[BUG] Slash command autocomplete always selects wrong command regardless of typed input

Description

When typing any slash command in the CLI input, the autocomplete dropdown appears but always highlights/selects /slack-formatting (a custom skill) regardless of what text is typed. The filtered list updates correctly to show matching commands, but the selection remains stuck on /slack-formatting.

Steps to Reproduce

1. Open Claude Code CLI
2. Type /context (or any other slash command)
3. Observe the autocomplete dropdown

Expected Behaviour

The autocomplete should highlight a command that matches the typed input (e.g., commands containing "context" when typing /context).

Actual Behaviour

The autocomplete dropdown shows a filtered list of commands, but /slack-formatting is always selected/highlighted regardless of typed input. The selection does not follow the typed text.

Screenshot

<img width="2078" height="602" alt="Image" src="https://github.com/user-attachments/assets/386d88af-e8b5-4b0d-952a-d7be131ef0cb" />

Environment

• Claude Code Version: 2.1.12
• Platform: macOS Darwin 24.6.0
• Installation Method: Native

Troubleshooting Attempted

• Cleared ~/.claude/history.jsonl - did not fix
• Verified /slack-formatting is not the most frequently used command (only 4 uses vs 268 for /clear)
• No unusual settings in ~/.claude/settings.json

Related Issues

• #10937 - Similar autocomplete selection bug (closed as fixed in Nov 2025, but this appears to be a regression or different manifestation)
• #1359 - Session files breaking autocomplete

Additional Context

The /slack-formatting skill is a standard custom skill in ~/.claude/skills/slack-formatting/ with no special priority or configuration. The bug affects all slash command inputs, not just specific ones.