From b3ec8edc87ece404b5f7b3706f5acf2a70de6862 Mon Sep 17 00:00:00 2001
From: tei <tei@Mac-mini-tei.lan>
Date: Thu, 24 Sep 2026 14:39:39 +0900
Subject: [PATCH] feat: add STEP-093 runtime validation tooling

---
 include/mbgl/renderer/retained_underlay.hpp   |  18 +
 .../MapLibreParticleRNTestHost/App.tsx        |   8 +
 .../weather/WeatherRuntimeBridgeModule.kt     |  20 +-
 .../ios/WeatherRuntimeBridge.mm               |  21 +-
 .../src/NativeWeatherRuntimeBridge.ts         |  10 +-
 packages/maplibre-particle-rn/src/types.ts    |  19 +
 .../src/cpp/native_map_view.cpp               |  21 +-
 .../maps/RetainedUnderlayDiagnostics.java     |  62 ++-
 .../src/main/AndroidManifest.xml              |   1 +
 .../ParticleCoreLayerValidationActivity.kt    | 405 +++++++++++++++++-
 ...ctivity_particle_core_layer_validation.xml |   2 +
 platform/ios/src/MLNMapView.h                 |  19 +
 platform/ios/src/MLNMapView.mm                |  26 ++
 src/mbgl/renderer/particle_fast_path.hpp      |   6 +
 src/mbgl/renderer/renderer_impl.cpp           |   6 +
 src/mbgl/renderer/renderer_impl.hpp           |   1 +
 src/mbgl/renderer/retained_underlay_cache.cpp |  16 +
 src/mbgl/renderer/retained_underlay_cache.hpp |   5 +
 .../retained_underlay_runtime_state.hpp       |  78 ++++
 .../renderer/retained_underlay_cache.test.cpp |  45 ++
 20 files changed, 765 insertions(+), 24 deletions(-)

diff --git a/include/mbgl/renderer/retained_underlay.hpp b/include/mbgl/renderer/retained_underlay.hpp
index 87a192605..4dfd3d28a 100644
--- a/include/mbgl/renderer/retained_underlay.hpp
+++ b/include/mbgl/renderer/retained_underlay.hpp
@@ -19,15 +19,33 @@ struct RetainedUnderlayDiagnostics {
     std::string endLayerId;
     int32_t startIndex = -1;
     int32_t endIndex = -1;
+    int32_t continuousBegin = -1;
+    int32_t continuousEndExclusive = -1;
     bool bottomPresent = false;
+    std::string bottomCacheState{"disabled"};
     uint64_t bottomBuild = 0;
     uint64_t bottomReuse = 0;
     uint64_t bottomInvalidation = 0;
+    std::string bottomLastInvalidationReason{"none"};
+    uint64_t bottomTextureCreate = 0;
+    uint64_t bottomCompositeCreate = 0;
+    uint64_t bottomResourceRelease = 0;
     bool topPresent = false;
+    std::string topCacheState{"disabled"};
     uint64_t topBuild = 0;
     uint64_t topReuse = 0;
     uint64_t topInvalidation = 0;
+    std::string topLastInvalidationReason{"none"};
+    uint64_t topTextureCreate = 0;
+    uint64_t topCompositeCreate = 0;
+    uint64_t topResourceRelease = 0;
     bool rangeFallback = false;
+    bool fastPathEligible = false;
+    bool fastPathActive = false;
+    std::string fastPathFallbackReason{"no-prepared-tree"};
+    uint64_t fastPathHit = 0;
+    uint64_t fastPathMiss = 0;
+    uint64_t fullCpuFrame = 0;
 };
 
 struct ContinuousLayerRangeConfig {
diff --git a/integration/react-native/MapLibreParticleRNTestHost/App.tsx b/integration/react-native/MapLibreParticleRNTestHost/App.tsx
index a253c8e64..f56283df3 100644
--- a/integration/react-native/MapLibreParticleRNTestHost/App.tsx
+++ b/integration/react-native/MapLibreParticleRNTestHost/App.tsx
@@ -364,6 +364,14 @@ export default function App() {
               Retained: {retainedSnapshot == null ? "not read" :
                 `${retainedSnapshot.enabled ? "ON" : "OFF"} build=${retainedSnapshot.build} reuse=${retainedSnapshot.reuse} fallback=${retainedSnapshot.fallback} invalidation=${retainedSnapshot.invalidation} reason=${retainedSnapshot.lastReason}`}
             </Text>
+            {retainedSnapshot != null && (
+              <Text selectable>
+                {`Range ${retainedSnapshot.rangeValid ? "VALID" : "INVALID"} [${retainedSnapshot.startIndex},${retainedSnapshot.endIndex}] continuous=[${retainedSnapshot.continuousBegin},${retainedSnapshot.continuousEndExclusive})\n`}
+                {`Bottom ${retainedSnapshot.bottomPresent ? retainedSnapshot.bottomCacheState : "absent"} b/r/i=${retainedSnapshot.bottomBuild}/${retainedSnapshot.bottomReuse}/${retainedSnapshot.bottomInvalidation} tex/comp/rel=${retainedSnapshot.bottomTextureCreate}/${retainedSnapshot.bottomCompositeCreate}/${retainedSnapshot.bottomResourceRelease}\n`}
+                {`Top ${retainedSnapshot.topPresent ? retainedSnapshot.topCacheState : "absent"} b/r/i=${retainedSnapshot.topBuild}/${retainedSnapshot.topReuse}/${retainedSnapshot.topInvalidation} tex/comp/rel=${retainedSnapshot.topTextureCreate}/${retainedSnapshot.topCompositeCreate}/${retainedSnapshot.topResourceRelease}\n`}
+                {`Fast eligible=${retainedSnapshot.fastPathEligible} active=${retainedSnapshot.fastPathActive} hit/miss/full=${retainedSnapshot.fastPathHit}/${retainedSnapshot.fastPathMiss}/${retainedSnapshot.fullCpuFrame} reason=${retainedSnapshot.fastPathFallbackReason}`}
+              </Text>
+            )}
             <View style={styles.row}>
               <Button
                 title={`Retained ${retainedSnapshot?.enabled === false ? "OFF" : "ON"}`}
diff --git a/packages/maplibre-particle-rn/android/src/main/java/org/navsea/maplibre/particle/weather/WeatherRuntimeBridgeModule.kt b/packages/maplibre-particle-rn/android/src/main/java/org/navsea/maplibre/particle/weather/WeatherRuntimeBridgeModule.kt
index a6a9888e7..7708b4c17 100644
--- a/packages/maplibre-particle-rn/android/src/main/java/org/navsea/maplibre/particle/weather/WeatherRuntimeBridgeModule.kt
+++ b/packages/maplibre-particle-rn/android/src/main/java/org/navsea/maplibre/particle/weather/WeatherRuntimeBridgeModule.kt
@@ -85,15 +85,33 @@ class WeatherRuntimeBridgeModule(private val context: ReactApplicationContext) :
             putString("endLayerId", value.endLayerId)
             putInt("startIndex", value.startIndex)
             putInt("endIndex", value.endIndex)
+            putInt("continuousBegin", value.continuousBegin)
+            putInt("continuousEndExclusive", value.continuousEndExclusive)
             putBoolean("bottomPresent", value.bottomPresent)
+            putString("bottomCacheState", value.bottomCacheState)
             putDouble("bottomBuild", value.bottomBuild.toDouble())
             putDouble("bottomReuse", value.bottomReuse.toDouble())
             putDouble("bottomInvalidation", value.bottomInvalidation.toDouble())
+            putString("bottomLastInvalidationReason", value.bottomLastInvalidationReason)
+            putDouble("bottomTextureCreate", value.bottomTextureCreate.toDouble())
+            putDouble("bottomCompositeCreate", value.bottomCompositeCreate.toDouble())
+            putDouble("bottomResourceRelease", value.bottomResourceRelease.toDouble())
             putBoolean("topPresent", value.topPresent)
+            putString("topCacheState", value.topCacheState)
             putDouble("topBuild", value.topBuild.toDouble())
             putDouble("topReuse", value.topReuse.toDouble())
             putDouble("topInvalidation", value.topInvalidation.toDouble())
-            putBoolean("fallback", value.fallback)
+            putString("topLastInvalidationReason", value.topLastInvalidationReason)
+            putDouble("topTextureCreate", value.topTextureCreate.toDouble())
+            putDouble("topCompositeCreate", value.topCompositeCreate.toDouble())
+            putDouble("topResourceRelease", value.topResourceRelease.toDouble())
+            putBoolean("rangeFallback", value.rangeFallback)
+            putBoolean("fastPathEligible", value.fastPathEligible)
+            putBoolean("fastPathActive", value.fastPathActive)
+            putString("fastPathFallbackReason", value.fastPathFallbackReason)
+            putDouble("fastPathHit", value.fastPathHit.toDouble())
+            putDouble("fastPathMiss", value.fastPathMiss.toDouble())
+            putDouble("fullCpuFrame", value.fullCpuFrame.toDouble())
         })
     }
     @ReactMethod override fun clearWindFields(reactTag: Double, promise: Promise) = command(reactTag, promise) { it.clearWindFields() }
diff --git a/packages/maplibre-particle-rn/ios/WeatherRuntimeBridge.mm b/packages/maplibre-particle-rn/ios/WeatherRuntimeBridge.mm
index 403d93de4..64a8faa96 100644
--- a/packages/maplibre-particle-rn/ios/WeatherRuntimeBridge.mm
+++ b/packages/maplibre-particle-rn/ios/WeatherRuntimeBridge.mm
@@ -177,10 +177,25 @@ RCT_EXPORT_MODULE(WeatherRuntimeBridge)
                @"lastReason": value.lastReason, @"rangeConfigured": @(value.rangeConfigured),
                @"rangeValid": @(value.rangeValid), @"startLayerId": value.startLayerId,
                @"endLayerId": value.endLayerId, @"startIndex": @(value.startIndex), @"endIndex": @(value.endIndex),
-               @"bottomPresent": @(value.bottomPresent), @"bottomBuild": @(value.bottomBuild),
+               @"continuousBegin": @(value.continuousBegin), @"continuousEndExclusive": @(value.continuousEndExclusive),
+               @"bottomPresent": @(value.bottomPresent), @"bottomCacheState": value.bottomCacheState,
+               @"bottomBuild": @(value.bottomBuild),
                @"bottomReuse": @(value.bottomReuse), @"bottomInvalidation": @(value.bottomInvalidation),
-               @"topPresent": @(value.topPresent), @"topBuild": @(value.topBuild),
-               @"topReuse": @(value.topReuse), @"topInvalidation": @(value.topInvalidation) });
+               @"bottomLastInvalidationReason": value.bottomLastInvalidationReason,
+               @"bottomTextureCreate": @(value.bottomTextureCreate),
+               @"bottomCompositeCreate": @(value.bottomCompositeCreate),
+               @"bottomResourceRelease": @(value.bottomResourceRelease),
+               @"topPresent": @(value.topPresent), @"topCacheState": value.topCacheState,
+               @"topBuild": @(value.topBuild), @"topReuse": @(value.topReuse),
+               @"topInvalidation": @(value.topInvalidation),
+               @"topLastInvalidationReason": value.topLastInvalidationReason,
+               @"topTextureCreate": @(value.topTextureCreate),
+               @"topCompositeCreate": @(value.topCompositeCreate),
+               @"topResourceRelease": @(value.topResourceRelease),
+               @"rangeFallback": @(value.rangeFallback), @"fastPathEligible": @(value.fastPathEligible),
+               @"fastPathActive": @(value.fastPathActive), @"fastPathFallbackReason": value.fastPathFallbackReason,
+               @"fastPathHit": @(value.fastPathHit), @"fastPathMiss": @(value.fastPathMiss),
+               @"fullCpuFrame": @(value.fullCpuFrame) });
   }];
 }
 
