CsharpAnalysis.txt

Yes, there **is** a C# library — the main one is **Roslyn**, officially called the **.NET Compiler Platform**.

But important point:

```text id="h7134c"
Roslyn is a .NET/C# library, not a normal Python library.
```

So from your **Python agent**, the best approach is:

```text id="n1f943"
Python Agent
  → calls C# Roslyn analyzer CLI
      → analyzes .sln / .csproj / .cs files
      → returns JSON
  → Python agent uses JSON for context, errors, symbols, dependencies
```

Roslyn gives you syntax APIs, semantic APIs, symbols, bindings, diagnostics, refactoring support, and analyzer support for C# and VB code. Microsoft describes Roslyn as APIs for understanding .NET code, spotting errors, and fixing them. ([Microsoft Learn][1])

---

# Best C# libraries/tools for your agent

| Purpose                                | Library / Tool                              |
| -------------------------------------- | ------------------------------------------- |
| C# syntax analysis                     | `Microsoft.CodeAnalysis.CSharp`             |
| C# semantic analysis                   | `Microsoft.CodeAnalysis`                    |
| Load `.sln` / `.csproj`                | `Microsoft.CodeAnalysis.Workspaces.MSBuild` |
| Analyzer/code fix development          | `Microsoft.CodeAnalysis.CSharp.Workspaces`  |
| Razor/Blazor support                   | `Microsoft.CodeAnalysis.Razor`              |
| .NET code quality analyzers            | built-in Roslyn analyzers / NuGet analyzers |
| Simple syntax-only parsing from Python | `tree-sitter-c-sharp`                       |
| Calling .NET from Python               | `pythonnet`, but I prefer CLI JSON bridge   |

The `Microsoft.CodeAnalysis.CSharp` NuGet package is specifically for C# compiler platform support and analyzing C# projects/solutions. ([NuGet][2]) The `Microsoft.CodeAnalysis.Workspaces.MSBuild` package is for analyzing MSBuild projects and solutions and is intended to be used with language workspace packages such as `Microsoft.CodeAnalysis.CSharp.Workspaces`. ([NuGet][3])

---

# What Roslyn can give your Python agent

Roslyn can extract:

```text id="7ll6kf"
namespaces
classes
interfaces
records
structs
enums
methods
properties
fields
constructors
attributes
using statements
inheritance
implemented interfaces
method references
diagnostics
compiler errors
nullable warnings
semantic type information
```

The syntax API represents the full structure of C# or Visual Basic programs, including incomplete code while editing. ([Microsoft Learn][4]) The semantic APIs provide symbol and binding information, including the meaning and types represented by symbols in the program. ([Microsoft Learn][5])

---

# Recommended design for your Python agent

Do **not** try to fully analyze C# directly in Python.

Create this:

```text id="yrgy9q"
tools/
  Beep.CSharpAnalyzer/
    Beep.CSharpAnalyzer.csproj
    Program.cs

beep/
  languages/
    csharp.py
  codeanalysis/
    csharp_roslyn_client.py
```

Your Python agent calls:

```bash id="85a9yl"
dotnet run --project tools/Beep.CSharpAnalyzer -- analyze --solution MyApp.sln --output json
```

Then it receives JSON like:

```json id="veh0kp"
{
  "projects": [
    {
      "name": "MyApp.Domain",
      "files": [
        {
          "path": "Domain/Orders/Order.cs",
          "symbols": [
            {
              "kind": "class",
              "name": "Order",
              "namespace": "MyApp.Domain.Orders",
              "methods": ["Approve", "Cancel", "AddItem"]
            }
          ]
        }
      ]
    }
  ],
  "diagnostics": [
    {
      "file": "Application/Orders/CreateOrderHandler.cs",
      "line": 42,
      "column": 17,
      "code": "CS0246",
      "message": "The type or namespace name could not be found"
    }
  ]
}
```

---

# Minimal Roslyn analyzer project

Create:

```bash id="7l0iet"
dotnet new console -n Beep.CSharpAnalyzer
cd Beep.CSharpAnalyzer
dotnet add package Microsoft.CodeAnalysis.CSharp.Workspaces
dotnet add package Microsoft.CodeAnalysis.Workspaces.MSBuild
dotnet add package Microsoft.Build.Locator
```

Example `Program.cs`:

```csharp id="3hgno5"
using System.Text.Json;
using Microsoft.Build.Locator;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.MSBuild;

if (!MSBuildLocator.IsRegistered)
{
    MSBuildLocator.RegisterDefaults();
}

var solutionPath = args.Length > 0 ? args[0] : throw new ArgumentException("Solution path required.");

using var workspace = MSBuildWorkspace.Create();
var solution = await workspace.OpenSolutionAsync(solutionPath);

var result = new List<object>();

foreach (var project in solution.Projects)
{
    var projectInfo = new
    {
        project.Name,
        project.FilePath,
        Documents = new List<object>()
    };

    foreach (var document in project.Documents)
    {
        var syntaxRoot = await document.GetSyntaxRootAsync();
        var semanticModel = await document.GetSemanticModelAsync();

        if (syntaxRoot is null || semanticModel is null)
        {
            continue;
        }

        var symbols = syntaxRoot
            .DescendantNodes()
            .Select(node => semanticModel.GetDeclaredSymbol(node))
            .Where(symbol => symbol is not null)
            .Select(symbol => new
            {
                Name = symbol!.Name,
                Kind = symbol.Kind.ToString(),
                Namespace = symbol.ContainingNamespace?.ToDisplayString(),
                Type = symbol.ToDisplayString()
            })
            .ToList();

        projectInfo.Documents.Add(new
        {
            document.Name,
            document.FilePath,
            Symbols = symbols
        });
    }

    result.Add(projectInfo);
}

Console.WriteLine(JsonSerializer.Serialize(result, new JsonSerializerOptions
{
    WriteIndented = true
}));
```

