acdream/tests/AcDream.Runtime.Tests/Session/RuntimeAcceptedPositionDriveControllerTests.cs

using System.Net;
using System.Numerics;
using AcDream.Core.Combat;
using AcDream.Core.Items;
using AcDream.Core.Net;
using AcDream.Core.Net.Messages;
using AcDream.Core.Physics;
using AcDream.Core.Spells;
using AcDream.Runtime.Entities;
using AcDream.Runtime.Gameplay;
using AcDream.Runtime.Physics;
using AcDream.Runtime.Session;
using AcDream.Runtime.World;

namespace AcDream.Runtime.Tests.Session;

/// <summary>
/// C4 route 2 (2026-08-03): the Runtime-owned accepted-Position execution
/// seam for a ForcePosition on an already-live local player. Fixture
/// construction mirrors <c>RuntimeLiveEntitySessionControllerTests</c>'
/// session/first-entry harness — a live <see cref="PlayerMovementController"/>
/// only exists once the local player's initial-Create residence has fully
/// drained through <see cref="RuntimeFirstEntryDriveController"/>.
/// </summary>
public sealed class RuntimeAcceptedPositionDriveControllerTests
{
    private const uint PlayerGuid = 0x50000001u;
    private const uint SpawnLandblock = 0x01010000u;
    private const float SpawnHeight = 5f;

    /// <summary>
    /// A landblock whose collision generation is deliberately NEVER committed
    /// in this fixture — the same id the deferred-park tests below use. The
    /// pre-engine quiescence check runs ahead of the engine and therefore
    /// ahead of any collision-readiness question, so its readiness is
    /// irrelevant to the round-3 destination-quiescence test.
    /// </summary>
    private const uint DestinationLandblock = 0x02020000u;

    /// <summary>
    /// <see cref="SpawnLandblock"/>'s +X neighbour: landblock ids pack the
    /// block X index in bits 24-31, so 0x0101 → 0x0201 is one block east, and
    /// <c>LandDefs.LcoordToGid</c> re-derives exactly this prefix for a global
    /// lcoord one cell past the 192 m seam.
    /// </summary>
    private const uint NeighbourLandblock = 0x02010000u;

    /// <summary>
    /// Cell (7, 0) of <see cref="SpawnLandblock"/> — block-local X in
    /// [168, 192), Y in [0, 24). <c>LandDefs.GidToLcoord</c>'s inverse:
    /// <c>low = (ly &amp; 7) + ((lx &amp; 7) &lt;&lt; 3) + 1 = 0 + 56 + 1 = 57</c>.
    /// </summary>
    private const uint SpawnSeamCell = SpawnLandblock | 57u;

    [Fact]
    public void NotApplicable_WhenDispositionIsNotForcePosition()
    {
        using StartedRuntime started = StartRuntime();
        (RuntimeEntityRecord record, PlayerMovementController controller) =
            EnterLocalPlayer(started.Runtime);
        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(started.Runtime, out List<byte[]> gameActions);

        RuntimeAcceptedPositionExecutionStatus status =
            drive.TryExecuteAcceptedLocalPosition(
                record,
                ForceUpdate(new Vector3(30f, 30f, 5f)),
                PositionTimestampDisposition.Apply,
                Timestamps(teleport: 0),
                previousTeleportSequence: 0);

        Assert.Equal(RuntimeAcceptedPositionExecutionStatus.NotApplicable, status);
        Assert.Empty(gameActions);
    }

    [Fact]
    public void NotApplicable_WhenRecordIsNotTheLocalPlayer()
    {
        using StartedRuntime started = StartRuntime();
        (RuntimeEntityRecord record, _) = EnterLocalPlayer(started.Runtime);
        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(started.Runtime, out _);

        // Same record, but the drive's own local-player-guid accessor no
        // longer matches it (as if it belonged to some other entity).
        started.Runtime.PlayerIdentity.ServerGuid = 0x70000099u;

        RuntimeAcceptedPositionExecutionStatus status =
            drive.TryExecuteAcceptedLocalPosition(
                record,
                ForceUpdate(new Vector3(30f, 30f, 5f)),
                PositionTimestampDisposition.ForcePosition,
                Timestamps(teleport: 0),
                previousTeleportSequence: 0);

        Assert.Equal(RuntimeAcceptedPositionExecutionStatus.NotApplicable, status);
    }

    [Fact]
    public void NotApplicable_WhileAnInitialCreateResidenceIsStillActive()
    {
        using StartedRuntime started = StartRuntime();
        GameRuntime runtime = started.Runtime;
        runtime.PlayerIdentity.ServerGuid = PlayerGuid;
        CommitLandblockCollision(runtime, SpawnLandblock);
        RuntimeEntityRecord record = runtime.EntityObjects
            .RegisterEntityWithInitialResidence(
                Spawn(PlayerGuid), isLocalPlayer: true)
            .Canonical!;
        // Deliberately do NOT drain the first-entry drive: the residence
        // (and hence no PhysicsBody/controller) is still open — route 1's
        // job, never route 2's.
        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(runtime, out List<byte[]> gameActions);

        RuntimeAcceptedPositionExecutionStatus status =
            drive.TryExecuteAcceptedLocalPosition(
                record,
                ForceUpdate(new Vector3(30f, 30f, 5f)),
                PositionTimestampDisposition.ForcePosition,
                Timestamps(teleport: 0),
                previousTeleportSequence: 0);

