Design a structured, wave-based implementation plan (`PLAN.md`) outlining tasks, dependency order, test cases, must-haves, and threat models for the target phase. @.opencode/references/hm-coordination-contracts.md @.opencode/references/hm-gate-triad.md Outputs generated by this workflow are consumed by: 1. **hm-execute**: Directly executes tasks wave-by-wave, resolving the defined code changes and TDD checks. 2. **hm-verify**: References must-haves (truths, artifacts, key links) in the plan to perform verification. **CRITICAL: Task alignment.** Every task in the plan must trace back to a requirement in `CONTEXT.md` or `SPEC.md`. Do not add tasks that are unrelated to the target phase goal. Load phase details. Read `CONTEXT.md` (and `SPEC.md` / `RESEARCH.md` if present) to ingest locked decisions, requirements, and codebase scouts. Decompose the implementation into sequential, dependency-ordered waves. - Wave 0: Foundations (types, interfaces, mock data, schema definitions). - Wave 1+: Core features, sequential implementation of modules. - Final Wave: Verification, wiring, and cleanup. Enforce concurrency limits: **max 2 parallel tasks** in any execution wave. For each task: - Detail exact file paths affected. - Define expected behaviors and edge cases. - Specify exact test files to run. - Write falsifiable completion criteria. Define explicit phase must-haves in the plan frontmatter: 1. **truths**: Clear, falsifiable statements of expected behavior. 2. **artifacts**: File paths that must exist and be non-empty. 3. **key_links**: Logical relationships and pattern matches between files. Construct the STRIDE threat register: - Define trust boundaries. - Catalog potential threats, category, component, and mitigation plan. Write the completed plan to `${phase_dir}/${padded_phase}-PLAN.md` using the standard `hm-plan` template structure. Stage and commit the generated `PLAN.md` file atomically to git. Record plan details in `.planning/STATE.md` and commit. - Plan partitioned into sequential waves. - No wave exceeds 2 parallel tasks. - Must-haves (truths, artifacts, links) defined in frontmatter. - STRIDE threat model mapped to components. - Atomic commit succeeded.