docs: consolidate agent execution and custody

docs/integrations/activity-core-handoff-wp0006.md

@@ -1,9 +1,15 @@
 # activity-core Handoff — Scheduled Agent Execution (WP-0006)
 
+> **Historical supplier handoff, completed for the initial resolver/pilot path.**
+> The current production composition is activity-core durable `ops_run` work
+> claimed by rein-aharness through its generic `agent-session` approach. The
+> resolver and preparation contracts below remain compatible inputs.
+
 Coordination checklist for the **activity-core** team to enable kaizen scheduled
 agent runs. kaizen-agentic owns the schedule contract, the prepare CLI, and the
-ActivityDefinition **drafts**; activity-core owns the resolver, the schedule
-firing, and task creation (repo boundary, ADR-005).
+ActivityDefinition **drafts**; activity-core owns the resolver, schedule firing,
+and durable work creation (repo boundary, ADR-005); rein-aharness owns governed
+execution.
 
 Open this as an activity-core issue/PR titled *"Enable kaizen scheduled agent
 execution (WP-0006)"* and track the boxes there.
@@ -56,7 +62,7 @@ in kaizen-agentic drafts) when engagement moves beyond coulomb-loop bootstrap co
 - [ ] Optional: add `kaizen_schedule_enabled` repo flag + `GET /repos/` filter
       (v2 pre-filter; the repo file remains the source of truth).
 
-## Smoke test (manual, runner-agnostic)
+## Smoke test (manual reference path)
 
 ```bash
 cd /path/to/pilot-repo
@@ -68,6 +74,9 @@ kaizen-agentic schedule prepare coach   # non-empty orientation bundle
 
 Then in activity-core: run the resolver (dry-run) and confirm one
 `scheduled_run` per enabled `(repo, agent)` with a correct `prepare_command`.
+For unattended operation, confirm the resulting `ops_run` is claimable and the
+rein-aharness worker selects the `agent-session` approach before enabling the
+schedule broadly.
 
 ## Pilot roster