feat(system): instrument worker pipeline stages

tests/test_e15_shadow_inference.py

@@ -394,3 +394,31 @@ def test_runtime_telemetry_captures_bounded_queue_snapshots() -> None:
     row = json.loads(stream.getvalue())
     assert row["schema_version"] == "missioncore.worker-runtime-telemetry/v1"
     assert row["queues"]["detector"]["maximum_depth"] == 1
+
+
+def test_stage_execution_telemetry_measures_named_spans_without_process_claims() -> None:
+    module = _module()
+    telemetry = module._StageExecutionTelemetry(("detector", "tracking"))
+
+    with telemetry.measure("detector", frame_index=42):
+        pass
+    with telemetry.measure("tracking", frame_index=42):
+        pass
+
+    snapshot = telemetry.snapshot()
+    assert snapshot["current_stage"] is None
+    assert snapshot["active_stages"] == []
+    assert snapshot["active_frame_index"] == 42
+    assert snapshot["stages"]["detector"]["activations"] == 1
+    assert snapshot["stages"]["tracking"]["activations"] == 1
+    assert snapshot["stages"]["detector"]["elapsed_seconds"] >= 0
+    assert snapshot["stages"]["tracking"]["elapsed_seconds"] >= 0
+    assert sum(
+        stage["share_percent"] for stage in snapshot["stages"].values()
+    ) == pytest.approx(100)
+
+    with (
+        pytest.raises(RuntimeError, match="unknown pipeline stage"),
+        telemetry.measure("unregistered"),
+    ):
+        pass