# Audit a C# Repo with Parallel Subagents in Atlas (2026)

> Atlas audits a C# solution by launching one read-only explore subagent per .csproj slice, so only findings return to the main session, not file dumps.

Atlas audits a C# repository by splitting the solution into independent slices and launching one subagent per slice with the task tool. Atlas fans out work to subagents that can run in the foreground or in parallel background sessions, and each subagent runs in its own session, so the file dumps from a hundred .cs files never enter your main context. Only the conclusions come back. For an audit where nothing should change, the explore subagent is the right choice because it is deny-by-default and read-only, which means it can grep and read your namespaces but cannot touch a .csproj or run dotnet build.

## Key takeaways

- The explore subagent is deny-by-default and read-only, which makes it the correct subagent type for a C# audit that must not mutate a .csproj.
- Subagents run in their own sessions, so a hundred .cs file dumps stay out of your main context window.
- Issue the task calls together so the slices of your .sln run concurrently rather than one after another.
- The task tool surfaces a failed subagent's error text verbatim, and Task cancelled if it was cancelled, so no slice disappears silently.
- Findings become a todowrite list, and fixes land in the main session with edit, verified by xUnit via dotnet test and cleaned with dotnet format.

## How do I audit an entire C# solution without filling the context window?

Atlas audits a C# solution by slicing it, usually one slice per .csproj in the .sln, and launching a subagent for each slice with the task tool. Each of the subagents runs in its own session in 2026, so the raw .cs file dumps never reach your main context.

A large C# solution can hold dozens of projects and thousands of .cs files, far more than any single session should read. Atlas fans out work to subagents that can run in the foreground or in parallel background sessions. Each subagent reads its own slice, using grep and glob to find the pattern you care about, and returns only its final message. The main session sees the conclusions, not the source. That is what keeps a repository-wide audit of a .NET solution tractable.

## Which subagent type should a C# audit use, explore or general?

Use the explore subagent for a C# audit in 2026. The explore subagent is deny-by-default and read-only, which makes it the right one for a sweep where nothing should change in your .csproj files. Choose general only when the subagent must also run a command such as dotnet build.

The distinction matters in .NET because auditing is often confused with fixing. The explore subagent cannot edit a .cs file, cannot rewrite a NuGet package reference, and cannot mutate your solution. That property is what lets you run several explore subagents concurrently across a large C# repo without worrying about two of them writing to the same file. The general subagent can act, so reserve it for a slice where you genuinely need dotnet test or dotnet format to run before the finding is meaningful.

## How do I slice a .NET repo so parallel subagents do not overlap?

Split a C# audit into independent slices so the subagents do not overlap: by directory, by project, or by rule. One task per .csproj in the .sln is the cleanest cut in 2026, because .NET project boundaries already partition the namespaces and the NuGet dependency sets.

Overlap is the failure mode of a parallel audit. Two subagents that both sweep src/Payments and src/Payments.Tests will report the same finding twice and waste tokens doing it. Slicing by .csproj gives clean, non-overlapping boundaries because every .cs file belongs to exactly one project. Slicing by rule is the other good axis: one subagent hunting blocking calls on async methods, another hunting IDisposable types that are never disposed, another checking that every public API has xUnit coverage.

## How do I make the C# subagents actually run in parallel?

Issue the task calls together so they run concurrently rather than one after another. Atlas fans out work to subagents that can run in the foreground or in parallel background sessions, so eight explore tasks across eight C# projects execute at once instead of serially in 2026.

Batching is the whole point. If Atlas issues one task call, waits for it, then issues the next, an audit of a twelve-project .NET solution takes twelve times as long as it needs to. When the task calls go out together, the explore subagents grep their assigned .cs files in parallel. The task tool surfaces the child's error text verbatim if a subagent fails, and reports Task cancelled if it was cancelled, so a slice that dies does not silently disappear from your audit.

## How do I turn C# audit findings into fixes?

Merge each subagent's final message into one todowrite list, then fix the items in the main session with the edit tool. In a C# repo that means one todo per offending .cs file, each verified with xUnit via dotnet test before the todo is marked complete in 2026.

The audit produces findings, and the todowrite list turns them into tracked work so partial progress is visible and nothing is silently skipped. Fixes happen in the main session with the edit tool, never inside the read-only explore subagents. Atlas computes a unified diff for every file edit and surfaces it for approval before writing, so you see exactly what changes in each .cs file. Run xUnit via dotnet test after each fix, then dotnet format so the diff carries the fix and not whitespace.

## How does Atlas keep a parallel C# audit safe?

Atlas keeps a parallel C# audit safe with 2 layers. Every Atlas tool call is permission-gated against allow, ask, and deny rules before it runs, and the explore subagent adds a second layer by being deny-by-default and read-only, so the audit cannot rewrite a .csproj or restore a NuGet package without your explicit approval.

Safety in a .NET audit comes from two independent mechanisms. The permission system checks every tool call, so you can allow grep and glob across your solution, ask on bash, and deny writes entirely for the duration of the sweep. The explore subagent's read-only permission set means the audit slices are incapable of mutation regardless of what the model decides to try. When you do move to fixes, Atlas snapshots file changes as git patches so any edit to a .cs file can be diffed and rolled back.

## Steps

1. Run atlas in a solution with a .csproj or .sln and let Atlas read your namespaces, project references, and NuGet packages.
2. Split the audit into independent slices, one per .csproj or one per rule, so the subagents do not overlap.
3. Launch one task per slice with subagent_type explore for a read-only sweep, or general when the subagent must also run dotnet build.
4. Issue the task calls together so they run concurrently rather than one after another.
5. Collect each subagent's final message; the task tool surfaces the child's error text verbatim if it fails, and Task cancelled if it was cancelled.
6. Merge the findings into one todowrite list, one entry per offending .cs file.
7. Fix each item in the main session with the edit tool and review the unified diff Atlas surfaces before writing.
8. Run xUnit via dotnet test after each fix, then dotnet format, and mark the todo complete only once the suite is green.

## FAQ

### how to audit a large c# solution with an ai agent

Split the .sln into slices, usually one per .csproj, and launch one Atlas task per slice with subagent_type explore. The subagents run in parallel background sessions and return only their conclusions, so the raw .cs files never enter your main context.

### what is the difference between the explore and general subagent in atlas

The explore subagent is deny-by-default and read-only, so it can grep and read your C# sources but cannot change them. The general subagent can act, including running commands like dotnet build, so use it only when a slice genuinely needs to execute something.

### can atlas run multiple subagents at the same time on a dotnet repo

Yes. Atlas fans out work to subagents that can run in the foreground or in parallel background sessions. Issue the task calls together and each slice of your C# solution is swept concurrently rather than one after another.

### what happens if an atlas subagent fails mid audit

The task tool surfaces the child's error text verbatim if the subagent fails, and reports Task cancelled if it was cancelled. A failed slice of your .NET audit is therefore visible rather than silently missing from the merged findings.

### how do i track fixes found during a c# repo audit

Merge the subagents' findings into a single todowrite list, one entry per offending .cs file, then fix each in the main session with edit. Run xUnit via dotnet test before marking an entry complete.

### can i stop atlas from modifying my csproj during an audit

Yes. Every Atlas tool call is permission-gated against allow, ask, and deny rules before it runs, and the explore subagent is additionally deny-by-default and read-only, so an audit sweep cannot rewrite a .csproj or a NuGet reference.

### does an atlas c# audit use grep or semantic search

Both are available. Atlas searches code with hybrid semantic and keyword retrieval fused by reciprocal rank fusion, and the audit subagents also use grep and glob directly to enumerate the .cs files in their assigned slice.

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