feat(langchain): forward provider-native modelSettings to chat models [PC-4672]

[tudormatei1]

agent.json can now carry settings.modelSettings, but nothing consumed it — this is the consumer side. UiPathBaseChatModel gets a model_settings field and get_chat_model a matching param; each key is applied verbatim, with no per-provider mapping, since discovery is the source of truth for the shape.

A key that names a native field (by name or alias, e.g. timeout -> request_timeout) is coerced to that field's declared type and set; anything else goes to model_kwargs; keys in disabled_params are dropped. Values arrive as untyped JSON, so a value the field can't accept fails at construction rather than coming back as a provider 400.

Two things worth a look: the coercion goes through a TypeAdapter instead of pydantic assignment validation, because re-running the validator chain lets LangChain's build_extra sweep cached non-field entries into model_kwargs. And UiPathChatBedrockConverse overrides the apply step — Converse ignores model_kwargs entirely, so non-field keys (plus output_config, which is a field but has to be nested anyway) go into additional_model_request_fields.

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

This PR introduces provider-native model_settings support so settings from agent.json can be forwarded through get_chat_model and applied during model construction (including Bedrock Converse-specific routing), with accompanying tests and a version bump.

Changes:

• Add model_settings parameter to get_chat_model and forward it into the model constructor.
• Apply model_settings on UiPathBaseChatModel post-construction with type coercion, plus Bedrock Converse passthrough partitioning.
• Add/extend unit tests for forwarding, coercion, disabled params, alias handling, and Bedrock Converse mapping; bump version + changelog.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
tests/langchain/features/test_factory_function.py	Adds integration-style tests verifying model_settings forwarding and application semantics across providers.
tests/langchain/clients/bedrock/test_model_settings_mapping.py	Adds pure unit tests for Bedrock Converse model_settings partitioning behavior.
packages/uipath_langchain_client/src/uipath_langchain_client/factory.py	Adds model_settings param to factory and forwards it into constructor kwargs.
packages/uipath_langchain_client/src/uipath_langchain_client/clients/bedrock/chat_models.py	Adds Bedrock Converse-specific routing of settings into additional_model_request_fields.
packages/uipath_langchain_client/src/uipath_langchain_client/base_client.py	Adds model_settings field and post-init application logic with type coercion + alias resolution.
packages/uipath_langchain_client/src/uipath_langchain_client/version.py	Bumps package version to 1.18.0.
packages/uipath_langchain_client/CHANGELOG.md	Documents the new model_settings capability and behavior.

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