diff --git a/packages/maplibre-particle-rn/src/NativeWeatherRuntimeBridge.ts b/packages/maplibre-particle-rn/src/NativeWeatherRuntimeBridge.ts
index 26dbed8b8..83fd838a3 100644
--- a/packages/maplibre-particle-rn/src/NativeWeatherRuntimeBridge.ts
+++ b/packages/maplibre-particle-rn/src/NativeWeatherRuntimeBridge.ts
@@ -12,8 +12,14 @@ type RuntimeSnapshot = { state: RuntimeState; playbackState: PlaybackState; targ
 type RetainedUnderlaySnapshot = {
   enabled: boolean; build: number; reuse: number; fallback: number; invalidation: number; lastReason: string;
   rangeConfigured: boolean; rangeValid: boolean; startLayerId: string; endLayerId: string;
-  startIndex: number; endIndex: number; bottomPresent: boolean; bottomBuild: number; bottomReuse: number;
-  bottomInvalidation: number; topPresent: boolean; topBuild: number; topReuse: number; topInvalidation: number;
+  startIndex: number; endIndex: number; continuousBegin: number; continuousEndExclusive: number;
+  bottomPresent: boolean; bottomCacheState: string; bottomBuild: number; bottomReuse: number;
+  bottomInvalidation: number; bottomLastInvalidationReason: string; bottomTextureCreate: number;
+  bottomCompositeCreate: number; bottomResourceRelease: number;
+  topPresent: boolean; topCacheState: string; topBuild: number; topReuse: number; topInvalidation: number;
+  topLastInvalidationReason: string; topTextureCreate: number; topCompositeCreate: number;
+  topResourceRelease: number; rangeFallback: boolean; fastPathEligible: boolean; fastPathActive: boolean;
+  fastPathFallbackReason: string; fastPathHit: number; fastPathMiss: number; fullCpuFrame: number;
 };
 export interface Spec extends TurboModule {
   attach(reactTag: number): Promise<RuntimeSnapshot>;
diff --git a/packages/maplibre-particle-rn/src/types.ts b/packages/maplibre-particle-rn/src/types.ts
index b7df32d17..1fc7b4367 100644
--- a/packages/maplibre-particle-rn/src/types.ts
+++ b/packages/maplibre-particle-rn/src/types.ts
@@ -34,12 +34,31 @@ export type RetainedUnderlayDiagnostics = Readonly<{
   endLayerId: string;
   startIndex: number;
   endIndex: number;
+  continuousBegin: number;
+  continuousEndExclusive: number;
   bottomPresent: boolean;
+  bottomCacheState: string;
   bottomBuild: number;
   bottomReuse: number;
   bottomInvalidation: number;
+  bottomLastInvalidationReason: string;
+  bottomTextureCreate: number;
+  bottomCompositeCreate: number;
+  bottomResourceRelease: number;
   topPresent: boolean;
+  topCacheState: string;
   topBuild: number;
   topReuse: number;
   topInvalidation: number;
+  topLastInvalidationReason: string;
+  topTextureCreate: number;
+  topCompositeCreate: number;
+  topResourceRelease: number;
+  rangeFallback: boolean;
+  fastPathEligible: boolean;
+  fastPathActive: boolean;
+  fastPathFallbackReason: string;
+  fastPathHit: number;
+  fastPathMiss: number;
+  fullCpuFrame: number;
 }>;
diff --git a/platform/android/MapLibreAndroid/src/cpp/native_map_view.cpp b/platform/android/MapLibreAndroid/src/cpp/native_map_view.cpp
index 1e1845670..6b74ba0fa 100644
--- a/platform/android/MapLibreAndroid/src/cpp/native_map_view.cpp
+++ b/platform/android/MapLibreAndroid/src/cpp/native_map_view.cpp
@@ -729,7 +729,7 @@ jni::jboolean NativeMapView::setContinuousLayerRange(JNIEnv& env,
 
 jni::Local<jni::Array<jni::String>> NativeMapView::getRetainedUnderlayDiagnostics(JNIEnv& env) {
     const auto snapshot = map->getRetainedUnderlayDiagnostics();
-    const std::array<std::string, 20> values = {
+    const std::array<std::string, 39> values = {
         snapshot.enabled ? "true" : "false",
         std::to_string(snapshot.build),
         std::to_string(snapshot.reuse),
@@ -742,14 +742,33 @@ jni::Local<jni::Array<jni::String>> NativeMapView::getRetainedUnderlayDiagnostic
         snapshot.endLayerId,
         std::to_string(snapshot.startIndex),
         std::to_string(snapshot.endIndex),
+        std::to_string(snapshot.continuousBegin),
+        std::to_string(snapshot.continuousEndExclusive),
         snapshot.bottomPresent ? "true" : "false",
+        snapshot.bottomCacheState,
         std::to_string(snapshot.bottomBuild),
         std::to_string(snapshot.bottomReuse),
         std::to_string(snapshot.bottomInvalidation),
+        snapshot.bottomLastInvalidationReason,
+        std::to_string(snapshot.bottomTextureCreate),
+        std::to_string(snapshot.bottomCompositeCreate),
+        std::to_string(snapshot.bottomResourceRelease),
         snapshot.topPresent ? "true" : "false",
+        snapshot.topCacheState,
         std::to_string(snapshot.topBuild),
         std::to_string(snapshot.topReuse),
         std::to_string(snapshot.topInvalidation),
+        snapshot.topLastInvalidationReason,
+        std::to_string(snapshot.topTextureCreate),
+        std::to_string(snapshot.topCompositeCreate),
+        std::to_string(snapshot.topResourceRelease),
+        snapshot.rangeFallback ? "true" : "false",
+        snapshot.fastPathEligible ? "true" : "false",
+        snapshot.fastPathActive ? "true" : "false",
+        snapshot.fastPathFallbackReason,
+        std::to_string(snapshot.fastPathHit),
+        std::to_string(snapshot.fastPathMiss),
+        std::to_string(snapshot.fullCpuFrame),
     };
     auto result = jni::Array<jni::String>::New(env, values.size());
     for (std::size_t index = 0; index < values.size(); ++index) {
diff --git a/platform/android/MapLibreAndroid/src/main/java/org/maplibre/android/maps/RetainedUnderlayDiagnostics.java b/platform/android/MapLibreAndroid/src/main/java/org/maplibre/android/maps/RetainedUnderlayDiagnostics.java
index 7b117fd70..665b11822 100644
--- a/platform/android/MapLibreAndroid/src/main/java/org/maplibre/android/maps/RetainedUnderlayDiagnostics.java
+++ b/platform/android/MapLibreAndroid/src/main/java/org/maplibre/android/maps/RetainedUnderlayDiagnostics.java
@@ -18,18 +18,37 @@ public final class RetainedUnderlayDiagnostics {
   @NonNull public final String endLayerId;
   public final int startIndex;
   public final int endIndex;
+  public final int continuousBegin;
+  public final int continuousEndExclusive;
   public final boolean bottomPresent;
+  @NonNull public final String bottomCacheState;
   public final long bottomBuild;
   public final long bottomReuse;
   public final long bottomInvalidation;
+  @NonNull public final String bottomLastInvalidationReason;
+  public final long bottomTextureCreate;
+  public final long bottomCompositeCreate;
+  public final long bottomResourceRelease;
   public final boolean topPresent;
+  @NonNull public final String topCacheState;
   public final long topBuild;
   public final long topReuse;
   public final long topInvalidation;
+  @NonNull public final String topLastInvalidationReason;
+  public final long topTextureCreate;
+  public final long topCompositeCreate;
+  public final long topResourceRelease;
+  public final boolean rangeFallback;
+  public final boolean fastPathEligible;
+  public final boolean fastPathActive;
+  @NonNull public final String fastPathFallbackReason;
+  public final long fastPathHit;
+  public final long fastPathMiss;
+  public final long fullCpuFrame;
 
   RetainedUnderlayDiagnostics(@NonNull String[] values) {
-    if (values.length != 20) {
-      throw new IllegalArgumentException("Retained-range diagnostics require 20 values");
+    if (values.length != 39) {
+      throw new IllegalArgumentException("Retained-range diagnostics require 39 values");
     }
     enabled = Boolean.parseBoolean(values[0]);
     build = Long.parseLong(values[1]);
@@ -43,20 +62,41 @@ public final class RetainedUnderlayDiagnostics {
     endLayerId = values[9];
     startIndex = Integer.parseInt(values[10]);
     endIndex = Integer.parseInt(values[11]);
-    bottomPresent = Boolean.parseBoolean(values[12]);
-    bottomBuild = Long.parseLong(values[13]);
-    bottomReuse = Long.parseLong(values[14]);
-    bottomInvalidation = Long.parseLong(values[15]);
-    topPresent = Boolean.parseBoolean(values[16]);
-    topBuild = Long.parseLong(values[17]);
-    topReuse = Long.parseLong(values[18]);
-    topInvalidation = Long.parseLong(values[19]);
+    continuousBegin = Integer.parseInt(values[12]);
+    continuousEndExclusive = Integer.parseInt(values[13]);
+    bottomPresent = Boolean.parseBoolean(values[14]);
+    bottomCacheState = values[15];
+    bottomBuild = Long.parseLong(values[16]);
+    bottomReuse = Long.parseLong(values[17]);
+    bottomInvalidation = Long.parseLong(values[18]);
+    bottomLastInvalidationReason = values[19];
+    bottomTextureCreate = Long.parseLong(values[20]);
+    bottomCompositeCreate = Long.parseLong(values[21]);
+    bottomResourceRelease = Long.parseLong(values[22]);
+    topPresent = Boolean.parseBoolean(values[23]);
+    topCacheState = values[24];
+    topBuild = Long.parseLong(values[25]);
+    topReuse = Long.parseLong(values[26]);
+    topInvalidation = Long.parseLong(values[27]);
+    topLastInvalidationReason = values[28];
+    topTextureCreate = Long.parseLong(values[29]);
+    topCompositeCreate = Long.parseLong(values[30]);
+    topResourceRelease = Long.parseLong(values[31]);
+    rangeFallback = Boolean.parseBoolean(values[32]);
+    fastPathEligible = Boolean.parseBoolean(values[33]);
+    fastPathActive = Boolean.parseBoolean(values[34]);
+    fastPathFallbackReason = values[35];
+    fastPathHit = Long.parseLong(values[36]);
+    fastPathMiss = Long.parseLong(values[37]);
+    fullCpuFrame = Long.parseLong(values[38]);
   }
 
