ExplorerPatcher is a Windows shell customization utility that operates by DLL injection and API hooking inside explorer.exe and related shell processes. In production it ships a patcher DLL (loaded via a dxgi.dll stub renamed into the Explorer directory), a settings GUI (ep_gui.dll, launched via rundll32 dxgi.dll,ZZGUI), an installer/uninstaller (ep_setup.exe), a WebView2-based weather COM host, an Alt+Tab replacement module, and a Start menu patching module (ep_startmenu). At runtime it reads feature toggles from HKEY_CURRENT_USER\Software\ExplorerPatcher, hooks undocumented internal COM interfaces and WinRT activation factories, applies inline machine-code patches and vtable replacements, and restores Windows 10 taskbar, Start menu, context menus, and Alt+Tab behaviors on Windows 11. It also downloads symbols from Microsoft symbol servers and uses byte-pattern scanning to resolve version-specific function offsets. Architecturally this is a suite of loosely coordinated native Windows modules rather than a monolith: the core patcher coordinates them, a chainloader (ep_extra.dll) discovers and loads ep_extra_*.dll plugins, and everything is versioned and bundled by the setup program using AES-encrypted embedded ZIP resources. External dependencies include KNSoft.SlimDetours for hooking, Microsoft WIL, WebView2, zlib, libvalinet, SimpleWindowSwitcher, plus git submodules and a separately downloaded ep_taskbar.dll. The code is heavily build-specific, with x64/ARM64/IA-32 branches and fallback pattern sets for Windows 10/11 builds from 22000 through current 26100+ servicing builds. The craftsmanship is genuinely notable for a reverse-engineering project: ARM64 instruction encode/decode helpers, multi-stage pattern scanners with gap and bitmask variants, SlimDetours transactional IAT hitching, and clean reusable header templates for allocation policy strings and COM ref-counting. The maintenance burden is inherent and huge — every Windows cumulative update risks breaking hardcoded offsets, and the code carries architectural debt from this fight: monumental C files (dllmain.c exceeds 4000 lines), heavy preprocessor branching, dead #if 0 blocks, and no automated test suite. It is not a data/research repository despite containing bundled .pri and .mui localization assets; those are deployment resources, not data artifacts. Despite its fragility, the project tracks Windows updates aggressively (weekly fixes per the changelog) and delivers a working, widely deployed product.