diff --git a/.custodian-brief.md b/.custodian-brief.md
index 8582e16..7d73778 100644
--- a/.custodian-brief.md
+++ b/.custodian-brief.md
@@ -2,12 +2,13 @@
 # Custodian Brief — activity-core
 
 **Domain:** custodian  
-**Last synced:** 2026-05-08 10:49 UTC  
+**Last synced:** 2026-05-08 11:04 UTC  
 **State Hub:** http://127.0.0.1:8000 *(adjust if running on a remote machine)*
 
 ## Active Workstreams
 
-*(none — repo may need first-session setup)*
+### activity-core Foundation — Temporal Backbone
+Progress: 21/21 done  |  workstream_id: `e22516cc-4fdf-4dad-a928-a9e04a9fa7c7`
 
 ---
 ## MCP Orientation (when available)