feat(perception): trace M4.8S pipeline latency

tests/test_perception_graph.py

@@ -60,6 +60,7 @@ from k1link.perception.providers import (
     SourcePacket,
 )
 from k1link.perception.recorded_source import (
+    DecodedFrameTiming,
     DecodedRecordedSource,
     RecordedRavnoves00Source,
     RecordedSourceError,
@@ -869,6 +870,34 @@ def test_decoded_recorded_source_attaches_images_without_detector_logic(tmp_path
     assert int(packets[1].image_payload[0, 0, 0]) == 7
 
 
+def test_decoded_recorded_source_reports_per_frame_decode_timing(tmp_path: Path) -> None:
+    camera_path, timeline_path = _write_recorded_fixture(tmp_path)
+    source = RecordedRavnoves00Source(
+        camera_index_path=camera_path,
+        source_pack_path=timeline_path,
+        expected_frame_count=2,
+        expected_source_pack_sha256=None,
+    )
+    observed: list[DecodedFrameTiming] = []
+
+    class Decoder:
+        def frames(self, _stop_event: Event) -> Iterator[np.ndarray]:
+            yield np.zeros((600, 800, 3), dtype=np.uint8)
+            yield np.zeros((600, 800, 3), dtype=np.uint8)
+
+    packets = list(
+        DecodedRecordedSource(
+            source=source,
+            decoder=Decoder(),
+            timing_observer=observed.append,
+            clock_ns=iter((10, 30, 40, 90, 100)).__next__,
+        ).packets(Event())
+    )
+
+    assert len(packets) == 2
+    assert observed == [DecodedFrameTiming(0, 20), DecodedFrameTiming(1, 50)]
+
+
 def test_decoded_recorded_source_primes_decoder_before_source_clock() -> None:
     events: list[str] = []