Stardew Valley engine reference notes

Engine mechanics that the server/mod relies on. Prescriptive contributor rules live at .claude/rules/cabin-system.md and .claude/rules/host-automation.md (the festival rule lives under host-automation, item 3).

For full source-of-truth, the decompiled game lives at decompiled/sdv-1.6.15-24356/.

Sleep / wakeup / day-end

GameLocation.startSleep() does NOT set player.isInBed. isInBed is set dynamically by Farmer.Update() from tile properties — so setTileLocation() to a bed tile MUST run BEFORE startSleep().
On clients (!IsMasterGame), doSleep() does NOT call Game1.NewDay(). It uses message type 14 (newDaySync).

Ready-check messages use message type 31. They are blocked by PasswordProtectionService for unauthenticated players.
isGameAvailable() returns false during newDaySync. It stays false until newDaySync.destroy() (which runs AFTER all barriers + save + PollForEndOfNewDaySync).
When isGameAvailable() == false, the server sends message type 11 (Client_WaitForHostAvailability); the client shows "Waiting for host event" in FarmhandMenu and times out after 45s.
checkFarmhandRequest with isGameAvailable() == false sends type 11 and registers a whenGameAvailable callback that calls sendAvailableFarmhands (NOT Check()); the client bounces back to FarmhandMenu.

When a client disconnects during the barrier: playerDisconnected() enqueues into disconnectingFarmers, removeDisconnectedFarmers() removes the entry from otherFarmers, and with empty otherFarmers the barrierReady() check returns true immediately.

Prescriptive cabin invariants are in .claude/rules/cabin-system.md. Reference-only:

BuildStartingCabins uses map-designated positions (tile 29/30 in the Paths layer), capped by Game1.startingCabins.

LAN-only servers (AllowIpConnections=true, no Steam account configured) never write an invite code. InviteCodeFile.Read() returns null in that configuration.