Include external models in project snapshots

AGENTS.md

@@ -250,9 +250,11 @@ not change the project revision or undo/redo stacks. Restoring a server-stored
 snapshot verifies its checksum and the current-state hash, replaces supported
 project data atomically and records a new `restore` revision with a complete
 inverse command. Restore can therefore be undone and redone after a restart.
-Current snapshot schema version 3 additionally stores the optional project-wide
-Revit CSV configuration. Version 2 snapshots are upgraded with an empty external
-configuration. Supported baseline version 1 snapshots are additionally upgraded
+Current snapshot schema version 4 additionally stores the complete confirmed
+external-model source, import batches, room mappings and objects. Version 3
+snapshots are upgraded with an empty external-model state; version 2 snapshots
+are additionally upgraded with an empty external CSV configuration. Supported
+baseline version 1 snapshots are additionally upgraded
 with `isPublicBuilding = false`; pre-baseline snapshots remain unsupported. All
 supported versions contain circuit-group identity, distribution-board components and the
 separate circuit/component protection records. Portable duplicate imports
@@ -261,7 +263,7 @@ project graph.
 Project-wide Revit CSV configuration uses
 `external-csv-configuration.update`. Its complete expected/target snapshot is
 persisted through the shared project-command transaction, so create, update,
-delete, Undo and Redo are revision-safe. Snapshot schema 3, restore and portable
+delete, Undo and Redo are revision-safe. Snapshot schema 4, restore and portable
 project duplication preserve the configuration; duplication remaps its internal
 id and project link.
 The project page exposes the current Phase 14.1 Revit CSV modal. It edits the
@@ -274,8 +276,9 @@ immutable import batches with original bytes plus the classified cell matrix,
 normalized source-room mappings and external objects unique by
 `(sourceId, ifcGuid)`. Source values, planning values and overrides are separate.
 The current repository is read-only; no runtime import command writes these
-tables yet, and snapshot/transfer schema remains version 3 until the next work
-package adds version 4 atomically.
+tables yet. Snapshot/restore and portable project transfer schema version 4
+capture the complete external state and remap every internal UUID and link while
+preserving IFCGUIDs, source values, original bytes and the classified matrix.
 The central revision boundary creates an automatic logical snapshot after each
 25 new revisions and retains only the newest 12 automatic snapshots per
 project. Named snapshots are never removed by this retention policy.