Voice input: transcription rendered twice (duplicate text) in UI

Bug description

When using voice dictation in Claude Code, the transcribed text appears twice at the bottom of the screen — once in the real-time preview and once as a persistent duplicate after the message is sent.

Steps to reproduce

1. Open Claude Code (desktop/terminal, macOS darwin arm64)
2. Use voice dictation to compose a message
3. Send the message
4. Observe duplicate text appearing at the bottom of the interface

Expected behavior

Transcribed text appears once — in the input field while dictating, then disappears after sending.

Actual behavior

The transcription is rendered in two places simultaneously. After sending, the duplicate text remains visible at the bottom of the screen.

Environment

• Claude Code version: 2.1.175
• OS: macOS darwin arm64 (Apple Silicon)
• Shell: zsh
• Input method: Voice dictation (built-in macOS mic)

Screenshot

The duplicate appears at the bottom of the chat window as a second copy of the same transcribed message text.

Notes

• This is a visual/rendering bug only — the message is received correctly by Claude (no functional impact)
• Verified: version 2.1.175 is the latest available, so no update can fix this
• The binary is a compiled native arm64 Mach-O — no config or hook workaround is possible from outside