## Problem
`BaseFamiliar.OnThink` drove its own movement (`WalkMobileRange` toward the master) while the familiar was also a controlled pet running `Obey()`. `Summon → SetControlMaster` issues `Come`; `DoOrderCome` converts it to `Stay` within two tiles and anchors `Home`; from then on `OnThink` walked toward the caster while `DoOrderStay` greedy-stepped back toward the stale post — the backtracking. Combat never approached anything: main only copied `Combatant` while already adjacent to the caster. `CurrentSpeed = 0.01` was a 10 ms think / 50 ms step sprint hack, and `RangeCheck` teleported the familiar to a spot eight tiles *from* the caster.
## Change
A dedicated `FamiliarAI : BaseAI` (registered through `ForcedAI`, like `CloneAI`) owns every familiar decision, for both the controlled (`Obey`) and uncontrolled (`Think`) dispatch:
1. **Lifecycle** — caster gone → drop pack, delete. Caster on another map → stand down and wait for `TeleportPets`.
2. **Herding** (Dark Tides) — stands down, then `CheckHerding()`. Outranks combat.
3. **Assist** — combat-capable familiars (dark wolf, vampire bat, horde minion) engage the caster's target; otherwise anything in a fight with the caster's side — attacked the caster or the familiar, or attacked by the caster (a pet's attack is credited to the caster) — that is still fighting the caster, the familiar, or one of the caster's pets. Leashed to `RangePerception` of the caster; dropped when the caster hides. Shadow wisp and death adder never fight (`AssistsMaster => false`, enforced at the `Combatant` setter so no path can hand them a target).
4. **Follow** — `MoveTo(master, 1)` through the centralized `ApproachTarget` (greedy step / persistent `PathFollower` / stall detection).
5. **Keep-up** — snap to a validated tile beside the caster (on the caster's floor) when outpaced on open ground beyond 10 tiles, or when `ApproachTarget` gave up; never while a detour is working.
**Command immunity** is expressed inside the order machinery rather than around it: `FamiliarAI.IssueOrder` does nothing and rests the order on `Come`, so `TeleportPets` keeps working and no system-issued `Attack` (retaliation on ML's stand-down rule) can strand the familiar. `StandsDownOnCommand => false` so the ML rule never mutes it.
**Visibility** mirrors the caster from the familiar's own state (a step reveals a hidden NPC in `Mobile.OnMove`; the old cache compared the caster's previous state), `RevealingAction` is suppressed while the caster is hidden, and becoming hidden drops Warmode so no swing gives the caster away.
**Speed** is a flat 0.1 (`ReduceSpeedWithDamage => false`).
### Engine-side (all `Projects/UOContent`)
- `ApproachTarget` records which exit it took in `BaseAI.LastApproach` (`ApproachOutcome`: Arrived / Waiting / DirectProgress / Routing / Blocked / GaveUp / InvalidGoal). Callers' booleans are unchanged; keep-up reads this instead of running a second scheduler. `MoveTo`'s arrival return now also clears the move intent, as `ApproachTarget`'s own arrival does.
- `MoveToPoint(goal, range = 1)`; `CheckHerding` passes 0. **Fixes a main regression from #2591:** herding stopped one tile short, never cleared `TargetLocation`, and left the creature pinned to the herding pace — affects the shepherd's crook and the Dark Tides scroll fetch for every herded creature, not just familiars.
- `ChangeAIType` reads `ForcedAI` once. It read it twice, and each `BaseAI` ctor activates its timer for a non-sector-gated creature, so a `ForcedAI` creature with `PlayerRangeSensitive => false` got an orphan AI ticking it.
## Tests
`FamiliarAITests` are timer-wheel driven (the real `AITimer` thinks and moves; `PetPacingTests` style) against live Trammel statics, gated on client map data: follow without backtracking, the five-way assist theory, leash, retaliation, aggressor fallback (caster's own `Combatant` expired; caster's pet in the fight), target dropped when it stops fighting, keep-up on open ground / not while routing / after give-up, hidden mirror across steps, herding priority with a visible fighting caster, stand-down when left behind, no stale move intent. `ApproachOutcomeTests`, `HerdingTests` (fails on main), `ForcedAITests` (fails on main) cover the engine-side pieces.