   static RetainedUnderlayDiagnostics unavailable() {
     return new RetainedUnderlayDiagnostics(new String[] {
       "true", "0", "0", "0", "0", "unavailable", "false", "false", "", "", "-1", "-1",
-      "false", "0", "0", "0", "false", "0", "0", "0"
+      "-1", "-1", "false", "disabled", "0", "0", "0", "none", "0", "0", "0",
+      "false", "disabled", "0", "0", "0", "none", "0", "0", "0", "false", "false",
+      "false", "no-prepared-tree", "0", "0", "0"
     });
   }
 }
diff --git a/platform/android/MapLibreAndroidTestApp/src/main/AndroidManifest.xml b/platform/android/MapLibreAndroidTestApp/src/main/AndroidManifest.xml
index 679d63a6a..bcb46e34d 100644
--- a/platform/android/MapLibreAndroidTestApp/src/main/AndroidManifest.xml
+++ b/platform/android/MapLibreAndroidTestApp/src/main/AndroidManifest.xml
@@ -288,6 +288,7 @@
         </activity>
         <activity
             android:name=".activity.particle.ParticleCoreLayerValidationActivity"
+            android:configChanges="orientation|keyboardHidden|screenSize"
             android:description="@string/description_particle_core_layer_validation"
             android:exported="true"
             android:label="@string/activity_particle_core_layer_validation">
diff --git a/platform/android/MapLibreAndroidTestApp/src/main/java/org/maplibre/android/testapp/activity/particle/ParticleCoreLayerValidationActivity.kt b/platform/android/MapLibreAndroidTestApp/src/main/java/org/maplibre/android/testapp/activity/particle/ParticleCoreLayerValidationActivity.kt
index 15136d897..2ee11d3b0 100644
--- a/platform/android/MapLibreAndroidTestApp/src/main/java/org/maplibre/android/testapp/activity/particle/ParticleCoreLayerValidationActivity.kt
+++ b/platform/android/MapLibreAndroidTestApp/src/main/java/org/maplibre/android/testapp/activity/particle/ParticleCoreLayerValidationActivity.kt
@@ -2,6 +2,8 @@ package org.maplibre.android.testapp.activity.particle
 
 import android.graphics.Color
 import android.os.Bundle
+import android.os.Handler
+import android.os.Looper
 import android.text.InputType
 import android.util.Log
 import android.widget.Button
@@ -28,6 +30,7 @@ class ParticleCoreLayerValidationActivity : AppCompatActivity() {
     private lateinit var mapView: MapView
     private lateinit var maplibreMap: MapLibreMap
     private lateinit var status: TextView
+    private lateinit var diagnostics: TextView
     private var active = true
     private var enabled = true
     private var maskMode = MASK_GLOBAL
@@ -51,6 +54,21 @@ class ParticleCoreLayerValidationActivity : AppCompatActivity() {
     private var navSeaPbfRenderEnabled = true
     private var navSeaPbfLayerVisibility = emptyList<NavSeaPbfLayerVisibility>()
     private var retainedCacheEnabled = true
+    private var step093Mode = false
+    private var step093Topology = Step093Topology.BOTTOM_CONTINUOUS_TOP
+    private var step093Variant = Step093Variant.DEFAULT
+    private var step093StartVisible = true
+    private var step093EndVisible = true
+    private var step093CameraPreset = 0
+    private val step093Handler = Handler(Looper.getMainLooper())
+    private val step093DiagnosticsPoll = object : Runnable {
+        override fun run() {
+            if (step093Mode && this@ParticleCoreLayerValidationActivity::maplibreMap.isInitialized) {
+                refreshStep093Diagnostics(log = false)
+                step093Handler.postDelayed(this, STEP093_DIAGNOSTICS_INTERVAL_MS)
+            }
+        }
+    }
     private var realWeatherTuningMenu: PopupMenu? = null
     private var realWeatherMenuAnchor: android.view.View? = null
     private var openRealWeatherTuningAfterStyle = false
@@ -88,6 +106,13 @@ class ParticleCoreLayerValidationActivity : AppCompatActivity() {
             ?: NavSeaPbfPosition.AFTER_CLIP
         navSeaPbfRenderEnabled = savedInstanceState?.getBoolean(STATE_NAVSEA_PBF_RENDER_ENABLED, true) ?: true
         retainedCacheEnabled = savedInstanceState?.getBoolean(STATE_RETAINED_CACHE_ENABLED, true) ?: true
+        step093Mode = savedInstanceState?.getBoolean(STATE_STEP093_MODE, false) ?: false
+        step093Topology = savedInstanceState?.getString(STATE_STEP093_TOPOLOGY)
+            ?.let { value -> Step093Topology.values().firstOrNull { it.name == value } }
+            ?: Step093Topology.BOTTOM_CONTINUOUS_TOP
+        step093Variant = savedInstanceState?.getString(STATE_STEP093_VARIANT)
+            ?.let { value -> Step093Variant.values().firstOrNull { it.name == value } }
+            ?: Step093Variant.DEFAULT
         super.onCreate(savedInstanceState)
         Log.i(
             TAG,
@@ -98,6 +123,7 @@ class ParticleCoreLayerValidationActivity : AppCompatActivity() {
 
         mapView = findViewById(R.id.mapView)
         status = findViewById(R.id.validationStatus)
+        diagnostics = findViewById(R.id.validationDiagnostics)
         mapView.addOnDidFailLoadingMapListener { errorMessage ->
             if (navSeaPbfMode || purePbfMode) {
                 Log.e(TAG, "NAVSEA_PBF_STYLE_ERROR reason=$errorMessage")
@@ -119,7 +145,8 @@ class ParticleCoreLayerValidationActivity : AppCompatActivity() {
             updateNavSeaPbfButtonState()
             updatePbfModeButtonState()
             updateRetainedCacheButtonState()
-            loadValidationStyle(active = active, enabled = enabled, reason = "INITIAL")
+            if (step093Mode) loadStep093Style(configureBeforeStyle = false)
+            else loadValidationStyle(active = active, enabled = enabled, reason = "INITIAL")
         }
 
         findViewById<Button>(R.id.validationActive).setOnClickListener {
@@ -251,6 +278,7 @@ class ParticleCoreLayerValidationActivity : AppCompatActivity() {
         findViewById<Button>(R.id.validationMenuNavSeaPbf).setOnClickListener { showNavSeaPbfMenu(it) }
         findViewById<Button>(R.id.validationMenuPbfMode).setOnClickListener { showPbfModeMenu(it) }
         findViewById<Button>(R.id.validationMenuRetainedCache).setOnClickListener { showRetainedCacheMenu(it) }
+        findViewById<Button>(R.id.validationMenuStep093).setOnClickListener { showStep093Menu(it) }
         findViewById<Button>(R.id.validationMenuMore).setOnClickListener { dismissRealWeatherTuning(); showMenu(it, "MORE", intArrayOf(R.id.validationActive, R.id.validationStatic, R.id.validationDisable, R.id.validationEnable, R.id.validationUniformEast, R.id.validationUniformNorth, R.id.validationVortex, R.id.validationTimeWindow, R.id.validationHostFieldSubmit, R.id.validationProductionInvalid, R.id.validationHostFieldDuplicate, R.id.validationHostFieldInvalid, R.id.validationAdvanceWindow, R.id.validationDuplicateWindow)) }
     }
 
@@ -264,8 +292,32 @@ class ParticleCoreLayerValidationActivity : AppCompatActivity() {
         TOP("TOP")
     }
 
+    private enum class Step093Topology(val label: String, val bottom: Boolean, val top: Boolean) {
+        BOTTOM_CONTINUOUS_TOP("A BOTTOM + CONTINUOUS + TOP", true, true),
+        BOTTOM_CONTINUOUS("B BOTTOM + CONTINUOUS", true, false),
+        CONTINUOUS_TOP("C CONTINUOUS + TOP", false, true),
+        CONTINUOUS_ONLY("D CONTINUOUS ONLY", false, false),
+        SINGLE_LAYER("E SINGLE-LAYER CONTINUOUS", true, true)
+    }
+
+    private enum class Step093Variant {
+        DEFAULT,
+        CONTINUOUS_ADD,
+        CONTINUOUS_REORDER,
+        BOTTOM_ADD,
+        BOTTOM_REORDER,
+        TOP_ADD,
+        TOP_REORDER,
+        CROSS_BOTTOM,
+        CROSS_CONTINUOUS,
+        CROSS_TOP,
+        START_MISSING,
+        END_MISSING,
+        FAST_PATH_FAIL_CLOSED
+    }
+
     private fun activateRealWeather(anchor: android.view.View?) {
-        if (isPbfMatrixMode()) leaveRealWeatherMode()
+        if (isPbfMatrixMode() || step093Mode) leaveRealWeatherMode()
         realWeatherMenuAnchor = anchor ?: findViewById(R.id.validationMenuRealWeather)
         if (realWeatherMode) {
             if (realWeatherTuningMenu == null) showRealWeatherTuning(realWeatherMenuAnchor!!) else dismissRealWeatherTuning()
@@ -296,6 +348,8 @@ class ParticleCoreLayerValidationActivity : AppCompatActivity() {
     }
 
     private fun leaveRealWeatherMode() {
+        step093Mode = false
+        step093Handler.removeCallbacks(step093DiagnosticsPoll)
         dismissRealWeatherTuning()
         weatherRuntime?.dispose()
         weatherRuntime = null
@@ -381,6 +435,233 @@ class ParticleCoreLayerValidationActivity : AppCompatActivity() {
         )
     }
 
