## Summary
Fixes two related pet-behavior bugs and the underlying design flaw behind both:
1. **Post-combat erratic** — after a pet killed its `all kill` target it milled around erratically at the kill site (or failed to return to the master) until the player issued `all follow`/`all stop`.
2. **`all stop` returns home** — a pet with a non-zero `Home` walked back toward that location on `all stop` (on ML; on non-ML the old `DoOrderStop` was a no-op, so the sighting there came from a residual `Stay`).
### Root cause
`ControlOrder` and the wild-creature `Home` field were overloaded to express several distinct ideas, mutated/read inconsistently across order transitions:
- `Home` doubled as the controlled-pet "stay anchor" (`HandleStayOrder` set `Home = Location`) but nothing cleared it when the pet left the staying state; `HandleStopOrder` was the only handler that never touched it.
- `DoOrderStop` had dropped RunUO's `Home = Location` re-anchor, so on ML it walked to a stale anchor.
- The post-combat fallback was a fragile `_lastPetOrder` hack in `DoOrderNone` that re-anchored a resumed `Stay` at the corpse.
- Controlled idle-wander bypassed the `CheckIdle()` rest gate that every non-controlled creature uses, so idling pets jittered every AI tick.
## Approach
Separate three concepts that were tangled together:
- **`ControlOrder`** — the active order (may be transient: Come/Attack/Drop).
- **Persistent command** (`PersistentOrder` ∈ `{None, Stay, Follow, Guard}`) — the standing directive a pet falls back to when a transient order completes. Runtime-only (not serialized; reset to `None` on load) and **derived from master proximity on login** (near → Follow, far → Stay).
- **Anchor** (`Home`) — a pure function of the persistent command, set only when that command changes (never on transient transitions or fallback-resume), so it can't go stale.
### Behavior
- **Stop** is resolved immediately from what the pet was doing: Attack/Come → resume the persistent command; Follow/Guard → cancel to idle where it stands; Stay → stay put.
- **Stay** holds its post (returns only if displaced, e.g. after a fight) — no shuffle.
- **Idle** (`None`) is a gentle wander routed through `CheckMove/CanMoveNow/CheckIdle`, so idling pets take the same 15–25s rest periods as other creatures, on both ML and non-ML.
- **Post-combat** the pet resumes its persistent command (a staying pet returns to its original post, not the corpse).
- **Release** without a spawner anchors where the pet stands instead of pathing to a stale anchor.
This restores the RunUO-intended behavior (verified against the RunUO reference) while fixing the ModernUO regressions.
## Tests
New `PetOrderTests` (13 deterministic xUnit tests) cover: anchor lifecycle, the full Stop truth table, report 1 (post-combat return to post), report 2 (no stale-anchor walk-home), frozen-Stay/gated-idle wiring, release fix, derive-on-login, and a non-ML spot-check. The subjective wander *feel* is covered by a manual-QA checklist in the implementation plan.
## Notes
- Engine project (`Projects/Server`) untouched; the one `BaseCreature.cs` change is the `ControlOrder` setter passing the previous order to `OnCurrentOrderChanged`.
- `DoOrderCome` keeps auto-converting to `Stay` on arrival, which under the new model cleanly means "come and hold near me."
- Commits in this PR are temporarily **unsigned** (the signing agent's passphrase cache expired mid-session); happy to re-sign / amend on request.
## 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.
Kamron Batman