story-kit: queue 129_story_test_coverage_http_mcp_rs for QA

.story_kit/work/3_qa/129_story_test_coverage_http_mcp_rs.md

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+---
+name: "Add test coverage for http/mcp.rs (72% -> 85%+)"
+---
+
+# Story 129: Add test coverage for http/mcp.rs
+
+Currently at 72% line coverage (1826 lines, 475 missed). This is the MCP tool server — the largest module and the interface agents use to interact with the system.
+
+## What to test
+
+- Uncovered MCP tool handlers (check which tools lack test coverage)
+- Tool argument validation and error messages
+- Edge cases in existing tool handlers
+- The merge-queue and watcher-pause logic (added in story 119)
+- `resolve_simple_conflicts` edge cases
+- Tool dispatch routing
+
+## Notes
+
+- This is a large file — focus on the uncovered handlers rather than trying to test everything
+- Run `cargo llvm-cov --html` to identify specific uncovered lines/functions
+- The merge-related tools are the most critical gaps given recent changes
+- 475 missed lines is a lot — even covering half would be a big win
+
+## Acceptance Criteria
+
+- [ ] Line coverage for `http/mcp.rs` reaches 85%+
+- [ ] Tests pass with `cargo test`
+- [ ] `cargo clippy` clean