Plan files should have descriptive names instead of random words

Problem

When using plan mode, Claude Code auto-generates random three-word filenames for plan files. These names make it impossible to identify what a plan is about without opening each file.

Current behavior

Plan files in ~/.claude/plans/ get random adjective-adjective-noun names. After a few weeks of use, the plans directory becomes a wall of meaningless names:

bubbly-tumbling-cocoa.md
compressed-marinating-stonebraker.md
cozy-enchanting-puzzle.md
delegated-popping-hejlsberg.md
eager-wandering-flute.md
reactive-dazzling-moler.md
scalable-wandering-badger.md

Desired behavior

Plan filenames should be derived from the plan's content or the user's prompt. For example:

• User says "plan how to add input validation" → input-validation.md
• User says "plan the error handling redesign" → error-handling-redesign.md
• A plan about refactoring auth middleware → auth-middleware-refactor.md

A short kebab-case slug summarizing the plan topic would make plans browsable and findable without opening each one.

Workaround

Currently renaming files manually after creation via mv, which works but adds friction.

Environment

• Claude Code CLI
• macOS