v2.1.0 to git:20260908.d184cd7

---

name: csharp-dev

description: Use when writing C#/.NET backend code, ASP.NET Core controllers, application services, middleware, or OpenTelemetry instrumentation. Do not use for repositories, migrations, or schema design.

license: MIT

---

# .NET Developer

Identify your sub-task and read ONLY the relevant reference before proceeding.

| Sub-Task | When to Use | Reference |

|---|---|---|

| Clean Architecture | Layer placement, dependency direction, project structure, file location, SOLID principles | Refer to the path defined by the **Clean Architecture Rules** property in the root `AGENTS.md`. |

| Azure AI / RAG | Azure OpenAI, AI Search, agent orchestration, data ingestion pipelines | [Azure AI RAG](./references/azure-ai-rag.md) |

| BFF / YARP | WebUI BFF project, YARP reverse proxy, OIDC auth flow, token forwarding, SPA serving | [BFF YARP](./references/bff-yarp.md) |

| Build & Verification | dotnet build, test, and run commands | [Build Commands](./references/build-commands.md) |

| ASP.NET Core Web API | Controllers, TypedResults, sealed record DTOs, RFC 7807, OpenAPI with Swashbuckle | [Web API](./references/aspnetcore-webapi.md) |

| File Upload | IFormFile, size limits, magic byte validation, safe filenames | [File Upload](./references/file-upload.md) |

| OpenTelemetry | ActivitySource, traces, metrics, OTLP export, log-trace correlation | [OpenTelemetry](./references/opentelemetry.md) |

| MSBuild Modernization | Migrate legacy `.csproj` (ToolsVersion, packages.config, explicit file lists) to SDK-style | Refer to the path defined by the **MSBuild Modernization** property in the root `AGENTS.md`. |

| MSBuild Anti-patterns | Cross-platform failures, hardcoded paths, `<Exec>` shell commands, unquoted conditions, non-deterministic builds | Refer to the path defined by the **MSBuild Anti-patterns** property in the root `AGENTS.md`. |

| Directory.Build Organization | `Directory.Build.props`/`.targets`/`Directory.Packages.props`, Central Package Management, multi-level hierarchy | Refer to the path defined by the **Directory.Build Organization** property in the root `AGENTS.md`. |

| Build Performance | MSBuild parallelism (`-m`), `/graph` mode, RAR slowness, analyzer overhead, bottleneck diagnosis | Refer to the path defined by the **Build Performance** property in the root `AGENTS.md`. |

| Incremental Build | Fix targets that always rebuild; `Inputs`/`Outputs` attributes; `FileWrites` registration; volatile output paths | Refer to the path defined by the **Incremental Build** property in the root `AGENTS.md`. |

**Rule:** Read only the reference(s) relevant to your current task. Do not pre-load all references.