Research: dedicated-server save tree ("Cascade" endgame world)

Probe: tests/AbioticEditor.Tests/ServerSaveDeepDiveTests.cs (run 2026-06-12). Subject: D:\Development\uesave\b31789b5-37b6-4f61-9053-9529ce64722b\SaveGames\Server - a dedicated-server world that has finished the main story (StoryProgressionRow=EndGame, 47 009 minutes) and covers every late-game region the checked-in fixture and the client tree never reach. All 374 .sav files (live + all 5 backup generations) were parsed, round-tripped and schema-walked. Compare with research-new-save-gaps.md (client tree).

1. File tree and layout

SaveGames/Server/                          ← server root is literally "Server", no steamid64
├─ Admin.ini                               171 B  [Moderators]/[BannedPlayers] steamid lists
├─ Worlds/
│  └─ Cascade/                             63 .sav + 1 ini, 68.1 MB total (live saves)
│     ├─ SandboxSettings.ini               363 B  (per-WORLD, not per-server - see §5)
│     ├─ PlayerData/Player_<steamid64>.sav ×4 [Abiotic_CharacterSave_C]
│     ├─ WorldSave_MetaData.sav            [Abiotic_WorldMetadataSave_C]  story=EndGame
│     └─ WorldSave_*.sav                   ×58 [Abiotic_WorldSave_C]
└─ Backups/
   └─ Cascade/1..5/                        full copies of Worlds/Cascade (incl. PlayerData
                                           and SandboxSettings.ini), ~67.6 MB each

• Engine header identical across all three trees: GVAS v3, UE4 pkg 522 / UE5 pkg 1012, engine 5.4.4--2146453646 '++DF+ABF', 74 custom formats. The server is the same game build as the fixture (the client Worlds/Chrissie tree remains the only newer-build sample, -2146453647).
• ABF custom header on every world/metadata save: ABF_SAVE_VERSION v3/id1 - same as fixture and client. Player saves carry the bare Version+DataLength character header (no ABF_SAVE_VERSION marker) in all three trees.
• No new save class. Server saves use the exact class paths we already register (Abiotic_WorldSave_C, Abiotic_WorldMetadataSave_C, Abiotic_CharacterSave_C). No [SaveClassPath] addition needed.

Layout differences vs the client tree (Saved/SaveGames/<steamid64>/...)

	Client	Server
Root folder	<steamid64>/	Server/ (under a GUID install dir)
Account-level saves	PlayerStatsSave.sav, ScientistCustomization_1.sav, Unlocks.sav, UserSettings.sav, steam_autocloud.vdf	none - only Admin.ini
PlayerData	Worlds/<World>/PlayerData/ (host only)	Worlds/<World>/PlayerData/ - one Player_<steamid64>.sav per connected player (4 here)
WorldSave_MetaData.sav	per world folder	per world folder (same)
SandboxSettings.ini	per world folder	per world folder (same), copied into each backup
Backups	Backups/<World>/1..5	Backups/<World>/1..5 (same scheme)
Admin.ini	present (same format)	present - moderator/ban steamid lists

So the world-folder layout is identical; only the root differs (no account folder, no account-level saves). The editor's folder scanner (SaveFolderScanner.Scan is recursive from any root) and Fixtures-style discovery work unchanged; a "open server folder" flow only needs to accept a root that contains Worlds/ without a steamid64 segment.

Backup generations

Each generation is a complete snapshot (62–63 .sav + SandboxSettings.ini). Content dating (file mtimes were flattened by the copy): gen 1 MetaData is story=DarkLens, 42 689 min - older than live (EndGame, 47 009 min); gens 1–4 predate the world's first visit to WorldSave_V_ISLAND.sav (the post-boss island), which only gen 5 and live contain. So generation 5 is the newest snapshot here.

