Imported from Codebrew-company/CodebrewRouter (.agents/skills/codebrewrouter-architecture-routing/SKILL.md). Install upstream with npx skills add Codebrew-company/CodebrewRouter --skill codebrewrouter-architecture-routing. Copyright stays with the author.

CodebrewRouter Architecture Routing

Start Here

Read the smallest useful set before editing:

• AGENTS.md
• README.md
• .github/copilot-instructions.md
• Docs/design/adr/
• Blaze.LlmGateway.Infrastructure/InfrastructureServiceExtensions.cs
• Blaze.LlmGateway.Infrastructure/LlmRoutingChatClient.cs
• Blaze.LlmGateway.Infrastructure/RoutingStrategies/
• Blaze.LlmGateway.Api/ChatCompletionsEndpoint.cs
• Blaze.LlmGateway.Api/OpenAiProtocolMapper.cs
• Blaze.LlmGateway.Core/RouteDestination.cs
• Blaze.LlmGateway.Core/Configuration/

Rules

• Keep all LLM calls on Microsoft.Extensions.AI abstractions unless the user explicitly asks for a protocol adapter.
• Keep provider registration and pipeline assembly in infrastructure extension methods; keep Program.cs minimal.
• Resolve providers by keyed DI using names aligned with RouteDestination, router output text, and configuration keys.
• Preserve OpenAI-compatible streaming shape and the final data: [DONE] terminator.
• Treat routing, fallback, context sizing, and provider selection as behavioral contracts that need targeted tests.
• When changing router telemetry, also use codebrewrouter-logging-contract.
• When changing cloud escalation, MCP, tools, or provider secrets, also use codebrewrouter-mcp-provider-security.

Review Checklist

• Confirm the selected provider path is testable without real provider credentials.
• Confirm streaming and non-streaming behavior still map through the OpenAI protocol layer.
• Confirm cancellation tokens flow through new async paths.
• Confirm new destinations update enum values, DI registrations, model catalog behavior, configuration, and tests together.
• Confirm fallback behavior is explicit when a provider is unavailable, skipped, or over context budget.

Verification

Prefer targeted tests first, then broader checks when production code changes:

dotnet test Blaze.LlmGateway.Tests\Blaze.LlmGateway.Tests.csproj --filter FullyQualifiedName~Routing
dotnet test Blaze.LlmGateway.Tests\Blaze.LlmGateway.Tests.csproj --filter FullyQualifiedName~OpenAi
dotnet build Blaze.LlmGateway.slnx --no-incremental -warnaserror

For API contract changes, add the relevant endpoint or protocol mapper tests before relying on a full build alone.