Refactor API

[kevingosse]

• Convert APIs to async to remove sync over async
• Enforce one type per file where it makes sense
• Move factory methods to non-generic static classes to take advantage of type inference
• Rename interfaces with the I prefix
• Refactor config overrides
• Replace cursors with IAsyncEnumerable
• Use IParsable<T> in BaseConfig to make code simpler and cleaner

[Copilot]

Pull request overview

This pull request refactors the Braintrust SDK API to modernize the codebase with async/await patterns, improved type safety, and better organization. The refactoring eliminates sync-over-async anti-patterns, consolidates types into separate files following one-type-per-file convention, and replaces cursor-based iteration with IAsyncEnumerable.

Changes:

• Converted all API methods to async, removing sync-over-async patterns throughout IBraintrustApiClient and BraintrustApiClient
• Refactored config API from variadic string pairs to tuple-based overrides for better type safety and inference
• Replaced cursor-based dataset iteration with IAsyncEnumerable pattern for cleaner async enumeration
• Renamed interfaces with I prefix (Task → ITask, Scorer → IScorer, Dataset → IDataset) for .NET conventions
• Extracted types into separate files (ApiException, InstrumentedChatClient, FunctionScorer, MockBraintrustApiClient)
• Converted Score, TaskResult, and EvalResult to readonly structs for better performance
• Updated BaseConfig to use IParsable constraint, simplifying type conversion logic

Reviewed changes

Copilot reviewed 39 out of 39 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
src/Braintrust.Sdk/Api/BraintrustApiClient.cs	Converted all methods to async, added ConfigureAwait patterns
src/Braintrust.Sdk/Api/IBraintrustApiClient.cs	Updated interface to async Task-returning methods
src/Braintrust.Sdk/Api/ApiException.cs	Extracted to separate file following one-type-per-file
src/Braintrust.Sdk/Config/BaseConfig.cs	Refactored to use IParsable constraint, changed to abstract class
src/Braintrust.Sdk/Config/BraintrustConfig.cs	Updated to tuple-based config overrides API
src/Braintrust.Sdk/Eval/Eval.cs	Converted Build to BuildAsync, RunAsync uses IAsyncEnumerable
src/Braintrust.Sdk/Eval/IDataset.cs	Replaced ICursor with IAsyncEnumerable
src/Braintrust.Sdk/Eval/DatasetInMemoryImpl.cs	Implemented GetCasesAsync with iterator pattern
src/Braintrust.Sdk/Eval/IScorer.cs	Extracted interface, renamed from Scorer
src/Braintrust.Sdk/Eval/FunctionScorer.cs	Made public, extracted to separate file
src/Braintrust.Sdk/Eval/Score.cs	Converted to readonly record struct
src/Braintrust.Sdk/Eval/TaskResult.cs	Converted to readonly record struct
src/Braintrust.Sdk/Eval/EvalResult.cs	Converted to readonly struct with ToString override
src/Braintrust.Sdk/Braintrust.cs	Changed ProjectUri to async GetProjectUriAsync
src/Braintrust.Sdk/Instrumentation/OpenAI/InstrumentedChatClient.cs	Extracted to separate file
tests/Braintrust.Sdk.Tests/Eval/MockBraintrustApiClient.cs	Extracted mock to separate file with async methods
examples/*/Program.cs	Updated all examples to use async Main and await async APIs

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

This variable is manually disposed in a finally block - consider a C# using statement as a preferable resource management technique.

[Copilot]

This variable is manually disposed in a finally block - consider a C# using statement as a preferable resource management technique.

[Copilot]

Both branches of this 'if' statement write to the same variable - consider using '?' to express intent better.

Suggested change

	OrganizationAndProjectInfo? orgAndProject;
	if (_projectId == null)
	{
	orgAndProject = await _apiClient.GetProjectAndOrgInfo().ConfigureAwait(false)
	?? throw new InvalidOperationException("Unable to retrieve project and org info");
	}
	else
	{
	orgAndProject = await _apiClient.GetProjectAndOrgInfo(_projectId).ConfigureAwait(false)
	?? throw new InvalidOperationException($"Invalid project id: {_projectId}");
	}
	OrganizationAndProjectInfo? orgAndProject = _projectId == null
	? await _apiClient.GetProjectAndOrgInfo().ConfigureAwait(false)
	?? throw new InvalidOperationException("Unable to retrieve project and org info")
	: await _apiClient.GetProjectAndOrgInfo(_projectId).ConfigureAwait(false)
	?? throw new InvalidOperationException($"Invalid project id: {_projectId}");