File Associations, Shortcuts and System Resources

What is it?

File associations decide which program opens a file, shortcuts are small files that point at another file or program, and system resources are the shared sounds, fonts and icons the shell uses. This roadmap plans all of them: an extension-to-program map in the Registry, default associations written on first boot, an Open With dialog, .lnk shortcuts on the desktop and in the Start menu, Recycle Bin icon states, system sounds, a font manager and icon extraction from programs. None of its nine sections has shipped. Only the pieces it builds on exist: a file-type icon lookup, the Registry and the font loader.

How does it work?

Today.

File-type icons. icon_for_extension() in icon_store.c compares the extension against eight entries: .exe to the program icon, .dll and .sys to the library icon, and .txt, .md, .log, .cfg and .ini to the text file icon. Everything else, including an extension written without its dot or in capitals, gets the generic file icon. It chooses a picture only; it does not say which program opens the file.
Registry. HKEY_CLASSES_ROOT is an alias for HKLM\SOFTWARE\Classes, which registry.c creates empty at boot. No association is written into it.
Desktop. The desktop draws three fixed icons, and the Recycle Bin always shows its empty picture (desktop.c); see Desktop Icons.
Fonts. The font manager loads five fixed font slots from fixed file names under C:\Impossible\Fonts\, with Inter as a fallback (gfx_text.c). There is no directory scan and no way to reload fonts (font_mgr.h).
Sounds. There is no audio playback path and no sound files.

Planned design.

Mapping. file_assoc_get_app(), file_assoc_get_icon(), file_assoc_set() and file_assoc_open(), reading HKCR\.ext to a program ID and the program ID's shell\open\command, as Windows does.
Defaults. About a dozen built-in associations written once, guarded by HKLM\SYSTEM\FirstBoot\FileAssocsInit.
Open With. A dialog listing the registered programs, with "Always use this app" writing the default.
Shortcuts. A plain-text .lnk format (target, arguments, working folder, icon), readable in any editor. It is not the Windows binary Shell Link format, so Windows shortcut files will not work as shortcuts.
Desktop and Start menu. Shortcut arrow overlays and Start menu entries built from shortcut folders.
Recycle Bin states. The empty and full icons driven by the Recycle Bin's item count.
System sounds. A WAV parser and named system sounds, logged to serial until an audio driver exists.
Font manager. A window to list, preview, install and remove TrueType fonts.
Icon extraction. Icons read from EIF and PE program resources at any size.

What are its interfaces?

Interface	Status
`icon_for_extension()`	Shipped: eight extensions, icon only
`RegGetValue()`, `RegSetValueEx()`, `HKEY_CLASSES_ROOT`	Shipped: the Registry API the plan uses (`registry.h`)
`ttf_get()`, `ttf_draw_string()`	Shipped: fixed font slots
`file_assoc_*`, `shortcut_parse()`, `shortcut_execute()`, `shortcut_create()`	Planned
`ttf_mgr_reload()`, WAV playback, icon extraction	Planned

How do I use it?

It cannot be used yet. Nothing opens a file by type today: the shell runs only its built-in commands, so the one way to look at a file is type <file> (or cat) for text.

What is not implemented yet?

Extension-to-App Mapping and Default Associations on First Boot
Open With Dialog
Shortcut Files (.lnk) and Desktop Shortcut Integration
Recycle Bin Desktop Icon States, with the Recycle Bin itself owned by Recycle Bin, ZIP and Task Scheduler
System Sounds, Font Manager App and Icon Extraction

The desktop icon roadmap also plans a .lnk format and file-type icons (Desktop Icons); both plans describe the same plain-text shortcut, and the missing leading-dot and case handling in icon_for_extension() is owned there.

How does it compare with Windows 11 and Linux?

Windows 11 resolves a file through HKCR and ShellExecuteEx, ships default associations, offers Open With and "Always use", uses binary Shell Link .lnk files, and has sound schemes and a Fonts page in Settings. Linux desktops use the XDG MIME database (xdg-open, mimeapps.list), .desktop launcher files, freedesktop sound themes and GNOME or KDE font viewers. Impossible OS has only file-type icons today. The plan copies the Windows Registry layout so Windows tools find what they expect, and chooses a human-editable shortcut format instead of the binary one.