openclaw - 💡(How to fix) Fix Cron announce delivery fails when agent response contains only MEDIA: directives [1 participants]

Summary

When a cron job with delivery.mode: "announce" triggers an isolated agent session, and the agent's response contains only MEDIA: directives (no plain text), the delivery fails with:

Error: Slack send requires text, blocks, or media

Steps to reproduce

1. Configure a cron job with delivery.mode: "announce" targeting a Slack channel
2. Instruct the agent to return only MEDIA: lines (e.g., "Return only exactly two MEDIA lines and nothing else")
3. Wait for the cron job to fire

Expected behavior

The MEDIA: directives should be processed into file uploads by the delivery handler, and the files should be posted to the target channel — the same way MEDIA: works in interactive chat replies.

Actual behavior

The delivery handler appears to strip MEDIA: directives from the text but does not populate the media field on the outgoing Slack message, leaving no content to post. The job errors with "Slack send requires text, blocks, or media".

Workaround

Include a short text line before the MEDIA: directives in the agent prompt:

Morning Executive Summary — April 7, 2026
MEDIA: /sandbox/.openclaw/workspace/out/summary.pdf

This ensures the delivery handler always has text content even if MEDIA processing fails.

Environment

• OpenClaw 2026.4.5
• Slack channel plugin, Socket Mode
• Cron delivery mode: announce
• Gateway running inside OpenShell sandbox

Additional context

The same cron job prompt pattern works intermittently — it succeeded on previous days but failed after a gateway restart, suggesting the MEDIA file upload may also be timing-sensitive relative to the Slack connection state post-restart.

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