+    private fun showStep093Menu(anchor: android.view.View) {
+        PopupMenu(this, anchor).apply {
+            Step093Topology.values().forEachIndexed { index, topology ->
+                menu.add(0, index, index, topology.label)
+            }
+            menu.add(0, 10, 10, "MUTATION / FAST PATH")
+            menu.add(0, 11, 11, "ENDPOINT / VISIBILITY")
+            menu.add(0, 12, 12, "INVALID RANGE")
+            menu.add(0, 13, 13, "CAMERA NEXT")
+            menu.add(0, 14, 14, "READ DIAGNOSTICS")
+            menu.add(0, 15, 15, "RESET DEFAULT A")
+            setOnMenuItemClickListener { item ->
+                when (item.itemId) {
+                    in Step093Topology.values().indices -> applyStep093Scene(Step093Topology.values()[item.itemId])
+                    10 -> showStep093MutationMenu(anchor)
+                    11 -> showStep093EndpointMenu(anchor)
+                    12 -> showStep093InvalidMenu(anchor)
+                    13 -> applyStep093CameraPreset()
+                    14 -> refreshStep093Diagnostics(log = true)
+                    15 -> applyStep093Scene(Step093Topology.BOTTOM_CONTINUOUS_TOP)
+                }
+                true
+            }
+            show()
+        }
+    }
+
+    private fun showStep093MutationMenu(anchor: android.view.View) {
+        val actions = arrayOf(
+            "CONTINUOUS ADD", "CONTINUOUS REORDER", "BOTTOM ADD", "BOTTOM REORDER",
+            "TOP ADD", "TOP REORDER", "CROSS → BOTTOM", "CROSS → CONTINUOUS",
+            "CROSS → TOP", "FAST FAIL-CLOSED", "RESTORE DEFAULT"
+        )
+        PopupMenu(this, anchor).apply {
+            actions.forEachIndexed { index, label -> menu.add(0, index, index, label) }
+            setOnMenuItemClickListener { item ->
+                val variant = when (item.itemId) {
+                    0 -> Step093Variant.CONTINUOUS_ADD
+                    1 -> Step093Variant.CONTINUOUS_REORDER
+                    2 -> Step093Variant.BOTTOM_ADD
+                    3 -> Step093Variant.BOTTOM_REORDER
+                    4 -> Step093Variant.TOP_ADD
+                    5 -> Step093Variant.TOP_REORDER
+                    6 -> Step093Variant.CROSS_BOTTOM
+                    7 -> Step093Variant.CROSS_CONTINUOUS
+                    8 -> Step093Variant.CROSS_TOP
+                    9 -> Step093Variant.FAST_PATH_FAIL_CLOSED
+                    else -> Step093Variant.DEFAULT
+                }
+                applyStep093Scene(Step093Topology.BOTTOM_CONTINUOUS_TOP, variant)
+                true
+            }
+            show()
+        }
+    }
+
+    private fun showStep093EndpointMenu(anchor: android.view.View) {
+        val actions = arrayOf(
+            "START VISIBLE ↔ HIDDEN", "END VISIBLE ↔ HIDDEN", "DELETE START", "RESTORE START",
+            "DELETE END", "RESTORE END"
+        )
+        PopupMenu(this, anchor).apply {
+            actions.forEachIndexed { index, label -> menu.add(0, index, index, label) }
+            setOnMenuItemClickListener { item ->
+                when (item.itemId) {
+                    0 -> toggleStep093Endpoint(start = true)
+                    1 -> toggleStep093Endpoint(start = false)
+                    2 -> applyStep093Scene(Step093Topology.BOTTOM_CONTINUOUS_TOP, Step093Variant.START_MISSING)
+                    3 -> applyStep093Scene(Step093Topology.BOTTOM_CONTINUOUS_TOP)
+                    4 -> applyStep093Scene(Step093Topology.BOTTOM_CONTINUOUS_TOP, Step093Variant.END_MISSING)
+                    5 -> applyStep093Scene(Step093Topology.BOTTOM_CONTINUOUS_TOP)
+                }
+                true
+            }
+            show()
+        }
+    }
+
+    private fun showStep093InvalidMenu(anchor: android.view.View) {
+        val actions = arrayOf(
+            "MISSING START", "MISSING END", "REVERSED", "CONFIGURE WHILE STYLE LOADING", "EMPTY ID", "RESTORE VALID"
+        )
+        PopupMenu(this, anchor).apply {
+            actions.forEachIndexed { index, label -> menu.add(0, index, index, label) }
+            setOnMenuItemClickListener { item ->
+                if (!ensureStep093Scene()) {
+                    Log.i(TAG, "STEP093_ACTION scene initialized; repeat invalid-range action after READY")
+                    return@setOnMenuItemClickListener true
+                }
+                when (item.itemId) {
+                    0 -> setStep093Range("step093-missing-start", STEP093_PARTICLE_LAYER_ID, "INVALID_MISSING_START")
+                    1 -> setStep093Range(STEP093_WEATHER_LAYER_ID, "step093-missing-end", "INVALID_MISSING_END")
+                    2 -> setStep093Range(STEP093_PARTICLE_LAYER_ID, STEP093_WEATHER_LAYER_ID, "INVALID_REVERSED")
+                    3 -> applyStep093Scene(
+                        Step093Topology.BOTTOM_CONTINUOUS_TOP,
+                        Step093Variant.DEFAULT,
+                        configureBeforeStyle = true
+                    )
+                    4 -> {
+                        val accepted = maplibreMap.setContinuousLayerRange("", STEP093_PARTICLE_LAYER_ID)
+                        Log.i(TAG, "STEP093_RANGE action=EMPTY_ID accepted=$accepted expected=false")
+                        refreshStep093Diagnostics(log = true)
+                    }
+                    5 -> setStep093Range(STEP093_WEATHER_LAYER_ID, STEP093_PARTICLE_LAYER_ID, "RESTORE_VALID")
+                }
+                true
+            }
+            show()
+        }
+    }
+
+    private fun ensureStep093Scene(): Boolean {
+        if (step093Mode && styleReady) return true
+        applyStep093Scene(Step093Topology.BOTTOM_CONTINUOUS_TOP)
+        return false
+    }
+
+    private fun applyStep093Scene(
+        topology: Step093Topology,
+        variant: Step093Variant = Step093Variant.DEFAULT,
+        configureBeforeStyle: Boolean = false
+    ) {
+        leaveRealWeatherMode()
+        step093Mode = true
+        step093Topology = topology
+        step093Variant = variant
+        step093StartVisible = true
+        step093EndVisible = true
+        timeWindowMode = true
+        productionFeedMode = false
+        hostSubmissionMode = true
+        realWeatherMode = false
+        pureParticleMode = false
+        purePbfMode = false
+        navSeaPbfMode = false
+        active = true
+        enabled = true
+        retainedCacheEnabled = true
+        maplibreMap.setRetainedUnderlayEnabled(true)
+        updateRetainedCacheButtonState()
+        loadStep093Style(configureBeforeStyle)
+    }
+
+    private fun loadStep093Style(configureBeforeStyle: Boolean) {
+        weatherRuntime?.dispose()
+        weatherRuntime = null
+        styleReady = false
+        val epoch = ++styleLoadEpoch
+        val range = step093Range()
+        status.text = "STEP-093 · ${step093Topology.label} · ${step093Variant.name} · LOADING"
+        maplibreMap.setStyle(Style.Builder().fromJson(step093StyleJson())) {
+            if (!step093Mode || epoch != styleLoadEpoch) return@setStyle
+            styleReady = true
+            if (!configureBeforeStyle) maplibreMap.setContinuousLayerRange(range.first, range.second)
+            submitHostValidationDataset()
+            fitRealWeatherBounds()
+            status.text = "STEP-093 · ${step093Topology.label} · ${step093Variant.name}"
+            startStep093DiagnosticsPolling()
+            refreshStep093Diagnostics(log = true)
+            Log.i(
+                TAG,
+                "STEP093_SCENE_READY topology=${step093Topology.name} variant=${step093Variant.name} " +
+                "range=${range.first}..${range.second}"
+            )
+        }
+        if (configureBeforeStyle) {
+            maplibreMap.setContinuousLayerRange(range.first, range.second)
+            Log.i(TAG, "STEP093_RANGE action=CONFIGURE_WHILE_STYLE_LOADING start=${range.first} end=${range.second}")
+            refreshStep093Diagnostics(log = true)
+        }
+    }
+
+    private fun step093Range(): Pair<String, String> = if (step093Topology == Step093Topology.SINGLE_LAYER) {
+        STEP093_PARTICLE_LAYER_ID to STEP093_PARTICLE_LAYER_ID
+    } else {
+        STEP093_WEATHER_LAYER_ID to STEP093_PARTICLE_LAYER_ID
+    }
+
+    private fun setStep093Range(start: String, end: String, action: String) {
+        val accepted = maplibreMap.setContinuousLayerRange(start, end)
+        Log.i(TAG, "STEP093_RANGE action=$action accepted=$accepted start=$start end=$end")
+        refreshStep093Diagnostics(log = true)
+    }
+
+    private fun toggleStep093Endpoint(start: Boolean) {
+        if (!ensureStep093Scene()) return
+        val id = if (start) step093Range().first else step093Range().second
+        val visible = if (start) !step093StartVisible else !step093EndVisible
+        val accepted = maplibreMap.setStyleLayerVisibility(id, visible)
+        if (start) step093StartVisible = visible else step093EndVisible = visible
+        Log.i(TAG, "STEP093_VISIBILITY endpoint=${if (start) "start" else "end"} id=$id visible=$visible accepted=$accepted")
+        refreshStep093Diagnostics(log = true)
+    }
+
+    private fun applyStep093CameraPreset() {
+        if (!ensureStep093Scene()) return
+        step093CameraPreset = (step093CameraPreset + 1) % 4
+        val position = when (step093CameraPreset) {
+            1 -> CameraPosition.Builder().target(LatLng(31.0, 139.0)).zoom(3.5).bearing(0.0).tilt(0.0).build()
+            2 -> CameraPosition.Builder().target(LatLng(25.0, 132.0)).zoom(4.5).bearing(55.0).tilt(0.0).build()
+            3 -> CameraPosition.Builder().target(LatLng(37.0, 145.0)).zoom(5.0).bearing(120.0).tilt(45.0).build()
+            else -> CameraPosition.Builder().target(LatLng(28.0, 135.0)).zoom(3.0).bearing(0.0).tilt(0.0).build()
+        }
+        maplibreMap.animateCamera(CameraUpdateFactory.newCameraPosition(position), 700)
+        Log.i(TAG, "STEP093_CAMERA preset=$step093CameraPreset position=$position")
+    }
+
+    private fun startStep093DiagnosticsPolling() {
+        step093Handler.removeCallbacks(step093DiagnosticsPoll)
+        step093Handler.post(step093DiagnosticsPoll)
+    }
+
+    private fun refreshStep093Diagnostics(log: Boolean) {
+        val snapshot = maplibreMap.retainedUnderlayDiagnostics
+        val cacheCount = (if (snapshot.bottomPresent) 1 else 0) + (if (snapshot.topPresent) 1 else 0)
+        diagnostics.text = buildString {
+            append("Range cfg=${snapshot.rangeConfigured} valid=${snapshot.rangeValid} fallback=${snapshot.rangeFallback} reason=${snapshot.lastReason}\n")
+            append("${snapshot.startLayerId}[${snapshot.startIndex}]..${snapshot.endLayerId}[${snapshot.endIndex}] C=[${snapshot.continuousBegin},${snapshot.continuousEndExclusive}) caches=$cacheCount\n")
+            append("B ${snapshot.bottomPresent}/${snapshot.bottomCacheState} b/r/i=${snapshot.bottomBuild}/${snapshot.bottomReuse}/${snapshot.bottomInvalidation} res=${snapshot.bottomTextureCreate}/${snapshot.bottomCompositeCreate}/${snapshot.bottomResourceRelease} ${snapshot.bottomLastInvalidationReason}\n")
+            append("T ${snapshot.topPresent}/${snapshot.topCacheState} b/r/i=${snapshot.topBuild}/${snapshot.topReuse}/${snapshot.topInvalidation} res=${snapshot.topTextureCreate}/${snapshot.topCompositeCreate}/${snapshot.topResourceRelease} ${snapshot.topLastInvalidationReason}\n")
+            append("Fast e/a=${snapshot.fastPathEligible}/${snapshot.fastPathActive} h/m/full=${snapshot.fastPathHit}/${snapshot.fastPathMiss}/${snapshot.fullCpuFrame} ${snapshot.fastPathFallbackReason}")
+        }
+        if (log) {
+            Log.i(TAG, "STEP093_DIAGNOSTICS ${diagnostics.text.toString().replace('\n', ' ')}")
+        }
+    }
+
     private fun dismissRealWeatherTuning() { realWeatherTuningMenu?.dismiss(); realWeatherTuningMenu = null }
 