        Assert.Equal(RuntimeAcceptedPositionExecutionStatus.NotApplicable, status);
        Assert.Empty(gameActions);
    }

    [Fact]
    public void Rejected_WhenTheClassifierDeclinesTheFrame()
    {
        using StartedRuntime started = StartRuntime();
        (RuntimeEntityRecord record, PlayerMovementController controller) =
            EnterLocalPlayer(started.Runtime);
        Vector3 positionBefore = controller.Position;
        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(started.Runtime, out List<byte[]> gameActions);

        // RuntimeAuthoritativePositionRouteClassifier.ValidAcceptedAuthority's
        // ForcePosition case requires PreviousTeleportSequence ==
        // AcceptedTeleportSequence; a mismatch is a genuine data-validity
        // rejection (this call site never re-derives the timestamp gate's
        // own freshness rule — it is asserting the classifier's own
        // independent structural check).
        RuntimeAcceptedPositionExecutionStatus status =
            drive.TryExecuteAcceptedLocalPosition(
                record,
                ForceUpdate(new Vector3(30f, 30f, 5f)),
                PositionTimestampDisposition.ForcePosition,
                Timestamps(teleport: 6),
                previousTeleportSequence: 5);

        Assert.Equal(RuntimeAcceptedPositionExecutionStatus.Rejected, status);
        Assert.Equal(positionBefore, controller.Position);
        Assert.Empty(gameActions);
        AssertConverged(started.Runtime);
    }

    [Fact]
    public void Committed_MovesTheBodyPreservesHeadingAndAcksExactlyOnceAfterCommit()
    {
        using StartedRuntime started = StartRuntime();
        GameRuntime runtime = started.Runtime;
        (RuntimeEntityRecord record, PlayerMovementController controller) =
            EnterLocalPlayer(runtime);
        Quaternion headingBeforeCorrection = controller.BodyOrientation;

        var corrected = new Vector3(30f, 32f, 5f);
        WorldSession.EntityPositionUpdate wire = ForceUpdate(corrected);
        // A deliberately different wire rotation than the controller's own
        // heading, exactly like a real server correction carries whatever
        // heading it last observed — proves the seam never applies a SECOND
        // heading substitution on top of the one the upstream merge already
        // performed (contract §1c: RuntimeEntityObjectLifetime.TryApplyPosition's
        // forcePositionRotation argument, exercised for real below via
        // MergeAccepted).
        wire = wire with
        {
            Position = wire.Position with
            {
                RotationX = 0f,
                RotationY = 0f,
                RotationZ = 1f,
                RotationW = 0f,
            },
        };
        (PositionTimestampDisposition disposition, AcceptedPhysicsTimestamps timestamps) =
            MergeAccepted(runtime, controller, wire);
        Assert.Equal(PositionTimestampDisposition.ForcePosition, disposition);

        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(runtime, out List<byte[]> gameActions);

        RuntimeAcceptedPositionExecutionStatus status =
            drive.TryExecuteAcceptedLocalPosition(
                record,
                wire,
                disposition,
                timestamps,
                timestamps.PreviousTeleport);

        Assert.Equal(RuntimeAcceptedPositionExecutionStatus.Committed, status);
        Assert.Equal(corrected, controller.Position);
        Assert.Equal(headingBeforeCorrection, controller.BodyOrientation);
        Assert.Single(gameActions);
        AssertConverged(runtime);
    }

    [Fact]
    public void Contention_WhenTheEntityAlreadyOwnsAnActiveOperation()
    {
        using StartedRuntime started = StartRuntime();
        GameRuntime runtime = started.Runtime;
        (RuntimeEntityRecord record, PlayerMovementController controller) =
            EnterLocalPlayer(runtime);
        Vector3 positionBefore = controller.Position;
        WorldSession.EntityPositionUpdate wire =
            ForceUpdate(new Vector3(30f, 32f, 5f));
        (PositionTimestampDisposition disposition, AcceptedPhysicsTimestamps timestamps) =
            MergeAccepted(runtime, controller, wire);
        Assert.Equal(PositionTimestampDisposition.ForcePosition, disposition);

        // Mirrors the displaced-authority scenario the deleted
        // LocalForcePositionTransaction's trailing isCurrent() covered: some
        // OTHER operation is already in flight for this exact entity (e.g. a
        // remote-authoritative resolve mid-transaction) when the
        // ForcePosition arrives.
        RuntimeEntityPlacementToken displaced = runtime.EntityObjects.Physics
            .SetPosition.TryBeginExclusiveAuthoredPlacement(
                record,
                record.PositionAuthorityVersion,
                RuntimeSetPositionOperationKind.LocalAuthoritative);
        Assert.True(displaced.IsValid);
        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(runtime, out List<byte[]> gameActions);

        RuntimeAcceptedPositionExecutionStatus status =
            drive.TryExecuteAcceptedLocalPosition(
                record,
                wire,
                disposition,
                timestamps,
                timestamps.PreviousTeleport);

        Assert.Equal(RuntimeAcceptedPositionExecutionStatus.Contention, status);
        Assert.Equal(positionBefore, controller.Position);
        Assert.Empty(gameActions);

