In plan mode, Copilot creates a plan before implementation and saves that plan to plan.md. This makes the proposed approach available for review, refinement, and continuation rather than immediately executing repository changes.
The plan file creates a durable handoff point between planning and implementation. A developer can inspect the proposed work, assess dependencies and risk, adjust tasks, and decide whether implementation should proceed. This separation is essential for workflows that require approval before modification.
Plan mode does not automatically open a pull request or create a branch. It also does not begin implementation simply because a plan was generated. Those actions require a subsequent transition to an implementation workflow or a direct instruction from the user.
Study-guide topics: planning mode, durable plans, state persistence, and staged agent execution.