story-kit: queue 230_story_prevent_duplicate_stage_agents_on_same_story for QA

.story_kit/work/2_current/230_story_prevent_duplicate_stage_agents_on_same_story.md

@@ -1,22 +0,0 @@
----
-name: "Prevent duplicate stage agents on same story"
----
-
-# Story 230: Prevent duplicate stage agents on same story
-
-## User Story
-
-As a supervisor, I want start_agent to reject a second coder (or QA, or mergemaster) on a story that already has one running, so that two agents don't operate in the same worktree and corrupt each other's work.
-
-## Acceptance Criteria
-
-- [ ] start_agent rejects a second coder-stage agent on a story that already has a Running or Pending coder, with a clear error message naming both agents
-- [ ] The check covers all non-Other pipeline stages (Coder, Qa, Mergemaster), not just Coder
-- [ ] The check fires for both explicit agent_name requests and auto-selected agents
-- [ ] Auto-assign (auto_assign_available_work) is unaffected — it already has its own is_story_assigned_for_stage guard
-- [ ] Regression test: concurrent start_agent calls with two different coder names on the same story — exactly one succeeds
-- [ ] Regression test: two coders on different stories still works fine
-
-## Out of Scope
-
-- TBD