## Problem
Three coupled issues, each hiding the next:
1. **CI passed despite failing tests, with no test logs.** ([example run](https://github.com/modernuo/ModernUO/actions/runs/28639143286/job/84931544255) — the `Test` step produced zero output and the job went green.)
2. **Two `EmitsLowerStatReqWhenPassed` tests** fail with `KeyNotFoundException: '1060435'`.
3. Once CI actually ran the tests, **~337 UOContent tests failed** with `FileNotFoundException: tiledata.mul was not found` — the test bootstrap force-loaded copyrighted client data that CI doesn't have.
## Root causes & fixes
### 1. CI ran zero tests (`fix(ci)`)
The `Test` step ran `dotnet test --no-restore`, but the `Build` step only restores/builds `Application` — never the test projects. Without a restore, the test projects have no `project.assets.json`, so `Microsoft.NET.Test.Sdk`'s targets aren't imported, they aren't recognized as test projects, and `dotnet test` runs the `VSTest` target against **zero** projects → no output, **exit 0**.
- Both jobs now run `dotnet test --logger trx --results-directory ./TestResults` (test projects restore and run) **plus a guard** that fails the job if no `.trx` is produced — a permanent backstop against silent zero-test passes.
### 2. Impossible OPL tests (`fix(ci)` + `test(opl)`)
#2501 deliberately emits `LowerStatReq` (`1060435`) **inline in each item**, not in `GetProperties`. A follow-up "fix" dropped the `lowerStatReq:` argument to make the tests compile but left the assertions expecting `1060435`.
- Removed the two impossible tests, then removed the **entire `Tests/PropertyList/` OPL attribute set** from #2501: these assert exact cliloc/value/order of OPL emission per item base — a one-time proof of the #2501 rewire, now a permanent tax on modding (any admin reorder/value change/added line reddens the build). The one non-trivial case (LowerStatReq) is what just broke, because the test was wrong. Inline emission stays covered by the `BaseArmor`/`BaseClothing` tests.
### 3. Tile-data-dependent tests crashed CI (`test(uocontent)`)
UOContent.Tests' collection-fixture constructor force-loaded `tiledata.mul` unconditionally. On CI (no client files) it threw, and xUnit failed **every test in the collection** with the same error — mostly collateral (packet/scheduler/spawner tests that don't need tile data).
- Mirror Server.Tests' graceful pattern: `TestServerInitializer` probes for `tiledata.mul` and only loads tile/multi data (and runs the tile-dependent configure steps) when present, exposing `TileDataLoaded` so the fixture no longer throws.
- Add a shared `TileDataRequirement.SkipIfMissing()` guard and apply it to exactly the **31** pathfinding/multi/AI tests that genuinely need real tile data (`[SkippableFact]`/`[SkippableTheory]`).
## Verification (all local)
| Scenario | Server.Tests | UOContent.Tests |
|---|---|---|
| **Client data absent (CI)** | 726 pass, 17 skip, **0 fail** | 469 pass, 32 skip, **0 fail** |
| **Client data present (dev)** | 726 pass, 0 skip, **0 fail** | 501 pass, 0 skip, **0 fail** |
- Full `dotnet test` exits **0**; TRX files produced; the no-test guard trips (exit 1) only when zero `.trx` are produced.
## Summary
Removes the dated `DynamicJson` JSON helper and migrates spawner JSON (de)serialization to a polymorphic `record SpawnerDto` hierarchy. `DynamicJson` was the last remaining consumer (regions moved off it in #1400).
The key correctness improvement: **System.Text.Json deserializes plain DTO records, never a live `Item`.** Previously, deserializing directly into an `Item` meant STJ constructed world-registered objects *before* the data was validated — a malformed/hand-edited spawn file could leave orphaned spawner Items in the world save. Now a parse failure is GC-only; `dto.ToSpawner()` constructs the spawner only from a fully-validated DTO and self-cleans on failure.
## What changed
- **New:** `SpawnerDto` (abstract) + `SpawnerDataDto` / `RegionSpawnerDto` / `ProximitySpawnerDto`, each marked with a reusable `[JsonDiscoverableType]` opt-in attribute. Auto-discovered at the `Configure` phase — no manual registration list (avoids the regions `Register<T>()` footgun), open to custom spawner subtypes.
