fix: P0+P1 audit — memory leak, hardcoded camera/GPS, lifespan init, background processing, batch validation, ABC interfaces

src/gps_denied/api/deps.py

@@ -1,7 +1,7 @@
 from collections.abc import AsyncGenerator
 from typing import Annotated
 
-from fastapi import Depends
+from fastapi import Depends, Request
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from gps_denied.core.processor import FlightProcessor
@@ -12,17 +12,32 @@ from gps_denied.db.repository import FlightRepository
 # Singleton instance of SSE Event Streamer
 _sse_streamer = SSEEventStreamer()
 
+# Singleton FlightProcessor (one per process, reused across requests)
+_processor: FlightProcessor | None = None
+
+
 def get_sse_streamer() -> SSEEventStreamer:
     return _sse_streamer
 
 async def get_repository(session: AsyncSession = Depends(get_session)) -> FlightRepository:
     return FlightRepository(session)
 
+
 async def get_flight_processor(
+    request: Request,
     repo: FlightRepository = Depends(get_repository),
     sse: SSEEventStreamer = Depends(get_sse_streamer),
 ) -> FlightProcessor:
-    return FlightProcessor(repo, sse)
+    global _processor
+    if _processor is None:
+        _processor = FlightProcessor(repo, sse)
+        # Attach pipeline components from lifespan (P1#4)
+        components = getattr(request.app.state, "pipeline_components", None)
+        if components:
+            _processor.attach_components(**components)
+    # Always update repo (new session per request)
+    _processor.repository = repo
+    return _processor
 
 
 # Type aliases for cleaner router definitions