phase 1

core/api/detect/sse.py

@@ -0,0 +1,79 @@
+"""
+SSE endpoint for detection pipeline events.
+
+Uses Redis as the event bus between pipeline workers and the SSE stream.
+Mirrors chunker_sse.py but polls detect_events:{job_id}.
+
+GET /detect/stream/{job_id} → text/event-stream
+"""
+
+import asyncio
+import json
+import logging
+import time
+from typing import AsyncGenerator
+
+from fastapi import APIRouter
+from starlette.responses import StreamingResponse
+
+from core.events import poll_events
+from detect.events import DETECT_EVENTS_PREFIX, TERMINAL_EVENTS
+
+logger = logging.getLogger(__name__)
+
+router = APIRouter(prefix="/detect", tags=["detect"])
+
+
+async def _event_generator(job_id: str) -> AsyncGenerator[str, None]:
+    cursor = 0
+    timeout = time.monotonic() + 3600  # 1 hour max
+
+    while time.monotonic() < timeout:
+        events, cursor = poll_events(job_id, cursor, prefix=DETECT_EVENTS_PREFIX)
+
+        if not events:
+            await asyncio.sleep(0.2)
+            continue
+
+        is_terminal = False
+        for data in events:
+            event_type = data.pop("event", "update")
+            payload = {**data, "job_id": job_id}
+
+            yield f"event: {event_type}\ndata: {json.dumps(payload)}\n\n"
+
+            if event_type in TERMINAL_EVENTS:
+                is_terminal = True
+
+        if is_terminal:
+            yield f"event: done\ndata: {json.dumps({'job_id': job_id})}\n\n"
+            # Don't return — keep connection alive so EventSource doesn't reconnect.
+            # Just idle until the client disconnects or timeout.
+            while time.monotonic() < timeout:
+                await asyncio.sleep(5)
+            return
+
+        await asyncio.sleep(0.05)
+
+    yield f"event: timeout\ndata: {json.dumps({'job_id': job_id})}\n\n"
+
+
+@router.get("/stream/{job_id}")
+async def stream_detect_job(job_id: str):
+    """
+    SSE stream for a detection pipeline job.
+
+    The UI connects via native EventSource:
+        const es = new EventSource('/api/detect/stream/<job_id>');
+        es.addEventListener('graph_update', (e) => { ... });
+        es.addEventListener('detection', (e) => { ... });
+    """
+    return StreamingResponse(
+        _event_generator(job_id),
+        media_type="text/event-stream",
+        headers={
+            "Cache-Control": "no-cache",
+            "Connection": "keep-alive",
+            "X-Accel-Buffering": "no",
+        },
+    )