Region coverage vs fixture

Server-only regions (17, absent from tests/fixtures/Cascade/): Facility_Botanical, Facility_DarkFusion, Facility_DF_Central, Facility_DF_Labs, Facility_DF_Overgrowth, Facility_DF_War, Facility_Fracture, Facility_Plant, Facility_Pool, Facility_Residence, V_Anteverse_C, V_BOTANICAL, V_Inq, V_ISLAND, V_Signal, V_SUOMI, V_TheWall. The fixture has nothing the server lacks. V_ISLAND is absent even from the client Cascade tree - this is the only tree with a post-final-boss island save.

2. Parse results (typed readers)

Reader	Files	Result
PlayerSaveReader	8 (4 live + 4 backup gen 1)	All OK. skills=15, equip=13, hotbar=8; PhDs HumanBio ×2, TheoreticalPhys, NutritonalSci; recipes up to 470.
WorldSaveReader	120 (60 live + 60 backup gen 1, incl. MetaData)	All OK. Largest: live Facility - 292 containers, 214 flags, 728 dropped, 947 deployables.

No parse failures anywhere, including every late-game region.

3. Round-trips - nothing would corrupt a server save today

• Binary: all 374 server .sav files (live + every backup generation) round-trip byte-identical through SaveGame.LoadFrom -> WriteTo.
• JSON (SaveJsonBridge / SaveGameSerializer) on the sample set - MetaData, small world (H_Japan), the 16.5 MB Facility (-> 133 MB JSON), late-game DF_Labs (-> 18.7 MB JSON), and a player save (-> 1.1 MB JSON) - byte-identical, and the ABF_SAVE_VERSION v3/id1 header survives export+import. The serializer fix (commit 1917a22 + the registered AbioticWorldSaveJsonSerializer / AbioticCharacterSaveJsonSerializer) holds on server saves.

Caveats (pre-existing, not server-specific): the delta-serialization writer no-op issue from research-new-save-gaps.md §5 still applies to fresh characters, and the 133 MB Facility JSON is far beyond what the in-app raw-JSON text tab should attempt (use the export-to-file path).

4. Schema findings (late-game regions vs fixture)

Nothing is version-new - every top-level key in every late-game region already appears somewhere in the fixture (same game build). Two keys are however unmodeled and previously undocumented because the earlier deep dive only walked WorldSave_Facility, which carries neither:

• DayDiscovered (IntProperty) - on every region save except Facility itself (40 fixture files have it too). Day the level was first entered. Trivial to model; read-only display value for a "world map" view.
• CorpseMap (MapProperty) - Map<Str actorPath, {ActorPath (SoftObjectPath), IsGibbed (Bool), IsLooted (Bool)}>; NPC corpses, e.g. ...PersistentLevel.CharacterCorpse_OrderSniper_C_1. Present in 9 server and 5 fixture files. Harmless to leave unmodeled (round-trips untouched).

-> both should be added to docs/world-save-schema.md and the deep-dive tests' KnownUnmodeledWorldKeys.

Late-game content the fixture lacks (all parse fine with existing readers):

• 67 deployable classes new to the server tree (fixture 212 -> server 262). Functional ones the base-manager UI will now meet: Deployed_TeleporterPad_C, Deployed_LaserEmitter_C / Deployed_LaserPowerConverter_C / Container_LaserCollector_C, Deployed_NeutrinoEmitter_C, Deployed_ChargingPad_C / Deployed_StorageCrate_Charging_C, Deployed_GatekeeperForceField_C, Deployed_Inhibitor_PestScarecrow_C / Deployed_Inhibitor_RadioScrambler_C, Deployed_PestTrap_C, Deployed_Moisture_Teleporter_C, Deployed_StorageCrate_Makeshift_T4_C, GardenPlot_Large_C, Faucet_Alien_C, plus ~40 cosmetics (VOTV crossover furniture, bobbleheads, figurines, cubicles).
• 8 narrative-NPC actor classes new to the server tree (fixture 7 -> server 15): NarrativeNPC_ExorChieftain_C, NarrativeNPC_HammeringHank_C, NarrativeNPC_Kyliebot_C, NarrativeNPC_Nibbles_C, NarrativeNPC_Penguin_VWinter_C, NarrativeNPC_SignPost_VWinter_C, NarrativeNPC_UnlostMage_C, NarrativeNPC_Waterbot_C. (NPCClass inside the struct serializes as None - the actor class must be taken from the map key.)
• 105 world flags new to the server tree (fixture 109 -> server 214): whole late-game chapters - Dams_* (pumps/Kylie/witch), Fracture_DL_* (Dark Lens eyes and bosses), Plant_* (Anteverse C, warhead), Reactors_* (~40 flags for the DF reactor-station sequence), EndBoss*/End_* (incl. End_MainStoryComplete, post-boss island NPC meets), KylieVocalizer_Activated, Flathill_CornWeb. QuestFlagCatalog/story-sync should be checked against this list - it is the first complete-story flag inventory we have.
• Value-struct shapes (DeployedObjectMap 18 fields, NarrativeNPCMap 8 fields, DestructibleMap, NPCSpawnMap 7 fields) are identical to the client tree census - no field drift.

