.NET: Add additional build, test and project structure skills

dotnet/.github/skills/build-and-test/SKILL.md

@@ -0,0 +1,43 @@
+---
+name: build-and-test
+description: How to build and test .NET projects in the Agent Framework repository. Use this when verifying or testing changes.
+---
+
+# Build and Test
+
+- Only **UnitTest** projects need to be run locally; IntegrationTests require external dependencies.
+- See `../project-structure/SKILL.md` for project structure details.
+
+## Speeding Up Builds
+
+The full solution is large. Use these shortcuts:
+
+| Change type | What to do |
+|-------------|------------|
+| Internal logic | Build only the affected project and its `*.UnitTests` project. Fix issues, then build the full solution and run all unit tests. |
+| Public API surface | Build the full solution and run all unit tests immediately. |
+
+Example: Building a single code project for all target frameworks
+
+```bash
+cd /workspaces/agent-framework/dotnet
+dotnet build ./src/Microsoft.Agents.AI.Abstractions/Microsoft.Agents.AI.Abstractions.csproj
+```
+
+Example: Building a single code project for just .NET 10.
+
+```bash
+cd /workspaces/agent-framework/dotnet
+dotnet build ./src/Microsoft.Agents.AI.Abstractions/Microsoft.Agents.AI.Abstractions.csproj -f net10.0
+```
+
+Example: Running tests for a single project using .net 10.
+
+```bash
+cd /workspaces/agent-framework/dotnet
+dotnet test ./tests/Microsoft.Agents.AI.Abstractions.UnitTests/Microsoft.Agents.AI.Abstractions.UnitTests.csproj -f net10.0
+```
+
+### Multi-target framework tip
+
+Most projects target multiple .NET frameworks. If the affected code does **not** use `#if` directives for framework-specific logic, pass `--framework net10.0` to speed up building and testing.

dotnet/.github/skills/project-structure/SKILL.md

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+---
+name: project-structure
+description: Explains the project structure of the agent-framework .NET solution
+---
+
+# Agent Framework .NET Project Structure
+
+## Folders
+
+| Folder | Contents |
+|--------|----------|
+| `src/` | Source code projects |
+| `tests/` | Test projects — named `<Source-Code-Project>.UnitTests` or `<Source-Code-Project>.IntegrationTests` |
+| `samples/` | Sample projects |
+| `src/Shared`, `src/LegacySupport` | Shared code files included by multiple source code projects (see README.md files in these folders or their subdirectories for instructions on how to include them in a project) |

dotnet/.github/skills/verify-dotnet-samples/SKILL.md

@@ -1,6 +1,6 @@
 ---
 name: verify-dotnet-samples
-description: > How to build, run and verify the .NET sample projects in the Agent Framework repository. Use this when a user wants to verify that the samples still function as expected.
+description: How to build, run and verify the .NET sample projects in the Agent Framework repository. Use this when a user wants to verify that the samples still function as expected.
 ---
 
 # Verifying .NET Sample Projects