Improve .NET SDK build infrastructure and documentation (#643)

* Improve .NET SDK build infrastructure and documentation

- Add Central Package Management (Directory.Packages.props) with all package versions centralized
- Add Directory.Build.props with shared properties (TargetFramework, ImplicitUsings, Nullable, TreatWarningsAsErrors)
- Add nuget.config with single nuget.org source and package source mapping (required by CPM)
- Add global.json specifying .NET 10 SDK (the library is still built with a net8.0 TFM)
- Update all CI workflows from .NET 8.0.x to .NET 10.0.x
- Enable XML documentation file generation (GenerateDocumentationFile)
- Add XML doc comments to all non-generated public types and members
- Add valid-value lists in XML docs for string properties with known values (e.g. PermissionRequest.Kind, ToolResultObject.ResultType)
- Add #pragma warning disable CS1591 to generated files (SessionEvents.cs, Rpc.cs) and codegen scripts
- Enable EmbedUntrackedSources, IncludeSymbols, SymbolPackageFormat
- Enable ContinuousIntegrationBuild conditional on CI/TF_BUILD environment variables
- Add PackageProjectUrl to package metadata
- Add [EditorBrowsable(Never)] to obsolete GithubToken property
- Upgrade analysis level and fix some diagnostics

* Exclude nodejs/scripts/ from Node.js SDK test triggers

Changes to development utility scripts (codegen, protocol version updates)
should not trigger the Node.js test suite, as they don't affect SDK runtime
code and the workflow fails on fork PRs that lack the COPILOT_HMAC_KEY secret.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Mock sendRequest in session.resume unit tests

These tests verify that the correct parameters are forwarded to the RPC
call, not that the CLI handles them. Mock sendRequest (like the setModel
test already does) so the tests don't depend on CLI authentication,
which is unavailable on fork PRs.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Fix PermissionRequestResultKind type in custom-agents docs

Use PermissionRequestResultKind.Approved instead of string literal
"approved" to match the strongly-typed struct in the .NET SDK.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: stephentoub

.github/workflows/copilot-setup-steps.yml

@@ -58,7 +58,7 @@ jobs:
       - name: Set up .NET
         uses: actions/setup-dotnet@v5
         with:
-          dotnet-version: "8.0.x"
+          dotnet-version: "10.0.x"
 
       # Install just command runner
       - name: Install just

.github/workflows/docs-validation.yml

@@ -108,7 +108,7 @@ jobs:
 
       - uses: actions/setup-dotnet@v5
         with:
-          dotnet-version: "8.0.x"
+          dotnet-version: "10.0.x"
 
       - name: Install validation dependencies
         working-directory: scripts/docs-validation

.github/workflows/dotnet-sdk-tests.yml

@@ -43,7 +43,7 @@ jobs:
       - uses: actions/checkout@v6.0.2
       - uses: actions/setup-dotnet@v5
         with:
-          dotnet-version: "8.0.x"
+          dotnet-version: "10.0.x"
       - uses: actions/setup-node@v6
         with:
           node-version: "22"

.github/workflows/nodejs-sdk-tests.yml

@@ -12,6 +12,7 @@ on:
       - 'nodejs/**'
       - 'test/**'
       - '.github/workflows/nodejs-sdk-tests.yml'
+      - '!nodejs/scripts/**'
       - '!**/*.md'
       - '!**/LICENSE*'
       - '!**/.gitignore'

.github/workflows/publish.yml

@@ -121,7 +121,7 @@ jobs:
       - uses: actions/checkout@v6.0.2
       - uses: actions/setup-dotnet@v5
         with:
-          dotnet-version: "8.0.x"
+          dotnet-version: "10.0.x"
       - name: Restore dependencies
         run: dotnet restore
       - name: Build and pack

.github/workflows/scenario-builds.yml

@@ -152,7 +152,7 @@ jobs:
 
       - uses: actions/setup-dotnet@v5
         with:
-          dotnet-version: "8.0.x"
+          dotnet-version: "10.0.x"
 
       - uses: actions/cache@v4
         with:

.github/workflows/update-copilot-dependency.yml

@@ -38,7 +38,7 @@ jobs:
 
       - uses: actions/setup-dotnet@v5
         with:
-          dotnet-version: "8.0.x"
+          dotnet-version: "10.0.x"
 
       - name: Update @github/copilot in nodejs
         env:

dotnet/Directory.Build.props

@@ -0,0 +1,12 @@
+<Project>
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <LangVersion>14</LangVersion>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <AnalysisLevel>10.0-minimum</AnalysisLevel>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+  </PropertyGroup>
+
+</Project>

dotnet/Directory.Packages.props

@@ -0,0 +1,19 @@
+<Project>
+
+  <PropertyGroup>
+    <ManagePackageVersionsCentrally>true</ManagePackageVersionsCentrally>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageVersion Include="coverlet.collector" Version="6.0.4" />
+    <PackageVersion Include="Microsoft.Extensions.AI.Abstractions" Version="10.2.0" />
+    <PackageVersion Include="Microsoft.Extensions.Logging.Abstractions" Version="10.0.2" />
+    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.3.0" />
+    <PackageVersion Include="Microsoft.SourceLink.GitHub" Version="10.0.102" />
+    <PackageVersion Include="StreamJsonRpc" Version="2.24.84" />
+    <PackageVersion Include="System.Text.Json" Version="10.0.2" />
+    <PackageVersion Include="xunit" Version="2.9.3" />
+    <PackageVersion Include="xunit.runner.visualstudio" Version="3.1.5" />
+  </ItemGroup>
+
+</Project>

dotnet/global.json

@@ -0,0 +1,6 @@
+{
+  "sdk": {
+    "version": "10.0.100",
+    "rollForward": "major"
+  }
+}