refactor(lab): canonicalize recorded spatial replay

src/k1link/web/session_api.py

@@ -37,7 +37,10 @@ from k1link.sessions import (
     SessionStore,
     validate_recorded_media_timeline,
 )
-from k1link.sessions.canonical_lab_spatial import canonical_lab_spatial_frame
+from k1link.sessions.canonical_lab_spatial import (
+    CANONICAL_LAB_SPATIAL_PROFILE,
+    canonical_lab_spatial_frame,
+)
 from k1link.sessions.plugin_contract import RecordedPointColorRenderer
 from k1link.viewer.recorded import (
     APPLICATION_ID as RECORDED_APPLICATION_ID,
@@ -832,6 +835,7 @@ def build_session_router(
         session_id: str,
         generation: Annotated[str, Query(min_length=64, max_length=64)],
         time_ns: Annotated[int, Query(ge=0, le=MAX_SAFE_INTEGER)],
+        profile: Literal["source-paced-ground-v2"],
     ) -> JSONResponse:
         """Serve one body-frame sample for the canonical recorded-LAB clock.
 
@@ -890,7 +894,10 @@ def build_session_router(
             payload,
             headers={
                 "Cache-Control": "private, max-age=31536000, immutable",
-                "ETag": f'"{generation}:{payload["source_time_ns"]}"',
+                "ETag": (
+                    f'"{generation}:{CANONICAL_LAB_SPATIAL_PROFILE}:'
+                    f'{payload["source_time_ns"]}"'
+                ),
                 "X-Content-Type-Options": "nosniff",
             },
         )