add .NET project file support (.sln, .csproj, .fsproj, .vbproj, .razor, .cshtml)

Adds extract_sln, extract_csproj, and extract_razor extractors. Captures NuGet
package refs, project-to-project dependencies, target frameworks, SDK attribute,
@using/@inject/@inherits/@model directives, Blazor component refs, and @code
methods. Resolves relative project paths to absolute paths so sln/csproj nodes
link correctly when the graph is assembled. Closes #515.

Co-Authored-By: aksrathore <aksrathore@users.noreply.github.com>
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/fixtures/sample.csproj

@@ -0,0 +1,21 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.AspNetCore.Authentication.JwtBearer" Version="8.0.0" />
+    <PackageReference Include="Swashbuckle.AspNetCore" Version="6.5.0" />
+    <PackageReference Include="MediatR" Version="12.2.0" />
+    <PackageReference Include="FluentValidation" Version="11.9.0" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Domain\Domain.csproj" />
+    <ProjectReference Include="..\Infrastructure\Infrastructure.csproj" />
+  </ItemGroup>
+
+</Project>

tests/fixtures/sample.razor

@@ -0,0 +1,36 @@
+@page "/counter"
+@using Microsoft.AspNetCore.Components
+@using MyApp.Services
+@inject ICounterService CounterService
+@inject NavigationManager Navigation
+@inherits ComponentBase
+
+<h1>Counter</h1>
+
+<p>Current count: @currentCount</p>
+
+<Button OnClick="IncrementCount">Click me</Button>
+<WeatherDisplay City="@city" />
+<DataGrid TItem="CounterRecord" Items="@records" />
+
+@code {
+    private int currentCount = 0;
+    private string city = "Seattle";
+    private List<CounterRecord> records = new();
+
+    private void IncrementCount()
+    {
+        currentCount++;
+        CounterService.Increment();
+    }
+
+    public async Task LoadData()
+    {
+        records = await CounterService.GetRecords();
+    }
+
+    protected override async Task OnInitializedAsync()
+    {
+        await LoadData();
+    }
+}

tests/fixtures/sample.sln

@@ -0,0 +1,20 @@
+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.0.31903.59
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "WebApi", "src\WebApi\WebApi.csproj", "{A1B2C3D4-E5F6-7890-ABCD-EF1234567890}"
+	ProjectSection(ProjectDependencies) = postProject
+		{B2C3D4E5-F6A7-8901-BCDE-F12345678901} = {B2C3D4E5-F6A7-8901-BCDE-F12345678901}
+	EndProjectSection
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Domain", "src\Domain\Domain.csproj", "{B2C3D4E5-F6A7-8901-BCDE-F12345678901}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Tests", "tests\Tests\Tests.csproj", "{C3D4E5F6-A7B8-9012-CDEF-123456789012}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+EndGlobal

tests/test_dotnet.py

@@ -0,0 +1,125 @@
+"""Tests for .NET project file extraction (.sln, .csproj, .razor)."""
+from pathlib import Path
+import tempfile
+import pytest
+from graphify.extract import extract_sln, extract_csproj, extract_razor
+
+FIXTURES = Path(__file__).parent / "fixtures"
+
+
+def _labels(r):
+    return [n["label"] for n in r["nodes"]]
+
+
+def _relations(r):
+    return {e["relation"] for e in r["edges"]}
+
+
+# ── .sln ─────────────────────────────────────────────────────────────────────
+
+def test_sln_extracts_projects():
+    r = extract_sln(FIXTURES / "sample.sln")
+    assert "error" not in r
+    labels = set(_labels(r))
+    assert "WebApi" in labels
+    assert "Domain" in labels
+    assert "Tests" in labels
+
+
+def test_sln_contains_edges():
+    r = extract_sln(FIXTURES / "sample.sln")
+    contains = [e for e in r["edges"] if e["relation"] == "contains"]
+    assert len(contains) == 3
+
+
+def test_sln_project_dependency():
+    r = extract_sln(FIXTURES / "sample.sln")
+    assert "imports" in _relations(r)
+
+
+# ── .csproj ──────────────────────────────────────────────────────────────────
+
+def test_csproj_packages():
+    r = extract_csproj(FIXTURES / "sample.csproj")
+    assert "error" not in r
+    labels = _labels(r)
+    assert any("MediatR" in l for l in labels)
+    assert any("FluentValidation" in l for l in labels)
+    assert any("Swashbuckle" in l for l in labels)
+
+
+def test_csproj_project_references():
+    r = extract_csproj(FIXTURES / "sample.csproj")
+    imports = [e for e in r["edges"] if e["relation"] == "imports"]
+    assert len(imports) == 6  # 4 packages + 2 project refs
+
+
+def test_csproj_target_framework():
+    r = extract_csproj(FIXTURES / "sample.csproj")
+    assert "net8.0" in _labels(r)
+
+
+def test_csproj_sdk():
+    r = extract_csproj(FIXTURES / "sample.csproj")
+    assert "Microsoft.NET.Sdk.Web" in _labels(r)
+
+
+def test_csproj_invalid_xml():
+    with tempfile.NamedTemporaryFile(suffix=".csproj", mode="w", delete=False) as f:
+        f.write("<Project><Invalid></Project>")
+        f.flush()
+        r = extract_csproj(Path(f.name))
+    assert "error" in r
+
+
+# ── .razor ───────────────────────────────────────────────────────────────────
+
+def test_razor_using_and_inject():
+    r = extract_razor(FIXTURES / "sample.razor")
+    assert "error" not in r
+    targets = {e["target"] for e in r["edges"] if e["relation"] == "imports"}
+    assert any("microsoft" in t for t in targets)
+    assert any("counterservice" in t.lower() for t in targets)
+
+
+def test_razor_components():
+    r = extract_razor(FIXTURES / "sample.razor")
+    targets = {e["target"] for e in r["edges"] if e["relation"] == "calls"}
+    assert any("weatherdisplay" in t for t in targets)
+    assert any("datagrid" in t for t in targets)
+
+
+def test_razor_page_route():
+    r = extract_razor(FIXTURES / "sample.razor")
+    assert any("/counter" in l for l in _labels(r))
+
+
+def test_razor_inherits():
+    r = extract_razor(FIXTURES / "sample.razor")
+    assert "inherits" in _relations(r)
+
+
+def test_razor_code_methods():
+    r = extract_razor(FIXTURES / "sample.razor")
+    labels = _labels(r)
+    assert "IncrementCount" in labels
+    assert "LoadData" in labels
+
+
+def test_razor_missing_file():
+    r = extract_razor(Path("/nonexistent/file.razor"))
+    assert "error" in r
+
+
+# ── dispatch & detect integration ────────────────────────────────────────────
+
+def test_dispatch_table():
+    from graphify.extract import _get_extractor
+    for ext in (".sln", ".csproj", ".fsproj", ".vbproj", ".razor", ".cshtml"):
+        assert _get_extractor(Path(f"foo{ext}")) is not None, f"{ext} not in dispatch"
+
+
+def test_code_extensions():
+    from graphify.detect import CODE_EXTENSIONS
+    for ext in (".sln", ".csproj", ".fsproj", ".vbproj", ".razor", ".cshtml"):
+        assert ext in CODE_EXTENSIONS, f"{ext} missing"