        // Cleanup: release the displaced operation so the fixture converges.
        RuntimePlacementCancellationReceipt cancellation = runtime.EntityObjects
            .Physics.SetPosition.ForgetExactPlacement(displaced);
        if (cancellation.IsValid)
        {
            runtime.EntityObjects.Physics.SetPosition
                .PublishCancellation(cancellation);
        }
    }

    /// <summary>
    /// C5b (#275) proof obligation 4 — the assertion that makes AD-60's
    /// legacy-half retirement mean something. A local ForcePosition whose
    /// drive execution CONTENDS performs no placement, so nothing may write
    /// residency for that packet: the merge no longer stamps the wire cell
    /// (C5b), there is no placement receipt, and the OnPosition generic tail
    /// (W2) is never reached because the force path returns before it.
    /// <c>FullCellId</c> is the pre-packet committed cell throughout.
    ///
    /// <para>
    /// Retail cannot refuse at all (AD-62), and its body simply keeps the
    /// last cell <c>set_cell</c> gave it — so the surviving shape here is the
    /// retail-reachable one. Before C5b the merge stamped the refused
    /// packet's wire cell, which is the AD-60 legacy-half divergence.
    /// </para>
    /// </summary>
    [Fact]
    public void ContendedForcePosition_WritesNoResidencyAnywhere()
    {
        using StartedRuntime started = StartRuntime();
        GameRuntime runtime = started.Runtime;
        (RuntimeEntityRecord record, PlayerMovementController controller) =
            EnterLocalPlayer(runtime);
        uint committedCellBefore = record.FullCellId;
        Assert.NotEqual(0u, committedCellBefore);

        // A wire cell that is deliberately NOT the committed one, so the
        // pre-C5b stamp would have been observable.
        const uint wireCell = SpawnLandblock | 0x0002u;
        Assert.NotEqual(wireCell, committedCellBefore);
        WorldSession.EntityPositionUpdate wire = ForceUpdate(
            new Vector3(30f, 32f, SpawnHeight),
            landblockId: wireCell);
        (PositionTimestampDisposition disposition, AcceptedPhysicsTimestamps timestamps) =
            MergeAccepted(runtime, controller, wire);
        Assert.Equal(PositionTimestampDisposition.ForcePosition, disposition);

        // (1) The merge itself wrote no residency.
        Assert.Equal(committedCellBefore, record.FullCellId);

        RuntimeEntityPlacementToken displaced = runtime.EntityObjects.Physics
            .SetPosition.TryBeginExclusiveAuthoredPlacement(
                record,
                record.PositionAuthorityVersion,
                RuntimeSetPositionOperationKind.LocalAuthoritative);
        Assert.True(displaced.IsValid);
        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(runtime, out List<byte[]> gameActions);

        Assert.Equal(
            RuntimeAcceptedPositionExecutionStatus.Contention,
            drive.TryExecuteAcceptedLocalPosition(
                record,
                wire,
                disposition,
                timestamps,
                timestamps.PreviousTeleport));

        // (2) No receipt, so no residency change from the execution either.
        Assert.Equal(committedCellBefore, record.FullCellId);
        Assert.Empty(gameActions);

        // (3) And nothing rebounds it on the settle.
        drive.Advance();
        Assert.Equal(committedCellBefore, record.FullCellId);

        RuntimePlacementCancellationReceipt cancellation = runtime.EntityObjects
            .Physics.SetPosition.ForgetExactPlacement(displaced);
        if (cancellation.IsValid)
        {
            runtime.EntityObjects.Physics.SetPosition
                .PublishCancellation(cancellation);
        }
    }

    [Fact]
    public void DeferredCell_ParksThenCommitsAndNeverDoubleAcksAfterTheCollisionGenerationWakes()
    {
        using StartedRuntime started = StartRuntime();
        GameRuntime runtime = started.Runtime;
        (RuntimeEntityRecord record, PlayerMovementController controller) =
            EnterLocalPlayer(runtime);
        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(runtime, out List<byte[]> gameActions);

        // A destination landblock whose collision generation was never
        // committed (mirrors RuntimeSetPositionStateTests' CrossLandblockRequest
        // pattern — re-admitting an ALREADY-ready landblock through this
        // simple Begin/CommitCollisionGeneration pair does not block a new
        // placement; only a genuinely fresh landblock does) parks the
        // operation instead of committing it. Runtime's world-frame
        // resolution is arithmetic once ANY frame is observed
        // (RuntimePhysicsState.TryGetWorldFrameOffset:598-617), so this
        // parks on collision readiness specifically, not on an unresolved
        // frame.
        const uint deferredLandblock = 0x02020000u;
        var deferredPosition = new Vector3(10f, 10f, SpawnHeight);
        WorldSession.EntityPositionUpdate parkedUpdate = ForceUpdate(
            deferredPosition,
            landblockId: deferredLandblock | 0x0001u);
        (PositionTimestampDisposition disposition, AcceptedPhysicsTimestamps timestamps) =
            MergeAccepted(runtime, controller, parkedUpdate);
        Assert.Equal(PositionTimestampDisposition.ForcePosition, disposition);

        RuntimeAcceptedPositionExecutionStatus parked =
            drive.TryExecuteAcceptedLocalPosition(
                record,
                parkedUpdate,
                disposition,
                timestamps,
                timestamps.PreviousTeleport);

