### Summary
Fixes the long-standing reports of monsters losing track of players who run around a corner ("Is monster AI not using pathfinding? It seems to be LOS blocked by statics"). Root-cause investigation compared current behavior against RunUO line-by-line and traced the regressions through the AI overhaul era (#2232, #2246, #2379, #2401, #2461).
### Root causes and fixes
1. **Movement contract** — `MoveTo`/`ApproachTarget` returned false on every healthy mid-chase tick (true only on arrival), so MeleeAI's RunUO-inherited *"move failed and beyond RangePerception+1 → Guard"* clause — which RunUO only evaluated on genuine blockage — fired **every tick of every chase**. A mounted player trivially opens 17 tiles at a corner, the monster guards, Guard nulls the combatant, and re-acquisition is LOS-gated — unrecoverable through a wall. Movement now reports failure only on genuine failure (no step taken with no working path, or approach give-up). ArcherAI's equivalent clause moves to the hard leash.
2. **Last-known-position pursuit** — while a combatant is in LOS its position is recorded each think tick. When the target vanishes (corner, hiding, recall), the creature walks to the last-seen spot, stands guard there ~10s (restoring RunUO's guard grace, which had decayed to a single tick since #2246), and **re-engages instantly** if the same target re-enters view — bypassing the 10s reacquire throttle.
3. **`ChaseLeashRange`** — new virtual on BaseCreature (default `RangePerception * 2` = 32 tiles) replaces the inline `RangePerception * 3` (48) in Melee/Mage/Archer AI. Per-creature tunable via `[props`.
4. **Group movement demoted to a crowding refinement** — previously any uncontrolled creature with one ally within 8 tiles on the same target used greedy ring-stepping for the *entire* chase, with wall-slides counted as success, never invoking the pathfinder — the "aggroed but won't come around the corner" symptom for spawn groups. It now engages only near the target when allies actually contest the ring, and blocked/wall-slid steps escalate to the pathfinding approach primitive.
5. **Mages close distance on broken LOS** — a mage within casting range but LOS-blocked by geometry stood at the wall holding a spell target until the 60s combatant expiry (ProcessTarget short-circuits Think and its RunTo stands off at RangeFight). Geometry-blocked mages now close in until LOS returns, both pre-cast and while holding a target. Hidden targets (CanSee) and poison-cure priority unchanged. The new movement contract also stops the constant spurious `OnFailedMove` teleport rolls mid-chase.
6. **Move budget: one actual step per AI tick** — nothing advanced `NextMove` on a normal step (RunUO's `m_NextMove` budget was lost), so code paths attempting several moves in one think tick could cross multiple tiles at once — visible as "warping" when crowded creatures jockey for position. A successful step now consumes a half-step budget (floor 50ms): blocks intra-tick double moves, stays safely below the timer interval so legitimate next-tick moves are never jitter-throttled, and does not reintroduce `TransformMoveDelay` inflation. Blocked attempts consume nothing, so retry ladders (repath-and-step, the collision fan) are unaffected. `CanMoveNow` is also wraparound-safe now.
### Reference behavior
RunUO requires LOS to *acquire* a target and to *land* a hit or spell — never to *continue* a chase (its MeleeAI LOS bail-out is literally commented out in stock code). Chases drop only on: target hidden, target dead/off-map, beyond `RangePerception * 3`, 60s without combat interaction, or blocked movement while far away. This PR restores those semantics while adding the last-known-position investigation on top. NPC run flags are untouched — pace is AI-timer-driven and most NPC art has no run animation.
## 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
- Fixes pets falling behind mounted masters in AOS+ by setting `CurrentSpeed = 0.1` when following master
- Fixes AI timer permanently stopping when `Obey()`/`Think()` returns `false` for transient conditions
- Fixes controlled pets losing AI in inactive sectors (pet follows owner across sector boundary, sector deactivates, AI dies)
- Adds defense-in-depth: AI timer restarts on pet resurrection and order changes
## AI Timer Permanent Stop (Bug Fix)
`AITimer.OnTick()` called `Stop()` when `Obey()` or `Think()` returned `false`. By that point, `ShouldStop()` had already validated the creature is alive, on a valid map, and in an active sector — so any `false` return was a **transient** condition, not terminal. The timer stopped permanently with no mechanism to restart it.
**Scenarios that triggered permanent AI death:**
- Dead bonded pet with attack order (`DoOrderAttack` returned `false` for `IsDeadPet`)
- Failed pet transfer — loyalty refusal, combat, disconnected player, or pending trade (`DoOrderTransfer` returned `false` for 5 different transient conditions)
- Unknown `OrderType` or `ActionType` (defensive defaults)
**Fixes:**
- Removed `Stop()` from the `Obey()`/`Think()` failure path — timer skips the tick and fires again next interval
- Changed `DoOrderAttack()` and all five `DoOrderTransfer()` failure paths to return `true` (correct semantics: these are recoverable states, not "stop AI forever" signals)
- Added `Activate()` call in `ResurrectPet()` — ensures dead bonded pets have AI running after resurrection
- Added `Activate()` call in `OnCurrentOrderChanged()` — self-heals timer if any voice command is issued to a pet with a stopped timer
## Controlled Pet Sector Deactivation (Bug Fix)
`ShouldStop()` stopped the AI timer for **all** `PlayerRangeSensitive` creatures in inactive sectors, including controlled pets. But `Deactivate()` intentionally exempted controlled pets. The exemption was dead code — `ShouldStop()` bypassed it.
This matters when a pet follows its owner across a sector boundary: the owner enters the next sector (active), the pet's old sector deactivates (no more players), and the pet's AI dies. The pet stops following and stands there until the player backtracks far enough to reactivate the sector.
**Fix:** Added `Controlled` check to `ShouldStop()` to match `Deactivate()`. Controlled pets now keep their AI running in inactive sectors. The overhead is negligible — controlled pets are bounded by follower slots.
## Movement Speed Simplification
- Simplifies `AITimer` to use `CurrentSpeed` directly as the tick interval (in seconds), removing the complex multiplier/floor logic in `GetBaseInterval`
- Refactors `DoMoveImpl` speed assignment into explicit if/else for clarity
- AOS+ pets following master use `CurrentSpeed = 0.1` (100ms), matching `RunMountDelay`
## Files Changed
- `AITimer.cs` — removed `Stop()` on Obey/Think failure, added `Controlled` exemption to `ShouldStop()`, simplified interval logic
- `BaseAI.cs` — renamed `_timer` to `AITimer` (public), simplified `Deactivate()`, fixed `ReturnToHome` to use `Activate()`
- `PetOrders.cs` — `DoOrderAttack` and `DoOrderTransfer` return `true` for transient failures
- `PetOrderHandlers.cs` — `OnCurrentOrderChanged()` calls `Activate()` to self-heal stopped timers
- `BaseCreature.cs` — `ResurrectPet()` calls `Activate()`, fixed `GoHome_Callback` PlayerRangeSensitive check
- `AIMovement.cs` — refactored speed assignment, AOS+ follow-master speed fix
### Summary
* Refactors AI so it is easier to read and maintain
* Fixes NPC speed issues
* Fixes pet sector AI issue that was causing stuttering
* Fixes direction snapping for Melee/Mage AI
* Refactors pet orders
* Refactors speech commands
* Removes scale speed by dex for HS+ (it was a stupid feature anyways)
