Address CodeRabbit's second-pass review comments

- urimap.json: add the /api/api alias for the no_active_trip fixture,
  matching its sibling HART trip-details entries (the Tampa region's
  base URL produces the doubled path).
- TripExtrapolationController: every failed-frame exit now hides the
  vehicle marker and estimate overlays — the state-missing/shape-missing
  early returns and the degenerate-schedule catch previously left a
  prior frame's marker on screen, unlike the other failure paths. The
  thrice-duplicated hide pair is now one hideFrameOverlays(), and the
  non-finite-median and null-interpolation branches collapse into a
  single failed-frame branch.
- TripState.withStatus KDoc: the "0 to use local clock" fallback never
  existed — entries without a server time are skipped (and tested as
  such); the doc now says so.
- SingleFlight rethrows CancellationException instead of masking a
  cancelled scope as a logged null result, matching the convention
  everywhere else on this branch.

Author: bmander

onebusaway-android/src/androidTest/res/raw/urimap.json

@@ -74,6 +74,7 @@
     "/api/where/trip-details/Hillsborough%20Area%20Regional%20Transit_1389962.json": "trip_details_hart_1389962",
     "/api/api/where/trip-details/Hillsborough%20Area%20Regional%20Transit_1389962.json": "trip_details_hart_1389962",
     "/api/where/trip-details/Hillsborough%20Area%20Regional%20Transit_1389962_no_active_trip.json": "trip_details_hart_1389962_no_active_trip",
+    "/api/api/where/trip-details/Hillsborough%20Area%20Regional%20Transit_1389962_no_active_trip.json": "trip_details_hart_1389962_no_active_trip",
     "/api/where/trip-details/1_18196913.json?includeSchedule=false": "trip_details_1_18196913_no_schedule",
     "/api/where/trip-details/1_18196913.json?includeStatus=false": "trip_details_1_18196913_no_status",
     "/api/where/trip-details/1_18196913.json?includeTrip=false": "trip_details_1_18196913_no_trip",

onebusaway-android/src/google/java/org/onebusaway/android/map/googlemapsv2/tripmap/TripExtrapolationController.kt

@@ -41,8 +41,14 @@ internal constructor(
     fun stop() = frameLoop.stop()
 
     private fun doFrame(now: Long) {
-        val state = lookupTripState(tripId) ?: return
-        val shapeData = state.polyline ?: return
+        val state = lookupTripState(tripId)
+        val shapeData = state?.polyline
+        if (state == null || shapeData == null) {
+            // Nothing to render this frame (trip evicted or shape not hydrated) — don't
+            // leave a previous frame's marker on screen
+            hideFrameOverlays()
+            return
+        }
         val result =
                 try {
                     state.extrapolate(now)
@@ -51,37 +57,34 @@ internal constructor(
                     // surfaces, then skip this frame; the next frame retries. Anything else
                     // propagates rather than degrading silently at 20fps.
                     Log.w(TAG, "Extrapolation failed for $tripId", e)
+                    hideFrameOverlays()
                     return
                 }
 
         when (result) {
             is ExtrapolationResult.Success -> {
                 val distribution = result.distribution
                 val medianDist = distribution.median()
-                if (medianDist.isFinite()) {
-                    val loc = shapeData.interpolate(medianDist)
-                    if (loc != null) {
-                        vehicleOverlay.updateVehiclePosition(loc, state.anchor, now)
-                        vehicleOverlay.updateEstimateOverlays(distribution)
-                    } else {
-                        // Interpolation failed (degenerate polyline) — treat the frame as
-                        // failed rather than leaving a stale marker on screen
-                        vehicleOverlay.hideVehicleMarker()
-                        vehicleOverlay.hideEstimateOverlays()
-                    }
+                val loc = if (medianDist.isFinite()) shapeData.interpolate(medianDist) else null
+                if (loc != null) {
+                    vehicleOverlay.updateVehiclePosition(loc, state.anchor, now)
+                    vehicleOverlay.updateEstimateOverlays(distribution)
                 } else {
-                    // Bisect could not converge on a quantile — treat as a failed
-                    // extrapolation frame rather than propagating NaN into rendering.
-                    vehicleOverlay.hideVehicleMarker()
-                    vehicleOverlay.hideEstimateOverlays()
+                    // Bisect could not converge on a quantile, or interpolation failed on a
+                    // degenerate polyline — treat the frame as failed rather than leaving a
+                    // stale marker or propagating NaN into rendering.
+                    hideFrameOverlays()
                 }
             }
-            else -> {
-                vehicleOverlay.hideVehicleMarker()
-                vehicleOverlay.hideEstimateOverlays()
-            }
+            else -> hideFrameOverlays()
         }
 
         state.anchor?.let { vehicleOverlay.showOrUpdateDataReceivedMarker(it, now) }
     }
+
+    /** Every failed frame renders the same way: no vehicle marker, no estimate overlays. */
+    private fun hideFrameOverlays() {
+        vehicleOverlay.hideVehicleMarker()
+        vehicleOverlay.hideEstimateOverlays()
+    }
 }

onebusaway-android/src/main/java/org/onebusaway/android/extrapolation/data/TripState.kt

@@ -107,7 +107,8 @@ data class TripState(
      * keeps the snapshot — and with it the lazily fitted extrapolator and the anchor
      * instance — intact.
      *
-     * @param serverTimeMs the server's currentTime from the API response, or 0 to use local clock
+     * @param serverTimeMs the server's currentTime from the API response; entries without one
+     *   (zero or negative) are skipped, since the anchor clocks couldn't be derived
      * @param localTimeMs local device clock time when the response was received
      */
     fun withStatus(status: ObaTripStatus, serverTimeMs: Long, localTimeMs: Long): TripState {

onebusaway-android/src/main/java/org/onebusaway/android/util/SingleFlight.kt

@@ -16,6 +16,7 @@
 package org.onebusaway.android.util
 
 import android.util.Log
+import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Deferred
 import kotlinx.coroutines.async
@@ -44,6 +45,8 @@ class SingleFlight<K : Any, V : Any>(private val scope: CoroutineScope) {
                         scope.async {
                             try {
                                 block()
+                            } catch (e: CancellationException) {
+                                throw e // scope cancelled — propagate, don't mask as a null result
                             } catch (e: Exception) {
                                 Log.e(TAG, "Single-flight block failed for $key", e)
                                 null