docs: accept leader summary notification architecture

.project-docs/05-agent-entry/integration-gate.md

@@ -6,6 +6,7 @@ Use this gate to promote completed task facts into canonical project memory.
 
 - Run in an exclusively owned integration worktree.
 - Hold the repository integration lock.
+- For a single completed Feature, create the Integration worktree from that Feature commit so its task-owned records are already inside the Integration task's recorded base. Verify the target default branch is an ancestor or reconcile it explicitly before canonical edits; starting from the older default branch and then introducing another task's record will correctly fail the drift gate.
 - Verify the task commits being integrated are present.
 - Review source task records, task-prefixed supporting records, promotion candidates, and semantic conflicts in read-only mode.
 - Write integration notes only to the integration task's own task record or `{task_id}__<slug>.md` supporting records.