Amazon Bedrock rewrites deepseek.v3.2 and foundation-model ARNs to invalid us.* model IDs #18812

Description

Amazon Bedrock model IDs are being rewritten incorrectly in OpenCode before the request is sent to Bedrock.

This breaks DeepSeek V3.2 specifically, and also breaks foundation-model ARNs.

What I verified locally:

• aws bedrock list-foundation-models --by-provider deepseek --region us-east-1 returns:
  • deepseek.v3.2
  • deepseek.r1-v1:0
• aws bedrock-runtime converse --region us-east-1 --model-id deepseek.v3.2 ... succeeds
• aws bedrock-runtime converse --region us-east-1 --model-id arn:aws:bedrock:us-east-1::foundation-model/deepseek.v3.2 ... succeeds
• aws bedrock-runtime converse --region us-east-1 --model-id us.deepseek.v3.2 ... fails with:
  • ValidationException: The provided model identifier is invalid.
• aws bedrock-runtime converse --region us-east-1 --model-id us.arn:aws:bedrock:us-east-1::foundation-model/deepseek.v3.2 ... also fails with the same validation error

What OpenCode is doing:

• My selected model is deepseek.v3.2
• The models.dev entry is providers/amazon-bedrock/models/deepseek.v3.2.toml
• But OpenCode sends Bedrock requests to:
  • https://bedrock-runtime.us-east-1.amazonaws.com/model/us.deepseek.v3.2/converse-stream
• If I override the model ID to a full foundation-model ARN, OpenCode sends:
  • https://bedrock-runtime.us-east-1.amazonaws.com/model/us.arn%3Aaws%3Abedrock%3Aus-east-1%3A%3Afoundation-model%2Fdeepseek.v3.2/converse-stream

I traced this to OpenCode source:

• fromModelsDevModel() preserves the raw model ID from models.dev:
  • packages/opencode/src/provider/provider.ts#L839-L847
• The rewrite happens later in the Bedrock loader:
  • packages/opencode/src/provider/provider.ts#L316-L346
• In the US-region branch, OpenCode treats "deepseek" as a model family that always requires a us. prefix:
  • packages/opencode/src/provider/provider.ts#L333-L345
• There is no guard for ARNs, so ARNs also get prefixed.
• The existing tests appear to cover prefixed cross-region Bedrock models, but not deepseek.v3.2 or foundation-model ARNs:
  • packages/opencode/test/provider/amazon-bedrock.test.ts#L238-L447

This looks like a Bedrock model-ID transformation bug in OpenCode, not a models.dev issue.

Plugins

oh-my-opencode-slim (disabled and removed in testing)

OpenCode version

1.3.0

Steps to reproduce

1. Configure Amazon Bedrock in OpenCode with access to DeepSeek V3.2.
2. Use region us-east-1.
3. Select amazon-bedrock/deepseek.v3.2.
4. Send a prompt.
5. Observe the request fails with:
   • undefined: The provided model identifier is invalid.

Additional repro:

1. Define a custom Bedrock model whose id is:
   • arn:aws:bedrock:us-east-1::foundation-model/deepseek.v3.2
2. Run:
   • opencode run hi --model amazon-bedrock/deepseek-v3.2-arn --print-logs
3. Observe OpenCode rewrites it to:
   • us.arn:aws:bedrock:us-east-1::foundation-model/deepseek.v3.2
4. Bedrock rejects it with:
   • The provided model identifier is invalid.

(edited out duplicated text)

Screenshot and/or share link

All first 3 calls are the respective Bedrock Deepseek models.

Operating System

Pop!_OS 24.04 LTS

Terminal

Kitty, Cosmic, Ghosty