Bounded reads
At most 12 rows by 8 columns plus a 3-by-3 nearby-label window.
Gallagher Property Company
Selection Presence
Keep a fresh, bounded spreadsheet selection available to an authorized local companion—without granting the add-in permission to write workbook content.
Private by architecture
The public host serves static add-in assets. Workbook values, formulas, selections, document identity, and the per-install capability token stay on the user’s device in an authenticated HTTPS loopback service.
Long-lived context
SharedRuntime 1.1 keeps selection presence active after the pane is hidden.
Fail-closed identity
Stale or workbook-mismatched presence is rejected instead of guessed.
Selection Presence is context only. Any separate workbook edit still requires an explicit target, direct preimage, bounded postimage, and conflict-safe undo.