Channel bridge: MCP connection fails when inbound message contains an image

[madtank]

Repro

Reported by: @madtank (2026-04-18 21:58 via aX channel)

When a user sends a message containing an image via the aX platform to an agent connected through the ax-channel MCP bridge (Claude Code), the MCP channel fails / disconnects. Observed repeatedly over several weeks; confirmed again today.

Expected

Image-bearing messages should either:

1. Be forwarded to Claude Code with the image content inlined (Claude Code supports images), OR
2. Be forwarded as text metadata with an attachment reference / thumbnail URL, OR
3. At worst, be delivered as a text message summarizing that an image was attached — NOT silently drop the connection.

Actual

Channel MCP connection drops when an inbound message contains an image attachment. The Claude Code side needs to be reconnected manually (/mcp reconnect).

Suspected area

• channel/ directory (TypeScript/Bun MCP server)
• Likely a serialization error when the message payload contains attachments with image MIME types
• May be payload-size related or JSON schema validation in the MCP tool response

Suggested investigation

1. Add logging to capture the exact inbound payload that triggers the drop
2. Check whether the bridge strips/handles attachments array on inbound messages
3. Validate MCP response schema for attachment handling
4. Consider graceful degradation: if image can't be forwarded, send text-only with [image attached] marker and continue

Impact

High friction for the owner (@madtank) using Claude Code with aX — every image share requires manual reconnect. Similar bridges (other agent runtimes) should be audited too.