Implement the specified task (or determine the next task) from docs/SPEC.md Section 7.2.
Follow the TDD workflow and task execution procedure defined in .codex/agents/developer.md.
Critical path: 001 -> 003 -> 004 -> 011 -> 004a -> 012a -> 012b -> 015 -> 018b -> 018c -> 020.
OpenSpec integration: use /prompts:opsx-apply for changes, /prompts:opsx-new or /prompts:opsx-ff to create changes,
/prompts:opsx-verify before archiving, /prompts:opsx-archive when complete.