fix(replay): recover failed archives and release deleted sessions

src/k1link/web/session_api.py

@@ -372,8 +372,10 @@ def build_session_router(
         try:
             store.get_session(session_id)
             recorded_artifacts = store.list_recorded_media(session_id)
-        except SessionNotFoundError as exc:
-            raise HTTPException(status_code=404, detail=str(exc)) from exc
+        except SessionNotFoundError:
+            # DELETE is idempotent. Multiple mounted catalogs or another
+            # operator tab may have already removed the exact session.
+            return Response(status_code=204)
         except ValueError as exc:
             raise HTTPException(
                 status_code=422,
@@ -427,8 +429,10 @@ def build_session_router(
                 (artifact.artifact_id for artifact in recorded_artifacts),
             )
             await run_in_threadpool(store.delete_session, session_id)
-        except SessionNotFoundError as exc:
-            raise HTTPException(status_code=404, detail=str(exc)) from exc
+        except SessionNotFoundError:
+            # A concurrent idempotent delete won the race after both callers
+            # resolved the catalog row.
+            return Response(status_code=204)
         except (OSError, SessionIntegrityError) as exc:
             raise HTTPException(
                 status_code=409,
@@ -469,7 +473,12 @@ def build_session_router(
                         recording_preparation_manager.restore_published,
                         command,
                     )
-                if snapshot is None:
+                if snapshot is None or snapshot.state in {"failed", "cancelled"}:
+                    # A terminal preparation describes one attempt, not the
+                    # durable session. A fresh POST /replay is explicit retry
+                    # intent and must replace that attempt. This also recovers
+                    # the camera-finalization race where the RRD is already
+                    # published but the media archive seals moments later.
                     snapshot = recording_preparation_manager.enqueue(
                         command,
                         retry_failed=True,