test(android): isolate internal annotation symbol from STEP-102 retained ranges

platform/android/MapLibreAndroidTestApp/src/main/java/org/maplibre/android/testapp/activity/particle/ParticleCoreLayerValidationActivity.kt

@@ -105,6 +105,26 @@ class ParticleCoreLayerValidationActivity : AppCompatActivity() {
                     "fullCpuFrame=${snapshot.optLong("fullCpuFrame")} ranges=${ranges.joinToString(";")}"
                 diagnostics.text = "STEP-102 $message"
                 Log.i(TAG, "STEP102_SAMPLE $message")
+                if (step102Tick == 8L) {
+                    // One-shot proof of actual runtime style ordering and annotation boundary.
+                    val styleLayers = snapshot.optJSONArray("styleLayers")
+                    val layerOrder = buildList {
+                        for (index in 0 until (styleLayers?.length() ?: 0)) {
+                            val layer = styleLayers?.optJSONObject(index) ?: continue
+                            add("${layer.optInt("layerIndex")}:${layer.optString("layerId")}:${layer.optString("layerType")}")
+                        }
+                    }
+                    val rangeOrder = buildList {
+                        for (index in 0 until (segments?.length() ?: 0)) {
+                            val segment = segments?.optJSONObject(index) ?: continue
+                            add("${segment.optInt("segmentIndex")}:${segment.optString("strategy")}" +
+                                "[${segment.optInt("beginIndex")},${segment.optInt("endExclusive")})" +
+                                "=${segment.optJSONArray("layers")?.length() ?: 0}")
+                        }
+                    }
+                    Log.i(TAG, "STEP102_STYLE_LAYER_LAYOUT scenario=$scenario layers=${layerOrder.joinToString(";")}" +
+                        " segments=${rangeOrder.joinToString(";")}")
+                }
                 if (step102Tick == 8L || step102Tick == 130L) {
                     Log.i(TAG, "STEP102_WINDOW_MARKER phase=${if (step102Tick == 8L) "baseline" else "final"} " +
                         "scenario=$scenario tick=$step102Tick")

platform/android/MapLibreAndroidTestApp/src/main/java/org/maplibre/android/testapp/activity/particle/Step102PlacementFixture.kt

@@ -3,7 +3,13 @@ package org.maplibre.android.testapp.activity.particle
 import org.json.JSONArray
 import org.json.JSONObject
 
-/** Offline STEP-102 R-C-R fixture; only the upper retained range changes placement capability. */
+/**
+ * Offline STEP-102 locality fixture.
+ * R0 / particle C0 / upper R1 keep identical boundaries for T1 and T2.
+ * MapLibre appends its internal annotation Symbol layer after the style layers:
+ * keep that layer in a final live C2 range, outside the upper Retained cache.
+ * Never bypass Renderer placement safety gates to make a fixture pass.
+ */
 internal object Step102PlacementFixture {
     enum class Scenario { T1_FREE_SYMBOL, T2_TWO_FREE }
 
@@ -12,6 +18,8 @@ internal object Step102PlacementFixture {
     private const val PARTICLE_SOURCE = "step102-field"
     private const val PARTICLE_LAYER = "step102-particle"
     private const val UPPER_LAYER = "step102-upper"
+    // Built into MapLibre AnnotationManager; it is a Symbol even when the fixture has no symbols.
+    private const val INTERNAL_ANNOTATION_LAYER = "org.maplibre.annotations.points"
 
     fun styleJson(scenario: Scenario): String {
         val sources = JSONObject()
@@ -56,7 +64,8 @@ internal object Step102PlacementFixture {
         .put("segments", JSONArray()
             .put(JSONObject().put("strategy", "RETAINED"))
             .put(JSONObject().put("strategy", "CONTINUOUS").put("startLayerId", PARTICLE_LAYER))
-            .put(JSONObject().put("strategy", "RETAINED").put("startLayerId", UPPER_LAYER)))
+            .put(JSONObject().put("strategy", "RETAINED").put("startLayerId", UPPER_LAYER))
+            .put(JSONObject().put("strategy", "CONTINUOUS").put("startLayerId", INTERNAL_ANNOTATION_LAYER)))
         .toString()
 
     private fun geoJsonSource(geometryJson: String): JSONObject = JSONObject().put("type", "geojson")