diff --git a/Home.md b/Home.md
index b1151ca..5df801f 100644
--- a/Home.md
+++ b/Home.md
@@ -39,6 +39,9 @@ Extracts only the last 5 digits from Connect ID stickers.
 ### Auto Check-in on Creation
 New assets automatically check in with GPS coordinates on creation via all three entry modes (barcode, OCR, manual). Best-effort — silently skips if GPS is not available yet.
 
+### Building # → Trailer Number Sync
+When building_number is entered in the manual asset form or location form, it auto-copies to the trailer_number field via `oninput` handler (commit 02b3ba6).
+
 ## API
 
 | Endpoint | Method | Description |