SC4 Mod Migration Assistant

A Windows desktop tool for SimCity 4 modders. It scans your Plugins folder and flags files in your 075-my-plugins and 895-my-overrides folders that duplicate content already present elsewhere in Plugins, so you can safely move them out of the way.

Built with WPF (.NET 10).

The tool was developed with Claude's support and under human supervision

Features

• Recursively scans a Plugins folder for .dat, .sc4lot, .sc4model, and .sc4desc files
• Detects duplicate content by comparing TGI (Type-Group-Instance) identifiers
• Automatically excludes non-content bookkeeping TGI entries (e.g. the DBPF directory record) that would otherwise cause false positives
• Extra file-name check for 895-my-overrides, since that folder is meant to hold intentional overrides that share a TGI with the original file by design
• Low memory footprint, suitable for machines with as little as 4–8 GB of RAM
• Live, color-coded log and progress bars for both the scan and the comparison step
• Moves (never deletes) duplicates to a folder of your choice, preserving the original subfolder structure
• Cancel support for long-running scans
• Check sc4pac Catalog: scans 075-my-plugins / 895-my-overrides, matches their TGIs against the community-run SC4 Prop Texture Catalog, and lists any sc4pac package that already provides that content — so you can install it properly instead of keeping a loose manual copy

Screenshots

Requirements

• Windows 10/11
• .NET 10 SDK to build, or the .NET 10 Desktop Runtime to run a published build
• Internet access the first time you use Check sc4pac Catalog (to download Catalog.db, ~22 MB); the scan/move features work fully offline

Setup

1. Clone this repository.

2. Build and run:

   dotnet build
   dotnet run

Usage

1. Browse... – select your SimCity 4 Plugins folder (the one containing 075-my-plugins and 895-my-overrides).

2. Scan TGIs – scans the whole folder tree and identifies duplicates. Files are color-coded by origin, and detected duplicates are highlighted.

3. Move Duplicates – choose a destination folder; all detected duplicates are moved there (with their relative subfolder structure preserved), freeing them from Plugins without permanently deleting anything.

4. Check sc4pac Catalog – scans only 075-my-plugins / 895-my-overrides and checks their TGIs against the SC4 Prop Texture Catalog (downloaded automatically on first use, then cached locally). Any matching sc4pac package is listed with:

   • Copy ID – copies the sc4pac package identifier (group:package-name)
   • Copy sc4pac add – copies the ready-to-run sc4pac add group:package-name command
   • Open Page – opens the mod's actual download/info page in your browser, when known

   sc4pac itself doesn't expose a documented way to trigger an install from an external link, so installing is a two-step, always-accurate process: copy the ID (or the command) here, then paste it into sc4pac's own Find Packages search (or run the copied command in a terminal).

How duplicate detection works

A file inside 075-my-plugins is flagged as a duplicate if it shares at least one TGI with a file in the main Plugins folder.

A file inside 895-my-overrides is flagged as a duplicate only if both are true:

• it shares at least one TGI with a file in Plugins, and
• a file with the same name already exists in Plugins.

This extra check exists because 895-my-overrides is meant to hold intentional overrides, which by design share a TGI with the file they replace — a TGI match alone there is expected, not a mistake.

Duplicates are only ever compared against the main Plugins folder; files within 075-my-plugins and 895-my-overrides are never compared against each other.

How the sc4pac catalog check works

Catalog.db is a SQLite database built and maintained by the SC4 Prop Texture Catalog project. It's downloaded directly from GitHub on first use and cached at %LocalAppData%\SC4ModMigrationAssistant\Catalog.db (delete that file to force a fresh download). It maps individual TGIs to the file they came from, and that file to the sc4pac package(s) that ship it.

For every distinct TGI found in 075-my-plugins / 895-my-overrides, the app looks up whether that exact TGI (or, for entries where the catalog only records Group+Instance, that Group and Instance) belongs to a known package, then groups the results by package so you see one entry per mod rather than one per file.

There's no publicly documented way to make an external link launch an install directly inside sc4pac, so results are given as a package ID / CLI command you paste into sc4pac (see Usage) plus, when available, a link to the mod's real page — not a fabricated "click to install" link that might not actually work.

Configuration

A few constants in Services/DbpfScanService.cs can be adjusted:

Constant	Purpose	Default
DbpfExtensions	File extensions treated as DBPF files	.dat, .sc4lot, .sc4model, .sc4desc
Overrides075FolderName / Overrides895FolderName	Override folder names to look for	075-my-plugins, 895-my-overrides
ExcludedTgis	TGIs excluded from comparison as non-content entries	DBPF Directory record, default LD entry
ProgressReportInterval	How often the scan progress bar updates	every 100 files

The catalog download URL and local cache path are in Services/CatalogDatabaseService.cs (CatalogDownloadUrl, CacheFilePath).

Project structure

SC4ModMigrationAssistant.csproj
LICENSE
App.xaml / App.xaml.cs
MainWindow.xaml / MainWindow.xaml.cs
LogEntryView.cs
Models/
  SourceCategory.cs
  TgiKey.cs
  ScannedFile.cs
  CatalogScanFile.cs
  Sc4pacMatch.cs
  LogColor.cs
Services/
  DbpfScanService.cs
  DuplicateMoverService.cs
  CatalogDatabaseService.cs
  Sc4pacLookupService.cs

Contributing

Issues and pull requests are welcome.

License

This project is licensed under the MIT License

Disclaimer

This tool moves files out of your Plugins folder based on automated heuristics. Back up your Plugins folder before running it, and review the log before moving files if you're unsure.