## Code Review ### Spec Pattern Search (REQUIRED) - Searched for existing spec patterns: `find spec -name "*spec.rb" | sort` - Found existing spec files: - spec/models/agent_spec.rb (existing, extended) - spec/requests/api/v1/mcp_spec.rb (existing, extended) - Similar patterns found: Model specs and request specs follow established patterns ### Test Results - Test suite run for PR files: `bundle exec rspec spec/models/agent_spec.rb spec/requests/api/v1/mcp_spec.rb` - Results: **126 examples, 0 failures** Note: Full suite has pre-existing failures in `spec/jobs/orchestrator_ping_job_spec.rb` (syntax error) and `spec/features/dashboard_spec.rb` - these are NOT caused by this PR. ### Spec Coverage Check - Files changed: - app/controllers/api/v1/mcp_controller.rb (mark_busy handler) - app/models/agent.rb (busy_without_session scope and methods) - Required specs found: - spec/models/agent_spec.rb - 3 specs for `busy_without_session?` - spec/models/agent_spec.rb - 5 specs for `mark_idle_if_no_session!` and scope - spec/requests/api/v1/mcp_spec.rb - 4 specs for updated `mark_busy` handler - spec/requests/api/v1/mcp_spec.rb - existing mark_busy specs now require running session (before block added) - Missing specs: **NONE** - All new code is covered ### Findings - **Code quality**: Clean implementation, follows fail-fast principle - **Security**: No issues detected - **Implementation**: - Enforces agents can only mark busy with active running session - Helpful error message includes session creation instructions - Returns session_id in success response for debugging - Added zombie detection scope and auto-cleanup method - **Breaking changes**: None - API returns helpful error instead of silently allowing invalid state ### Decision **PASS** - All tests pass, comprehensive spec coverage, clean fix that addresses the root cause by enforcing the invariant that busy agents must have running sessions.