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Opencode calls 'Claude 3.5 Haiku' on session start, despite selecting a custom model #1243
Description
This is an edge case that I keep finding myself in.
Given the following opencode.json config (bodging together suggestions from a comment in #1050 & a comment in #1038):
{
"$schema": "https://opencode.ai/config.json",
"provider": {
"openrouter": {
"options": {
"name": "OpenRouter"
},
"models": {
"moonshotai/kimi-k2:free": {
"name": "MoonshotAI: Kimi K2 (free) - Chutes",
"attachment": false,
"reasoning": true,
"temperature": true,
"tool_call": true,
"limit": {
"context": 60000,
"output": 60000
},
"options": {
"tools": true,
"openrouter": {
"provider": {
"order": ["chutes/fp8"],
"allow_fallbacks": false
}
},
"OpenRouter": {
"provider": {
"order": ["chutes/fp8"],
"allow_fallbacks": false
}
}
}
}
}
}
}
}(the almost-similar "openrouter" keys are just there to make sure opencode actually shoves in the specified provider info)
And selecting the custom model, when I start a new session and enter a test prompt, these prompts appear on my 'Activity' page using the Claude model instead of the specified Kimi K2 model:
Afterwards, the issue no longer appears: It only pops up when a new session is created & the first prompt is given (any prompt).
Reacted by PhilGlau and chromatic
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rekram1-node commentedon Jul 23, 2025
opencode does use a small model to generate titles, in many cases claude 3.5 haiku if it is available
That seems like what you are seeing especially since you mentioned it only happens at session start (and that is when title is generated)
thdxr commentedon Jul 23, 2025
^ yes that's right and you can override small model in the config if you want to control that
SteveHere commentedon Jul 28, 2025
Belated response (& note for future me): Fixed the issue by specifying the
small_modelvalue in the config file.DX note: It took looking at the hosted
config.jsonschema to see which value should be changed. I couldn't see it in the documentation because it was out of sync with the .mdx file.Will be making a new issue for this.
filmo commentedon Mar 11, 2026
Can you provide a sample of your revised opencode.json config for setting the small_model?
EDIT: 2026-03-27 => Here's what I did to adjust it to Mistral Small in my opencode.json file:
{ "$schema": "https://opencode.ai/config.json", "small_model": "openrouter/mistralai/mistral-small-3.2-24b-instruct", "mcp": { ... }, ... }And it seems to work.
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fix(share): harden legacy publish endpoints (anomalyco#1243)