        Assert.Equal(RuntimeAcceptedPositionExecutionStatus.DeferredCell, parked);
        Assert.Empty(gameActions);
        Assert.Equal(1, drive.PendingCount);

        // Advance() before the destination is ready makes no progress.
        drive.Advance();
        Assert.Empty(gameActions);
        Assert.Equal(1, drive.PendingCount);

        CommitLandblockCollision(runtime, deferredLandblock);
        // Production always has a LIVE host subscription
        // (RuntimePlacementProjectionSubscription) that applies-and-
        // acknowledges the resubmitted Place synchronously the instant
        // RetryDeferred's CommitCanonical publishes it — that is what
        // promotes this controller's own Watch into an observable
        // acknowledged completion (RuntimeSetPositionState.AcknowledgeProjection's
        // Place branch). This bare-Runtime fixture has no host wired, so it
        // stands in for that subscription exactly like
        // RuntimeLiveEntitySessionControllerTests' own DrainPlacementFifo.
        DrainPlacementFifo(runtime);

        // A single Advance() pump resolves the deferred commit.
        drive.Advance();

        Assert.Equal(0, drive.PendingCount);
        // World position, not the cell-local wire position: the deferred
        // landblock (0x0202) sits one landblock diagonally from the spawn
        // landblock (0x0101) in Runtime's world frame, a (192, 192, 0) m
        // offset (RuntimePhysicsState.TryGetWorldFrameOffset).
        Assert.Equal(deferredPosition + new Vector3(192f, 192f, 0f), controller.Position);
        // R8 review fix (2026-08-03): the ack is gated on retail's own
        // independent CanSendPositionEvent requirement (Contact + OnWalkable
        // — PlayerMovementController.cs:1517). Measured directly: this
        // synthetic cross-landblock jump resolves with InContact=false in
        // this bare-Runtime fixture (no subsequent physics tick runs here to
        // sweep the body onto the terrain it was placed exactly tangent to —
        // unlike the WITHIN-landblock move
        // Committed_MovesTheBodyPreservesHeadingAndAcksExactlyOnceAfterCommit
        // exercises, which measures Contact=true and DOES get its ack). This
        // test therefore does NOT verify the single-ack-after-wake sequence
        // end to end — it only proves the non-double-ack invariant below.
        // Asserting exactly one ack here would require driving a real
        // physics tick after the wake to establish ground contact, which is
        // out of this fixture's scope; do not report this sequence as
        // ack-verified (docs/ISSUES.md #285) until a harness does that.
        int acksAfterFirstResolve = gameActions.Count;

        // Further pumps are no-ops — the ack must never fire twice, however
        // many times Advance() is pumped (still true wants Contact to
        // eventually flip and the ack to fire exactly once, whenever that
        // happens).
        drive.Advance();
        drive.Advance();
        Assert.Equal(acksAfterFirstResolve, gameActions.Count);
        AssertConverged(runtime);
    }

    /// <summary>
    /// Round 2 unified rule, branch 1 of 3 — <b>EQUAL</b>. The parked
    /// operation dies (here through the exact
    /// <c>RuntimeSetPositionState.Forget</c> funnel every mid-session
    /// cancellation shares: supersession, the lost-cell deadline,
    /// <c>ParkCollisionResidents</c>, a generation change) while NO newer
    /// accepted position has taken the authority, so the record's
    /// <c>PositionAuthorityVersion</c> still equals the dead operation's own.
    /// Nothing is outstanding: <c>_pending</c> clears, and the drive must NOT
    /// re-issue. Re-issuing on an unchanged authority is precisely the shape
    /// that produced N1's second placement + second ack.
    /// </summary>
    [Fact]
    public void Equal_ClearsPendingWithoutReissuingWhenNoNewerAcceptedAuthorityArrived()
    {
        using StartedRuntime started = StartRuntime();
        GameRuntime runtime = started.Runtime;
        (RuntimeEntityRecord record, PlayerMovementController controller) =
            EnterLocalPlayer(runtime);
        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(runtime, out List<byte[]> gameActions);

        const uint deferredLandblock = 0x02020000u;
        var deferredPosition = new Vector3(10f, 10f, SpawnHeight);
        WorldSession.EntityPositionUpdate parkedUpdate = ForceUpdate(
            deferredPosition,
            landblockId: deferredLandblock | 0x0001u);
        (PositionTimestampDisposition disposition, AcceptedPhysicsTimestamps timestamps) =
            MergeAccepted(runtime, controller, parkedUpdate);
        Assert.Equal(PositionTimestampDisposition.ForcePosition, disposition);

        RuntimeAcceptedPositionExecutionStatus parked =
            drive.TryExecuteAcceptedLocalPosition(
                record,
                parkedUpdate,
                disposition,
                timestamps,
                timestamps.PreviousTeleport);
        Assert.Equal(RuntimeAcceptedPositionExecutionStatus.DeferredCell, parked);
        Assert.Equal(1, drive.PendingCount);
        ulong authorityAtPark = record.PositionAuthorityVersion;
        Vector3 positionAtPark = controller.Position;

