System data folders

Where Napple keeps data that is not part of one game. One root serves every generated game app, Napple Studio and the developer scripts, so a Mii created in one game exists in all of them and nothing is configured twice.

The root

~/Library/Application Support/Napple/ (the "support directory"), or NAPPLE_SUPPORT_DIR when set. The runtime resolves it once at boot (g_cfg.support_dir, helper napple_support_dir() in runtime/src/napple.h). --save-root does not move it: that option only moves per-game saves (<save root>/<title id>/). The launcher, the runtime, Studio (SystemData.supportDir), tools/prepare_game.sh, tools/boot_test.sh and tools/golden/golden.py all resolve the same root; runtime/tests/test_svc_sysroot.c and the Studio test SystemDataTests check it. The generated Mac apps are not sandboxed (no com.apple.security.app-sandbox; a Rust test guards it), because a sandboxed app could not see this folder, the user's key file or an iCloud Drive Mii folder. iOS apps are sandboxed and use their own container (runtime/src/main.c).

Path under the root	What	Written by	Read by
system.json	the one configuration file for the simulators and the online hook (keys below)	Studio (Settings > Mii / Amiibo / Online), the in-game overlay (amiibo tab)	the runtime at boot (sysconfig_core.c)
system/mii/MiiDatabase.dat (+ .bak, .lock)	the Mii database shared by every game (up to 100 Miis; the six defaults are code)	mii:u / mii:e, the Mii Maker applet	every game, Studio's Mii pane
system/amiibo/<uid>.json	virtual amiibo and their game data (application area)	the amiibo picker, NAPPLE_AMIIBO	nfp / nfc
system/amiibo-cache/amiibo.json	the last fetched amiibo list (offline fallback; metadata only, never committed)	the amiibo list reload	the picker
system/fonts/*.ttf	the shared system fonts (pl:u)	the launcher on start (from the game bundle), napple build --dump-fonts	pl:u
system/icon/SubstituteUserIcon.jpg	the default profile picture	napple build	acc
system/applet-run-<pid>/	scratch storages of a running Mii Maker child	applet.c	the child; removed afterwards
<title id>/ (save root)	per-game saves, settings.json, input.json, caches	the runtime / overlay	the runtime
keysets/<name>/, engine/, Builds/, library.json, logs/	Studio's own data (keys are owner-only)	Studio	Studio
goldens/	approved golden frames of the graphics gate (never in the repository)	tools/golden/golden.py approve	golden.py run

system.json

A flat JSON object, all keys optional and empty by default. At boot each non-empty key becomes its environment variable unless that variable is already set (the environment always wins, so scripts and tests override the file). Unknown keys are ignored.

Key	Environment variable	Meaning
amiibo_database	NAPPLE_AMIIBO_DB	amiibo list source: URL, a .json file, or a folder holding amiibo.json / database/amiibo.json (default: the AmiiboAPI repository's raw database/amiibo.json, configuration only, no data shipped)
amiibo_key	NAPPLE_AMIIBO_KEY	key_retail.bin for importing real dumps (default ~/.switch/key_retail.bin)
amiibo_store	NAPPLE_AMIIBO_STORE	folder of the virtual amiibo (default system/amiibo)
online_provider	NAPPLE_ONLINE_PROVIDER	shared library implementing the online provider ABI; empty or unloadable = the offline NullProvider, with one log line
mii_dir	NAPPLE_MII_DIR	folder of MiiDatabase.dat (any folder; an iCloud Drive one included)

See hardware simulators, network providers and Studio.