[Bug] Opus 4.8 on Bedrock: "thinking.type.enabled" not supported — regression from #51439

Summary

Claude Code 2.1.156 sends thinking.type: "enabled" when using aws.claude-opus-4.8 on AWS Bedrock, but this model only accepts thinking.type: "adaptive" with output_config.effort. This results in a 400 error, making Opus 4.8 unusable on Bedrock.

This is a regression of the same issue previously fixed in #51439 / #50100 (fixed in v2.1.121 for Opus 4.7). The fix apparently does not cover the new Opus 4.8 model ID.

Error

API Error: 400 "thinking.type.enabled" is not supported for this model. Use "thinking.type.adaptive" and "output_config.effort" to control thinking behavior.
(Service: BedrockRuntime, Status Code: 400, Request ID: 4ca3008d-466e-4042-b0fb-6c21618cf8a9)

Steps to reproduce

1. Configure Claude Code to use AWS Bedrock as the provider
2. /model aws.claude-opus-4.8
3. Send any message

Expected behavior

Claude Code should use thinking.type: "adaptive" for Opus 4.8, same as it does for Opus 4.7 on Bedrock.

Actual behavior

Immediate 400 error on every message sent.

Workaround

Switch to aws.claude-opus-4.6-b which works correctly.

Environment

• Claude Code version: 2.1.156
• Platform: macOS (Darwin, ARM64)
• Provider: AWS Bedrock
• Model: aws.claude-opus-4.8