feat: add SSE endpoint for streaming ticket notes generation

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/api/endpoints/ai_sessions.py

@@ -924,6 +924,52 @@ async def get_documentation(
         raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail=str(e))
 
 
+@router.get("/{session_id}/documentation/stream")
+@limiter.limit("20/minute")
+async def stream_documentation(
+    request: Request,
+    session_id: UUID,
+    current_user: Annotated[User, Depends(get_current_active_user)],
+    db: Annotated[AsyncSession, Depends(get_db)],
+):
+    """Stream AI-generated ticket notes as Server-Sent Events."""
+    from starlette.responses import StreamingResponse
+
+    # Verify session ownership
+    result = await db.execute(
+        select(AISession).where(AISession.id == session_id)
+    )
+    session = result.scalar_one_or_none()
+    if not session:
+        raise HTTPException(status_code=404, detail="Session not found")
+    if session.user_id != current_user.id:
+        raise HTTPException(status_code=403, detail="Not authorized")
+
+    async def event_generator():
+        try:
+            async for chunk in flowpilot_engine.stream_ticket_notes(
+                session_id=session_id,
+                user_id=current_user.id,
+                db=db,
+            ):
+                # SSE format: data: <text>\n\n
+                yield f"data: {chunk}\n\n"
+            yield "data: [DONE]\n\n"
+        except Exception as e:
+            logger.exception("SSE stream error for session %s: %s", session_id, e)
+            yield f"data: [ERROR] {str(e)}\n\n"
+
+    return StreamingResponse(
+        event_generator(),
+        media_type="text/event-stream",
+        headers={
+            "Cache-Control": "no-cache",
+            "Connection": "keep-alive",
+            "X-Accel-Buffering": "no",  # Disable nginx buffering
+        },
+    )
+
+
 # ── Status Update ──
 
 @router.post("/{session_id}/status-update", response_model=StatusUpdateResponse)