A GM flipping Movable (or Visible) back on for a long-frozen item registered
it with a deadline computed from its stale LastMoved, so the scheduler
deleted it on the next tick. The old save-time decay sweep had the same
semantics but hid them behind the save cadence.
Introduce DecayResetTime (CompactInfo-backed, persisted as delta minutes
under a new SaveFlag with an Item version bump): the decay countdown now
runs from the later of LastMoved and DecayResetTime. RestartDecay() stamps
it only when the item can decay and the stamp extends the deadline, so hot
paths with a fresh LastMoved allocate nothing.
- Movable/Visible/Spawner setters restart the countdown instead of
registering a stale deadline
- The region-refusal retry in DecayScheduler restarts the countdown without
rewriting LastMoved, which is reserved for actual moves
- A raw Map assignment (e.g. props) now counts as a move: it stamps
LastMoved and enrolls/withdraws the item, closing the gap where an item
moved out of Map.Internal via the setter never decayed
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
## Problem
Items dropped on the ground never decay. Corpses do, which makes the breakage look selective — but corpses are unaffected only because `Corpse.BeginDecay` runs its own `InternalTimer` and never touches `DecayScheduler`. Ordinary items are the only things that depend on the scheduler.
## Root cause
`Item.MoveToWorld` called `SetLastMoved()` — which triggers `UpdateDecayRegistration()` — at the *top* of the method, before detaching the item from its parent and before assigning the new map. `CanDecay()` reads `Decays`, `Parent`, **and** `Map`, so registration was evaluated against the item's *pre-move* state.
Because the `Item` constructor sets `m_Map = Map.Internal`, and `Mobile.Lift` calls `item.Internalize()` to put an item on the cursor, registration was consistently one step behind:
| State | Tracked for decay? | |
|---|---|---|
| Item on the ground | **No** | never decays |
| Item held on the cursor | **Yes** | backwards |
Nothing corrected it afterwards: the later `m_Map = map` assigns the field directly, bypassing the `Map` property setter, and that setter does not refresh registration either. With no parent, `RemoveItem` (which *does* re-register) never runs.
World load masked this — `ItemPersistence.PostDeserialize` re-registers every item against its final state, so decay appears to work for items that survive a restart. Only freshly dropped items are affected.
**Fix:** stamp `LastMoved` up front so decay math stays correct, then call `UpdateDecayRegistration()` once the parent, map, and location are final.
## Audit of the rest of the call sites
All 16 `SetLastMoved()` call sites were reviewed. `SetLastMoved()` must keep refreshing registration — `LastMoved` feeds `ScheduledDecayTime` and therefore which bucket an item belongs in — but it may only run once parent/map are final. The vendor, house, lift and drop sites already satisfy that. The rest of this PR fixes the ones that did not, plus what the audit turned up:
- **`Item.Deserialize`** stamped via `SetLastMoved()` before the version data was read, registering against an unread `Map`/`Parent`. Safe only by accident (the `Item(Serial)` ctor leaves flags at 0, so `Decays` is false), and it cost an unregister per item per world load. Now stamps only; `PostDeserialize` does the registration.
- **`Item` constructor** registered then immediately unregistered every item — the `Movable` setter saw `m_Map` still null, so `CanDecay()` was true. Also removes a `Configure`-order landmine: constructing an `Item` before `DecayScheduler.Configure()` would have thrown in `Shared.Start()`.
- **`Container.Destroy`** stamped `LastMoved` immediately before `MoveToWorld`, which now stamps it itself.
- **`Unregister` was documented O(1)** but scanned twelve buckets and did a linear `PriorityQueue.Remove`, on every construction, deserialize and move. Items now record where they are tracked in `Item.DecaySlot` (1 byte), so untracked items — the common case — leave in O(1).
- **A refused decay silently dropped the item.** `ProcessActiveQueue` deleted on `OnDecay() == true` but did nothing when a region refused, leaving the item dequeued, untracked and on the ground forever. It now restarts the decay clock; re-registering as-is would spin, since `ScheduledDecayTime` is already past.
## Two content bugs of the same class
The decay system replaced a polling sweep. Under polling, a `Decays`/`DecayTime` override could read live state every pass. Under a registration model it cannot — the scheduler drops items that stop being eligible, but nothing enrols one that becomes eligible while untracked.
- **`TreasureChestLevel1-4`** overrode `DecayTime` as `Utility.Random(15, 60)` — a fresh roll on every read. `ScheduledDecayTime` is read repeatedly (to bucket, to re-bucket on rotation, to test whether due), so those reads disagreed: the chest re-bucketed every tick and decayed early instead of after its intended interval. Now rolled once per chest. Distribution unchanged — `Utility.Random(from, count)` is RunUO's `from + Next(count)`, so this is 15–74 minutes, as before.
- **`StrongBox`** overrode `Decays` with a live check on `_house`, `_owner.Deleted` and `IsCoOwner`. Nothing notifies the box when any of those change, so it was never enrolled and the override never decayed anything — and it could not have: `HouseRegion.OnDecay` refuses a secured item inside a standing house, and the box is in `Secures`. Decay was never the mechanism here.
- A strongbox is only ever its owner's. Without a house, or without an owner still co-owning that house, it would be a free container anyone could loot, so `Validate()` destroys it. The old check missed exactly those two cases — it required a non-null owner and treated a null house as valid. A deleted owner deserializes back as null, which `IsCoOwner` rejects. The now meaningless `Decays`/`DecayTime` overrides and an unhelpful `Console.WriteLine` are gone.
`DecayScheduler` now documents both constraints.
## Tests
`DecayRegistrationTests` (Server) covers world placement, lift/drop, container round-trip, cursor-held (must *not* track), `Container.Destroy` spill, `DecaySlot`/structure agreement, refused decay, and a full decay lifecycle driven through the scheduler. `TreasureChestDecayTests` (UOContent) locks `DecayTime`/`ScheduledDecayTime` stability across all four chest levels.
To make the lifecycle testable deterministically, `DecayScheduler` gains `internal` members (visible only via existing `InternalsVisibleTo`): `IsRegistered()`, `ProcessTick(now)` — extracted from `OnTick()` with no behaviour change — and `ResetForTests()`.
Red/green verified. Without the `MoveToWorld` fix, 5 of 6 of the original tests fail, including `ItemOnGround_ActuallyDecaysAfterDecayTime`, which shows a ground item never decays even after a full simulated hour. Without the chest fix, 8 of 8 chest tests fail. Without the refused-decay fix, that test fails.
Server.Tests 737/737 and UOContent.Tests 509/509 pass.
