Problem

When a user sends a silent or near-empty voice note, the audio file is under 1024 bytes and gets skipped by the transcription pipeline (as documented: "Tiny/empty audio files below 1024 bytes are skipped before provider/CLI transcription").

However, the agent doesn't receive a clear indication that the voice note was empty/silent. Instead, the missing or broken transcript context causes the agent to hallucinate an explanation — typically telling the user there's an API quota issue, which is inaccurate and confusing.

Expected behavior

When a voice note is skipped due to being under the 1024-byte threshold, OpenClaw should inject a clear message to the agent, e.g.:

• [Voice note was empty or contained only silence]
• Or set {{Transcript}} to a descriptive placeholder

This way the agent can respond appropriately ("Looks like the voice note was silent — want to try again?") instead of fabricating an error explanation.

Steps to reproduce

1. Send a voice note with no speech (just silence or very short accidental tap)
2. The audio file will be under 1024 bytes
3. Transcription is skipped
4. Agent receives unclear context and responds with a misleading API error message

Environment

• OpenClaw on Raspberry Pi 5
• Local Whisper model for transcription
• Affects all agent configurations