diff --git a/.custodian-brief.md b/.custodian-brief.md
index 0739d17..d8d251c 100644
--- a/.custodian-brief.md
+++ b/.custodian-brief.md
@@ -2,11 +2,14 @@
 # Custodian Brief — activity-core
 
 **Domain:** custodian  
-**Last synced:** 2026-03-27 12:43 UTC  
+**Last synced:** 2026-03-27 13:00 UTC  
 **State Hub:** http://127.0.0.1:8000 *(adjust if running on a remote machine)*
 
 ## Active Workstreams
 
+### activity-core Foundation — Temporal Backbone
+Progress: 21/21 done  |  workstream_id: `e22516cc-4fdf-4dad-a928-a9e04a9fa7c7`
+
 ### activity-core Triggers & Ops
 Progress: 0/12 done  |  workstream_id: `3a4f47d9-8bc1-434e-acb4-bed5d4dacda0`