Session corruption from terminal escape sequences in tool output

Summary

When a Bash tool command emits raw terminal escape sequences (e.g., mouse tracking, alternate screen buffer), these get stored in the session JSONL file. When the session is later resumed with --resume, displaying the conversation history causes the terminal to interpret these escape sequences, corrupting the terminal state (enabling mouse tracking, messing up display, etc.).

Steps to Reproduce

1. Run a command that emits terminal escape sequences, such as:

• jj split (interactive by default)
• Any command that opens a TUI and fails mid-execution
• Commands with --interactive flags

1. The command fails with output containing raw ESC sequences like:

``
\x1b[?1049h\x1b[?1000h\x1b[?1002h\x1b[?1003h\x1b[?1015h\x1b[?1006h
``

1. These sequences get stored in the session's toolUseResult.stdout field

1. Later, run claude --resume <session-id>

1. When the session history is displayed, the terminal interprets the escape sequences, enabling mouse tracking and corrupting the terminal

Expected Behavior

Terminal escape sequences in tool output should be:

• Stripped/sanitized before storing in the session log, OR
• Escaped when displaying session history so they render as text rather than being interpreted

Actual Behavior

Raw escape sequences are stored and later interpreted by the terminal when displaying session history, corrupting terminal state.

Suggested Fix

Options:

1. Sanitize on capture: Strip ANSI/terminal escape sequences from Bash tool stdout/stderr before storing in session
2. Sanitize on display: Escape or strip control sequences when rendering session history
3. Both: Defense in depth

Relevant escape sequence patterns to filter:

• \x1b[?1000h - Enable mouse tracking
• \x1b[?1049h - Alternate screen buffer
• \x1b[?1002h, \x1b[?1003h, \x1b[?1006h, \x1b[?1015h - Various mouse modes
• Generally: \x1b[ followed by parameters and a letter

Environment

• Claude Code CLI
• macOS (likely affects all platforms)
• Triggered by jj split command (jujutsu VCS) but could happen with any TUI/interactive command