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AGENTS.md

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+# Repository Guidelines
+
+## Project Structure & Module Organization
+
+This repository contains a small .NET CLI for patching the parent path stored in classic VHD differencing disks.
+
+- `src/VHDPatchFix/` contains the CLI, VHD footer/header parsing, checksum logic, and patch operation.
+- `VHDPatchFix.sln` is the canonical solution file for build and test commands.
+
+Keep VHD binary parsing code isolated in small classes. Prefer adding focused helpers under `src/VHDPatchFix/` instead of expanding `Program.cs`.
+
+## Build, and Development Commands
+
+- `dotnet build VHDPatchFix.sln -v minimal` restores and builds the CLI and tests.
+- `dotnet run --project src\VHDPatchFix\VHDPatchFix.csproj -- --help` shows CLI usage.
+- `dotnet run --project src\VHDPatchFix\VHDPatchFix.csproj -- --vhd "I:\internal_1.vhd" --parent "\Device\FscryptDisk_APP_0\internal_0.vhd" --dry-run` validates a target without writing.
+
+Use `--dry-run` before patching real disks. Ensure the child VHD is detached before writing.
+
+## Coding Style & Naming Conventions
+
+Use C# nullable reference types and implicit usings as configured in the project files. Use four-space indentation, PascalCase for public types and methods, and camelCase for locals and parameters.
+
+Keep binary offsets explicit and close to the relevant VHD structure parser. Avoid unrelated formatting-only edits in functional changes.
+
+## Commit & Pull Request Guidelines
+
+This checkout has no Git history, so no repository-specific convention is established. Use short imperative subjects such as `Add VHD parent locator patcher`.
+
+Pull requests should include the target scenario, before/after command output when relevant, and test results from `dotnet build` plus the test runner.
+
+## Security & Data Safety
+
+Do not patch attached VHDs. Keep backup creation enabled by default for real disks. Avoid logging full local paths unless needed for troubleshooting, and never validate parent existence as a requirement because NT device paths may only exist on another machine.