Research: account-level saves (Unlocks, PlayerStatsSave, UserSettings)
Source: the three files in tests/fixtures/SteamSaves/SaveGames/76561197993781479/. Reader: Core/Serialization/Player/AccountSaveReader.cs (read-only). Tests: tests/AbioticEditor.Tests/AccountSaveReaderTests.cs.
All three round-trip byte-exact through SaveGame.LoadFrom -> WriteTo (asserted in the tests). None has a custom header. They live in the account folder beside Worlds/, and on Game Pass are the wgs containers ProfileUnlocks, ProfilePlayerStatsSave, ProfileUserSettings (already carried by GamePassConverter; the blobs are plain GVAS so the same reader works on those bytes).
Unlocks.sav (Abiotic_CustomizationUnlocks_Save_C)
One property: CustomizationUnlocks, an ArrayProperty of NameProperty. Each entry is a row name from a DT_Customization_* table (Head_M01chemist, UpperBody_Engineer, id_hydro, Tie_Christmas_01, Glasses_Goggles_Broken, Belt_Mgt_Miner ...). The list is a flat union across all tables; there is no table tag, so the slot is inferred from the row-name prefix (display only, see AccountSaveReader.CategoryOf). Some rows do not follow a prefix (Engineer_Orange, M_Signal, F_Mgt_Miner, M_SweaterVest), so their category reads "Other".
Owned vs unavailable: CustomizationUnlocksModel.Partition(catalogRows) splits a catalog table's rows (from CustomizationCatalog.LoadFrom, needs the game paks) into owned and unavailable, and UnknownTo lists stored names the catalog does not contain. Only catalog rows are ever reported as unavailable, so no invalid name can be offered.
Open: which rows are unlocked by default versus by gameplay (the paks may carry an "unlocked by default"/"unlock source" column); whether adding a row here is honoured or re-validated on load; whether the Game Pass and Steam builds share identical row vocabularies. No write is provided.
PlayerStatsSave.sav (native /Script/AbioticFactor.PlayerStatsSave)
Stats_Int:MapPropertyofNamePropertytoIntProperty. Fixture holds 10 keys, allSTAT_KILLS_*(PEST, ORDER, GKMAGE, GKCHIEF, GKWITCH, GKPHYTER, GKHEAVY, SKINK, SYMPH, GK).Achievements:ArrayPropertyofNameProperty, the Steam API names (ACH_CRAFTY,ACH_KILL_PEST_1,ACH_SECTOR_1...). 51 entries in the fixture.
Relation to Steam achievements (unverified, from structure only): the array looks like a local mirror of already-granted achievements, and the kill counters look like the inputs to the tiered kill achievements (ACH_KILL_PEST_1 / _5). Steam holds its own authoritative state; editing this file would not grant or revoke a Steam achievement, and Steam stats are per-account cloud data that steam_autocloud.vdf may overwrite. It is not known whether the game re-derives the mirror from Steam on launch or trusts the file. That must be tested in-game before any write is offered. No write is provided.
UserSettings.sav (Abiotic_SettingsSave_C)
Top-level properties (all read-only modeled): FavouriteRecipesList (names), PinnedRecipeList (names), HasCreatedACharacter (bool), HasPlayedTutorial (bool), UIPopupsSeen (names, e.g. journalnotes, jobscreen), TutorialHintPopupsSeen, TutorialPanelsSeen, HostPreferences (struct HostPreferences_Struct), RecentServers (array of StrProperty: host:port and a 32-hex id).
HostPreferences_Struct leaves in the fixture: SinglePlayer_1_<hash> (bool) and Password_4_<hash> (StrProperty). The password is stored in plaintext. The reader never copies the value out: HostPreferencesModel carries only HasPassword, any leaf whose name contains password/secret/token/passphrase is masked this way, and a test asserts the fixture's password text does not appear in the serialized model. Any future UI must show "set / not set" only and should not log the raw tree. RecentServers holds real IP addresses, so treat it as personal data in screenshots.
Delta serialization applies: absent booleans read as null, absent arrays as empty. Unrecognised top-level properties are reported in UnmodeledProperties (empty in the fixture; BenchUpgrades and Weight seen in the raw strings are struct/array child names, not top-level).
Open: valid value sets for popup/tutorial names (need the paks or a wider fixture set); whether HasCreatedACharacter=false re-triggers the intro; whether recipe names must exist in the recipe catalog (favourites/pins with stale names are likely ignored, unverified). No write is provided.
Not delivered
No Razor surface was added (it needs account-folder discovery for Steam, Game Pass and dedicated hosts plus localization resources; the reader takes bytes or a path so it can be wired to either). No writes for any of the three files.