opencode-bedrock-1m

OpenCode plugin that unlocks the 1M token context window for Claude models on AWS Bedrock.

Problem

Claude Opus 4.6 and Sonnet 4.6/4.5 support a 1M token context window, but AWS Bedrock requires the beta header context-1m-2025-08-07 to unlock it. Without this header, the API enforces a hard 200K input token limit.

OpenCode currently sends this header only for claude-sonnet-* models. This plugin fixes the issue for all supported models.

Features

• Injects anthropic-beta: context-1m-2025-08-07 for all supported Claude models on Bedrock
• Works across all inference profiles: eu.*, us.*, global.*

Supported models

• claude-opus-4-6 (all variants)
• claude-sonnet-4-6 (all variants)
• claude-sonnet-4-5 (all variants)
• claude-sonnet-4 / claude-sonnet-4-20250514

Installation

Add to your opencode.json:

{
  "plugin": ["opencode-bedrock-1m"]
}

Context limits override (recommended)

Since OpenCode may still display the wrong context limit in the UI, add these overrides to your opencode.json:

{
  "provider": {
    "amazon-bedrock": {
      "models": {
        "eu.anthropic.claude-sonnet-4-6": { "limit": { "context": 1000000, "output": 64000 } },
        "global.anthropic.claude-sonnet-4-6": { "limit": { "context": 1000000, "output": 64000 } },
        "us.anthropic.claude-sonnet-4-6": { "limit": { "context": 1000000, "output": 64000 } },
        "eu.anthropic.claude-sonnet-4-5-20250929-v1:0": { "limit": { "context": 1000000, "output": 64000 } },
        "global.anthropic.claude-sonnet-4-5-20250929-v1:0": { "limit": { "context": 1000000, "output": 64000 } },
        "us.anthropic.claude-sonnet-4-5-20250929-v1:0": { "limit": { "context": 1000000, "output": 64000 } }
      }
    }
  }
}

License

MIT