QuantConnect Lean API Client OpenAPI Spec Synchronization

QuantConnect Lean engine's API client has been fully synchronized with the OpenAPI spec. Missing endpoints (file patch, project update, live insights read, etc.

QuantConnect Lean — C#/Python Backtest & Live Trading Engine · Release 18125: Sync the api client with the OpenAPI spec (#9815) · 2026-09-23

QuantConnect Lean engine's API client has been fully synchronized with the OpenAPI spec. Missing endpoints (file patch, project update, live insights read, etc.) have been added, and request/response structure mismatches have been fixed. A new ReadLiveInsights(projectId, algorithmId, start, end) overload has been added for live insights retrieval, while the existing signature is maintained for backward compatibility. Response handling for several API methods including optimization result reads and file updates has been improved to match actual API behavior.

weltiq perspective: weltiq users utilizing the Lean engine can experience more accurate and stable API communication when managing projects, monitoring live trading, and retrieving optimization results.

Release Notes Excerpt

Audit the api client against the OpenAPI spec Adds the documented endpoints the client did not cover (file patch, project update, live auth0 read, the ai tools), the request and response members it was missing, fixes the mismatches with the documented request and response shapes, and aligns the IApi defaults with the class. Tests in the credentialed fixtures are still to be written. Drop the project collaboration endpoints from the audit Drop the ai tool endpoints from the audit Cover the audited api changes with tests in the credentialed fixtures One test or case per audited change in ProjectTests, LiveTradingTests, OptimizationTests and ObjectStoreTests, which CI runs with api credentials,…

Source: https://github.com/QuantConnect/Lean/releases/tag/18125