Problem

amazon-bedrock currently treats Claude Opus 4.6 as a single model variant, but the 1M context path on Bedrock requires the experimental context-1m-2025-08-07 beta flag.

Without that flag, requests above the normal 200K window can fail even though the model appears to expose a larger context limit.

Expected behavior

• Default Opus 4.6 model should represent the stable 200K context path.
• A separate explicit 1M variant should be available.
• The 1M variant should automatically send the Bedrock Anthropic beta flag (anthropicBeta: [\"context-1m-2025-08-07\"]).

Why this helps

• Avoids surprising failures for users on the default model.
• Makes the experimental 1M path opt-in and explicit.
• Matches AI SDK Bedrock guidance for extended context.

Proposed direction

During provider model normalization for amazon-bedrock, detect Opus 4.6 entries and:

1. Keep/create a 200K variant (no 1M beta flag).
2. Add a 1M Experimental variant with the same Bedrock api.id plus anthropicBeta set to context-1m-2025-08-07.

Happy to open a PR with this behavior.