app: unload stream-probe cells before map transitions tear them down

src/skate3_draw_distance.cpp

@@ -416,6 +416,26 @@ extern "C" REX_FUNC(sub_8247B3A0) {
       (list_mode != 0 && list_count != 0) || cell_size > 4096) {
     return;
   }
+  // Loading screens and the frontend stream one world set out and another
+  // in, then destroy the departing collection objects. Any probe record
+  // kept in the gather output here stays loaded past that teardown and its
+  // content leaks into the arriving map (the differ cannot unload a record
+  // whose collection object is already gone - the ProcessEntries sanitizer
+  // below drops such descriptors without an unload). Leave the output
+  // untouched so probe cells unload through the same differ passes as the
+  // departing vanilla set while their collections are still live, and drop
+  // the caches: their neighbourhood is the departing map's. The in-game
+  // pause menu keeps the world resident and reports false; it merges the
+  // cache below instead.
+  if (skate3::native_scene::LoadingOrFrontendActive()) {
+    if (debug && (g_probe_cache[0].count > 0 || g_probe_cache[1].count > 0)) {
+      REXLOG_INFO(
+          "draw_distance: stream probe caches dropped (loading/frontend)");
+    }
+    g_probe_cache[0] = {};
+    g_probe_cache[1] = {};
+    return;
+  }
 
   ProbeRecord records[192];
   size_t record_count = 0;
@@ -499,8 +519,12 @@ extern "C" REX_FUNC(sub_8247B3A0) {
   const bool set_resident = desc_total > 0 && desc_loaded >= desc_total;
   const bool in_gameplay =
       rex::kernel::guest_presence::GameplayContextValue() == 1;
-  if (cache_valid || (cache_usable && cache.count > 0 &&
+  // An empty vanilla gather is the game clearing this focus (teardown or a
-                      (!set_resident || !in_gameplay))) {
+  // transient); never inject on top of it - the differ is about to unload
+  // everything the focus held.
+  if (vanilla_count > 0 &&
+      (cache_valid || (cache_usable && cache.count > 0 &&
+                       (!set_resident || !in_gameplay)))) {
     // The neighbourhood cannot have changed (cell membership is quantized
     // to the grid): merge the cached probe results instead of re-running
     // the gather fan. Cached distances are slightly stale; they are only
@@ -525,10 +549,10 @@ extern "C" REX_FUNC(sub_8247B3A0) {
         ++record_count;
       }
     }
-  } else if (!set_resident || !in_gameplay) {
+  } else if (vanilla_count == 0 || !set_resident || !in_gameplay) {
-    // Initial load, a fresh focus, or outside gameplay (loading screen /
+    // Initial load, a fresh focus, an emptied focus, or outside gameplay:
-    // frontend): let the vanilla set finish streaming first; the fan
+    // let the vanilla set finish streaming first; the fan starts on a
-    // starts on a later cycle.
+    // later cycle.
   } else {
     // Full probe fan: every grid cell within the probe radius, stepped in
     // cell multiples. The 7x7 cap bounds the fan at 48 gather calls; the

src/skate3_native_scene.cpp

@@ -6092,6 +6092,23 @@ bool FreecamGuestPose(float out_pos[3]) {
   return true;
 }
 
+bool LoadingOrFrontendActive() {
+  if (rex::kernel::guest_presence::GameplayContextValue() != 0) {
+    return false;
+  }
+  // Same publish-staleness window as YieldForMenus: the pause menu keeps
+  // the world resubmitting perspective scenes behind it, loading screens
+  // and the frontend stop publishing.
+  const int64_t last_ns = g_last_publish_ns.load(std::memory_order_relaxed);
+  if (last_ns < 0) {
+    return true;
+  }
+  const int64_t now_ns = std::chrono::duration_cast<std::chrono::nanoseconds>(
+                             std::chrono::steady_clock::now().time_since_epoch())
+                             .count();
+  return now_ns - last_ns >= 300'000'000;
+}
+
 // Guest render thread only. Returns true when vp_out/cam_out hold a
 // re-timed pose for `now`; false = keep the raw guest pose (no history yet,
 // or a cut/teleport snapped).

src/skate3_native_scene.h

@@ -500,6 +500,15 @@ void GetCapturedSunDir(float out[3]);
 // SetViewMatrix override in skate3_native_scene.cpp.
 bool FreecamGuestPose(float out_pos[3]);
 
+// True while the guest sits on a loading screen or in the frontend: the
+// presence context is out of gameplay AND the world has stopped publishing
+// perspective scenes. The in-game pause menu keeps publishing behind the
+// menu and reports false. Mirrors the pause-vs-loading distinction in
+// YieldForMenus (same 300 ms publish-staleness window). With scene capture
+// disabled entirely, publishes never arrive and every out-of-gameplay
+// context reports true (the conservative side).
+bool LoadingOrFrontendActive();
+
 // The game's per-entity spawn/streaming fade as carried by the item's
 // validated character-lighting capture (peds c21.x, defaultcharacter c13.x,
 // cacstamp c22.x, vehicle body c20.x, hair strand scale). 1.0 for items