- **Symmetric mapping:** `BaseSpawner.ToDto()` (export) ⇄ `SpawnerDto.ToSpawner()` (import). `ToSpawner()` deletes-and-rethrows on any failure, so the importer can never orphan an Item.
- **`SpawnerJsonSerializer`** wires `$type` polymorphism on the `SpawnerDto` root with loud collision/constructibility validation.
- **Import/export commands** rewired to the typed DTO path (reflection `FindTypeByName`/`CreateInstance` removed).
- **Data migration:** the 109 `Distribution/Data/Spawns/**` files moved from `"type"`→`"$type"` and legacy `homeRange`→`spawnBounds`. The runtime still *reads* legacy `homeRange` for external files. The `homeRange→spawnBounds` formula is proven equivalent to the runtime conversion (`BoundsEquivalenceTests`, hr=0/1/3/7).
- **Deleted:** `Projects/Server/Json/DynamicJson.cs`.
Sparse export output matches the legacy `ToJson` (nullable DTO properties + `WhenWritingNull`). Binary world-save serialization is untouched.
## Tests
- DTO round-trip per spawner type; sparse-default omission; legacy `homeRange` read; export/import file round-trip.
- `Import_MalformedFile_LeaksNoWorldItems` — proves a mid-array parse failure constructs zero world Items.
- `AllSpawnFilesLoadTests` — every migrated spawn file deserializes and builds.
- Duplicate-discriminator validation.
- UOContent.Tests 485/485, Server.Tests 710/710, build clean.
## Follow-up (not in this PR)
`Rectangle3DConverter.Write` (in `Projects/Server/`) omits `z1/z2` when `Start.Z == -128`, so a future server-side export of a `homeRange`-style spawner round-trips depth 256→255. Pre-existing and out of scope here (Server change); the migrated data reads correctly. Worth a separate small converter PR.
## 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.
## Problem
Running the full `UOContent.Tests` suite, the test host **hangs ~2.5 minutes at shutdown and then crashes** (`Test host process crashed` / run aborted). The tests themselves are fine — they complete in ~1s — but the process can't exit.
Captured via `--blame-hang` dump. The blocking thread:
```
System.Threading.WaitHandle.WaitOne()
Server.SerializationThreadWorker.Sleep() SerializationThreadWorker.cs:54 (_stopEvent.WaitOne())
Server.SerializationThreadWorker.Exit() SerializationThreadWorker.cs:61
Server.World.ExitSerializationThreads() World.cs:429
Server.Tests.UOContentFixture..ctor()
```
### Root cause
Both collection fixtures (`UOContentFixture` and `PathfindingTestFixture`) each run the **full process-global ModernUO bootstrap**. `World.Load()` is guarded to run once per process, so the **second** fixture's `World.Load()` is a no-op and does **not** respawn the serialization workers — but `World.ExitSerializationThreads()` is **not** guarded, so the second fixture calls `Exit()` on workers whose threads have already terminated. `Exit()` → `Sleep()` → `_stopEvent.WaitOne()` then blocks forever (a dead thread never sets the event). The first collection's tests run; the second collection's fixture deadlocks in its constructor; the host eventually gets killed.
This is why single-collection (filtered) runs were fine — only one fixture ever bootstraps — but the full suite hangs. It's not a parallelization race: even strictly sequential, the second fixture deadlocks.
## Fix
**(a) Engine — idempotent `SerializationThreadWorker.Exit()`**
A second `Exit()` is now a safe no-op instead of a permanent block. Only the owning (main) thread calls `Exit()`, so no synchronization is needed, and the single-call production shutdown path is unchanged.
**(b) Tests — one shared bootstrap, strictly sequential collections**
- New `TestServerBootstrap.EnsureInitialized()` runs the superset global init **exactly once per process** (lock + once-flag).
- `UOContentFixture` / `PathfindingTestFixture` slim down to delegate to it and no longer tear down global state (which the single-bootstrap model owns for the host's lifetime).
- `[assembly: CollectionBehavior(DisableTestParallelization = true)]` so collections never overlap.
## Result
| | Before | After |
|---|---|---|
| Tests run (full suite) | 258 (UOContent collection deadlocked) | **418** |
| Outcome | 2.5-min hang → host crash | **418 passed, clean exit** |
| Wall time | killed | **~7s** |
## Summary
Creatures (pets following, monsters chasing, NPCs approaching) would **oscillate — "pace back and forth really fast"** at concave obstacles (reported at the Britain Inn L-desk: a pet at `(1493,1614,20)` never reaching its master at `(1494,1605,21)`) instead of routing around them.
