IDE extension: expanding a long user message pushes 'Show less' off-screen with no in-message scroll — can't collapse without scrolling the whole session

What happened

In the Claude Code VS Code extension chat, expanding a very long user message ("Show more") makes it impossible to collapse the message again without a workaround:

• The "Show less" control renders below the visible viewport.
• The message's internal scroll does not work — the expanded message just grows past the viewport.
• The only way to reach "Show less" is to scroll the entire session to the very bottom until the button re-appears, collapse it there, then scroll back up.

Effectively an expanded long message hijacks navigation until you manually work around it.

Steps to reproduce

1. Have a chat where a single user message contains a large amount of text (long enough to be truncated behind a "Show more" toggle).
2. Click Show more to expand that message.
3. Try to collapse it again.

Expected

The expanded message is scrollable within its own bounds, or the "Show less" control stays reachable (sticky / inside the message container), so the message can be collapsed in place — without scrolling the whole conversation.

Actual

"Show less" is off-screen and there is no in-message scroll; you must scroll to the end of the entire session to find the button, collapse, and scroll back.

Environment

• Claude Code VS Code extension: anthropic.claude-code v2.1.207 (darwin-arm64)
• VS Code: 1.128.0 (commit fc3def6774c76082adf699d366f31a557ce5573f, 2026-07-07)
• Electron: 42.5.0 · Chromium: 148.0.7778.271 · Node.js: 24.17.0
• OS: macOS (Darwin arm64 25.5.0)

Severity

Usability / Minor–Medium — no data loss, but interaction is blocked until a non-obvious workaround, and it gets worse the longer the message and the session.