Tool progress messages rejected by streaming validator due to invalid union type #36428

Version

opencode 1.17.18

What happened

When opencode runs tool calls, it sometimes fails with:

Opencode failed to send message with error: Type validation failed:
Value: {"tool":"search_files","emoji":"🔎","label":"*","toolCallId":"call_00_ldqno5lweRBQjYVaLOab5496","status":"running"}

[ { "code": "invalid_union", "errors": [
[ { "expected": "array", "code": "invalid_type", "path": [ "choices" ] } ],
[ { "expected": "object", "code": "invalid_type", "path": [ "error" ] } ]
] } ]

Root cause

Tool progress/status messages ({tool, emoji, label, toolCallId, status}) are being sent through the same streaming channel as OpenAI-format response chunks. The Zod union validator on that endpoint expects either {"choices": [...]} or {"error": {...}}. The progress message structure matches neither variant.

Suggested fix

Either send progress messages through a separate channel, or wrap them in a valid format (e.g. add an empty choices array or nest the progress data as a sub-field of a valid message).