**Root cause** (the A* pathfinder itself was correct): all goal-seeking funnels through `MoveTo` and `WalkMobileRange` → `MoveTowardsOrAwayFrom`, which step greedily via `DoMove(dir, badStateOk:true)`. `DoMove` returns `true` even when the direct step was blocked and the creature merely **auto-turned and sidestepped** (`MoveResult.SuccessAutoTurn`), and the caller then set `Path = null`, discarding the `PathFollower`. So at a concave obstacle a non-progressing sidestep was mistaken for progress and the creature never committed to a route. (AOS pet-follow runs at `CurrentSpeed = 0.1`, hence the "really fast" shuffle.)
## What changed
- **New centralized `BaseAI.ApproachTarget(target, run, range)` primitive.** A greedy step is committed only when it **fully succeeds (`MoveResult.Success`) and actually gets closer**; otherwise the creature commits to a **persistent `PathFollower`** that routes around the obstacle and is never discarded by a greedy step. The open-terrain fast path (one greedy step, no pathfinding) is preserved. `MoveTo`, `MoveTowardsOrAwayFrom`, and `MoveToWithCollisionAvoidance` all delegate to it — public signatures unchanged, so no AI-class call site changes.
- **Best-distance give-up + idle.** A creature that cannot reach a **stationary** in-range goal stops shuffling and idles after `ApproachGiveUpTicks` (40) ticks without lowering its closest-ever distance; a **moving** goal (active chase) never gives up. It resumes the moment the goal moves.
- **Pathfinder fix (required):** `BitmapAStarAlgorithm.IsBlockedByDynamic` now skips the dynamic mobile-block check **at the goal cell only** (`MoveImpl.Goal`). Previously A* returned `null` whenever the target mobile stood on the goal cell, so creatures could never pathfind *toward* another mobile — only toward empty ground. The follower stops within `range` short of it. Static/item blocking and all non-goal mobile blocking are unchanged.
## Tests
New AI-loop integration tests in `ApproachTargetTests.cs` drive the real `BaseAI` primitives against live Britain Inn map statics: exact-repro pet follow, open-terrain (asserts zero pathfinding), `MoveTo` chase (static + walking-away target), route-around-a-dynamic-wall, and walled-off give-up-and-idle.
- Pathfinding + AI subset: **52/52** pass.
- Full `UOContent.Tests`: **301/301** pass. (Note: the test host lingers on shutdown — a pre-existing infra quirk unrelated to this change; all tests complete and pass.)
- Full solution build: clean (0 warnings / 0 errors).
## Notes
- Branched off `main`; independent of the in-flight step-cache work.
- Out of scope (future work): proactive "SmartAI" look-ahead pathfinding so clever creatures plan a route before walking into the obstacle, rather than reacting after they hit it.
## Test Plan
- [X] In-game: order a pet to `follow`/`come` across the Britain Inn L-desk; confirm it routes around and reaches you instead of pacing.
- [X] Aggro a monster and kite it around a building/treeline; confirm it chases around obstacles.
- [X] Confirm open-terrain following/chasing feels unchanged (no extra latency).
- [X] Confirm a creature with a genuinely unreachable target idles rather than shuffling forever.
## Summary
Replaces `FastAStarAlgorithm` with `BitmapAStarAlgorithm`: one cache lookup per cell expansion (8-direction mask + per-direction destination Z) instead of 8 separate `MovementImpl.CheckMovement` calls. Adds the supporting cache infrastructure to back it.
Public API unchanged — `MovementPath` / `Mobile.Move` / `CalcMoves.Find` return the same shapes; the algorithm swap is internal.
## What's in this PR
- **`BitmapAStarAlgorithm`** — A* that issues one `StepCache.TryGetMask` call per cell expansion. Inline fallthrough to the per-cell slow path for multi-Z, off-map, source-Z mismatch, and non-default walkers.
- **`StepCache`** — singleton chunk store keyed by `(mapId, chunkX, chunkY)`. Lazily built on first query, invalidated by `Sector.MultisVersion` mismatch, memory-bounded by sampled probabilistic LRU.
- **`StepProbe`** — computes static-only walkability for a single cell, mirroring `MovementImpl.Check` minus the item / mobile collision phases.