5. SandboxSettings.ini - yes, worth an editor feature

Per-world, plain ini, [SandboxSettings] section. Keys observed:

Key	Effective value here
GameDifficulty	3
EnemySpawnRate	1.5
PlayerXPGainMultiplier	1.5
ItemStackSizeMultiplier	3.0
RefrigerationEffectivenessMultiplier	3.0
SinkRefillRate	2.0
DamageToAlliesMultiplier	0

Quirk that matters for an editor: the game appends rather than rewrites - the file contains two blocks and 6 of 7 keys appear twice (last occurrence wins). An editor should parse last-wins, and on save either rewrite the file canonically (the game accepts a clean single block - the first block here was clearly hand-written) or append, but never naively "update the first match". Low effort, high value for server admins: it's the only sandbox-settings surface outside the in-game host menu, and the same file/format exists in client worlds too.

Admin.ini (server root): [Moderators] Moderator=<steamid64> lines and [BannedPlayers] BannedPlayer=<id> lines - equally trivial to expose alongside it.

6. Prioritized gaps / actions

1. No corruption risk found. Binary and JSON round-trips are clean on all server files; safe to edit with today's code. (The JSON-import header loss documented in research-new-save-gaps.md §4 is confirmed fixed.)
2. Adopt this tree as the checked-in fixture (see below).
3. Doc/test upkeep: add DayDiscovered + CorpseMap to world-save-schema.md and to KnownUnmodeledWorldKeys in the deep-dive tests.
4. QuestFlagCatalog/StoryProgressionCatalog: extend with the 105 endgame flags and the EndGame story row (first sample of a completed story).
5. SandboxSettings.ini + Admin.ini editor panel (last-wins parse, canonical rewrite).
6. Friendly names for the new functional deployables (teleporter pads, laser network, charging crates) in whatever catalog drives the base-manager display.

7. Fixture recommendation

Yes - this tree is a strictly better fixture than the current tests/fixtures/Cascade/:

• Same game build (engine build -2146453646) - swapping does not change version coverage, it only adds content.
• Superset of regions: 17 extra saves including all DarkFusion/Fracture/Botanical and the unique post-boss V_ISLAND (absent even from the client tree).
• Completed story: EndGame row, end-boss + post-boss flags, 105 extra flags, 67 extra deployable classes, 8 extra NPC classes, CorpseMap populated.
• Adds the server-specific artifacts (Admin.ini, per-world SandboxSettings.ini with the append quirk) - good test material for §5's feature.
• Cost: live Worlds/Cascade is 68.1 MB vs the current fixture's 51.9 MB (backups not needed in a fixture; keep one small backup generation only if rotation logic ever gets tested). Keep Fixtures.CascadeDir pointing at the world folder (.../Worlds/Cascade content moved to tests/fixtures/Cascade) and existing tests keep working - file names are a superset and WorldSave_MetaData.sav (the discovery sentinel) is present. Hash-suffix-prefix matching means no reader changes. Tests that assert exact counts/story values against the old fixture would need re-baselining (e.g. story row EndGame vs the old fixture's value).