        RuntimePlacementCancellationReceipt cancellation =
            runtime.EntityObjects.Physics.SetPosition.Forget(record);
        if (cancellation.IsValid)
        {
            runtime.EntityObjects.Physics.SetPosition
                .PublishCancellation(cancellation);
        }

        // The precondition this branch is defined by: a bare Forget cancels
        // the operation WITHOUT merging anything, so the accepted authority
        // has not moved.
        Assert.Equal(authorityAtPark, record.PositionAuthorityVersion);

        drive.Advance();

        // No re-issue: a re-issue against this still-unready destination would
        // park AGAIN and leave PendingCount at 1 (that is exactly what the
        // round-1 shape did here).
        Assert.Equal(0, drive.PendingCount);
        Assert.Equal(positionAtPark, controller.Position);
        // Round 3 (2026-08-03): the packet's placement WAS begun and then
        // died without committing, so retail's unconditional position event is
        // owed and goes out here carrying the unchanged pose
        // (SmartBox::BlipPlayer @0x00453940 discards SetPositionSimple's
        // error; SmartBox::HandleReceivedPosition @0x00453FD0 acks at
        // @0x00454091 regardless). Before round 3 this asserted Empty, which
        // encoded the defect: neither the body moved NOR an ack left.
        Assert.Single(gameActions);

        // Repeated pumps stay silent — the funnel cleared, it did not park a
        // retry marker for an authority nothing is waiting on, and retail
        // never retries a force that failed.
        drive.Advance();
        drive.Advance();
        Assert.Equal(0, drive.PendingCount);
        Assert.Single(gameActions);
        Assert.Equal(positionAtPark, controller.Position);
        AssertConverged(runtime);
    }

    /// <summary>
    /// Round 2 unified rule, branch 2 of 3 — <b>ADVANCED, newest accepted
    /// event is still a ForcePosition</b>; also the B1 regression. Exact
    /// production shape: a park wakes and its <c>Place</c> is ACCEPTED, so the
    /// operation leaves <c>_operations</c> but its completion is RETAINED;
    /// <c>Forget</c> then early-returns
    /// (<c>RuntimeSetPositionState.CancelCoreDeferred</c>'s
    /// <c>_operations.Remove</c> guard) and the retained completion survives
    /// the next packet's merge. That next ForcePosition therefore cannot
    /// begin (<c>HasRetainedCompletion</c> → <c>Contention</c>) — and before
    /// the unified funnel its correction was lost outright, because the next
    /// pump consumed the OLD completion and acked the OLD pose with nothing
    /// left pointing at the new one. The one-frame window is real on the
    /// graphical host, whose inbound dispatch precedes <c>RetryPending</c>.
    /// </summary>
    [Fact]
    public void Advanced_ReissuesWhenTheNewestAcceptedEventIsStillAForcePosition()
    {
        using StartedRuntime started = StartRuntime();
        GameRuntime runtime = started.Runtime;
        (RuntimeEntityRecord record, PlayerMovementController controller) =
            EnterLocalPlayer(runtime);
        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(runtime, out List<byte[]> gameActions);

        const uint deferredLandblock = 0x02020000u;
        var firstCorrection = new Vector3(10f, 10f, SpawnHeight);
        WorldSession.EntityPositionUpdate parkedUpdate = ForceUpdate(
            firstCorrection,
            landblockId: deferredLandblock | 0x0001u);
        (PositionTimestampDisposition parkedDisposition,
            AcceptedPhysicsTimestamps parkedTimestamps) =
            MergeAccepted(runtime, controller, parkedUpdate);
        Assert.Equal(
            PositionTimestampDisposition.ForcePosition, parkedDisposition);
        Assert.Equal(
            RuntimeAcceptedPositionExecutionStatus.DeferredCell,
            drive.TryExecuteAcceptedLocalPosition(
                record,
                parkedUpdate,
                parkedDisposition,
                parkedTimestamps,
                parkedTimestamps.PreviousTeleport));

        // The park wakes and its Place is accepted, leaving a RETAINED
        // completion. Deliberately no Advance() yet: this is the host frame in
        // which the next packet arrives before the pump runs.
        CommitLandblockCollision(runtime, deferredLandblock);
        DrainPlacementFifo(runtime);

        var secondCorrection = new Vector3(14f, 12f, SpawnHeight);
        WorldSession.EntityPositionUpdate secondUpdate = ForceUpdate(
            secondCorrection,
            landblockId: deferredLandblock | 0x0001u,
            positionSequence: 3,
            forcePositionSequence: 2);
        (PositionTimestampDisposition secondDisposition,
            AcceptedPhysicsTimestamps secondTimestamps) =
            MergeAccepted(runtime, controller, secondUpdate);
        Assert.Equal(
            PositionTimestampDisposition.ForcePosition, secondDisposition);

        Assert.Equal(
            RuntimeAcceptedPositionExecutionStatus.Contention,
            drive.TryExecuteAcceptedLocalPosition(
                record,
                secondUpdate,
                secondDisposition,
                secondTimestamps,
                secondTimestamps.PreviousTeleport));

        // One pump: consume the older completion (its own reconcile + ack),
        // then re-issue the newest accepted force — which the funnel proves by
        // landing the body on the SECOND correction, not the first.
        drive.Advance();

