feat(node): push USB changes and preserve sensor setup across sessions

src/k1link/web/fleet_api.py

@@ -2,11 +2,15 @@
 
 from __future__ import annotations
 
+import asyncio
 import ipaddress
+import json
+from contextlib import suppress
 from typing import Annotated
 from urllib.parse import urlsplit
 
 from fastapi import APIRouter, Depends, HTTPException, Request, Response
+from fastapi.responses import StreamingResponse
 from pydantic import BaseModel, ConfigDict, Field
 
 from k1link.fleet.registry import FleetRegistry
@@ -53,6 +57,31 @@ def fleet_list(response: Response, fleet: Annotated[FleetRegistry, Depends(local
     return fleet.listing()
 
 
+@router.get("/events")
+async def fleet_events(fleet: Annotated[FleetRegistry, Depends(local_operator)]):
+    async def stream():
+        queue, close = fleet.events.subscribe()
+        try:
+            while not fleet.stop.is_set():
+                # Full replacement snapshots recover missed events/reconnections.
+                # The timeout updates link expiry locally; it never queries a Node.
+                value = await asyncio.to_thread(fleet.listing)
+                yield "retry: 3000\ndata: " + json.dumps(value) + "\n\n"
+                with suppress(TimeoutError):
+                    await asyncio.wait_for(queue.get(), timeout=5)
+        finally:
+            close()
+
+    return StreamingResponse(
+        stream(),
+        media_type="text/event-stream",
+        headers={
+            "Cache-Control": "no-store",
+            "X-Accel-Buffering": "no",
+        },
+    )
+
+
 @router.post("/preview")
 def fleet_preview(
     body: PreviewRequest,