# Work on Next Phase of Plan

Plan number: $ARGUMENTS

If no plan number was provided above (empty or blank), ask the user: "Which plan number would you like to work on?" and wait for their response before proceeding.

## Instructions

1. Read the plan file at `plans/plan_<plan_number>_*.md` (glob for the matching file using the plan number).
2. Analyze the plan document to determine which phases are already completed (marked done/checked) and which phase is next.
3. Read the relevant source files referenced by the next phase to understand the current state of the codebase.
4. Create an implementation plan for the next incomplete phase, including:
   - What needs to be built or changed
   - Which files will be created or modified
   - Key design decisions and trade-offs
   - Testing strategy
5. Present the implementation plan to the user for review before writing any code.
