rnd(M03): add rendered ground query facade

RENDER.md

@@ -929,11 +929,25 @@ $exe = Join-Path $env:TEMP 'godot-4.6.1-openwc\Godot_v4.6.1-stable_win64.exe'
   matches those ownership categories.
 - Scene composition may still reference the loader script and the facade's
   implementation path; those are composition details, not mutable queue access.
-- Renderer diagnostic probes are outside this gameplay/editor checklist.
-  `probe_render_terrain_height.gd` remains a documented temporary exception until
-  readiness and ground-query facade contracts replace its internal inspection.
+- Renderer diagnostic probes are added explicitly as their facade contracts land.
 - This is a source-only boundary check and changes no renderer behavior or fidelity.
 
+## 2026-07-16 Rendered Ground Query Facade
+
+- `WorldRenderFacade.sample_ground_height()` accepts `GodotWorldPosition` and
+  returns renderer-owned immutable `RenderedGroundSample` from already loaded
+  quality/tile-LOD render meshes, avoiding a render-to-gameplay dependency.
+- `renderer_ground_query_snapshot()` preserves the terrain probe's tile readiness,
+  queue position, mesh bounds and nearby seam-fallback diagnostics as a detached
+  Dictionary; callers receive no queue, tile-state, Mesh or Node reference.
+- `probe_render_terrain_height.gd` now uses this facade snapshot and no longer reads
+  `_tile_states`, `_tile_load_queue`, `_tile_loading_tasks` or `_available_tiles`.
+- Gameplay continues using the independently composed M02 `TerrainQuery`/
+  `AdtTerrainQuery`. Loaded render meshes are diagnostic and are not authoritative
+  movement collision.
+- The ray height, 3x3 tile search and `2/5/10/20/40`-unit nearby fallback are
+  preserved. No terrain geometry, cache, streaming or visual behavior changed.
+
 ## Practical Rule For Future Work
 
 If something improves quality but creates visible hitch, it is not done. Move it to bake/cache/background work, split finalization over frames, or prewarm it before the player can see it.