VSCode extension: "Unknown skill" errors from slash commands are not displayed in the chat UI

Bug Description

When typing an unknown slash command (e.g. /status) into the VSCode extension's chat input, the command is silently swallowed. No error is shown to the user. The error message Unknown skill: <name> does reach the model as a <local-command-caveat> block, but the user sees nothing and assumes the command ran (or was ignored intentionally).

In the terminal CLI the same input produces a visible Unknown skill: <name> error in the output — so this is a UI regression specific to the VSCode extension.

Steps to Reproduce

1. Open Claude Code in the VSCode extension
2. Type /status (or any non-existent slash command) and submit
3. Observe: nothing appears in the chat; the model answers as if the text was a normal user prompt
4. Ask the model "did you see an error?" — it will report having received Unknown skill: status via a local-command-caveat

Expected Behavior

The Unknown skill: <name> error should be rendered visibly in the chat transcript, matching terminal CLI behavior, so users know their command was rejected.

Environment

• OS: Windows 10 Pro
• Shell: bash (git-bash)
• Claude Code: VSCode extension

🤖 Generated with Claude Code