feat: Use OpenRouter Default Model instead of OpenRouter/auto

[RONNCC]

• [X] I have searched the existing issues

Is your feature request related to a problem? Please describe it

Currently Jan defaults to using "openrouter/auto" which costs money.

Describe the solution

It may be better if Jan instead does not pass a model parameter.

This would make OpenRouter fallback to the default model chosen in settings which could be a free model or it also could also be set to openrouter/auto which would be the same as the current functionality.

Teachability, documentation, adoption, migration strategy

Users will be able to use this the same way as the current OpenRouter model.

What is the motivation / use case for changing the behavior?

So I can use the free models on OpenRouter

[RONNCC]

Change would just require removing "openrouter/auto" in the pertinent transformPayload function

[tmobilon]

Why not show a dropdown so the user can choose between all the available models in Openrouter?

[RONNCC]

@tmobilon Sounds great but seems more complicated to implement?

From my understanding reverting to the DefaultModel is the default behavior of the OpenRouter API if a model string is not explicitly provided in an API call.

https://openrouter.ai/docs/requests

[RONNCC]

@hahuyhoang411 wondering if y'all would be open to the above change? I can write up a PR?

[ghz]

+1 for adding a models selection dropdown

[josemnbcamacho]

Why not allow for all the OpenRouter available models? It is possible to list all the available models via API at openrouter.ai/api/v1/models

[RONNCC]

@josemnbcamacho @ghz those all require a lot more work and knowledge to interface with the Jan UI.

[Van-QA]

As of nightly Jan v0.5.2-603, the open router now redirected to default instead of auto