Bifrost HTTP Transport Release v1.6.6

✨ Features

• Anthropic Default Fallback Routing — Added support for Anthropic's fallbacks: "default" preset, preserving it through the Bifrost round-trip and injecting the server-side-fallback-2026-07-01 beta header for default-routing requests.
• Mid-Conversation Tool Changes — Added support for the mid-conversation-tool-changes-2026-07-01 beta header, enabled for Anthropic and Bedrock Mantle.

🐞 Fixed

• Opus 5 Compatibility — Added Opus 5 detection to the Anthropic provider so it inherits Opus 4.8's request surface: budget_tokens, temperature, top_p, and top_k are stripped, and native effort, fast mode, and mid-conversation system messages are enabled.

Installation

Docker

docker run -p 8080:8080 maximhq/bifrost:v1.6.6

Binary Download

npx @maximhq/bifrost --transport-version v1.6.6

Docker Images

• maximhq/bifrost:v1.6.6 - This specific version
• maximhq/bifrost:latest - Latest version (updated with this release)

This release was automatically created with dependencies: core v1.7.4, framework v1.5.4. All plugins have been validated and updated.