Against `origin/main` with the familiar tests dropped in: 16/16 fail, including the reported backtracking. On this branch: `UOContent.Tests` 1082 passed / 2 skipped, `Server.Tests` 891/891, solution builds with 0 warnings.
Stacked on #2594. Fixes jerky creature movement (lich / Fast-bucket melee chases) by choosing the client animation flag from the actual step pace instead of a caller-supplied `run` argument, and fixes three step-pacing defects in the move budget found while verifying it with paired server/client traces.
### Why
The `Direction.Running` bit does nothing for creatures server-side (`Mobile.OnMove` reads it only for the player throttle and stealth reveal). Its whole effect is on the client, which animates each step over a fixed time selected by that bit: walk 400 ms / run 200 ms on foot, 200 / 100 ms mounted. ClassicUO queues up to 5 steps and *drops* the sixth, so a creature stepping every 300 ms while flagged as walking backs the queue up until it snaps forward — the observed jerk.
The `run` argument never carried the one fact that matters (the step interval). RunUO passed `true` in combat / `false` for pets and gated it on `dist > 5`; #2271 flipped every combat site to `false`; pets passed `currentDistance > 2`. None of that is a coherent signal.
### What
**Pace-derived run flag**
- `BaseAI.ShouldRun()`: run iff the effective step delay (move clock + badly-hurt inflation) is shorter than `Movement.WalkFootDelay` / `WalkMountDelay` (mounted or flying) — with a continuity rule: an *isolated* step (taken after standing at least a walk interval) goes out as a walk, because the client renders each step alone and a lone run-flagged step is a 200 ms dart. Only a continuing cadence flags run; a true sprinter (pace under the run interpolation) always runs, since a walk-rendered first step would flood the client's 5-step queue. This reproduces RunUO's close-in feel (its `dist > 5` gate) from first principles.
- `DoMoveImpl` stamps the bit; it is the single place the flag is set.
- `run` removed from `MoveTo`, `WalkMobileRange`, `ApproachTarget`, `MoveToPoint`, `MoveToWithGroup`, `MoveToWithCollisionAvoidance`, the move intent, and `PathFollower.Follow`. All 35 call sites updated. **API change** for custom scripts — documented in the RunUO migration docs (`09-items-mobiles-creatures.md`, `11-api-reference.md`) and `content-patterns.md` § Creature Speeds.
**Move-budget pacing fixes** (each confirmed by UTC-aligned server/client step traces)
- A stall no longer banks catch-up steps: the budget's snap-to-now released up to three steps in ~300 ms when a creature resumed chasing after standing beside its target — rendered as a teleport.
- Debt accrual removed entirely: a step landing sub-period late (think-grid vs budget misalignment during reactive mirroring) kept the remainder and fired a follow-up ~100 ms later — a dart pair. `ConsumeMoveBudget` now paces every step from when it was actually taken; in continuous pursuit the move-wake lands within wheel resolution of the deadline, so the cost is single-digit-ms drift.
- Net effect: a creature can never step faster than its pace, verified across a full chase session (zero sub-pace steps; metronomic 350 ms cadence for a 0.3 s lich).
- Test fixture now runs `Movement.Configure()` (the walk delays were 0 in tests).
### Accepted trade-off
Animal (LOW group) bodies without a run animation slide on their stand frames when flagged as running. Most are slow enough to stay flagged as walking; the client-side fallback is in ClassicUO/ClassicUO#1930.
### Tests
`RunFlagTests`: foot thresholds (0.3 / 0.125 run; 0.4 / 0.45 / 1.05 walk), flying uses the mount threshold, badly-hurt inflation flips a 0.35 s creature back to walk, a real `DoMove` stamps the bit, isolated steps drop to walk (sprinters keep running), a stall restarts the cadence with no banked steps, and a late step earns no quicker follow-up. Full suite: 837 Server + 747 UOContent green.
## 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
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