MiniMax providers: @ai-sdk/anthropic sends x-api-key but MiniMax requires Authorization: Bearer

[mugnimaestra]

Problem

All 4 MiniMax providers (minimax, minimax-cn, minimax-coding-plan, minimax-cn-coding-plan) use npm = "@ai-sdk/anthropic" in their provider.toml. However, @ai-sdk/anthropic sends the API key via the x-api-key header, while MiniMax's Anthropic-compatible endpoints require Authorization: Bearer <key>.

This causes HTTP 401 errors:

login fail: Please carry the API secret key in the 'Authorization' field of the request header, using the 'Bearer' authentication scheme.

Affected providers

Provider	Endpoint
minimax	https://api.minimax.io/anthropic/v1
minimax-cn	https://api.minimaxi.com/anthropic/v1
minimax-coding-plan	https://api.minimax.io/anthropic/v1
minimax-cn-coding-plan	https://api.minimaxi.com/anthropic/v1

Root cause

@ai-sdk/anthropic always sends authentication via x-api-key header (the Anthropic standard). MiniMax's Anthropic-compatible endpoint does not accept x-api-key — it requires the standard Authorization: Bearer <token> format instead.

Prior art

This is a well-known issue across the ecosystem:

• LiteLLM #24493 — fixed by adding Bearer auth
• OpenClaw #29095 — same fix
• Charmbracelet/Crush #2222 — same fix

Possible solutions

1. Client-side workaround (what we did in opencode): detect minimax in the provider ID and inject Authorization: Bearer header alongside the SDK's x-api-key.

2. Schema enhancement in models.dev: Add an optional auth or auth_type field to the Provider schema (e.g., auth_type = "bearer" vs auth_type = "api-key") so clients know which auth mechanism a provider expects. This would make the fix data-driven instead of requiring hardcoded provider checks in every client.

3. Static headers in provider.toml: The schema already supports provider.headers on models, but this can't be used for dynamic auth tokens (it's for static key-value pairs).

Option 2 would be the cleanest long-term solution, enabling any Anthropic-compatible provider that uses Bearer auth to declare it in their TOML config.

[seffhunnn]

I would like to work on this.