Feature request: Store plan mode files in project .claude/plans/ instead of ~/.claude/plans/

Problem

Plan mode files accumulate in ~/.claude/plans/ with random names (e.g., misty-sleeping-cherny.md), making it difficult to:

• Associate plans with specific projects
• Organize or clean up old plans
• Share plans with team members via git

Current behavior

• Plan files are always saved to ~/.claude/plans/ (user-level)
• File names are randomly generated
• No cleanup or listing command exists
• Moving files breaks plan mode editing (Ctrl+G)

Inconsistency

Other project-scoped files already use project-level .claude/:

• .claude/rules/ ✅
• .claude/agents/ ✅
• .claude/skills/ ✅
• .claude/plans/ ❌ (missing)

Suggested improvements

1. Option to save plans in project .claude/plans/ instead of (or in addition to) ~/.claude/plans/
2. Meaningful file names — date + summary (e.g., 2026-03-14_auth-refactor.md) instead of random words
3. A command to list/clean up old plan files (e.g., /plans list, /plans clean)

Use case

When working on multiple projects, plan files from all projects mix together in ~/.claude/plans/. Storing them at the project level would keep plans organized, version-controllable, and easier to reference later.