feat(bedrock): add tool_runner support with message sanitization

[lingjiekong]

Summary

This PR enables the tool_runner API on AWS Bedrock by adding message sanitization to strip Bedrock-unsupported fields.

Fixes #1106

Problem

When using client.beta.messages.tool_runner() with Bedrock, the SDK adds internal tracking fields that Bedrock's stricter API validation rejects with 400 errors:

Error code: 400 - {'message': 'messages.1.content.1.text.parsed_output: Extra inputs are not permitted'}

Error code: 400 - {'message': 'messages.1.content.2.tool_use.caller: Extra inputs are not permitted'}

Root Cause

1. tool_runner not exposed: The Bedrock Messages class only delegates create, not tool_runner
2. parsed_output rejection: The SDK's .parse() method adds parsed_output to text blocks for structured output tracking
3. caller rejection: The SDK adds caller to tool_use blocks for code execution features

Solution

1. Add tool_runner delegation - Expose the tool_runner API on Bedrock clients
2. Add _sanitize_for_bedrock() helper - Strip unsupported fields from message content blocks
3. Wrap create, parse, stream methods - Apply sanitization transparently before API calls

The sanitization is applied at the Bedrock layer so it doesn't affect direct Anthropic API usage.

Changes

• Add BEDROCK_UNSUPPORTED_FIELDS set for extensibility
• Add _sanitize_for_bedrock() sanitization function
• Wrap create, parse, stream methods with sanitization
• Add tool_runner delegation to both sync and async classes

Tested Features

• tool_runner API access on Bedrock
• Automatic tool execution loop
• Compaction control (context management with token_threshold)
• parsed_output field sanitization
• caller field sanitization
• Sync and async clients

Example Usage

from anthropic import AsyncAnthropicBedrock

client = AsyncAnthropicBedrock(aws_region="us-west-2")

# Now tool_runner works with Bedrock!
result = await client.beta.messages.tool_runner(
    model="us.anthropic.claude-sonnet-4-5-20250929-v1:0",
    max_tokens=16384,
    tools=[...],
    messages=[...],
    compaction_control={
        "type": "auto",
        "enabled": True,
        "token_threshold": 20000,
    }
)

Test plan

• Verified tool_runner works with Bedrock after patch
• Verified compaction control triggers correctly at token threshold
• Verified no 400 errors from parsed_output or caller fields
• Verified existing create functionality still works

🤖 Generated with Claude Code