     private fun showRealWeatherTuning(anchor: android.view.View) {
@@ -564,7 +845,7 @@ class ParticleCoreLayerValidationActivity : AppCompatActivity() {
     }
 
     private fun enterPbfMatrix() {
-        if (realWeatherMode) leaveRealWeatherMode()
+        if (realWeatherMode || step093Mode) leaveRealWeatherMode()
         if (!isPbfMatrixMode()) {
             preRealWeatherVisuals = ParticleVisuals(particleCount, lineWidth, particleLength, particleOpacity, trailOpacity, trailFade)
             particleCount = REAL_WEATHER_PARTICLE_COUNT
@@ -1277,6 +1558,10 @@ class ParticleCoreLayerValidationActivity : AppCompatActivity() {
     }
 
     private fun statusText(): String {
+        if (step093Mode) {
+            return "STEP-093 · ${step093Topology.label} · ${step093Variant.name} · " +
+                "CACHE ${if (retainedCacheEnabled) "ON" else "OFF"}"
+        }
         val mask = when (maskMode) {
             MASK_OCEAN_A -> "OCEAN A"
             MASK_OCEAN_B -> "OCEAN B"
@@ -1318,6 +1603,94 @@ class ParticleCoreLayerValidationActivity : AppCompatActivity() {
 
     private fun realWeatherHudValues(): String = "FPS ${realWeatherTargetFps.name.removePrefix("FPS_")} · P $particleCount · W ${"%.2f".format(lineWidth)} · L ${"%.4f".format(particleLength)} · O ${"%.2f".format(particleOpacity)} · T ${"%.2f".format(trailOpacity)} · F ${"%.2f".format(trailFade)}"
 
+    private fun step093StyleJson(): String {
+        val sources = JSONObject()
+            .put(PARTICLE_SOURCE_ID, JSONObject().put("type", "raster-array").put("host-field-submission", true))
+            .put("step093-bottom-shape", step093GeoJsonSource("""{"type":"Polygon","coordinates":[[[112,0],[158,0],[158,56],[112,56],[112,0]]]}"""))
+            .put("step093-semi-shape", step093GeoJsonSource("""{"type":"Polygon","coordinates":[[[134,8],[151,8],[151,49],[134,49],[134,8]]]}"""))
+            .put("step093-opaque-shape", step093GeoJsonSource("""{"type":"Polygon","coordinates":[[[124,18],[136,18],[136,42],[124,42],[124,18]]]}"""))
+            .put("step093-line-shape", step093GeoJsonSource("""{"type":"LineString","coordinates":[[115,6],[154,50],[154,6],[115,50]]}"""))
+
+        fun fill(id: String, source: String, color: String, opacity: Double) = JSONObject()
+            .put("id", id).put("type", "fill").put("source", source)
+            .put("paint", JSONObject().put("fill-color", color).put("fill-opacity", opacity))
+        fun line(id: String, source: String, color: String, width: Double) = JSONObject()
+            .put("id", id).put("type", "line").put("source", source)
+            .put("paint", JSONObject().put("line-color", color).put("line-width", width).put("line-opacity", 0.95))
+
+        val layers = JSONArray()
+        if (step093Topology.bottom) {
+            layers.put(JSONObject().put("id", STEP093_BOTTOM_BACKGROUND_ID).put("type", "background")
+                .put("paint", JSONObject().put("background-color", "#0b2942")))
+            val bottomBase = fill(STEP093_BOTTOM_FILL_ID, "step093-bottom-shape", "#176b87", 0.72)
+            val bottomExtra = fill(STEP093_BOTTOM_EXTRA_ID, "step093-semi-shape", "#2aa198", 0.18)
+            if (step093Variant == Step093Variant.BOTTOM_REORDER) {
+                layers.put(bottomExtra).put(bottomBase)
+            } else {
+                layers.put(bottomBase)
+                if (step093Variant == Step093Variant.BOTTOM_ADD) layers.put(bottomExtra)
+            }
+            if (step093Variant == Step093Variant.CROSS_BOTTOM) {
+                layers.put(fill(STEP093_CROSS_LAYER_ID, "step093-opaque-shape", "#9b59b6", 0.18))
+            }
+        }
+
+        if (step093Variant != Step093Variant.START_MISSING) {
+            layers.put(
+                JSONObject().put("id", STEP093_WEATHER_LAYER_ID).put("type", "weather-color")
+                    .put("source", PARTICLE_SOURCE_ID)
+                    .put("paint", JSONObject().put("weather-color-opacity", 0.32))
+            )
+        }
+        if (step093Variant == Step093Variant.CONTINUOUS_ADD ||
+            step093Variant == Step093Variant.CONTINUOUS_REORDER) {
+            val first = fill(STEP093_CONTINUOUS_A_ID, "step093-semi-shape", "#ff00ff", 0.16)
+            val second = fill(STEP093_CONTINUOUS_B_ID, "step093-opaque-shape", "#00ffff", 0.12)
+            if (step093Variant == Step093Variant.CONTINUOUS_REORDER) layers.put(second).put(first)
+            else layers.put(first).put(second)
+        }
+        if (step093Variant == Step093Variant.CROSS_CONTINUOUS) {
+            layers.put(fill(STEP093_CROSS_LAYER_ID, "step093-opaque-shape", "#9b59b6", 0.18))
+        }
+        if (step093Variant == Step093Variant.FAST_PATH_FAIL_CLOSED) {
+            layers.put(fill(STEP093_UNKNOWN_CONTINUOUS_ID, "step093-semi-shape", "#ff5500", 0.20))
+        }
+        if (step093Variant != Step093Variant.END_MISSING) layers.put(navSeaParticleLayer(active = true))
+        if (step093Variant == Step093Variant.CROSS_TOP) {
+            layers.put(fill(STEP093_CROSS_LAYER_ID, "step093-opaque-shape", "#9b59b6", 0.18))
+        }
+
+        if (step093Topology.top) {
+            val semi = fill(STEP093_TOP_SEMI_ID, "step093-semi-shape", "#ffd166", 0.42)
+            val opaque = fill(STEP093_TOP_OPAQUE_ID, "step093-opaque-shape", "#ef476f", 1.0)
+            val outline = line(STEP093_TOP_LINE_ID, "step093-line-shape", "#ffffff", 6.0)
+            val extra = line(STEP093_TOP_EXTRA_ID, "step093-opaque-shape", "#00ff99", 3.0)
+            if (step093Variant == Step093Variant.TOP_REORDER) {
+                layers.put(outline).put(opaque).put(semi)
+            } else {
+                layers.put(semi).put(opaque).put(outline)
+                if (step093Variant == Step093Variant.TOP_ADD) layers.put(extra)
+            }
+        }
+
+        return JSONObject()
+            .put("version", 8)
+            .put("name", "STEP-093 Continuous Range Runtime Validation")
+            .put("sources", sources)
+            .put("layers", layers)
+            .toString()
+    }
+
+    private fun step093GeoJsonSource(geometryJson: String): JSONObject = JSONObject()
+        .put("type", "geojson")
+        .put(
+            "data",
+            JSONObject()
+                .put("type", "Feature")
+                .put("properties", JSONObject())
+                .put("geometry", JSONObject(geometryJson))
+        )
+
     private fun validationStyle(active: Boolean, enabled: Boolean, reason: String): String {
         val fixtureId = fixtureId()
         val nextFixtureId = if (timeWindowMode) {
@@ -1396,11 +1769,11 @@ class ParticleCoreLayerValidationActivity : AppCompatActivity() {
     """.trimIndent()
     }
 
-    override fun onStart() { super.onStart(); mapView.onStart() }
+    override fun onStart() { super.onStart(); mapView.onStart(); if (step093Mode) startStep093DiagnosticsPolling() }
     override fun onResume() { super.onResume(); mapView.onResume() }
     override fun onPause() { mapView.onPause(); super.onPause() }
-    override fun onStop() { mapView.onStop(); super.onStop() }
-    override fun onDestroy() { weatherRuntime?.dispose(); weatherRuntime = null; mapView.onDestroy(); super.onDestroy() }
+    override fun onStop() { step093Handler.removeCallbacks(step093DiagnosticsPoll); mapView.onStop(); super.onStop() }
+    override fun onDestroy() { step093Handler.removeCallbacks(step093DiagnosticsPoll); weatherRuntime?.dispose(); weatherRuntime = null; mapView.onDestroy(); super.onDestroy() }
     override fun onLowMemory() { super.onLowMemory(); mapView.onLowMemory() }
 