        Assert.Equal(0, drive.PendingCount);
        Assert.Equal(
            secondCorrection + new Vector3(192f, 192f, 0f),
            controller.Position);
        // Round 3 (2026-08-03): the former `gameActions.Count <= 2` assertion
        // was deleted here. It could not fail: this fixture's
        // CommitLandblockCollision adds BOTH landblocks at worldOffsetX/Y 0f
        // while Runtime's world frame places the deferred landblock at
        // +192/+192, so the body lands over no terrain, resolves with
        // InContact=false, and retail's own CanSendPositionEvent gate
        // suppresses every ack — gameActions.Count is 0 here. It was also far
        // too loose to encode "at most one per packet". The real
        // discriminators (body landed on the SECOND correction, PendingCount)
        // remain; the ack-count contract is pinned by
        // TerminalWithoutCommit_SendsExactlyOnePositionEventAndLeavesTheBodyUnmoved
        // and Committed_SendsExactlyOnePositionEventAcrossTheCommitAndTheSettle,
        // whose fixtures genuinely satisfy the contact gate.

        // Further pumps are no-ops: the funnel settled on the Equal branch.
        drive.Advance();
        Assert.Equal(0, drive.PendingCount);
        Assert.Equal(
            secondCorrection + new Vector3(192f, 192f, 0f),
            controller.Position);
        AssertConverged(runtime);
    }

    /// <summary>
    /// Round 2 unified rule, branch 3 of 3 — <b>ADVANCED, newest accepted
    /// event is an ordinary Apply</b> (N2). The park is cancelled by the
    /// ordinary echo's own merge-time <c>Forget</c>, and that echo — not the
    /// force — now owns the accepted pose. Re-issuing here would apply the
    /// force route's <c>Teleport|Slide</c> flags to an ordinary pose, send an
    /// ack retail never sends on that branch, and skip the <c>ConstrainTo</c>
    /// the ordinary branch runs
    /// (<c>RuntimeAuthoritativePositionRouteClassifier.cs:368-388</c>). So the
    /// funnel must clear without placing and without acking.
    /// </summary>
    [Fact]
    public void Advanced_DoesNotReissueWhenTheNewestAcceptedEventIsAnOrdinaryApply()
    {
        using StartedRuntime started = StartRuntime();
        GameRuntime runtime = started.Runtime;
        (RuntimeEntityRecord record, PlayerMovementController controller) =
            EnterLocalPlayer(runtime);
        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(runtime, out List<byte[]> gameActions);

        const uint deferredLandblock = 0x02020000u;
        WorldSession.EntityPositionUpdate parkedUpdate = ForceUpdate(
            new Vector3(10f, 10f, SpawnHeight),
            landblockId: deferredLandblock | 0x0001u);
        (PositionTimestampDisposition parkedDisposition,
            AcceptedPhysicsTimestamps parkedTimestamps) =
            MergeAccepted(runtime, controller, parkedUpdate);
        Assert.Equal(
            PositionTimestampDisposition.ForcePosition, parkedDisposition);
        Assert.Equal(
            RuntimeAcceptedPositionExecutionStatus.DeferredCell,
            drive.TryExecuteAcceptedLocalPosition(
                record,
                parkedUpdate,
                parkedDisposition,
                parkedTimestamps,
                parkedTimestamps.PreviousTeleport));
        Assert.Equal(1, drive.PendingCount);
        ulong authorityAtPark = record.PositionAuthorityVersion;
        Vector3 positionAtPark = controller.Position;

        // ACE's next ordinary broadcast, ~100-200 ms later. It merges (which
        // Forgets the park and advances the accepted authority) and is NEVER
        // dispatched to this route — both hosts gate the dispatch on
        // ForcePosition.
        var ordinaryPose = new Vector3(31f, 33f, SpawnHeight);
        (PositionTimestampDisposition ordinaryDisposition, _) = MergeAccepted(
            runtime,
            controller,
            OrdinaryUpdate(ordinaryPose, positionSequence: 3));
        Assert.Equal(PositionTimestampDisposition.Apply, ordinaryDisposition);
        Assert.NotEqual(authorityAtPark, record.PositionAuthorityVersion);

        drive.Advance();

        Assert.Equal(0, drive.PendingCount);
        // The force route never ran again: the body is exactly where the
        // cancelled park left it, and specifically NOT on the ordinary echo's
        // pose — which is what a re-issue would have placed it on, with the
        // force route's Teleport|Slide flags and no ConstrainTo.
        Assert.Equal(positionAtPark, controller.Position);
        Assert.NotEqual(ordinaryPose, controller.Position);
        // Exactly ONE AutonomousPosition, and it belongs to the FORCE packet,
        // not the ordinary echo: the force's placement was begun and died
        // without committing, which retail still acknowledges
        // (SmartBox::HandleReceivedPosition @0x00453FD0 acks @0x00454091 with
        // whatever SetPositionSimple left the body at). The ordinary echo
        // never reaches this route at all — retail's ordinary branch has no
        // unconditional SendPositionEvent. Round 3 (2026-08-03) corrected this
        // from Empty, which encoded the lost-ack defect.
        Assert.Single(gameActions);

        drive.Advance();
        Assert.Equal(0, drive.PendingCount);
        Assert.Equal(positionAtPark, controller.Position);
        Assert.Single(gameActions);
        AssertConverged(runtime);
    }

