# C4 route 4b-2 — remote far-snap: pinned contract (2026-08-04)

Split rationale:
[`2026-08-04-c4-route-4b-scoping-and-split.md`](2026-08-04-c4-route-4b-scoping-and-split.md).
4b-1 (the infrastructure) landed dormant at `2e8e09ac`; the park restore it
depends on landed at `634bc551`.

**4b-2 flips ONE classifier branch on: `SetPositionSimple` — contact,
`PlayerDistance >= 96 m`.** Teleport and cell-less stay legacy; 4b-3 owns them.

## Retail truth — verify each yourself

`CPhysicsObj::MoveOrTeleport` @0x00516330, far branch @0x005163C1-@0x005163E8:

```
if (player_distance >= 96f) {
    if (position_manager != 0) PositionManager::StopInterpolating(position_manager);
    CPhysicsObj::SetPositionSimple(this_1, arg2, 1);
    return 1;                                    // @0x005163E8
}
```

Two things that decide this slice:

1. **`StopInterpolating` runs BEFORE `SetPositionSimple`** (@0x005163CB before
   @0x005163D9). The classifier already carries `StopInterpolating: !nearby`.
   Preserve the order.
2. **The branch returns 1**, so `SmartBox::HandleReceivedPosition`
   @0x00454254 takes the nonzero path and arms `ConstrainTo` @0x00454272,
   anchored to `&arg2->m_position` read live — i.e. POST-move.

`SetPositionSimple` @0x005162B0 with `arg3 != 0` builds flags `0x1012`
(`Teleport|Slide|SendPositionEvent`) — the classifier's
`AuthoritativeTeleportFlags`.

**`MoveOrTeleport` discards `SetPositionSimple`'s `SetPositionError` return and
returns 1 regardless.** So retail arms the leash even when the placement failed.
4b-2 must arm on refusal and rejection too, not only on commit. "Arm on
Committed" is the natural misreading and is the same shape as the already-filed
unarmed-leash bug.

## Scope

**Flip on:** `SetPositionSimple` for `RuntimePositionEntityKind.Remote`, routed
through 4b-1's `RuntimeRemotePlacementDriveController`.

**Delete** (far half only, both arms):
- The player-remote far branch and its `MaxPhysicsDistance = 96f` /
  `BodySnapThreshold = 4f` constants.
- The NPC-remote copy and its `MaxPhysicsDistanceNpc` / `BodySnapThresholdNpc`.
- Both `_playerController?.Position ?? Vector3.Zero` fabrications on those
  paths. `GameRuntime` states the rule for this field: a null controller "must
  yield null, never a fabricated Vector3.Zero that would misclassify every
  remote entity as implausibly far."

**Do NOT touch:** `RemoteTeleportController`, `RemoteTeleportPlacement`,
`remotePlacementRequired`, the teleport/cell-less branches, AP-135's two
airborne writes, the near/interpolate path 4a owns, the airborne no-op, or
route 1's executor.

## The trap that will bite you

**Deleting the legacy far block removes the only handler for `null` and
`Rejected*` classifications.** `ClassifyRemoteAcceptedPosition` returns null
whenever `_playerController` is null — **during the login window that is every
remote packet.** Today those fall into the legacy block and hard-snap. Delete it
without an explicit replacement and remotes will not move at all until the local
controller exists.

Retail has no analogue because retail always has a player. This needs a stated
acdream policy, decided deliberately and recorded — it is the same shape as
route 4a's "'not Interpolate' is not 'far'" finding, one level up.

## AP-87 does not apply here

AP-87's `bodyToTarget > 4 m` and `!willBeDrTicked` conditions are **near-branch**
guards: they decide snap-vs-enqueue within `Interpolate`. The far branch snaps
unconditionally, so they are subsumed. **Do not carry them forward into a branch
that does not need them** — but do not delete the near-branch copies either;
those are 4a's and still load-bearing.

## Contract

1. `SetPositionSimple` for remotes executes through 4b-1's owner; nothing else
   changes classification.
2. `StopInterpolating` precedes the placement, matching @0x005163CB.
3. `ConstrainTo` is armed once, after the operation, anchored post-move, on
   commit **and** on refusal/rejection — retail arms on any nonzero return.
   Do not add a second arming site; retail has exactly one (@0x00454272).
4. `null` and `Rejected*` have an explicit, stated handler. No silent drop.
5. No behaviour change to teleport, cell-less, near/interpolate, or airborne.
6. Both hosts drive the identical Runtime entry point, or the divergence is
   stated plainly rather than satisfied vacuously.
7. Per-entity currency across GUID reuse, incarnation, generation, teardown.

## Acceptance

- Focused Runtime tests for the far branch, the `StopInterpolating` ordering,
  the arm-on-failure case, and the null/`Rejected*` policy.
- **Behavioural** App tests — not source-text pins. Route 2 settled for a pin
  and that gap is #292; route 4a's first attempt shipped tautologies that
  passed with production reverted. A test that cannot fail against a broken
  implementation is worse than no test.
- Complete Release suite green. Baseline **10,973 / 4 / 0**. Two known flakes,
  do not chase and do NOT conflate: **#302** (`PortalProjectionTests…`,
  GC-allocation assertion, App.Tests) and **#308** (`NakEmissionTests.LossSoak_…`,
  wall-clock deadline, Core.Net.Tests, full-suite load only).
- **Connected gate (user-gated), and it is easy**: stand still in open ground;
  second character runs past ~100 m, stops, turns, runs back, three or four
  times. Correct: they stay visible and correctly positioned at range, and
  resume smooth interpolation on the way back in with no jolt at the crossover.
  Regressions: a freeze or stutter at the boundary, a Z pop, a vanish, or —
  the loud one — invisible-but-solid on the way back in.

## Budget

**~350-500 non-comment production lines.** For calibration: route 4a was 364
(91% of its ~400), and 4b-1 was 230 plus a 57-line park fix. Exceed 500 and stop
and report rather than pushing through.