agent: add plan-issue command for interactive implementation planning

[p-iknow]

Requirement

What agent rule/command needs to be created/updated:

Create a new custom command /plan-issue that:

• Takes a GitHub issue number as input
• Fetches the issue details using gh CLI
• Enters plan mode to create a detailed work plan
• Interacts with the user to review and refine the plan with clear rationale
• Shows WHY the plan is structured that way, WHAT problem it solves, and HOW it will be solved

Implementation Plan (optional)

Rule/Command type:
Custom slash command (.claude/commands/plan-issue.md)

Trigger conditions:
User executes /plan-issue [issue-number]

Expected behavior:

1. Fetch issue data using gh issue view {issue-number} --json
2. Parse and analyze the issue content (requirement, implementation details, expected outcomes)
3. Generate a structured plan with:
   • Problem Analysis: What needs to be solved and why
   • Solution Approach: How we'll solve it (architecture, strategy)
   • Implementation Steps: Specific tasks with rationale
   • Success Criteria: How we'll know it's done
4. Present plan to user with clear reasoning for each decision
5. Interactive review loop to get user feedback and iterate
6. Enter plan mode using ExitPlanMode tool with finalized plan

Files to be modified:

• Create .claude/commands/plan-issue.md

Should be tested

• Rule/command should be tested locally
• Edge cases should be covered
• Documentation should be updated (if applicable)
• Documentation should referenced properly

Reference