fix(replay): serve admitted AI overlays without revalidation

src/k1link/device_plugins/xgrids_k1/rrd_export.py

@@ -55,6 +55,7 @@ JS_MAX_SAFE_INTEGER = (1 << 53) - 1
 RECORDED_VIEW_POINT_DECIMATION_THRESHOLD = 100_000
 RECORDED_VIEW_POINT_STRIDE = 4
 RECORDED_VIEW_POINT_FRAME_STRIDE = 5
+RECORDED_RRD_IDENTITY_VERSION = "missioncore.recorded-rrd/v1"
 
 # Rerun keys viewer state by these IDs.  Reusing them for every settings-only
 # blueprint update makes the update overwrite the existing scene instead of
@@ -216,13 +217,26 @@ def export_k1mqtt_to_rrd(
     _validate_paths(source, destination)
     destination.parent.mkdir(parents=True, exist_ok=True)
 
-    recording_id = str(uuid4())
-    temporary = destination.with_name(f".{destination.name}.{recording_id}.tmp")
     source_sha256 = _sha256_file(
         source,
         cancel_event=cancel_event,
         activity_callback=activity_callback,
     )
+    capture_clock = _optional_capture_clock(source, capture_clock_path)
+    capture_clock_origin = _optional_capture_clock_origin(
+        source,
+        capture_clock_origin_path,
+    )
+    # Rerun uses this identity to merge independently delivered base,
+    # blueprint and perception streams. Bind it to immutable source evidence
+    # so regenerating an unchanged recording does not invalidate every derived
+    # overlay cache.
+    recording_id = _stable_recording_id(
+        source_sha256,
+        capture_clock,
+        capture_clock_origin,
+    )
+    temporary = destination.with_name(f".{destination.name}.{uuid4()}.tmp")
     settings = RerunSceneSettings()
     blueprint = _recorded_blueprint(settings)
     recording: rr.RecordingStream | None = None
@@ -231,11 +245,6 @@ def export_k1mqtt_to_rrd(
 
     counters = _ExportCounters()
     trajectory = _TrajectoryBuffer.empty()
-    capture_clock = _optional_capture_clock(source, capture_clock_path)
-    capture_clock_origin = _optional_capture_clock_origin(
-        source,
-        capture_clock_origin_path,
-    )
     if (
         capture_clock is not None
         and capture_clock_origin is not None
@@ -449,6 +458,31 @@ def _validate_paths(source: Path, destination: Path) -> None:
         raise RrdExportError("RRD export accepts only native K1MQTT captures")
 
 
+def _stable_recording_id(
+    source_sha256: str,
+    capture_clock: CaptureClockEnvelope | None,
+    capture_clock_origin: CaptureClockOrigin | None,
+) -> str:
+    identity = hashlib.sha256()
+    for value in (
+        RECORDED_RRD_IDENTITY_VERSION,
+        source_sha256,
+        str(capture_clock.started_at_epoch_ns) if capture_clock is not None else "-",
+        str(capture_clock.started_monotonic_ns) if capture_clock is not None else "-",
+        str(capture_clock.completed_at_epoch_ns) if capture_clock is not None else "-",
+        str(capture_clock.completed_monotonic_ns) if capture_clock is not None else "-",
+        str(capture_clock_origin.started_at_epoch_ns)
+        if capture_clock_origin is not None
+        else "-",
+        str(capture_clock_origin.started_monotonic_ns)
+        if capture_clock_origin is not None
+        else "-",
+    ):
+        identity.update(value.encode("ascii"))
+        identity.update(b"\0")
+    return f"k1-{identity.hexdigest()}"
+
+
 def _optional_capture_clock(
     source: Path,
     explicit_path: Path | None,