## Summary
House customization rejected ~40% of components — all classic/base tiles such as **sandstone** — for non-staff players. The pieces appeared briefly in the editor, then vanished before commit; only staff (GM+) could add them.
## Root cause
A data-convention mismatch introduced when housing.bin support was added (#2329).
- The OSI `housing.bin` encodes pre-AOS base pieces with the client **T2A** feature bit (`0x1`).
- `walls.txt` (and RunUO) encode the same pieces as `FeatureMask = 0` (always valid).
- `ComponentVerification.CheckValidity` validates against `ExpansionInfo.HousingFlags`, whose enum has no `0x1` bit, so base pieces failed `(HousingFlags & 0x1) != 0`.
- `HouseFoundation.Designer_Build` only enforces `ValidPiece` for `AccessLevel < GameMaster`, so staff bypassed validation while players had placements rejected — the server re-sends the design state and the client rebuilds the house from it, erasing the just-placed piece.
This only affects servers loading `housing.bin` from a UOP client; the old txt-only path (pre-#2329, like RunUO) was unaffected because base pieces are `0` there.
## Fix
Normalize the `housing.bin` feature mask to the housing-tier bits on load (`& HousingFlags.HousingEJ`). Base pieces collapse to `0` (always valid, exactly as `walls.txt` encodes them); `AOS`/`SE`/`ML`/... pass through unchanged. Both data sources now produce an identical validity table, matching RunUO behavior. `CheckValidity` and the `val != -1` anti-cheat guard are unchanged.
## Verification
- Parsed the real `housing.bin` from a 7.0.x client: sandstone (`0x345`) loads as `0x1` → `& HousingEJ` → `0` → valid; tier pieces (`0x40` SE, etc.) pass through; unregistered tiles stay `-1` → rejected.
- Confirmed OSI's own files disagree for the same pieces: `walls.txt` base `FeatureMask = 0` vs `housing.bin` `0x1`.
- `dotnet build` clean (0 warnings, 0 errors).
## Problem
Houses and boats (multis) were pathed correctly only by **delegation to the slow path**: `StepCache.TryGetMask` returns `Fallthrough_Multi` for any multi-covered cell, and `GetSuccessors` ran `CheckMovement` **8× per cell** (each re-resolving the tile stack via `GetStaticAndMultiTiles`) — a sustained per-step cost near every house/boat. There was also no automated test pinning multi pathfinding.
This branch is the full multi-pathfinding effort in phases on one branch.
## Phase 1 — characterization tests (the oracle)
Implementation-agnostic invariants: a cache-on≡cache-off whole-path invariant, a per-cell sweep vs `CheckMovement` over footprint+halo (incl. destination Z), hand-verified routing (around walls, demolish-reopens, foundation-redesign-honored), classic-house / foundation / boat fixtures, non-vacuity guards. These gate every later phase byte-for-byte.
## Phase 2 — live single-pass synthesizer
`StepProbe.ComputeMultiMaskAt` synthesizes a covered cell's full 8-direction `StepMask` in one pass (the existing surface/step logic over `GetStaticAndMultiTiles` instead of 8× `CheckMovement`). `GetSuccessors` routes `Fallthrough_Multi` cells through it. No new cache, no `.swb` change. **~1.5×**, zero added allocations.
## Phase 3 / 3.1 — warm per-`multiID` interior cache (airtight)
`MultiMaskCache` caches each fixed multi's local-frame `StepMask` for **interior** cells (cell + all 8 neighbours covered → terrain-neighbour-free → position-invariant), keyed by `multiID & 0x3FFF`, built lazily from the MCL. Interior cells become ~20 ns lookups.
The cache is gated on a **per-instance footprint-clean flag** (`BaseMulti.PathInteriorCacheState`): an instance whose whole footprint terrain is below its floor (`maxTerrain < minFloor`) serves from the cache; a **dirty** instance (terrain intrudes — a contrived/GM placement) **degrades to live-synth, never a wrong mask**. This closes a cross-instance soundness gap (the cached mask depends on neighbour terrain too) found in a holistic review. The gate resets whenever the footprint's world-terrain relationship can change — **location, map, or ItemID** (a boat's heading swaps the MCL).
**Boats are cached too.** Their per-`multiID` deck masks are movement-invariant (built once per heading), so a sailing boat never rebuilds them; only the cheap clean-flag rescan repeats per move (and only when pathed near). Narrow existing boats have little interior; wide galleons (`multi.mul`) would gain Castle-class. `HouseFoundation` (per-instance runtime `DesignState`) is the one type that stays on the live path.
## Verification
- `UOContent.Tests` **454/454**, `Server.Tests` **708/708**, 0 failures.
