feat(aux): add Bedrock Converse adapter for auxiliary LLM tasks

[kobewang1234]

Summary

Add BedrockAuxiliaryClient that enables AWS Bedrock-hosted models (e.g. Claude Sonnet) to serve as auxiliary LLMs for tasks like context compression, web extraction summarization, session search, and vision.

Currently, users with provider: bedrock cannot use auxiliary LLM features because resolve_provider_client() has no Bedrock path. This PR adds the missing adapter.

Changes

• _BedrockCompletionsAdapter: Translates chat.completions.create(**kwargs) into Bedrock Converse() API calls, reusing the existing bedrock_adapter.py helpers (convert_messages_to_converse, normalize_converse_response)
• BedrockAuxiliaryClient (sync): OpenAI-client-compatible wrapper with .chat.completions interface
• AsyncBedrockAuxiliaryClient: Async variant using asyncio.to_thread
• _to_async_client(): Added Bedrock dispatch
• resolve_provider_client(): Added if provider == "bedrock": branch that checks IAM credentials and creates the client

Configuration

Users can configure per-task auxiliary models in config.yaml:

auxiliary:
  compression:
    model: us.anthropic.claude-sonnet-4-6
  web_extract:
    model: us.anthropic.claude-sonnet-4-6

No provider key needed — when the main provider is bedrock, auxiliary resolution automatically uses the Bedrock path.

Testing

• Verified resolve_provider_client('bedrock', 'us.anthropic.claude-sonnet-4-6') returns a valid BedrockAuxiliaryClient
• Verified real API call through the adapter returns correct response
• Verified _resolve_auto() picks up Bedrock client when main provider is bedrock

[alt-glitch]

Supersedes #12365 — same feature (Bedrock auxiliary client). Also related to #11946 (feature request) and #12979 (full Bedrock Converse).

[teknium1]

Thanks for the contribution, @kobewang1234! This feature was implemented on main just before this PR was opened.

This is an automated hermes-sweeper review.

Evidence:

• agent/auxiliary_client.py lines 2038–2069 already contain a Bedrock path in resolve_provider_client(): when pconfig.auth_type == "aws_sdk", it checks AWS credentials via has_aws_credentials(), builds a client via build_anthropic_bedrock_client(), and wraps it in AnthropicAuxiliaryClient with full async support.
• This was added by commit 7dc6eb9fb (fix(agent): handle aws_sdk auth type in resolve_provider_client), merged 2026-04-24 — the same day this PR was opened.
• Member @alt-glitch also noted this supersedes feat: add AWS Bedrock support for auxiliary LLM tasks #12365, which covers the same gap.

The implementation on main uses the Anthropic Bedrock SDK path rather than a hand-rolled Converse API shim, which is the preferred approach for the existing codebase. Closing as already implemented.