    /// <summary>
    /// N1 regression (2026-08-03): ONE server correction must produce EXACTLY
    /// one canonical placement and EXACTLY one outbound
    /// <c>AutonomousPosition</c> — never two. The round-1 shape left a dead
    /// <c>_pending</c> entry behind whenever a fresh packet's own placement
    /// committed while an older park was still tracked, and the next pump
    /// re-issued from that dead entry: a second placement and a second ack for
    /// a single correction, which is the exact duplicate-authority class
    /// <c>670f307c</c> deleted and this whole slice exists to remove.
    /// </summary>
    [Fact]
    public void OneServerCorrectionProducesExactlyOnePlacementAndOneAck()
    {
        using StartedRuntime started = StartRuntime();
        GameRuntime runtime = started.Runtime;
        (RuntimeEntityRecord record, PlayerMovementController controller) =
            EnterLocalPlayer(runtime);
        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(runtime, out List<byte[]> gameActions);

        // An earlier force parks on a landblock whose collision is not ready.
        const uint deferredLandblock = 0x02020000u;
        WorldSession.EntityPositionUpdate parkedUpdate = ForceUpdate(
            new Vector3(10f, 10f, SpawnHeight),
            landblockId: deferredLandblock | 0x0001u);
        (PositionTimestampDisposition parkedDisposition,
            AcceptedPhysicsTimestamps parkedTimestamps) =
            MergeAccepted(runtime, controller, parkedUpdate);
        Assert.Equal(
            RuntimeAcceptedPositionExecutionStatus.DeferredCell,
            drive.TryExecuteAcceptedLocalPosition(
                record,
                parkedUpdate,
                parkedDisposition,
                parkedTimestamps,
                parkedTimestamps.PreviousTeleport));
        Assert.Equal(1, drive.PendingCount);
        Assert.Empty(gameActions);

        // THE one server correction under test: a second force, into the
        // already-ready spawn landblock, so it commits synchronously. Its
        // merge Forgets the park.
        var corrected = new Vector3(30f, 32f, SpawnHeight);
        WorldSession.EntityPositionUpdate correction = ForceUpdate(
            corrected,
            positionSequence: 3,
            forcePositionSequence: 2);
        (PositionTimestampDisposition disposition, AcceptedPhysicsTimestamps timestamps) =
            MergeAccepted(runtime, controller, correction);
        Assert.Equal(PositionTimestampDisposition.ForcePosition, disposition);

        Assert.Equal(
            RuntimeAcceptedPositionExecutionStatus.Committed,
            drive.TryExecuteAcceptedLocalPosition(
                record,
                correction,
                disposition,
                timestamps,
                timestamps.PreviousTeleport));

        Assert.Equal(0, drive.PendingCount);
        Assert.Single(gameActions);
        Assert.Equal(corrected, controller.Position);
        ulong placementsAfterCorrection = record.PlacementCommitVersion;

        // Every subsequent pump must be a no-op. Before the fix the FIRST of
        // these re-issued the dead park entry: PlacementCommitVersion advanced
        // again and a SECOND AutonomousPosition left for the same correction.
        drive.Advance();
        drive.Advance();

        Assert.Equal(0, drive.PendingCount);
        Assert.Single(gameActions);
        Assert.Equal(corrected, controller.Position);
        Assert.Equal(placementsAfterCorrection, record.PlacementCommitVersion);
        AssertConverged(runtime);
    }

    /// <summary>
    /// Round 3 blocker (2026-08-03) — <b>the terminal-without-commit ack</b>.
    /// Retail attempts the placement, and if it fails the body simply does not
    /// move — but the packet is acknowledged regardless and never retried:
    /// <c>SmartBox::BlipPlayer</c> @0x00453940 calls
    /// <c>CPhysicsObj::SetPositionSimple</c> @0x005162B0, which returns an
    /// <c>enum SetPositionError</c> that other retail sites test
    /// (<c>== OK_SPE</c> @0x0055605D) and that <c>BlipPlayer</c> DISCARDS;
    /// <c>BlipPlayer</c> returns <c>void</c>, and its caller
    /// <c>SmartBox::HandleReceivedPosition</c> @0x00453FD0 then runs
    /// <c>cmdinterp-&gt;SendPositionEvent()</c> @0x00454091 unconditionally
    /// before returning @0x0045409D.
    ///
    /// Unlike
    /// <see cref="Equal_ClearsPendingWithoutReissuingWhenNoNewerAcceptedAuthorityArrived"/>
    /// (whose subject is the no-re-issue decision) this test's subject is the
    /// ack contract itself: EXACTLY one outbound <c>AutonomousPosition</c> for
    /// the failed packet, carrying whatever pose the retired operation left
    /// behind, with no further placement performed by the settle. Before round
    /// 3 this path sent zero — the correction never took AND the server was
    /// never told it had not taken.
    /// </summary>
    [Fact]
    public void TerminalWithoutCommit_SendsExactlyOnePositionEventAndLeavesTheBodyUnmoved()
    {
        using StartedRuntime started = StartRuntime();
        GameRuntime runtime = started.Runtime;
        (RuntimeEntityRecord record, PlayerMovementController controller) =
            EnterLocalPlayer(runtime);
        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(runtime, out List<byte[]> gameActions);