     override fun onSaveInstanceState(outState: Bundle) {
@@ -1425,6 +1798,9 @@ class ParticleCoreLayerValidationActivity : AppCompatActivity() {
         outState.putString(STATE_NAVSEA_PBF_POSITION, navSeaPbfPosition.name)
         outState.putBoolean(STATE_NAVSEA_PBF_RENDER_ENABLED, navSeaPbfRenderEnabled)
         outState.putBoolean(STATE_RETAINED_CACHE_ENABLED, retainedCacheEnabled)
+        outState.putBoolean(STATE_STEP093_MODE, step093Mode)
+        outState.putString(STATE_STEP093_TOPOLOGY, step093Topology.name)
+        outState.putString(STATE_STEP093_VARIANT, step093Variant.name)
         super.onSaveInstanceState(outState)
         mapView.onSaveInstanceState(outState)
     }
@@ -1458,9 +1834,26 @@ class ParticleCoreLayerValidationActivity : AppCompatActivity() {
         private const val STATE_NAVSEA_PBF_POSITION = "particle_validation.navsea_pbf_position"
         private const val STATE_NAVSEA_PBF_RENDER_ENABLED = "particle_validation.navsea_pbf_render_enabled"
         private const val STATE_RETAINED_CACHE_ENABLED = "particle_validation.retained_cache_enabled"
+        private const val STATE_STEP093_MODE = "particle_validation.step093_mode"
+        private const val STATE_STEP093_TOPOLOGY = "particle_validation.step093_topology"
+        private const val STATE_STEP093_VARIANT = "particle_validation.step093_variant"
         private const val PARTICLE_LAYER_ID = "particle-raster-core"
         private const val WEATHER_COLOR_LAYER_ID = "weather-color-real"
         private const val PARTICLE_SOURCE_ID = "particle-fixture"
+        private const val STEP093_DIAGNOSTICS_INTERVAL_MS = 1000L
+        private const val STEP093_WEATHER_LAYER_ID = WEATHER_COLOR_LAYER_ID
+        private const val STEP093_PARTICLE_LAYER_ID = PARTICLE_LAYER_ID
+        private const val STEP093_BOTTOM_BACKGROUND_ID = "step093-bottom-background"
+        private const val STEP093_BOTTOM_FILL_ID = "step093-bottom-fill"
+        private const val STEP093_BOTTOM_EXTRA_ID = "step093-bottom-extra"
+        private const val STEP093_CONTINUOUS_A_ID = "step093-continuous-a"
+        private const val STEP093_CONTINUOUS_B_ID = "step093-continuous-b"
+        private const val STEP093_UNKNOWN_CONTINUOUS_ID = "step093-unknown-continuous"
+        private const val STEP093_CROSS_LAYER_ID = "step093-cross-layer"
+        private const val STEP093_TOP_SEMI_ID = "step093-top-semi"
+        private const val STEP093_TOP_OPAQUE_ID = "step093-top-opaque"
+        private const val STEP093_TOP_LINE_ID = "step093-top-line"
+        private const val STEP093_TOP_EXTRA_ID = "step093-top-extra"
         private const val MASK_GLOBAL = 0
         private const val MASK_OCEAN_A = 1
         private const val MASK_OCEAN_B = 2
diff --git a/platform/android/MapLibreAndroidTestApp/src/main/res/layout/activity_particle_core_layer_validation.xml b/platform/android/MapLibreAndroidTestApp/src/main/res/layout/activity_particle_core_layer_validation.xml
index b2bb94f59..cf27da6eb 100644
--- a/platform/android/MapLibreAndroidTestApp/src/main/res/layout/activity_particle_core_layer_validation.xml
+++ b/platform/android/MapLibreAndroidTestApp/src/main/res/layout/activity_particle_core_layer_validation.xml
@@ -3,6 +3,7 @@
   <org.maplibre.android.maps.MapView android:id="@id/mapView" android:layout_width="match_parent" android:layout_height="match_parent" />
   <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_gravity="bottom" android:background="#DD102030" android:orientation="vertical" android:padding="4dp">
     <TextView android:id="@+id/validationStatus" android:layout_width="match_parent" android:layout_height="42dp" android:gravity="center_vertical" android:maxLines="2" android:paddingLeft="4dp" android:paddingRight="4dp" android:textColor="@android:color/white" android:textSize="12sp" />
+    <TextView android:id="@+id/validationDiagnostics" android:layout_width="match_parent" android:layout_height="92dp" android:fontFamily="monospace" android:gravity="center_vertical" android:maxLines="6" android:paddingLeft="4dp" android:paddingRight="4dp" android:text="STEP-093 diagnostics: open STEP 093" android:textColor="#FFDD88" android:textSize="9sp" />
     <LinearLayout android:layout_width="match_parent" android:layout_height="40dp" android:orientation="horizontal">
       <Button android:id="@+id/validationMenuTime" style="@style/ParticleValidationButton" android:layout_width="0dp" android:layout_weight="1" android:text="TIME" />
       <Button android:id="@+id/validationMenuVisual" style="@style/ParticleValidationButton" android:layout_width="0dp" android:layout_weight="1" android:text="VIS" />
@@ -12,6 +13,7 @@
       <Button android:id="@+id/validationMenuPbfMode" style="@style/ParticleValidationButton" android:layout_width="0dp" android:layout_weight="1" android:text="PBF MODE" android:textSize="9sp" />
       <Button android:id="@+id/validationMenuNavSeaPbf" style="@style/ParticleValidationButton" android:layout_width="0dp" android:layout_weight="1" android:text="NAVSEA PBF" android:textSize="9sp" />
       <Button android:id="@+id/validationMenuRetainedCache" style="@style/ParticleValidationButton" android:layout_width="0dp" android:layout_weight="1" android:text="CACHE ON" android:textSize="9sp" />
+      <Button android:id="@+id/validationMenuStep093" style="@style/ParticleValidationButton" android:layout_width="0dp" android:layout_weight="1" android:text="STEP 093" android:textSize="9sp" />
       <Button android:id="@+id/validationMenuMore" style="@style/ParticleValidationButton" android:layout_width="0dp" android:layout_weight="1" android:text="MORE" />
     </LinearLayout>
     <!-- Existing action IDs are invisible menu targets; no permanent button grid. -->
diff --git a/platform/ios/src/MLNMapView.h b/platform/ios/src/MLNMapView.h
index 6ae61f767..07da1d4c7 100644
--- a/platform/ios/src/MLNMapView.h
+++ b/platform/ios/src/MLNMapView.h
@@ -44,14 +44,33 @@ MLN_EXPORT
 @property (nonatomic, copy, readonly) NSString *endLayerId;
 @property (nonatomic, readonly) NSInteger startIndex;
 @property (nonatomic, readonly) NSInteger endIndex;
+@property (nonatomic, readonly) NSInteger continuousBegin;
+@property (nonatomic, readonly) NSInteger continuousEndExclusive;
 @property (nonatomic, readonly) BOOL bottomPresent;
+@property (nonatomic, copy, readonly) NSString *bottomCacheState;
 @property (nonatomic, readonly) uint64_t bottomBuild;
 @property (nonatomic, readonly) uint64_t bottomReuse;
 @property (nonatomic, readonly) uint64_t bottomInvalidation;
+@property (nonatomic, copy, readonly) NSString *bottomLastInvalidationReason;
+@property (nonatomic, readonly) uint64_t bottomTextureCreate;
+@property (nonatomic, readonly) uint64_t bottomCompositeCreate;
+@property (nonatomic, readonly) uint64_t bottomResourceRelease;
 @property (nonatomic, readonly) BOOL topPresent;
+@property (nonatomic, copy, readonly) NSString *topCacheState;
 @property (nonatomic, readonly) uint64_t topBuild;
 @property (nonatomic, readonly) uint64_t topReuse;
 @property (nonatomic, readonly) uint64_t topInvalidation;
+@property (nonatomic, copy, readonly) NSString *topLastInvalidationReason;
+@property (nonatomic, readonly) uint64_t topTextureCreate;
+@property (nonatomic, readonly) uint64_t topCompositeCreate;
+@property (nonatomic, readonly) uint64_t topResourceRelease;
+@property (nonatomic, readonly) BOOL rangeFallback;
+@property (nonatomic, readonly) BOOL fastPathEligible;
+@property (nonatomic, readonly) BOOL fastPathActive;
+@property (nonatomic, copy, readonly) NSString *fastPathFallbackReason;
+@property (nonatomic, readonly) uint64_t fastPathHit;
+@property (nonatomic, readonly) uint64_t fastPathMiss;
+@property (nonatomic, readonly) uint64_t fullCpuFrame;
 
 - (instancetype)init NS_UNAVAILABLE;
 
diff --git a/platform/ios/src/MLNMapView.mm b/platform/ios/src/MLNMapView.mm
index 2d9df59c8..29a38a22e 100644
--- a/platform/ios/src/MLNMapView.mm
+++ b/platform/ios/src/MLNMapView.mm
@@ -267,6 +267,13 @@ int processIsTranslated() {
     _endLayerId = @"";
     _startIndex = -1;
     _endIndex = -1;
+    _continuousBegin = -1;
+    _continuousEndExclusive = -1;
+    _bottomCacheState = @"disabled";
+    _bottomLastInvalidationReason = @"none";
+    _topCacheState = @"disabled";
+    _topLastInvalidationReason = @"none";
+    _fastPathFallbackReason = @"no-prepared-tree";
   }
   return self;
 }
@@ -278,14 +285,33 @@ int processIsTranslated() {
   _endLayerId = [NSString stringWithUTF8String:snapshot.endLayerId.c_str()];
   _startIndex = snapshot.startIndex;
   _endIndex = snapshot.endIndex;
+  _continuousBegin = snapshot.continuousBegin;
+  _continuousEndExclusive = snapshot.continuousEndExclusive;
   _bottomPresent = snapshot.bottomPresent;
+  _bottomCacheState = [NSString stringWithUTF8String:snapshot.bottomCacheState.c_str()];
   _bottomBuild = snapshot.bottomBuild;
   _bottomReuse = snapshot.bottomReuse;
   _bottomInvalidation = snapshot.bottomInvalidation;
+  _bottomLastInvalidationReason = [NSString stringWithUTF8String:snapshot.bottomLastInvalidationReason.c_str()];
+  _bottomTextureCreate = snapshot.bottomTextureCreate;
+  _bottomCompositeCreate = snapshot.bottomCompositeCreate;
+  _bottomResourceRelease = snapshot.bottomResourceRelease;
   _topPresent = snapshot.topPresent;
+  _topCacheState = [NSString stringWithUTF8String:snapshot.topCacheState.c_str()];
   _topBuild = snapshot.topBuild;
   _topReuse = snapshot.topReuse;
   _topInvalidation = snapshot.topInvalidation;
+  _topLastInvalidationReason = [NSString stringWithUTF8String:snapshot.topLastInvalidationReason.c_str()];
+  _topTextureCreate = snapshot.topTextureCreate;
+  _topCompositeCreate = snapshot.topCompositeCreate;
+  _topResourceRelease = snapshot.topResourceRelease;
+  _rangeFallback = snapshot.rangeFallback;
+  _fastPathEligible = snapshot.fastPathEligible;
+  _fastPathActive = snapshot.fastPathActive;
+  _fastPathFallbackReason = [NSString stringWithUTF8String:snapshot.fastPathFallbackReason.c_str()];
+  _fastPathHit = snapshot.fastPathHit;
+  _fastPathMiss = snapshot.fastPathMiss;
+  _fullCpuFrame = snapshot.fullCpuFrame;
 }
 @end
 
