chore(perception): trace Python GC pauses

tests/test_m48s_reference_graph_timing.py

@@ -1,15 +1,14 @@
 from __future__ import annotations
 
 import importlib.util
+import time
 from pathlib import Path
 
 from k1link.perception.detector import DetectorFrameTiming
 from k1link.perception.recorded_source import DecodedFrameTiming
 
 REPOSITORY_ROOT = Path(__file__).resolve().parents[1]
-RUNNER_PATH = (
-    REPOSITORY_ROOT / "experiments/perception/run_m48s_reference_graph_shadow_worker.py"
-)
+RUNNER_PATH = REPOSITORY_ROOT / "experiments/perception/run_m48s_reference_graph_shadow_worker.py"
 SPEC = importlib.util.spec_from_file_location("m48s_timed_shadow_runner", RUNNER_PATH)
 assert SPEC is not None and SPEC.loader is not None
 RUNNER = importlib.util.module_from_spec(SPEC)
@@ -81,3 +80,24 @@ def test_pipeline_timing_metrics_preserve_single_pass_stage_breakdown() -> None:
     assert metrics["graph_unattributed_ms"]["maximum"] == 6.0
     assert metrics["maximum_graph_sequence"] == 3
     assert metrics["additional_inference_passes"] == 0
+
+
+def test_gc_pause_telemetry_attributes_collection_to_active_stage() -> None:
+    telemetry = RUNNER.GcPauseTelemetry()
+    telemetry.enter_stage("rolling", 3928)
+    telemetry._observe("start", {"generation": 2})
+    time.sleep(0.001)
+    telemetry._observe(
+        "stop",
+        {"generation": 2, "collected": 17, "uncollectable": 0},
+    )
+    telemetry.exit_stage()
+
+    summary = RUNNER._gc_telemetry_summary(telemetry.events)
+
+    assert summary["event_count"] == 1
+    assert summary["pipeline_attributed_event_count"] == 1
+    assert summary["maximum_event"]["generation"] == 2
+    assert summary["maximum_event"]["stage_id"] == "rolling"
+    assert summary["maximum_event"]["sequence"] == 3928
+    assert summary["maximum_event"]["duration_ms"] >= 1.0