docs(design-view): resolve snapshot-durability + reconcile open questions

Reconcile-on-delete shipped; narrow the remaining deferrals to the FX-GUID
keying hazard and dormant-membership compaction. Drop the resolved
snapshot-durability question.

CONTEXT.md

@@ -311,10 +311,17 @@ togglable per selection.
 
 ## Open questions to resolve during build
 
-- Snapshot durability across a save-while-parked (persisted here by decision; the
-  lean alternative is force-restore-to-Arrange on save — see product notes item 4).
-- Reconcile behavior when a tagged leaf is deleted or a folder restructured while
-  parked (ignore-and-prune stale GUIDs on next toggle/open).
+- Reconcile residuals (bulk behavior shipped — `ViewModeModel::reconcile(liveGuids)`
+  prunes orphaned snapshots on every toggle/load; folder restructure is self-healing
+  because the tree is rebuilt each toggle; membership is intentionally kept so
+  undo-delete preserves the tag). Two sub-items remain deferred:
+  - **FX-GUID keying for `restoreFxOffline`:** currently restores by slot index; a
+    reshuffled FX chain while parked will restore to the wrong slot. Fix requires
+    FX-GUID keying + snapshot-schema migration — deferred.
+  - **Dormant membership entries:** truly-deleted tracks accumulate stale entries in
+    persisted `view_state` (harmless and bounded); natural home is a future
+    user-initiated "compact" action, not automatic pruning (which would reintroduce
+    undo-delete tag-loss).
 - Interaction with the user having a screenset active (Design View drives the same
   flags a screenset recall would; last writer wins — confirm no surprising fight).