- The Phase-1 oracle (`MultiPathInvariantTests`, cache-on ≡ cache-off) stays **byte-identical** with the synthesizer + interior cache active.
- Tests pin: footprint-cleanliness (clean vs sunk), dirty/cluttered placement degrades to live-synth while still pathing, clean placement serves, and the gate resets on move/ItemID change.
## Performance (modernuo/ModernUO-Benchmarks#8, full-fixture)
Houses at **Green Acres** (flat staff region → clean footprints, the legit-placement case):
| Route | Slow path | Phase 3.1 (interior cache) | Speedup |
|-------|----------:|---------------------------:|--------:|
| `around_a` (29 steps) | 238.3 µs | **49.1 µs** | **4.85×** |
| `around_b` (29 steps) | 224.3 µs | **49.5 µs** | **4.53×** |
~130 of ~167 multi cells/route serve from the cache (~20 ns) vs 37 live-synth. Per-cell, the slow path's 8× `CheckMovement` grows with multi complexity (GuildHouse ~857 ns → Castle ~1,194 ns), the synthesizer is a flat ~780 ns, and the cache serve is ~20 ns — so big/tall multis (and wide galleons) gain most. Identical allocations throughout.
## Summary
- Converts `HouseGumpAOS` from legacy `Gump` to `DynamicGump` with a private constructor and the static `DisplayTo` entry-point pattern.
- `AddPageButton`, `AddButtonLabeled`, and `AddList` helpers now write directly to the `DynamicGumpBuilder` via `ref` parameters.
- All internal re-display calls and the `HouseSign` / `ConfirmResizeHouseGump` callers route through `HouseGumpAOS.DisplayTo`.
- Field naming updated to underscore-prefix convention (`_house`, `_page`, `_from`, `_list`, `_hangerNumbers`, `_foundationNumbers`, `_postNumbers`, `_houseSigns`).
## Summary
- Converts the legacy pre-AOS `HouseGump` to `DynamicGump` with a private constructor and the static `DisplayTo` entry-point pattern.
- `HouseListGump` and `HouseRemoveGump` now route back through `HouseGump.DisplayTo` instead of constructing the gump directly.
- Updates the `HouseSign` caller accordingly.
### Summary
Updates all calls to container.EnumerateItems() to properly dispose of the underlying PooledRefQueue so that we are properly recycling pooled arrays.
### Summary
Changes component verification so the order is now housing.bin, then txt files in client, then txt files in Data/Components folder on the server.
> [!Important]
> **Developer Note**
> This code change will **completely move gumps out of the core**
### Summary
- Adds `GetGumps()` convenience which exposes methods to Find/Close/Send multiple gumps. This helper is a performance improvement by eliminating the Dictionary<Player, List> lookup for gumps.
## Summary
- Removes allocation of a `List<ContextMenuEntry>` every time a context menu is created.
- Moves packet/context menu creation logic out of the core
- Fixes tame entry
## BREAKING CHANGE
> [!Important]
> **Developer Note**
> ```cs
> public virtual void GetContextMenuEntries(Mobile from, List<ContextMenuEntry> list)
> ```
> and similar functions changed to
> ```cs
> public virtual void GetContextMenuEntries(Mobile from, ref PooledRefList<ContextMenuEntry> list)
> ```
## Summary
### Changes
- Adds `[IgnoreDupe]` and `[SerializedIgnoreDupe]`
- Updates all _known_ classes that need the attribute. Some might be missing, please helps us find them!
- Adds `Item.Dupe()` command and encapsulates `CopyProperties` and `OnAfterDuped`. This is also overridable.
- Updates Dupe command to use the new logic.
- Fixes duping multiple kinds of objects that used to be outright broken.
### Bug Fixes
- Fixes issue with durability after duping
- Fixes issue with hue after duping
> [!Note]
> **Developer Note**
> Customizing how duping an item works now requires two steps:
> 1. Add `[IgnoreDupe]` or `[SerializedIgnoreDupe]` to the property/field
> 2. Add custom logic in an `OnAfterDuped` override
>
> When do you need to do this?
> *When the property being copied is not a primitive, and you need to manually deep-clone the contents of the property such as with Lists, Dictionaries, or sub classes.*
> [!Warning]
> Users on Linux/OSX will need to follow the Readme
> and make sure `libdeflate` is properly installed
> [!Note]
> **Developer Note**
> The API for compression has changed. Use `Deflate.Standard` for the same functionality.
### Summary
* Replaces Zlib with LibDeflate for a 50% performance improvement!
* Adds MacOS 14 to properly test Arm64
### Summary
* Adds `StaticNoticeGump<T>` and `StaticWarningGump<T>`
* Converts NoticeGump/WarningGump to use `DynamicGump`
* Changes various uses of notice gump and warning gump to their static counterpart.
