[BUG] Cannot scroll transcript in JetBrains Air (Fleet-based terminal) - mouse wheel triggers prompt-history recall

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

When Claude Code runs inside the integrated terminal of JetBrains Air (air.dev, JetBrains' agentic IDE built on the Fleet codebase; the terminal identifies as TERM_PROGRAM=Jetbrains.Fleet), the conversation transcript cannot be scrolled. Moving the mouse wheel over the transcript does not scroll it - it cycles through previously submitted prompts in the input box (as if Up/Down arrows were pressed) or does nothing. The terminal's native scrollback is also unavailable while Claude Code runs, so any output taller than the viewport is unreachable.

The mechanism appears identical to #77428 (PhpStorm "Reworked 2025" terminal engine): the JetBrains terminal translates wheel events into arrow-key sequences ("alternate scroll" behavior), and Claude Code's input box interprets Up/Down as prompt-history recall. Filing separately because JetBrains Air uses the Fleet terminal engine - a different implementation from the IntelliJ-family engine covered there - and Air is positioned as an agent-centric IDE, so it is likely to become a common host for Claude Code sessions.

What Should Happen?

Mouse wheel over the transcript scrolls the transcript (or the terminal's native scrollback), as it does in Terminal.app, iTerm2, or Ghostty. Wheel input should never be interpreted as prompt-history navigation.

Error Messages/Logs

TERM=xterm-256color
TERM_PROGRAM=Jetbrains.Fleet
TERM_PROGRAM_VERSION=262.132.35
COLORTERM=truecolor
macOS 26.4 (Darwin 25.4.0), Apple Silicon

Steps to Reproduce

1. Install JetBrains Air (air.dev) on macOS. Its integrated terminal identifies as TERM_PROGRAM=Jetbrains.Fleet.
2. Open any project, open the integrated terminal, run claude.
3. Produce output taller than the viewport (any long response).
4. Move the mouse wheel over the transcript.
5. Observe: the transcript does not scroll; wheel-up recalls previous prompts into the input box instead, and no native scrollback is available.

Claude Model

Not sure / Multiple models

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.243 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Other

Additional Information

Related reports in the same symptom family (JetBrains terminals):

• #77428 - same mechanism in the PhpStorm integrated terminal (IntelliJ-family engine)
• JetBrains YouTrack IJPL-233851 (uncontrollable high-speed scrolling), IJPL-243207 (scroll position jumps in Claude Code sessions)

Terminal/Shell is set to "Other" because JetBrains Air / Fleet is not in the dropdown list.