Build a multi-agent analysis system with GitHub Copilot SDK in C#. Learn the AgentBase reusable pattern, SystemMessageMode.Replace for agent isolation, sequenti

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A step-by-step guide to building a multi-agent code analysis system using the GitHub Copilot SDK in C#. The system runs three specialist agents (Code Review, Documentation, Testing) sequentially against a C# source file and assembles their outputs into a unified markdown report. Key patterns covered include the AgentBase abstract class that encapsulates all SDK ceremony, SystemMessageMode.Replace for clean agent isolation, the AgentPipeline orchestrator for sequential execution, and the TaskCompletionSource+SessionIdleEvent synchronization mechanism. The article also explains why sequential execution is preferred over parallel for this use case, covering rate limiting, error recovery, and undocumented SDK concurrency behavior.

Build a Multi-Agent Analysis System with GitHub Copilot SDK in C#

What We're Building: a Multi-Agent Analysis System with GitHub Copilot SDK in C#

Why SystemMessageMode.Replace for Agent Isolation

Sequential vs Parallel: Why Sequential Wins Here