Folder Sync Inspector
Desktop verification utility comparing directories and Git commit tree integrity via SHA-256 checksums and line-by-line diffing.
System Overview
Prior to building Deploy Packager, deploying to air-gapped on-premise servers required executing manual shell scripts (such as git diff-tree coupled with xargs cp --parents) to generate a folder containing only changed files. However, there was no quick way to audit that the resulting folder accurately captured all commit modifications without silent omissions.
Folder Sync Inspector was created to bridge this verification gap: it compares source and target directories using cryptographic SHA-256 checksums, inspects Git commit trees, and presents line-by-line visual differences directly within a clean desktop interface.
Architectural & Technical Challenges
Comparing folders solely through file modification timestamps is notoriously unreliable across operating systems, as file copy and extraction operations update timestamps arbitrarily. The utility needed to compute cryptographic content hashes rapidly across hundreds of files without freezing the UI and provide a clean visual diff viewer for code discrepancies.
Key Architectural Decisions
Content hashing over timestamp comparison
Utilized SHA-256 content hashing rather than filesystem modified dates, completely eliminating false positives caused by file copy and transfer processes.
In-app line-by-line diff rendering
Integrated the diff_match_patch algorithm directly inside a custom modal viewer, allowing immediate inspection of differing lines without launching external comparison software.
The evolutionary catalyst for Deploy Packager
Using Folder Sync Inspector confirmed that while verification was essential, the manual shell extraction step was still the core operational bottleneck. This realization directly inspired the development of Deploy Packager two days later, combining extraction, tree preservation, and packaging into a unified tool.
Engineering Contributions
Desktop Utility Conception & UI
Designed and developed the Flutter desktop application with a focused Material 3 layout, folder selection pickers, and real-time path filtering.
Cryptographic SHA-256 Verification
Implemented high-speed SHA-256 checksum comparison across directory trees, accurately categorizing files into Match, Different, and Missing states.
Git Commit Tree Validation
Built the commit inspection routine that cross-references a prepared folder's file manifest against the file list extracted from specific Git commit hashes.
Embedded Visual Code Diff
Integrated an in-app side-by-side and inline syntax diff viewer using diff_match_patch with dual line numbering and change highlighting.
Technologies & Core Stack
Flutter • Dart • SHA-256 • diff_match_patch • Desktop Tool