diff --git a/src/mbgl/renderer/particle_fast_path.hpp b/src/mbgl/renderer/particle_fast_path.hpp
index a7226e818..ebb266008 100644
--- a/src/mbgl/renderer/particle_fast_path.hpp
+++ b/src/mbgl/renderer/particle_fast_path.hpp
@@ -28,6 +28,7 @@ enum class ParticleFastPathMissReason : uint8_t {
     StillImageRequest,
     UnsupportedMode,
     DebugOptions,
+    UnsupportedContinuousLayer,
     UnsupportedScene,
     AnnotationMutation,
 };
@@ -56,6 +57,7 @@ inline const char* particleFastPathMissReasonText(ParticleFastPathMissReason rea
         case ParticleFastPathMissReason::StillImageRequest: return "still-image-request";
         case ParticleFastPathMissReason::UnsupportedMode: return "unsupported-mode";
         case ParticleFastPathMissReason::DebugOptions: return "debug-options";
+        case ParticleFastPathMissReason::UnsupportedContinuousLayer: return "unsupported-continuous-layer";
         case ParticleFastPathMissReason::UnsupportedScene: return "unsupported-scene";
         case ParticleFastPathMissReason::AnnotationMutation: return "annotation-mutation";
     }
@@ -84,6 +86,7 @@ struct ParticleFastPathGateInput {
     bool stillImageRequest = false;
     bool continuousMode = false;
     bool debugDisabled = false;
+    bool unsupportedContinuousLayer = false;
     bool supportedScene = false;
     bool annotationMutation = false;
 };
@@ -115,6 +118,9 @@ inline ParticleFastPathDecision evaluateParticleFastPath(const ParticleFastPathG
     if (input.stillImageRequest) return {false, ParticleFastPathMissReason::StillImageRequest};
     if (!input.continuousMode) return {false, ParticleFastPathMissReason::UnsupportedMode};
     if (!input.debugDisabled) return {false, ParticleFastPathMissReason::DebugOptions};
+    if (input.unsupportedContinuousLayer) {
+        return {false, ParticleFastPathMissReason::UnsupportedContinuousLayer};
+    }
     if (!input.supportedScene) return {false, ParticleFastPathMissReason::UnsupportedScene};
     if (input.annotationMutation) return {false, ParticleFastPathMissReason::AnnotationMutation};
     return {true, ParticleFastPathMissReason::None};
diff --git a/src/mbgl/renderer/renderer_impl.cpp b/src/mbgl/renderer/renderer_impl.cpp
index af1229ec2..0c1cf004f 100644
--- a/src/mbgl/renderer/renderer_impl.cpp
+++ b/src/mbgl/renderer/renderer_impl.cpp
@@ -265,11 +265,13 @@ bool Renderer::Impl::tryRenderParticleFastFrame(const std::shared_ptr<UpdatePara
         .stillImageRequest = updateParameters->stillImageRequest,
         .continuousMode = updateParameters->mode == MapMode::Continuous,
         .debugDisabled = updateParameters->debugOptions == MapDebugOptions::NoDebug,
+        .unsupportedContinuousLayer = particlePreparedContinuousUnsupported,
         .supportedScene = particlePreparedSceneSupported,
         .annotationMutation = annotationMutation,
     };
     const auto decision = evaluateParticleFastPath(input);
     particleFastPathLastReason = decision.reason;
+    retainedUnderlayCache->recordFastPathDecision(decision.candidate, decision.reason);
     if (!decision.candidate) {
         particle::incrementRendererDebugCounter(particle::RendererDebugCounter::ParticleFastFrameMiss);
         return false;
@@ -310,6 +312,7 @@ void Renderer::Impl::clearPreparedRenderTree() {
     particlePreparedRangeConfigRevision = 0;
     particlePreparedBottomPresent = false;
     particlePreparedTopPresent = false;
+    particlePreparedContinuousUnsupported = false;
     particlePreparedBackendSize = {};
     particlePreparedSceneSupported = false;
 }
@@ -321,6 +324,7 @@ void Renderer::Impl::render(const RenderTree& renderTree,
     particle::incrementRendererDebugCounter(particle::RendererDebugCounter::FullRendererFrame);
     if (!particleFastFrame) {
         particle::incrementRendererDebugCounter(particle::RendererDebugCounter::ParticleFullFrame);
+        retainedUnderlayCache->recordFullCpuFrame();
     }
     auto& context = backend.getContext();
     context.setObserver(this);
@@ -591,6 +595,8 @@ void Renderer::Impl::render(const RenderTree& renderTree,
         ? orchestrator.continuousRangeSupportsParticleFastPath(
               ranges.continuousBegin, ranges.continuousEndExclusive)
         : retainedSupported;
+    if (!particleFastFrame) particlePreparedContinuousUnsupported = rangeMode && !fastContinuousSupported;
+    retainedUnderlayCache->recordFastPathEligibility(retainedSupported && fastContinuousSupported);
     if (!particleFastFrame) particlePreparedSceneSupported = retainedSupported && fastContinuousSupported;
     const char* retainedFallbackReason = nullptr;
     if (!retainedMode) {
diff --git a/src/mbgl/renderer/renderer_impl.hpp b/src/mbgl/renderer/renderer_impl.hpp
index 84b57c0b8..3971fb64b 100644
--- a/src/mbgl/renderer/renderer_impl.hpp
+++ b/src/mbgl/renderer/renderer_impl.hpp
@@ -112,6 +112,7 @@ private:
     uint64_t particlePreparedRangeConfigRevision = 0;
     bool particlePreparedBottomPresent = false;
     bool particlePreparedTopPresent = false;
+    bool particlePreparedContinuousUnsupported = false;
     Size particlePreparedBackendSize;
     bool particlePreparedSceneSupported = false;
     ParticleFastPathMissReason particleFastPathLastReason = ParticleFastPathMissReason::NoPreparedTree;
diff --git a/src/mbgl/renderer/retained_underlay_cache.cpp b/src/mbgl/renderer/retained_underlay_cache.cpp
index dd52419ad..d3cfb6762 100644
--- a/src/mbgl/renderer/retained_underlay_cache.cpp
+++ b/src/mbgl/renderer/retained_underlay_cache.cpp
@@ -134,11 +134,14 @@ void RetainedUnderlayCache::synchronizeRuntimeState(
             valid = false;
             lastInvalidationReason = "runtime-disabled";
             runtimeState->recordRangeInvalidation(role == RetainedRangeRole::Top);
+            runtimeState->recordRangeInvalidationReason(
+                role == RetainedRangeRole::Top, RetainedUnderlayReason::RuntimeDisabled);
         }
     }
     releaseResources();
     if (!runtimeState->isEnabled()) {
         lastInvalidationReason = "runtime-disabled";
+        runtimeState->recordRangeCacheState(role == RetainedRangeRole::Top, RetainedRangeCacheState::Fallback);
         particle::incrementRendererDebugCounter(particle::RendererDebugCounter::RetainedUnderlayInvalidation);
     }
 }
@@ -155,12 +158,14 @@ RetainedUnderlayDecision RetainedUnderlayCache::evaluate(const std::optional<Ret
             invalidate(fallbackReason ? fallbackReason : "no-boundary");
             releaseResources();
         }
+        runtimeState->recordRangeCacheState(role == RetainedRangeRole::Top, RetainedRangeCacheState::Disabled);
         return RetainedUnderlayDecision::Disabled;
     }
     if (runtimeState && !runtimeState->isEnabled()) {
         ++fallbackCount;
         runtimeState->recordFallback();
         particle::incrementRendererDebugCounter(particle::RendererDebugCounter::RetainedUnderlayFallback);
+        runtimeState->recordRangeCacheState(role == RetainedRangeRole::Top, RetainedRangeCacheState::Fallback);
         return RetainedUnderlayDecision::Fallback;
     }
     if (!supported) {
@@ -169,6 +174,7 @@ RetainedUnderlayDecision RetainedUnderlayCache::evaluate(const std::optional<Ret
         particle::incrementRendererDebugCounter(particle::RendererDebugCounter::RetainedUnderlayFallback);
         invalidate(fallbackReason ? fallbackReason : "unsupported");
         if (revisionChanged) releaseResources();
+        runtimeState->recordRangeCacheState(role == RetainedRangeRole::Top, RetainedRangeCacheState::Fallback);
         return RetainedUnderlayDecision::Fallback;
     }
     if (revisionChanged) {
@@ -193,8 +199,10 @@ RetainedUnderlayDecision RetainedUnderlayCache::evaluate(const std::optional<Ret
         runtimeState->recordReuse();
         runtimeState->recordRangeReuse(role == RetainedRangeRole::Top);
         particle::incrementRendererDebugCounter(particle::RendererDebugCounter::RetainedUnderlayReuse);
+        runtimeState->recordRangeCacheState(role == RetainedRangeRole::Top, RetainedRangeCacheState::Reuse);
         return RetainedUnderlayDecision::Reuse;
     }
+    runtimeState->recordRangeCacheState(role == RetainedRangeRole::Top, RetainedRangeCacheState::BuildPending);
     return RetainedUnderlayDecision::Build;
 }
 
@@ -205,6 +213,7 @@ bool RetainedUnderlayCache::prepareResources(gfx::Context& context,
         if (!offscreenTexture || offscreenTexture->getSize() != nextKey.viewport) {
             offscreenTexture = context.createOffscreenTexture(
                 nextKey.viewport, gfx::TextureChannelDataType::UnsignedByte, true, true);
+            runtimeState->recordRangeTextureCreate(role == RetainedRangeRole::Top);
             compositeLayerGroup.reset();
         }
         if (!offscreenTexture || !offscreenTexture->isRenderable()) return false;
@@ -248,6 +257,7 @@ bool RetainedUnderlayCache::rebuildComposite(gfx::Context& context, gfx::ShaderR
     builder->flush(context);
     for (auto& drawable : builder->clearDrawables()) group->addDrawable(std::move(drawable));
     compositeLayerGroup = std::move(group);
+    runtimeState->recordRangeCompositeCreate(role == RetainedRangeRole::Top);
     return !compositeLayerGroup->empty();
 }
 
@@ -285,6 +295,7 @@ void RetainedUnderlayCache::markBuildSucceeded() {
     ++buildCount;
     runtimeState->recordBuild();
     runtimeState->recordRangeBuild(role == RetainedRangeRole::Top);
+    runtimeState->recordRangeCacheState(role == RetainedRangeRole::Top, RetainedRangeCacheState::Ready);
     particle::incrementRendererDebugCounter(particle::RendererDebugCounter::RetainedUnderlayBuild);
 }
 
@@ -293,6 +304,7 @@ void RetainedUnderlayCache::markBuildFailed(const char* reason) {
     runtimeState->recordFallback();
     particle::incrementRendererDebugCounter(particle::RendererDebugCounter::RetainedUnderlayFallback);
     invalidate(reason);
+    runtimeState->recordRangeCacheState(role == RetainedRangeRole::Top, RetainedRangeCacheState::Fallback);
     releaseResources();
 }
 
@@ -301,10 +313,14 @@ void RetainedUnderlayCache::invalidate(const char* reason) {
     lastInvalidationReason = reason ? reason : "unknown";
     runtimeState->recordInvalidation(retainedReason(reason));
     runtimeState->recordRangeInvalidation(role == RetainedRangeRole::Top);
+    runtimeState->recordRangeInvalidationReason(role == RetainedRangeRole::Top, retainedReason(reason));
     particle::incrementRendererDebugCounter(particle::RendererDebugCounter::RetainedUnderlayInvalidation);
 }
 
 void RetainedUnderlayCache::releaseResources() {
+    if (offscreenTexture || compositeLayerGroup) {
+        runtimeState->recordRangeResourceRelease(role == RetainedRangeRole::Top);
+    }
     valid = false;
     buildRevision = 0;
     key.reset();
diff --git a/src/mbgl/renderer/retained_underlay_cache.hpp b/src/mbgl/renderer/retained_underlay_cache.hpp
index 392348d9d..887197920 100644
--- a/src/mbgl/renderer/retained_underlay_cache.hpp
+++ b/src/mbgl/renderer/retained_underlay_cache.hpp
@@ -140,6 +140,11 @@ public:
     uint64_t getBuildRevision() const noexcept { return buildRevision; }
     const std::string& getLastInvalidationReason() const noexcept { return lastInvalidationReason; }
     RetainedUnderlayDiagnostics getDiagnostics() const { return runtimeState->snapshot(); }
+    void recordFastPathEligibility(bool eligible) { runtimeState->recordFastPathEligibility(eligible); }
+    void recordFastPathDecision(bool active, ParticleFastPathMissReason reason) {
+        runtimeState->recordFastPathDecision(active, reason);
+    }
+    void recordFullCpuFrame() { runtimeState->recordFullCpuFrame(); }
 
 private:
     bool rebuildComposite(gfx::Context&, gfx::ShaderRegistry&);
diff --git a/src/mbgl/renderer/retained_underlay_runtime_state.hpp b/src/mbgl/renderer/retained_underlay_runtime_state.hpp
index 59fee46a5..b2a2231f3 100644
--- a/src/mbgl/renderer/retained_underlay_runtime_state.hpp
+++ b/src/mbgl/renderer/retained_underlay_runtime_state.hpp
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <mbgl/renderer/particle_fast_path.hpp>
 #include <mbgl/renderer/retained_underlay.hpp>
 
