Add non-blocking operations design principle to summary

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

summary.md

@@ -63,8 +63,13 @@ for AI-assisted features.
 - **Context building server-side:** Backend fetches URL content and searches notes —
   frontend just sends the message text + optional note ID. Keyword extraction uses
   simple word splitting with stopword filtering (no embeddings).
-- **Auto-pull model on startup:** Non-blocking, logs warning on failure so the app
-  still starts even if Ollama isn't ready.
+- **No blocking long-running operations:** Any potentially slow operation (model
+  pulls, LLM calls, URL fetching, etc.) must never block app startup or freeze the
+  UI. Backend uses `asyncio.create_task()` for fire-and-forget work and SSE streaming
+  for incremental responses. Frontend keeps the UI responsive during async operations
+  (loading states, streaming indicators). This applies to all future features as well.
+- **Auto-pull model on startup:** Non-blocking background task, logs warning on
+  failure so the app still starts even if Ollama isn't ready.
 - **Backlinks:** `GET /api/notes/:id/backlinks` searches all note bodies for
   `[[Title]]` patterns referencing the given note. Results include `type: "note"` or
   `type: "task"` based on whether the linking note has `status IS NOT NULL`.