Add client billing and cost evidence workplans

.custodian-brief.md

@@ -2,18 +2,20 @@
 # Custodian Brief — fin-hub
 
 **Domain:** financials  
-**Last synced:** 2026-08-09 19:40 UTC  
+**Last synced:** 2026-08-10 18:08 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)*
+### Client attribution and billing basis
+Progress: 1/6 done  |  workplan_id: `ebc1d2de-ae11-4cde-b860-047922fc74b9`
 
-## Inbox Hygiene
-
-**Stale unread:** 1 message(s) older than 3 day(s) — triage at session start.
-**Missing thread_id:** 1 unread message(s) lack supersession chains.
-- ! the-custodian: Client-billing gap assessment — proposed FIN-WP-0002 skeleton  `9c8e8ed4`
+**Open tasks:**
+- ! Add engagement revenue and margin reporting  `f917bb0b`
+- ! Define shared-infrastructure allocation  `899a5c29`
+- ! Export a per-client billing basis  `b5886131`
+- ! Select the external invoicing system  `d30b606f`
+- · Add client attribution  `904e9edc`
 
 ---
 ## MCP Orientation (when available)