refactor(streaming): drop arguments no caller varies

resolve_owned_session's include_desktop was never passed, and the two
teardown helpers and stamp_launched defaulted arguments every caller
supplies. The 409 builder's holder snapshot no longer reuses the name of
the container above it.

backend/endpoints/streaming.py

@@ -358,7 +358,7 @@ async def _reserve_container(
         candidates, request.user.id, platform=platform
     )
     if held is not None:
-        holder, _, mine = held
+        own_container, _, mine = held
         if not session_is_stale(mine):
             raise HTTPException(
                 status_code=409,
@@ -371,7 +371,7 @@ async def _reserve_container(
             )
         # Their own session, abandoned. Take that container back rather than
         # rolling them onto a free one and stranding this one until its TTL.
-        candidates = [holder]
+        candidates = [own_container]
 
     async def try_claim(candidate: ResolvedContainer) -> bool:
         # SET NX is atomic: exactly one concurrent claim wins the key. The TTL
@@ -441,7 +441,7 @@ async def _reserve_container(
     # has to come from a live session or the message names no one.
     snapshots = [await get_session(candidate.key) or {} for candidate in candidates]
     draining = any(snapshot.get("draining") for snapshot in snapshots)
-    existing = next(
+    holder = next(
         (
             snapshot
             for snapshot in snapshots
@@ -460,8 +460,8 @@ async def _reserve_container(
         detail={
             "message": message,
             "draining": draining,
-            "rom_name": access.visible_rom_name(request, existing),
-            "claimed_at": existing.get("claimed_at"),
+            "rom_name": access.visible_rom_name(request, holder),
+            "claimed_at": holder.get("claimed_at"),
         },
     )
 

backend/handler/streaming/access.py

@@ -173,7 +173,7 @@ async def resolve_named_container(
 
 
 async def resolve_owned_session(
-    platform: str, request: Request, *, include_desktop: bool = False
+    platform: str, request: Request
 ) -> tuple[ResolvedContainer, str, dict[str, Any]]:
     """Find the caller's session for this platform in its first pool.
 
@@ -194,7 +194,8 @@ async def resolve_owned_session(
         session = await get_live_session(session_key)
         if session is None:
             continue
-        if not _session_in_scope(session, platform, include_desktop):
+        # These routes act on a game; a desktop is reached by naming it.
+        if not _session_in_scope(session, platform, include_desktop=False):
             continue
         if session.get("user_id") == request.user.id:
             return candidate, session_key, session

backend/handler/streaming/lifecycle.py

@@ -396,7 +396,7 @@ async def _teardown_abandoned_session(
     session_key: str,
     session: dict[str, Any],
     *,
-    claimed_by: int | None = None,
+    claimed_by: int,
 ) -> bool:
     """Free a container whose owner vanished without releasing (heartbeat went
     stale). Same order as an owner release: stop the emulator so the card is
@@ -470,7 +470,7 @@ async def await_teardown_within_budget(
     session: dict[str, Any],
     budget: float,
     *,
-    claimed_by: int | None = None,
+    claimed_by: int,
 ) -> bool:
     """Tear down an abandoned session, but only wait `budget` seconds for it.
 

backend/handler/streaming/session_store.py

@@ -426,7 +426,7 @@ async def hold_session_claim(session_key: str, claim: dict[str, Any]) -> None:
 
 
 async def stamp_launched(
-    session_key: str, claim: dict[str, Any], host: str | None = None
+    session_key: str, claim: dict[str, Any], host: str | None
 ) -> None:
     """Record that the activate returned, so the status poll stops asking the
     broker for an extraction phase.