[SKIP_TO_CONTENT]
Daniel Kindl
Case Study · Solo Developer

Directory Synchronization Tool (dirsync)

C#.NET 10xUnitGitHub Actions
Role
Solo Developer
Timeline
2025
Links
Repository · Release
Status
SHIPPED

Context

The initial prototype started as a take-home technical assessment during a job interview process. The problem itself, reliably mirroring a source directory to a replica, was compelling enough that I continued developing it into a fully-featured, production-quality tool after the interview.

What I delivered

  • Built a tiered comparison engine (size → timestamp → SHA-256 hash) to minimize unnecessary hashing while guaranteeing accurate change detection.
  • Implemented atomic file operations (temp file + move) and retry logic with exponential backoff to prevent corruption from interrupted or transient failures.
  • Added path traversal protection, symbolic link rejection, and disk space validation as safety rails before any destructive operation.
  • Shipped with 42 passing unit tests, multi-platform CI/CD (Ubuntu/Windows/macOS), CodeQL security scanning, and single-file release binaries for four platforms.

Outcome

Released as v1.0.0 with global .NET tool installation support (dotnet tool install --global DirectorySync.Cli) and pre-built binaries for Windows, Linux, and macOS.