Problem

Same as #57296 — TTS generates valid audio files but WebChat/Control UI never plays them or shows them as attachments.

Environment

• OpenClaw 2026.5.4 (325df3e)
• Windows 11 host, Loopback gateway
• MiniMax TTS via Portal OAuth (speech-2.8-hd, Chinese (Mandarin)_Mature_Woman)
• messages.tts.auto: always

Verified

• TTS API call succeeds — audio files ARE generated
• ffprobe confirms valid MP3: 9.85s, 32000Hz mono 128kbps, AIGC metadata from MiniMax
• Files land in %TEMP%\openclaw\tts-\voice-.mp3
• Gateway logs show no errors

Expected

Audio should be playable inline in WebChat or at minimum downloadable as an attachment.

Actual

No audio, no attachment, no player UI. Text reply only.

Related

• WebChat TTS reports success but produces no audible playback or downloadable audio (Telegram works) #57296 (macOS, same root cause)
• [Feature]: Add audio upload and playback support in webchat #65859 (feature request for audio upload/playback)
• WebChat TTS: add explicit routing/playback logs and user-visible delivery status #57297 (missing playback logs)