Opus 4.6 with beta string "anthropicBeta": ["context-1m-2025-08-07"] stopped working in AWS Bedrock

[SpotlightForBugs]

Description

A recent update broke Opus 4.6 with the beta string in AWS Bedrock
It now compacts every 200k tokens AND fails to do so with either "undefined: The content field in the Message object at messages.7 is empty. Add a ContentBlock object to the content field and try again." OR Errors referring to thinking or redactedthinking

Plugins

None

OpenCode version

1.2.10

Steps to reproduce

No response

Screenshot and/or share link

No response

Operating System

MacOS 26.3.1 (25D2128)

Terminal

Alacritty / Default Term

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• Amazon Bedrock Opus 4.6 compaction failure #14332: Amazon Bedrock Opus 4.6 compaction failure — same model, same errors about thinking/redacted_thinking blocks cannot be modified during compaction
• Auto-compact fails for Bedrock-hosted Claude models due to incorrect context limit #16356: Auto-compact fails for Bedrock-hosted Claude models due to incorrect context limit — Opus 4.6 on Bedrock hitting 200k limit with same compaction errors (closed with workaround)
• Split Bedrock Claude Opus 4.6 into 200K + 1M models and set 1M beta flag #13199: Split Bedrock Claude Opus 4.6 into 200K + 1M models and set 1M beta flag — directly related to the context-1m-2025-08-07 beta flag behavior
• ValidationException: text content blocks must be non-empty when using Bedrock Runtime #15715: ValidationException: text content blocks must be non-empty when using Bedrock Runtime — same "content field is empty" class of error