[Bug] Plugin auto-update leaves stale cached versions causing duplicate skill registrations

Bug Description
Issue: When plugins auto-update, old cached versions remain in ~/.claude/plugins/cache/, causing duplicate skill registrations.

Observed behavior:

• dev-browser@dev-browser-marketplace had two cached versions:
• 0563717610bb (newer, from auto-update)
• 45c3e37c9bdd (older, referenced in installed_plugins.json)
• Both versions' SKILL.md files were loaded, causing the skill to appear twice in the available skills list

Expected behavior:

• When a plugin updates, the old cache directory should be removed
• Only one version per plugin should exist in cache

Impact:

• Duplicate skills in skill list (token waste)
• Potential confusion about which version is active
• Cache bloat over time

Reproduction:

1. Install a plugin from a marketplace
2. Wait for or trigger auto-update
3. Check ~/.claude/plugins/cache/<marketplace>/<plugin>/ - multiple version directories may exist

---
Should I wait for the agent results to add more specifics, or do you want to file this now? The core issue is clear: stale cache cleanup missing from auto-update flow.

Environment Info

• Platform: darwin
• Terminal: WarpTerminal
• Version: 2.0.70
• Feedback ID: fba5b480-11fb-4754-8630-1907066f1846

Errors

[{"error":"Error: Request was aborted.\n    at dt._createMessage (file:///Users/andremachon/.nvm/versions/node/v22.14.0/lib/node_modules/@anthropic-ai/claude-code/cli.js:463:3151)\n    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)","timestamp":"2025-12-16T20:29:38.285Z"}]