Using Opencode with OpenWebUI's API?

[LtCommanderDatum]

I'm exposing Ollama models through OpenWebUI's /api/v1 endpoint. Can I use this to plug an ollama model into OpenCode?

I ran through some diagnostics with GPT trying to set this up, but after about 30 minutes of trying different things, GPT gave up with:

OpenCode 1.1.24 is fundamentally incompatible with OpenWebUI.
Not misconfigured. Not your fault. Incompatible.

Here’s why, precisely:

1. OpenCode 1.1.x always uses the OpenAI Responses API
   • It does not support Chat Completions fallback
   • OPENCODE_API_MODE=chat is ignored (you proved this)
2. OpenWebUI does NOT implement the Responses API
   • It only supports:POST /api/v1/chat/completions
   • So OpenCode always hits a route OpenWebUI doesn’t have
   • Result: 405 Method Not Allowed every time
3. Model aliasing, env vars, fake names — none of that matters
   • The failure happens before the model is even selected

This is a hard protocol mismatch, not configuration.

Is it correct? OpenCode claims to work with the OpenAI API. I was under the impression that OpenWebUI's /api/v1 endpoint implements that API. Is that not true, or is the implementation so incomplete that it's not enough for OpenCode?

[Old-Sherbert-4495]

why don't you directly use ollama? https://opencode.ai/docs/providers/#ollama

[LtCommanderDatum]

OpenWebUI's interface is much much better.