Add Bedrock structured output support

[llenodo]

What this does

Adds structured output support to the Bedrock Converse API provider. Bedrock uses a different payload format than the direct Anthropic API: the schema must be a JSON string (not a Hash), nested under outputConfig.textFormat.structure.jsonSchema with a required name field, using camelCase Converse API naming.

Type of change

• Bug fix
• New feature
• Breaking change
• Documentation
• Performance improvement

Scope check

• I read the Contributing Guide
• This aligns with RubyLLM's focus on LLM communication
• This isn't application-specific logic that belongs in user code
• This benefits most users, not just my specific use case

Required for new features

• I opened an issue before writing code and received maintainer approval
• Linked issue: [FEATURE] Add Structured Output for Amazon Bedrock #596

PRs for new features or enhancements without a prior approved issue will be closed.

Quality check

• I ran overcommit --install and all hooks pass
• I tested my changes thoroughly
  • For provider changes: Re-recorded VCR cassettes with bundle exec rake vcr:record[provider_name]
  • All tests pass: bundle exec rspec
• I updated documentation if needed
• I didn't modify auto-generated files manually (models.json, aliases.json)

AI-generated code

• I used AI tools to help write this code
• I have reviewed and understand all generated code (required if above is checked)

API changes

• Breaking change
• New public methods/classes
• Changed method signatures
• No API changes

[llenodo]

closing per community guidelines to have an issue first

[aniamisiorek]

Hey @llenodo ! Not sure of the process here, but would love to open this PR up again for review!

[llenodo]

I'm not sure either tbh. the contributing guidlines specify "You must open an issue first and wait for maintainer feedback before writing code. PRs for new features without an approved issue will be closed without review."

[llenodo]

@aniamisiorek in the meantime you can use this patch in your ruby_llm.rb initializer to get the functionality

# Patch to enable structured output (JSON schema) for AWS Bedrock Claude models
#
# Background:
# RubyLLM 1.12.1 doesn't support structured output for Bedrock. The `schema` parameter in
# `render_payload` is silently ignored (Lint/UnusedMethodArgument). This means `.with_schema()`
# has no effect when using Claude models via Bedrock — the LLM returns free-form text instead
# of JSON, causing parse failures in consumers like AgentTurn.
#
# This patch:
# 1. Overrides `render_payload` in Bedrock::Chat to inject `outputConfig` when a schema is present
# 2. Uses the Bedrock Converse API's `textFormat` type `json_schema` to enforce structured output
#
# Based on upstream PR: https://github.com/crmne/ruby_llm/pull/619
# Can be removed once RubyLLM ships native Bedrock structured output support.
module RubyLLMBedrockStructuredOutputPatch
  def render_payload(messages, tools:, temperature:, model:, stream: false, schema: nil, thinking: nil)
    payload = super

    if schema
      output_config = build_output_config(schema)
      payload[:outputConfig] = output_config if output_config
    end

    payload
  end

  private


  def build_output_config(schema)
    cleaned = RubyLLM::Utils.deep_dup(schema)
    cleaned.delete(:strict)
    cleaned.delete('strict')

    {
      textFormat: {
        type: 'json_schema',
        structure: {
          jsonSchema: {
            schema: JSON.generate(cleaned),
            name: 'response'
          }
        }
      }
    }
  end
end

# Prepend to Bedrock Chat module to enable structured output
RubyLLM::Providers::Bedrock::Chat.module_eval { prepend RubyLLMBedrockStructuredOutputPatch }

[llenodo]

Opening up to see if we can get this in soon so I can get rid of this patch in my codebase :)

[crmne]

you should use the test above and simply add the provider to it

[crmne]

additional comments

[crmne]

needs global in REGION_PREFIXES

[llenodo]

nice thanks for merging!