[BUG] Many Providers Silently do not Use Custom Model Selection

[DarkEden-coding]

Problem (one or two sentences)

When a user provides a custom model name for MiniMax (and other providers) (not in the predefined list), the model is silently replaced with the default "MiniMax-M2.5" and the user's choice is ignored.

Context (who is affected and when)

Any user trying to use a custom MiniMax model or a newly released model not yet in the hardcoded list.

Reproduction steps

1. Set up MiniMax provider with API key
2. Enter a custom model ID (e.g., "MiniMax-M2.7" or any model not in the predefined list)
3. Start a chat session
4. Check which model is actually used

Expected result

Either the custom model is used (with default model info), or an error message indicates the model is unknown.

Actual result

The API uses "MiniMax-M2.5" instead of the user's custom model, with no warning. The user's custom model selection is silently ignored.

Variations tried (optional)

No response

App Version

3.51.1

API Provider (optional)

Not Applicable / Other

Model Used (optional)

No response

Roo Code Task Links (optional)

No response

Relevant logs or errors (optional)

[DarkEden-coding]

This is actually an issue with all providers it seems (other than auto fill providers like openrouter)

[roomote-v0]

I've analyzed this issue and here's my proposed implementation plan:

Root Cause: In src/api/providers/minimax.ts, the getModel() method (line 274) checks if the user's model ID exists in the hardcoded minimaxModels map. If it doesn't, it silently replaces the user's choice with the default minimaxDefaultModelId ("MiniMax-M2.5"):

const id = modelId && modelId in minimaxModels ? (modelId as MinimaxModelId) : minimaxDefaultModelId

Fix: Adopt the same pattern used by other providers like Moonshot and DeepSeek, which preserve the user's custom model ID but fall back to the default model's info (capabilities/pricing metadata):

const id = this.options.apiModelId ?? minimaxDefaultModelId
const info = minimaxModels[id as MinimaxModelId] || minimaxModels[minimaxDefaultModelId]

This way the user's custom model name is sent to the API as-is, with reasonable default settings applied when the model isn't in the predefined list.

Changes:

1. src/api/providers/minimax.ts - Update getModel() to preserve custom model IDs instead of silently replacing them
2. src/api/providers/__tests__/minimax.spec.ts - Add a test verifying that custom/unknown model IDs are preserved (not replaced with the default)

This is consistent with how Moonshot (src/api/providers/moonshot.ts:29-39) and DeepSeek (src/api/providers/deepseek.ts:37-48) handle custom model IDs.

Please mention @roomote in a comment saying that you approve this plan, and I'll proceed with the implementation.

[DarkEden-coding]

@roomote check if this is an issue in other providers as well

[roomote-v0]

I've seen your comment and will check all providers for the same silent model replacement issue. I'll open a PR with fixes across all affected providers. Stay tuned!

[roomote-v0]

I checked all providers and confirmed this is indeed an issue across 9 providers total (not just MiniMax). Opened #11965 with fixes for: Anthropic, Anthropic Vertex, Gemini, MiniMax, OpenAI Codex, OpenAI Native, Vertex, xAI, and BaseOpenAiCompatibleProvider (which also affects SambaNova, Baseten, Fireworks, Z.ai). Feedback welcome!