Accept story 44: Agent Completion Report via MCP

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.story_kit/stories/archived/44_agent_completion_report_via_mcp.md

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+---
+name: Agent Completion Report via MCP
+test_plan: approved
+---
+
+# Story 44: Agent Completion Report via MCP
+
+## User Story
+
+As an agent finishing work on a story, I want to report my completion status via an MCP tool, so that the system can deterministically advance the workflow without relying on prompt compliance.
+
+## Acceptance Criteria
+
+- [ ] MCP tool report_completion(story_id, agent_name, summary) allows agents to signal they are done
+- [ ] Server rejects the report if the agent's worktree has uncommitted changes
+- [ ] Server runs acceptance gates (clippy, tests) automatically on report
+- [ ] Completion status and results are stored on the agent record for retrieval by wait_for_agent or the supervisor
+- [ ] Agent prompts are updated to call report_completion as their final action
+
+## Test Plan
+
+### Unit Tests (agents.rs)
+- `report_completion_rejects_nonexistent_agent` — calling on a non-existent agent returns Err
+- `report_completion_rejects_non_running_agent` — calling on an already-Completed agent returns Err
+- `report_completion_rejects_dirty_worktree` — calling with uncommitted changes returns Err containing "uncommitted"
+- `report_completion_stores_result_and_transitions_status` — with a clean real git worktree, completes and stores a CompletionReport
+
+### Unit Tests (mcp.rs)
+- `report_completion_in_tools_list` — tool appears in handle_tools_list output
+- `report_completion_tool_missing_story_id` — returns Err mentioning "story_id"
+- `report_completion_tool_missing_agent_name` — returns Err mentioning "agent_name"
+- `report_completion_tool_missing_summary` — returns Err mentioning "summary"
+- `report_completion_tool_nonexistent_agent` — isError response for unknown agent
+- `wait_for_agent_includes_completion_field` — wait_for_agent JSON output has "completion" key
+
+## Out of Scope
+
+- Frontend UI for displaying completion reports
+- Persisting completion reports to disk across server restarts
+- Running biome/frontend checks in the acceptance gates (Rust only for now)