% → done=100%
- Add a 2px progress bar that fills across the bottom of the repo card
during re-indexing, with a glowing accent color and smooth easing

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

backend/routers/ingestion.py

@@ -73,12 +73,14 @@ async def ingest_repo(
 
 
 @router.get("/ingest/stream")
-async def ingest_stream(repo: str, request: Request):
+async def ingest_stream(repo: str, request: Request, force: bool = False):
     """
     Stream ingestion progress as Server-Sent Events (SSE).
 
     Each event: { "step": "fetching|filtering|chunking|embedding|storing|done|error",
                   "detail": "human-readable message" }
+
+    force=true deletes and re-ingests from scratch (used by the re-index button).
     """
     check_rate_limit(request)
 
@@ -90,12 +92,15 @@ async def ingest_stream(repo: str, request: Request):
 
     async def _run():
         try:
-            await asyncio.to_thread(services.ingestion.ingest, repo, False, _progress)
+            await asyncio.to_thread(services.ingestion.ingest, repo, force, _progress)
             if services.diagram:
                 services.diagram.invalidate(repo)
             if services.repo_map:
                 services.repo_map.invalidate(repo)
-            repo_indexed_at[repo] = datetime.now(timezone.utc).isoformat()
+            now = datetime.now(timezone.utc).isoformat()
+            repo_indexed_at[repo] = now
+            if force:
+                repo_contextual_at[repo] = now
         except Exception as e:
             loop.call_soon_threadsafe(queue.put_nowait, {"step": "error", "detail": str(e)})
         finally:

ui/src/components/Sidebar.jsx

@@ -116,6 +116,7 @@ export default function Sidebar({ repos, reposLoading, activeRepo, onSelectRepo,
   const [isIngesting, setIsIngesting]   = useState(false);
   const [reindexing, setReindexing]     = useState(null);  // slug currently re-indexing
   const [reindexDone, setReindexDone]   = useState({});    // slug → bool (just finished)
+  const [reindexPct,  setReindexPct]    = useState({});    // slug → 0-100 progress %
   const [sessionSearch, setSessionSearch] = useState("");  // filter text for sessions list
 
   // Load MCP status once on mount
@@ -187,23 +188,50 @@ export default function Sidebar({ repos, reposLoading, activeRepo, onSelectRepo,
     }
   }
 
-  async function handleReindex(e, slug) {
+  function handleReindex(e, slug) {
     e.stopPropagation();
     if (reindexing) return;
     setReindexing(slug);
     setReindexDone(prev => ({ ...prev, [slug]: false }));
-    try {
-      // force=true deletes and re-ingests from scratch so the index is fully fresh
-      await ingestRepo(`https://github.com/${slug}`, true);
-      setReindexDone(prev => ({ ...prev, [slug]: true }));
-      onReposChange();
-      // Clear the "Re-indexed" badge after 3s
-      setTimeout(() => setReindexDone(prev => { const n = {...prev}; delete n[slug]; return n; }), 3000);
-    } catch (err) {
-      setStatus({ type: "error", text: `Re-index failed: ${err.message}` });
-    } finally {
+    setReindexPct(prev => ({ ...prev, [slug]: 5 }));
+
+    // Map ingestion steps to approximate % complete so the bar fills meaningfully.
+    // Embedding is the longest step (~60% of total time), so it gets the most range.
+    const STEP_PCT = { fetching: 10, filtering: 22, chunking: 38, embedding: 75, storing: 90, done: 100 };
+
+    // Use EventSource (GET SSE) instead of a POST fetch so the connection never
+    // times out — large repos take several minutes to re-embed. The backend sends
+    // keepalive pings every 15s to prevent proxy idle-disconnect.
+    const es = new EventSource(`${BASE}/ingest/stream?repo=${encodeURIComponent(`https://github.com/${slug}`)}&force=true`);
+
+    es.onmessage = (ev) => {
+      const event = JSON.parse(ev.data);
+      const pct = STEP_PCT[event.step] ?? null;
+      if (pct !== null) setReindexPct(prev => ({ ...prev, [slug]: pct }));
+
+      if (event.step === "done") {
+        es.close();
+        setReindexing(null);
+        setReindexDone(prev => ({ ...prev, [slug]: true }));
+        onReposChange();
+        setTimeout(() => {
+          setReindexDone(prev => { const n = {...prev}; delete n[slug]; return n; });
+          setReindexPct(prev => { const n = {...prev}; delete n[slug]; return n; });
+        }, 3000);
+      } else if (event.step === "error") {
+        es.close();
+        setReindexing(null);
+        setReindexPct(prev => { const n = {...prev}; delete n[slug]; return n; });
+        setStatus({ type: "error", text: `Re-index failed: ${event.detail}` });
+      }
+    };
+
+    es.onerror = () => {
+      es.close();
       setReindexing(null);
-    }
+      setReindexPct(prev => { const n = {...prev}; delete n[slug]; return n; });
+      setStatus({ type: "error", text: "Re-index failed: connection lost" });
+    };
   }
 
   const SEARCH_MODE_TITLES = {
@@ -454,11 +482,13 @@ export default function Sidebar({ repos, reposLoading, activeRepo, onSelectRepo,
               const staleness = stalenessLevel(r.indexed_at);
               const isReindexingThis = reindexing === r.slug;
               const justDone = reindexDone[r.slug];
+              const pct = reindexPct[r.slug] ?? null;
               return (
                 <div
                   key={r.slug}
                   className={`repo-item ${activeRepo === r.slug ? "active" : ""}`}
                   onClick={() => onSelectRepo(activeRepo === r.slug ? null : r.slug)}
+                  style={{ position: "relative", overflow: "hidden" }}
                 >
                   <div className="repo-item-main">
                     {/* GitHub mark — reinforces these are GitHub repos without taking space */}
@@ -532,6 +562,12 @@ export default function Sidebar({ repos, reposLoading, activeRepo, onSelectRepo,
                       >×</button>
                     )}
                   </div>
+                  {/* Progress bar — shown while re-indexing, fills from left to right */}
+                  {pct !== null && (
+                    <div className="repo-reindex-progress">
+                      <div className="repo-reindex-progress-bar" style={{ width: `${pct}%` }} />
+                    </div>
+                  )}
                 </div>
               );
             })}

ui/src/index.css

@@ -3335,6 +3335,23 @@ textarea:focus-visible {
   to   { transform: rotate(360deg); }
 }
 
+/* Re-index progress bar — sits flush at the bottom of the repo card */
+.repo-reindex-progress {
+  position: absolute;
+  bottom: 0;
+  left: 0;
+  right: 0;
+  height: 2px;
+  background: var(--surface-4);
+}
+.repo-reindex-progress-bar {
+  height: 100%;
+  background: var(--accent);
+  border-radius: 0 1px 1px 0;
+  transition: width 0.6s cubic-bezier(0.4, 0, 0.2, 1);
+  box-shadow: 0 0 6px var(--accent);
+}
+
 /* ══════════════════════════════════════════════════════════
    FEATURE 3: SESSION SEARCH + EDITABLE TITLE
    ══════════════════════════════════════════════════════════ */