tests/test_languages.py

@@ -1,4 +1,4 @@
-"""Tests for language extractors: Java, C, C++, Ruby, C#, Kotlin, Scala, PHP, Swift, Go, Julia, Fortran, JS/TS."""
+"""Tests for language extractors: Java, C, C++, Ruby, C#, Kotlin, Scala, PHP, Swift, Go, Julia, Fortran, JS/TS, .NET project files."""
 from __future__ import annotations
 from pathlib import Path
 import pytest
@@ -6,7 +6,7 @@ from graphify.extract import (
     extract_java, extract_c, extract_cpp, extract_ruby,
     extract_csharp, extract_kotlin, extract_scala, extract_php,
     extract_swift, extract_go, extract_julia, extract_js, extract_fortran,
-    extract_groovy,
+    extract_groovy, extract_sln, extract_csproj, extract_razor,
 )
 
 FIXTURES = Path(__file__).parent / "fixtures"
@@ -1058,3 +1058,75 @@ def test_groovy_spock_no_dangling_edges():
     node_ids = {n["id"] for n in r["nodes"]}
     for e in r["edges"]:
         assert e["source"] in node_ids
+
+
+# -- .NET project files (.sln, .csproj, .razor) -------------------------------
+
+def test_sln_no_error():
+    r = extract_sln(FIXTURES / "sample.sln")
+    assert "error" not in r
+
+def test_sln_finds_projects():
+    r = extract_sln(FIXTURES / "sample.sln")
+    labels = _labels(r)
+    assert any("WebApi" in l for l in labels)
+    assert any("Domain" in l for l in labels)
+
+def test_sln_contains_edges():
+    r = extract_sln(FIXTURES / "sample.sln")
+    assert "contains" in _relations(r)
+
+def test_sln_project_dependency_edges():
+    r = extract_sln(FIXTURES / "sample.sln")
+    assert "imports" in _relations(r)
+
+def test_csproj_no_error():
+    r = extract_csproj(FIXTURES / "sample.csproj")
+    assert "error" not in r
+
+def test_csproj_finds_packages():
+    r = extract_csproj(FIXTURES / "sample.csproj")
+    labels = _labels(r)
+    assert any("MediatR" in l for l in labels)
+    assert any("FluentValidation" in l for l in labels)
+
+def test_csproj_finds_project_references():
+    r = extract_csproj(FIXTURES / "sample.csproj")
+    labels = _labels(r)
+    assert any("Domain.csproj" in l for l in labels)
+
+def test_csproj_finds_target_framework():
+    r = extract_csproj(FIXTURES / "sample.csproj")
+    assert any("net8.0" in l for l in _labels(r))
+
+def test_csproj_finds_sdk():
+    r = extract_csproj(FIXTURES / "sample.csproj")
+    assert any("Microsoft.NET.Sdk.Web" in l for l in _labels(r))
+
+def test_razor_no_error():
+    r = extract_razor(FIXTURES / "sample.razor")
+    assert "error" not in r
+
+def test_razor_finds_using_directives():
+    r = extract_razor(FIXTURES / "sample.razor")
+    assert "imports" in _relations(r)
+
+def test_razor_finds_component_references():
+    r = extract_razor(FIXTURES / "sample.razor")
+    assert "calls" in _relations(r)
+
+def test_razor_finds_inherits():
+    r = extract_razor(FIXTURES / "sample.razor")
+    assert "inherits" in _relations(r)
+
+def test_razor_finds_code_block_methods():
+    r = extract_razor(FIXTURES / "sample.razor")
+    labels = _labels(r)
+    assert any("IncrementCount" in l for l in labels)
+    assert any("LoadData" in l for l in labels)
+
+def test_razor_no_dangling_edges():
+    r = extract_razor(FIXTURES / "sample.razor")
+    node_ids = {n["id"] for n in r["nodes"]}
+    for e in r["edges"]:
+        assert e["source"] in node_ids