Amazon Bedrock provider: DeepSeek V3/V3.1/V3.2 broken by incorrect "us." cross-region prefix in resolveModelID

Description

The built-in Amazon Bedrock provider plugin (packages/core/src/plugin/provider/amazon-bedrock.ts, function resolveModelID) unconditionally prepends a cross-region-inference prefix (us./eu./etc.) to any Bedrock model id containing the substring "deepseek":

if (regionPrefix === "us") {
  const requiresPrefix = ["nova-micro", "nova-lite", "nova-pro", "nova-premier", "nova-2", "claude", "deepseek"].some(
    (item) => modelID.includes(item),
  )
  if (requiresPrefix && !resolvedRegion.startsWith("us-gov")) return `${regionPrefix}.${modelID}`
  return modelID
}

This is correct for DeepSeek-R1, which has a real cross-region inference profile on Bedrock (us.deepseek.r1-v1:0). It is incorrect for DeepSeek V3 / V3.1 / V3.2, which AWS only exposes via their bare foundation-model id — there is no cross-region inference profile for these models. deepseek.v3.2 becomes us.deepseek.v3.2, which does not exist in Bedrock, so AWS rejects it.

Expected behavior

Request is sent to Bedrock with modelId: "deepseek.v3.2".

Actual behavior

resolveModelID rewrites it to us.deepseek.v3.2 before calling sdk.languageModel(...). Bedrock returns:
undefined: The provided model identifier is invalid.

Root cause

The requiresPrefix check does a blanket .includes("deepseek") instead of distinguishing DeepSeek-R1 (needs the prefix) from every other DeepSeek family model (must NOT be prefixed). Per AWS's Bedrock DeepSeek docs, V3.1/V3.2 are on-demand, in-region-only models invoked by their bare foundation-model id; only R1 has a documented cross-region inference profile.

Suggested fix

Narrow the match, e.g.:

const requiresPrefix = ["nova-micro", "nova-lite", "nova-pro", "nova-premier", "nova-2", "claude", "deepseek.r1", "deepseek-r1"].some(
  (item) => modelID.includes(item),
)

(or an explicit allow-list of the DeepSeek variants that actually have a cross-region profile, since this could grow/change as AWS adds inference profiles for other DeepSeek releases).

Workarounds attempted (both dead ends)

1. Route the model through @ai-sdk/amazon-bedrock/mantle (via a models override with "provider": {"npm": "@ai-sdk/amazon-bedrock/mantle"}) to skip resolveModelID entirely — it does bypass the bug (confirmed via source: the mantle branch returns early before calling resolveModelID), but selectMantleModel hardcodes every model except openai.gpt-oss-safeguard-20b/120b to sdk.responses(modelID). Bedrock Mantle rejects DeepSeek on that surface:
   The model 'deepseek.v3.2' does not support the '/v1/responses' API
   (This is a second, related bug: selectMantleModel should route DeepSeek — and likely other non-OpenAI families — through sdk.chat() instead of defaulting to sdk.responses().)

2. User-space plugin registering an aisdk.language hook to rebuild the language model from the untouched bare id: fails to load with error="Plugin export is not a function". The ctx.aisdk.language/ctx.catalog.transform hook system (@opencode-ai/plugin/v2/promise) is real and used internally by ProviderPlugins, but the documented local/npm plugin loader (.opencode/plugins/, ~/.config/opencode/plugins/) only accepts the older plugin shape (async ({project, client, $, directory, worktree}) => ({...hooks})), which has no hook capable of intercepting model-id resolution or the outgoing AI SDK request. So there is currently no way to work around this from user config or a user plugin — it requires a source fix.

Plugins

No response

OpenCode version

1.18.19

Steps to reproduce

1. Configure the amazon-bedrock provider with region us-east-1 (or any us-* region; this is also the fallback default when no region is configured).
2. Select the deepseek.v3.2 model (present in the built-in catalog: confirmed via opencode models amazon-bedrock, which lists amazon-bedrock/deepseek.v3.2 as a distinct bare-id entry alongside amazon-bedrock/us.deepseek.r1-v1:0).
3. Send any message.

Screenshot and/or share link

No response

Operating System

Windows 11

Terminal

Windows Terminal