Voice dictation: intermittent 'No audio detected from microphone' in some sessions but not others

Description

Voice dictation (hold Space to record) works correctly in some Claude Code sessions but fails in others, within the same VS Code instance and the same terminal application.

Environment

• Claude Code: VS Code integrated terminal
• OS: macOS (Darwin 25.2.0, MacBook Air)
• Audio input: MacBook Air built-in microphone (set as default input device)
• Other audio drivers loaded: Pro Tools Audio Bridge, eqMac (disabled), ZOOM R16, Parrot — but these are irrelevant since the issue is inconsistent across sessions in the same app

Behavior

• Working sessions: Holding Space → cursor animates (blue to green based on voice volume) → transcription works perfectly
• Broken sessions: Holding Space → cursor does NOT animate → on release, error message:

> No audio detected from microphone. Check that the correct input device is selected and that Claude…

Key observation

• Both working and broken sessions run in the same VS Code window, same terminal, same microphone permissions (granted), same default input device
• The issue is per-session, not per-app or per-device — ruling out OS-level permission or device routing problems
• Restarting a new session typically resolves the issue
• settings.json has "voiceEnabled": true and "language": "fr"

Expected behavior

Voice dictation should work consistently across all sessions, not randomly fail in some.

Steps to reproduce

1. Open Claude Code in VS Code terminal
2. Run /voice to enable dictation
3. Hold Space to record — works fine
4. Open another Claude Code session in the same VS Code terminal
5. Run /voice, hold Space — may or may not work (intermittent)

No reliable reproduction steps identified — the failure appears random across sessions.