editor: tile paint and collision strokes are one undo step, no collision option for tiles (visual-only model copy in the build), freed gl buffers and stale pick ids, export level as gltf/glb with textures and vertex colours

notes/editor-render.md

@@ -277,6 +277,22 @@ behind: game look / editor).
 (Ranges: several agents shared the CPU.) Scene conversion from WAD 160–290 ms. On any real GPU
 this is far below 1 ms of GPU time; the CPU side is ~150 draw calls per frame.
 
+## GPU resources (2026-11-07)
+
+* `GlRenderer.dispose()` frees everything it created: batches, texture array, pick FBO, programs and
+  the dynamic `dynVao`/`dynVbo` (gizmo, overlays).
+* Chunks that lose their last member are deleted with their batch (before: an empty chunk kept a
+  `Chunk` entry until the next full rebuild). Shared per-mesh batches (`meshBatches`, objects and
+  tiles without vertex colours) whose mesh no instance uses any more are freed once there are more
+  than 256 (limit doubles with the live count) – replaced meshes used to stay until a level switch.
+* `Viewport.liveGlBuffers()` counts live VAO/VBO pairs of all batches (diagnostics).
+  `ui.view.GlLeakCheck` (test sources, X display): 3 rounds over Village 1 / world 4 / Village 2, each
+  load followed by 60 rounds of tile moves, object moves, delete + undo while rendering → the count
+  is identical per level in every round (84 / 87 / 76), 0 with no level loaded.
+* `SceneRenderer` drops the pick ids of nodes that are no longer in the scene every 256 removals
+  (nodes that come back by undo get a new id; selected nodes keep theirs) – `SceneRendererIdsTest`.
+  Tiles marked "no collision" use a copy of their model mesh without the collision overlay.
+
 ## Known limits / next steps
 
 * Only the first vertex colour frame and the primary tile model (no alt/swap models).