Configuration file

~/.tg.json is a user-home state file. Theme Manager reads a missing or malformed file as defaults and preserves unknown keys when it writes known state. A file that exists but cannot be read or parsed (permission error, invalid JSON, not a JSON object) is never written over: commands that would save state fail with Refusing to overwrite … until the file is fixed or removed, so a transient failure cannot drop activeTheme or favorites.

Field	Default / shape	Owner
customThemes	string[]	Theme discovery during generation.
lastGeneratedTheme	theme ID or null	Last theme generated by the generation flow.
favoriteSeedColors	{ color, variant }[]	Favorites flow; legacy string favorites migrate on read.
lastUsedSeedColor	hex or null	Seed generation.
lastUsedVariant	variant or null	Seed generation.
activeTheme	theme ID or null	User-selected theme family; read by tman apply, which saves a configured fallback only when it is null.

Writes use the shared same-directory temporary-file-plus-rename helper. This gives atomic replacement for the ordinary state-file path, but does not create backups or offer a global rollback.