Harden Linear XLSX end to end

AGENTS.md

@@ -351,6 +351,12 @@ batch to metadata. `external-import.apply-follow-up` stores complete inverse
 states, so Undo/Redo never parses Excel. A separately confirmed
 `external-model-object.delete-missing` command removes missing objects and
 adjusts linked row quantities; Undo restores objects, links and quantities.
+R10 verifies the complete path through return workbook, follow-up import,
+snapshot restore, portable duplicate and restart-safe Undo/Redo. A 5,000-object
+synthetic workbook covers parser, command/snapshot size, transactions and the
+client-side virtual window. Complete external-state inserts use bounded batches
+inside their existing transaction for initial/follow-up import, restore and
+duplicate. See `docs/spec/revit-excel-r10-validation.md`.
 
 The target configuration has no independent version counter; `expectedRevision`
 invalidates stale plans, and each import batch stores a configuration copy.
@@ -604,7 +610,7 @@ Critical target rules:
   selected combined/separate mode block export.
 - Missing GZF defaults visibly to 1 without separate confirmation.
 - The corrected R2 return workbook was successfully imported into Linear on
-  2026-09-30; R3 through R9 are complete and R10 is the next package.
+  2026-09-30; R3 through R10 and Phase 14 are complete.
 - All confirmed writes use typed project commands with `expectedRevision`,
   complete inverse data and the shared project-command transaction boundary.
 - Do not add automatic circuit planning, Revit circuit adoption, multi-source