Plan a large feature spanning multiple PRs or requiring architectural decisions. Writes a technical, increment-by-increment plan to .plans/<slug>/plan.md (with optional sibling files), runs the same code-search-first question gate as plan-small, then runs deterministic structural checks over the plan (main path) with the plan-reviewer subagent gathering extra context, and improves the plan before presenting it. Use when the user describes multi-day work, cross-system changes, or sequencing dependencies.