- **`StepMask` / `StepChunk`** — value / storage types for the per-cell results.
- **`CacheEvictionTimer`** — periodic cap backstop (60s interval; early-returns when not over cap).
- **`Map.Sector.MultisVersion`** promoted to `public` so the cache can detect dynamic-static invalidations cheaply.
## Eviction strategy
Sampled probabilistic LRU (Redis-style). Per eviction, sample 5 random keys from a parallel `List<long>` kept in lockstep with the chunk dictionary; evict the oldest of the sample via swap-and-pop. O(1) per eviction regardless of resident count, so sustained cap pressure has no perpetual perf hit.
## Capability handling (interim)
Non-default walkers (non-GM players, creatures with `CanSwim` / `CanFly` / `CanOpenDoors` / `CanMoveOverObstacles`) route entirely through the per-cell slow path via `BitmapAStarAlgorithm.GetSuccessorsSlowPath`. The 2-pass design (cache + capability overlay + dynamic-obstacle pass) lands in the follow-up PR.
> [!IMPORTANT]
> **Breaking Changes**
> - DecodePacket and EncodePacket delegates replaced with IClientEncryption interface
> - NetState.Connection (Socket) replaced with internal RingSocket management
> - NetState.RecvPipe and NetState.SendPipe removed (buffers managed internally)
## Summary
Upgrades the networking stack from PollGroup-based I/O to io_uring, significantly improving I/O performance on Linux.
This also adds native client encryption support for encrypted UO clients.
## Major Changes
io_uring Networking Architecture
- Replaced PollGroup with IORingGroup for async socket I/O operations
- Removed Pipe.cs (mirrored ring buffer) and TcpServer.cs in favor of RingSocketManager
- Added NetState.Network.cs - centralized network infrastructure handling accept, recv, send, and disconnect
completions
- Added SocketHelper.cs - platform-specific socket utilities for raw socket handle operations (getpeername,
getsockname)
- Buffer management now handled by RingSocketManager with configurable slab allocation
### Client Encryption Support
- Added full encryption stack in Network/Encryption/:
- EncryptionConfig.cs - configurable encryption modes (None, Unencrypted, Encrypted, Both)
- EncryptionManager.cs - encryption detection and initialization for login/game packets
- LoginEncryption.cs - handles login packet encryption with version-derived keys
- GameEncryption.cs - handles game server encryption using Twofish
- TwofishEngine.cs - optimized Twofish block cipher implementation
- LoginKeys.cs - encryption key table for client versions
- IClientEncryption.cs - interface for client encryption implementations
### NetState Improvements
- Replaced Socket Connection with RingSocket _socket for managed socket lifecycle
- Changed from GCHandle polling to event-based completion processing
- Disconnect handling now properly waits for pending sends to flush
- Simplified connecting socket management using lazy queue removal
### Configuration
- New settings: network.encryptionMode and network.encryptionDebug
- Encryption mode flags: Unencrypted, Encrypted, or Both
### Dependencies
- Replaced PollGroup NuGet package with IORingGroup
- Linux requires liburing-dev / liburing-devel package
### Test plan
- Verify server starts and accepts connections on Linux with io_uring
- Verify server starts and accepts connections on Windows (fallback to IOCP)
- Test unencrypted client connections (ClassicUO with encryption disabled)
- Test encrypted client connections if available
- Verify graceful disconnect flushes pending data
- Confirm CI builds pass on all target platforms
> [!Note]
> **Developer Note**
> Now developers will only need to build/run the Application project instead of everything.
> When adding new projects, make sure to:
> 1. Add a reference to that project in the Application project.
> 2. Add the dll file to the Distribution/Data/assemblies.json file
### Summary
- Adds an application project
- Consolidates process restarts to use `Core.Kill(true)`
- Removes some old messaging, for example processor optimization
- Fixes missing build cleanup
* Makes EnsureDirectory properly work for relative and absolute paths
* Adds a `PathUtility.GetFullPath` which returns full paths for relative paths to `Core.BaseDirectory`. If the path is absolute, it will return as-is.
* Moves EnsureDirectory to `PathUtility`. So `ScriptsHandler.EnsureDirectory` and `AssemblyHandler.EnsureDirectory` are now `PathUtility.EnsureDirectory`
* Fixes crash guard so that it copies accounts properly.
* Changes world save and auto archive to use a random folder name inside of the temp folder.