 #include <atomic>
@@ -8,6 +9,19 @@
 
 namespace mbgl {
 
+enum class RetainedRangeCacheState : uint8_t { Disabled, BuildPending, Ready, Reuse, Fallback };
+
+inline const char* retainedRangeCacheStateText(RetainedRangeCacheState state) noexcept {
+    switch (state) {
+        case RetainedRangeCacheState::Disabled: return "disabled";
+        case RetainedRangeCacheState::BuildPending: return "build-pending";
+        case RetainedRangeCacheState::Ready: return "ready";
+        case RetainedRangeCacheState::Reuse: return "reuse";
+        case RetainedRangeCacheState::Fallback: return "fallback";
+    }
+    return "disabled";
+}
+
 enum class RetainedUnderlayReason : uint8_t {
     None,
     RuntimeDisabled,
@@ -152,6 +166,8 @@ public:
             result.endLayerId = rangeResolution.endLayerId;
             result.startIndex = rangeResolution.startIndex;
             result.endIndex = rangeResolution.endIndex;
+            result.continuousBegin = rangeResolution.begin();
+            result.continuousEndExclusive = rangeResolution.endExclusive();
             result.bottomPresent = bottomRangePresent;
             result.topPresent = topRangePresent;
             result.rangeFallback = rangeResolution.configured && !rangeResolution.valid;
@@ -159,6 +175,25 @@ public:
                 result.lastReason = rangeResolution.reason;
             }
         }
+        result.bottomCacheState = retainedRangeCacheStateText(bottomCacheState.load(std::memory_order_acquire));
+        result.bottomLastInvalidationReason =
+            retainedUnderlayReasonText(bottomLastInvalidationReason.load(std::memory_order_acquire));
+        result.bottomTextureCreate = bottomTextureCreate.load(std::memory_order_relaxed);
+        result.bottomCompositeCreate = bottomCompositeCreate.load(std::memory_order_relaxed);
+        result.bottomResourceRelease = bottomResourceRelease.load(std::memory_order_relaxed);
+        result.topCacheState = retainedRangeCacheStateText(topCacheState.load(std::memory_order_acquire));
+        result.topLastInvalidationReason =
+            retainedUnderlayReasonText(topLastInvalidationReason.load(std::memory_order_acquire));
+        result.topTextureCreate = topTextureCreate.load(std::memory_order_relaxed);
+        result.topCompositeCreate = topCompositeCreate.load(std::memory_order_relaxed);
+        result.topResourceRelease = topResourceRelease.load(std::memory_order_relaxed);
+        result.fastPathEligible = fastPathEligible.load(std::memory_order_acquire);
+        result.fastPathActive = fastPathActive.load(std::memory_order_acquire);
+        result.fastPathFallbackReason =
+            particleFastPathMissReasonText(fastPathReason.load(std::memory_order_acquire));
+        result.fastPathHit = fastPathHit.load(std::memory_order_relaxed);
+        result.fastPathMiss = fastPathMiss.load(std::memory_order_relaxed);
+        result.fullCpuFrame = fullCpuFrame.load(std::memory_order_relaxed);
         return result;
     }
 
@@ -178,6 +213,33 @@ public:
     void recordRangeInvalidation(bool top) noexcept {
         (top ? topInvalidation : bottomInvalidation).fetch_add(1, std::memory_order_relaxed);
     }
+    void recordRangeCacheState(bool top, RetainedRangeCacheState state) noexcept {
+        (top ? topCacheState : bottomCacheState).store(state, std::memory_order_release);
+    }
+    void recordRangeInvalidationReason(bool top, RetainedUnderlayReason reason) noexcept {
+        (top ? topLastInvalidationReason : bottomLastInvalidationReason).store(reason, std::memory_order_release);
+    }
+    void recordRangeTextureCreate(bool top) noexcept {
+        (top ? topTextureCreate : bottomTextureCreate).fetch_add(1, std::memory_order_relaxed);
+    }
+    void recordRangeCompositeCreate(bool top) noexcept {
+        (top ? topCompositeCreate : bottomCompositeCreate).fetch_add(1, std::memory_order_relaxed);
+    }
+    void recordRangeResourceRelease(bool top) noexcept {
+        (top ? topResourceRelease : bottomResourceRelease).fetch_add(1, std::memory_order_relaxed);
+    }
+    void recordFastPathEligibility(bool eligible) noexcept {
+        fastPathEligible.store(eligible, std::memory_order_release);
+    }
+    void recordFastPathDecision(bool active, ParticleFastPathMissReason reason) noexcept {
+        fastPathActive.store(active, std::memory_order_release);
+        fastPathReason.store(reason, std::memory_order_release);
+        (active ? fastPathHit : fastPathMiss).fetch_add(1, std::memory_order_relaxed);
+    }
+    void recordFullCpuFrame() noexcept {
+        fullCpuFrame.fetch_add(1, std::memory_order_relaxed);
+        fastPathActive.store(false, std::memory_order_release);
+    }
 private:
     std::atomic<bool> enabled{true};
     std::atomic<uint64_t> controlRevision{0};
@@ -192,6 +254,22 @@ private:
     std::atomic<uint64_t> topBuild{0};
     std::atomic<uint64_t> topReuse{0};
     std::atomic<uint64_t> topInvalidation{0};
+    std::atomic<RetainedRangeCacheState> bottomCacheState{RetainedRangeCacheState::Disabled};
+    std::atomic<RetainedUnderlayReason> bottomLastInvalidationReason{RetainedUnderlayReason::None};
+    std::atomic<uint64_t> bottomTextureCreate{0};
+    std::atomic<uint64_t> bottomCompositeCreate{0};
+    std::atomic<uint64_t> bottomResourceRelease{0};
+    std::atomic<RetainedRangeCacheState> topCacheState{RetainedRangeCacheState::Disabled};
+    std::atomic<RetainedUnderlayReason> topLastInvalidationReason{RetainedUnderlayReason::None};
+    std::atomic<uint64_t> topTextureCreate{0};
+    std::atomic<uint64_t> topCompositeCreate{0};
+    std::atomic<uint64_t> topResourceRelease{0};
+    std::atomic<bool> fastPathEligible{false};
+    std::atomic<bool> fastPathActive{false};
+    std::atomic<ParticleFastPathMissReason> fastPathReason{ParticleFastPathMissReason::NoPreparedTree};
+    std::atomic<uint64_t> fastPathHit{0};
+    std::atomic<uint64_t> fastPathMiss{0};
+    std::atomic<uint64_t> fullCpuFrame{0};
     mutable std::mutex rangeMutex;
     ContinuousLayerRangeConfig rangeConfig;
     ContinuousLayerRangeResolution rangeResolution;
diff --git a/test/renderer/retained_underlay_cache.test.cpp b/test/renderer/retained_underlay_cache.test.cpp
index e7afece95..f5c8f37b9 100644
--- a/test/renderer/retained_underlay_cache.test.cpp
+++ b/test/renderer/retained_underlay_cache.test.cpp
@@ -57,6 +57,7 @@ ParticleFastPathGateInput fastPathInput() {
         .stillImageRequest = false,
         .continuousMode = true,
         .debugDisabled = true,
+        .unsupportedContinuousLayer = false,
         .supportedScene = true,
         .annotationMutation = false,
     };
@@ -124,6 +125,46 @@ TEST(RetainedUnderlayCache, BuildReuseAndInvalidation) {
     EXPECT_EQ(cache.getLastInvalidationReason(), "camera-or-boundary");
 }
 
+TEST(RetainedUnderlayCache, RuntimeValidationDiagnosticsExposeRangeResourcesAndFastPath) {
+    RetainedUnderlayRuntimeState state;
+    ASSERT_TRUE(state.setContinuousLayerRange("weather", "particle"));
+    const auto config = state.continuousLayerRangeConfig();
+    state.recordRangeResolution(
+        {.configured = true,
+         .valid = true,
+         .startLayerId = "weather",
+         .endLayerId = "particle",
+         .startIndex = 2,
+         .endIndex = 3,
+         .configRevision = config.revision,
+         .reason = "explicit-range"},
+        true,
+        true);
+    state.recordRangeCacheState(false, RetainedRangeCacheState::Reuse);
+    state.recordRangeInvalidationReason(false, RetainedUnderlayReason::Viewport);
+    state.recordRangeTextureCreate(false);
+    state.recordRangeCompositeCreate(false);
+    state.recordRangeResourceRelease(false);
+    state.recordFastPathEligibility(true);
+    state.recordFastPathDecision(true, ParticleFastPathMissReason::None);
+    state.recordFullCpuFrame();
+
+    const auto snapshot = state.snapshot();
+    EXPECT_TRUE(snapshot.rangeValid);
+    EXPECT_EQ(snapshot.continuousBegin, 2);
+    EXPECT_EQ(snapshot.continuousEndExclusive, 4);
+    EXPECT_EQ(snapshot.bottomCacheState, "reuse");
+    EXPECT_EQ(snapshot.bottomLastInvalidationReason, "viewport");
+    EXPECT_EQ(snapshot.bottomTextureCreate, 1u);
+    EXPECT_EQ(snapshot.bottomCompositeCreate, 1u);
+    EXPECT_EQ(snapshot.bottomResourceRelease, 1u);
+    EXPECT_TRUE(snapshot.fastPathEligible);
+    EXPECT_FALSE(snapshot.fastPathActive);
+    EXPECT_EQ(snapshot.fastPathHit, 1u);
+    EXPECT_EQ(snapshot.fastPathMiss, 0u);
+    EXPECT_EQ(snapshot.fullCpuFrame, 1u);
+}
+
 TEST(RetainedUnderlayRevision, MonotonicAcrossCameraViewportStyleAndSourceChanges) {
     RetainedUnderlayRevisionTracker tracker;
     RetainedUnderlayCache cache;
@@ -556,6 +597,10 @@ TEST(ParticleFastPath, PendingStillAndUnsupportedPathsReject) {
     input = fastPathInput();
     input.supportedScene = false;
     EXPECT_EQ(evaluateParticleFastPath(input).reason, ParticleFastPathMissReason::UnsupportedScene);
+
+    input = fastPathInput();
+    input.unsupportedContinuousLayer = true;
+    EXPECT_EQ(evaluateParticleFastPath(input).reason, ParticleFastPathMissReason::UnsupportedContinuousLayer);
 }
 
 TEST(ParticleFastPath, FullFrameCanRestabilizeCandidate) {