Then from Python:

```python id="qn68lz"
import json
import subprocess
from pathlib import Path


def analyze_csharp_solution(solution_path: str) -> dict:
    command = [
        "dotnet",
        "run",
        "--project",
        "tools/Beep.CSharpAnalyzer",
        "--",
        solution_path,
    ]

    completed = subprocess.run(
        command,
        capture_output=True,
        text=True,
        check=False,
    )

    if completed.returncode != 0:
        return {
            "ok": False,
            "error": completed.stderr,
            "stdout": completed.stdout,
        }

    return {
        "ok": True,
        "data": json.loads(completed.stdout),
    }
```

---

# Why not use `pythonnet` directly?

You **can** use `pythonnet` to load .NET assemblies from Python. Python.NET allows Python code to integrate with the .NET CLR, and assemblies must be loaded explicitly with `AddReference`. ([pythonnet][6])

But for your coding agent, I would avoid direct Roslyn-in-Python at first because:

```text id="43lwm6"
Roslyn setup is easier inside a .NET console app
MSBuildWorkspace is easier to initialize in .NET
Errors are easier to debug
Version conflicts are easier to control
Python stays clean
The JSON bridge is language-neutral
```

So use `pythonnet` only if you really need in-process integration.

---

# What about `tree-sitter` for C#?

`tree-sitter` is useful for **syntax-level** C# analysis:

```text id="4nn9fz"
find classes
find methods
find properties
find using statements
find rough file structure
```

But it does **not** understand full C# semantics like Roslyn:

```text id="wmxpg2"
symbol resolution
type inference
project references
NuGet references
nullable analysis
compiler diagnostics
method overload resolution
```

So the practical rule is:

```text id="ezr32j"
Use tree-sitter for fast multi-language indexing.
Use Roslyn for serious C#/.NET analysis.
```

---

# Best implementation for your Beep agent

Add a C# adapter like this:

```python id="jqopws"
class CSharpLanguageAdapter:
    name = "csharp"
    extensions = [".cs", ".csproj", ".sln", ".razor"]

    def detect(self, root_path: str) -> bool:
        root = Path(root_path)
        return bool(list(root.glob("*.sln")) or list(root.rglob("*.csproj")))

    def analyze(self, root_path: str) -> dict:
        solution_files = list(Path(root_path).glob("*.sln"))

        if not solution_files:
            return {
                "ok": False,
                "error": "No solution file found."
            }

        return analyze_csharp_solution(str(solution_files[0]))

    def get_build_commands(self, root_path: str):
        return [["dotnet", "build"]]

    def get_test_commands(self, root_path: str):
        return [["dotnet", "test"]]
```

And later expand the Roslyn CLI to support:

```text id="ybxxaz"
analyze symbols
analyze dependencies
analyze diagnostics
find references
find implementations
detect layer violations
detect domain services
detect business logic in controllers
suggest refactor locations
```

---

# Final answer

Yes, there **is** a C# library: **Roslyn / Microsoft.CodeAnalysis**.

For your Python coding agent, the best design is:

```text id="wcw6a9"
Python agent core
  + tree-sitter for quick C# syntax indexing
  + Roslyn .NET CLI helper for deep C# analysis
  + dotnet build/test for validation
  + JSON bridge between Python and C#
```

That gives you real C# support instead of asking the LLM to guess.

[1]: https://learn.microsoft.com/en-us/dotnet/csharp/roslyn-sdk/?utm_source=chatgpt.com "The .NET Compiler Platform SDK (Roslyn APIs) - C#"
[2]: https://www.nuget.org/packages/microsoft.codeanalysis.csharp/?utm_source=chatgpt.com "Microsoft.CodeAnalysis.CSharp 5.3.0"
[3]: https://www.nuget.org/packages/Microsoft.CodeAnalysis.Workspaces.MSBuild/?utm_source=chatgpt.com "Microsoft.CodeAnalysis.Workspaces.MSBuild 5.3.0"
[4]: https://learn.microsoft.com/en-us/dotnet/csharp/roslyn-sdk/get-started/syntax-analysis?utm_source=chatgpt.com "Get started with syntax analysis (Roslyn APIs) - C#"
[5]: https://learn.microsoft.com/en-us/dotnet/csharp/roslyn-sdk/get-started/semantic-analysis?utm_source=chatgpt.com "Get started with semantic analysis - C#"
[6]: https://pythonnet.github.io/pythonnet/python.html?utm_source=chatgpt.com "Embedding .NET into Python - Python.NET documentation"