TUI selection spams clipboard on every render during streaming

Description

Claude Code's TUI writes selected text to the system clipboard on every re-render during streaming, flooding clipboard managers (e.g. CopyClip, Maccy, Paste) with hundreds of partial text fragments.

Reproduction

1. Open Claude Code CLI in a terminal (tested in Warp on macOS)
2. Have a clipboard history manager running (e.g. CopyClip)
3. Select some text in the Claude Code TUI (mouse click-drag)
4. Ask Claude something that produces a streaming text response
5. Check clipboard history — it will contain dozens/hundreds of entries with partial text fragments, space-padded to terminal width

Root cause (from binary analysis)

The clipboard write function (BM in the minified bundle) fires during TUI re-renders when a text selection is active. Each streaming chunk triggers a re-render, which re-syncs the selection to clipboard.

Additionally, the function writes to clipboard via two mechanisms simultaneously:

• OSC 52 escape sequence (terminal clipboard protocol)
• pbcopy subprocess (macOS) / xclip/xsel (Linux)

This means each re-render may produce 2 clipboard writes.

Evidence

Pasteboard monitoring with a Swift script showed:

• Zero clipboard writes at idle (no Claude streaming)
• Zero clipboard writes during tool calls (no visible text output)
• 5+ writes per 20 seconds during text streaming, containing fragments of the streamed response
• Zero clipboard writes during non-Claude terminal output in the same terminal (Warp)

The macOS pasteboard change count reached 4996+ during a single session.

Expected behavior

• Clipboard should only be written on explicit user action: /copy command, Cmd+C, or equivalent
• TUI re-renders should not re-sync selection to clipboard
• If selection-to-clipboard is intentional, it should be debounced during streaming (e.g. only write on selection end, not on every frame)
• Consider not using both OSC 52 and pbcopy simultaneously (double-writes)

Environment

• Claude Code CLI (Bun binary, installed via ~/.local/bin/claude)
• macOS (Darwin 25.3.0, arm64)
• Terminal: Warp
• Clipboard manager: CopyClip

🤖 Generated with Claude Code