fix(ui): scope spatial tools to scene

docs/adr/0008-durable-observation-sessions-and-workspace-layout.md

@@ -167,16 +167,19 @@ The first disk action in the spatial workspace saves only the versioned
 `observation.spatial` layout document:
 
 - scene display settings;
-- open tool windows and their z-order;
 - visible dynamic source identifiers;
 - active floating source;
 - source-window rectangles normalized to the observed viewport.
 
-The document uses optimistic revision control (`ETag` and `If-Match`) and is
-restored automatically on the next opening. Unknown source identifiers remain
-desired state so a temporarily disconnected camera can recover its saved
-window when that source returns. The save action never starts, completes or
-modifies an observation session.
+Schema v2 deliberately excludes open/closed state and z-order of the transient
+**Движок / Слои / Отображение** tool windows. They are children of the mounted
+spatial workspace, close on every workspace/root/content exit and always start
+closed. Startup migration removes the obsolete `tool_windows` object from a
+stored schema-v1 row. The document uses optimistic revision control (`ETag` and
+`If-Match`) and is restored automatically on the next opening. Unknown source
+identifiers remain desired state so a temporarily disconnected camera can
+recover its saved window when that source returns. The save action never starts,
+completes or modifies an observation session.
 
 ### API boundary