Create executable phase plans (PLAN.md files) for a roadmap phase with integrated research and verification. Headless SDK variant — runs autonomously. Research, planning, and plan-checking proceed without user prompts. Default flow: Research (if needed) -> Plan -> Verify -> Done. Load all context from injected context files. Extract: phase directory, phase number, phase name, research status, context status, plan count, requirement IDs. If planning directory is missing: report error via event stream. Validate phase exists in roadmap. If not found: report error with available phases. Load CONTEXT.md if it exists. This contains user decisions that constrain planning. If no CONTEXT.md exists: proceed without — plan using research and requirements only. In headless mode, there is no interactive discuss-phase; context comes from prior artifacts or is skipped. If RESEARCH.md exists: use existing research. If RESEARCH.md is missing and research is enabled: 1. Execute research phase (spawn researcher agent) 2. Researcher writes RESEARCH.md 3. Continue to planning If research is disabled: skip to planning step. Execute planning with the planner agent definition. Provide: - Phase number, name, and goal - Context files: state, roadmap, requirements, context, research - Phase requirement IDs (every ID must appear in a plan's requirements field) The planner creates PLAN.md files with task breakdown, dependency analysis, and verification criteria. - **PLANNING COMPLETE** — Plans created. If plan checker is enabled: proceed to verification. - **PLANNING BLOCKED** — Log blocker, report via event stream. - **PLANNING INCONCLUSIVE** — Report with available context. If plan checker is enabled, execute verification with the plan-checker agent. Provide: - Phase number and goal - Plan files to verify - Roadmap, requirements, context, research files - Phase requirement IDs The checker verifies plans will achieve the phase goal before execution. - **VERIFICATION PASSED** — Plans ready for execution. - **ISSUES FOUND** — Enter revision loop (max 3 iterations): 1. Send issues back to planner for targeted revision 2. Re-run plan checker 3. If max iterations reached: proceed with current plans, log remaining issues After plans pass the checker (or checker is skipped), verify all phase requirements are covered: 1. Extract requirement IDs claimed by plans 2. Compare against phase requirements from roadmap 3. If gaps found: log as warning, continue (headless mode does not block for coverage gaps) - Phase validated against roadmap - Research completed (unless skipped or existing) - PLAN.md file(s) created with valid structure - Plan checker passed (or issues logged) - Requirements coverage verified