[FEATURE] Allow descriptive/custom plan file naming instead of random adjective-noun combinations

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

Plan files are currently named with random adjective-noun combinations (e.g., lively-bubbling-umbrella.md). This makes it difficult to:

• Identify what a plan was about without opening it
• Manage multiple plans across sessions
• Keep the ~/.claude/plans directory organized over time

Proposed Solution

Allow Claude to generate descriptive filenames based on the task context:

1. Auto-descriptive naming (preferred): Derive filename from the task/conversation context

• fts-search-refactoring.md
• auth-flow-implementation.md

1. User-specified naming: Allow users to specify a plan name via flag or prompt

• /plan --name "fts-refactor"

1. Hybrid: Auto-generate descriptive name, allow override

Additional Considerations:

• Collision handling: append timestamp or short hash if name exists
• Setting to toggle between current random naming and descriptive naming
• Filename sanitization for special characters

---

Reopened from #18789 which was auto-closed by the stale bot as a false duplicate.