[Bug] Disabling Extended Thinking via button shows raw <thinking> tags in chat (VSCode extension)

Environment: Claude Code VSCode extension

Steps to reproduce:

1. Enable Extended Thinking (via the toggle button in the chat UI)
2. Disable it via the same button

Expected: thinking is hidden, chat works normally

Actual: <thinking>...</thinking> tags appear as raw text in the chat window

Workaround: /clear after disabling, or avoid toggling mid-session