Co-plan a non-trivial change with Gemini CLI as a second-opinion planner. Trigger when the user says "co-plan with gemini", "plan this with gemini", "let's get gemini's take on the plan", "plan this together", or types `/co-plan`. Use this for architectural decisions, multi-step migrations, or any plan where a second model's review materially reduces the chance of a missed dependency, wrong-approach choice, or unconsidered failure mode. Skip for trivial fixes — the round-trip cost isn't worth it. Different shape from `code-research` (which is one-shot Q&A); this skill is an iterative draft-critique-revise loop.