        // The body sits on the spawn landblock's flat terrain, so retail's own
        // CanSendPositionEvent admission (Contact + OnWalkable) is genuinely
        // satisfied — this fixture can observe the ack rather than silently
        // measuring a suppression.
        Assert.True(controller.CanSendPositionEvent);

        // A force whose destination landblock has no published collision
        // generation parks instead of committing.
        const uint deferredLandblock = 0x02020000u;
        WorldSession.EntityPositionUpdate correction = ForceUpdate(
            new Vector3(10f, 10f, SpawnHeight),
            landblockId: deferredLandblock | 0x0001u);
        (PositionTimestampDisposition disposition, AcceptedPhysicsTimestamps timestamps) =
            MergeAccepted(runtime, controller, correction);
        Assert.Equal(PositionTimestampDisposition.ForcePosition, disposition);
        Assert.Equal(
            RuntimeAcceptedPositionExecutionStatus.DeferredCell,
            drive.TryExecuteAcceptedLocalPosition(
                record,
                correction,
                disposition,
                timestamps,
                timestamps.PreviousTeleport));

        // Measured, not assumed: this park happens AFTER
        // `_physics.Engine.SetPosition` has already run, so the canonical body
        // already sits at the destination while the placement itself is
        // withdrawn and parked. Specifically it is the engine-result deferral
        // (RuntimeSetPositionState.cs, the park taken once `operation.Result`
        // has been assigned) — NOT either `TryGetBlockingQuiescence` branch:
        // `_collisionPrefixQuiescence` is populated only by
        // `BeginCollisionPrefixQuiescence`, and this fixture's
        // `CommitLandblockCollision` calls `BeginCollisionGeneration` instead,
        // so that map is empty and both quiescence branches are unreachable
        // here. Same side of the engine call either way; the distinction only
        // matters so a future reader does not go looking in the wrong branch.
        // The subject of this test is the TERMINAL SETTLE, so the
        // unmoved/no-further-placement baselines are captured here, at the park.
        Vector3 poseAtPark = controller.Position;
        ulong placementVersionAtPark = record.PlacementCommitVersion;

        // Nothing has been acknowledged yet: retail's ack follows BlipPlayer,
        // and the placement has not reached any terminal outcome.
        Assert.Empty(gameActions);

        // The park is retired without ever committing — the exact
        // RuntimeSetPositionState.Forget funnel every mid-session cancellation
        // shares (supersession, the lost-cell deadline, ParkCollisionResidents,
        // a generation change).
        RuntimePlacementCancellationReceipt cancellation =
            runtime.EntityObjects.Physics.SetPosition.Forget(record);
        if (cancellation.IsValid)
        {
            runtime.EntityObjects.Physics.SetPosition
                .PublishCancellation(cancellation);
        }

        drive.Advance();

        // Retail's two simultaneous facts at @0x0045409D: the placement did
        // not take (the settle performs no placement of its own — the body is
        // exactly where the retired operation left it and no further
        // placement committed), and the position event went out anyway,
        // carrying that unchanged pose. Before round 3 this path sent zero.
        Assert.Equal(poseAtPark, controller.Position);
        Assert.Equal(placementVersionAtPark, record.PlacementCommitVersion);
        Assert.Single(gameActions);
        Assert.Equal(0, drive.PendingCount);

        // Retail never retries a force whose placement failed, so no further
        // pump may place OR acknowledge anything more for this packet.
        drive.Advance();
        drive.Advance();
        Assert.Single(gameActions);
        Assert.Equal(poseAtPark, controller.Position);
        Assert.Equal(placementVersionAtPark, record.PlacementCommitVersion);
        AssertConverged(runtime);
    }

    /// <summary>
    /// Round 3 companion invariant (2026-08-03): the terminal-without-commit
    /// ack must not become a SECOND ack on the committed path. A commit runs
    /// <c>ReconcileAndAcknowledge</c> and then immediately settles through the
    /// same funnel, so a funnel that acknowledged unconditionally would send
    /// two <c>AutonomousPosition</c> messages for one server correction — the
    /// exact duplicate-ack class <c>670f307c</c> deleted. Retail sends exactly
    /// one per handled packet (<c>SmartBox::HandleReceivedPosition</c>
    /// @0x00453FD0 reaches <c>SendPositionEvent</c> @0x00454091 once, then
    /// returns @0x0045409D).
    /// </summary>
    [Fact]
    public void Committed_SendsExactlyOnePositionEventAcrossTheCommitAndTheSettle()
    {
        using StartedRuntime started = StartRuntime();
        GameRuntime runtime = started.Runtime;
        (RuntimeEntityRecord record, PlayerMovementController controller) =
            EnterLocalPlayer(runtime);
        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(runtime, out List<byte[]> gameActions);

        // Within the already-published spawn landblock, so the placement
        // commits synchronously AND the contact gate admits the ack.
        var corrected = new Vector3(30f, 32f, SpawnHeight);
        WorldSession.EntityPositionUpdate correction = ForceUpdate(corrected);
        (PositionTimestampDisposition disposition, AcceptedPhysicsTimestamps timestamps) =
            MergeAccepted(runtime, controller, correction);
        Assert.Equal(PositionTimestampDisposition.ForcePosition, disposition);

        Assert.Equal(
            RuntimeAcceptedPositionExecutionStatus.Committed,
            drive.TryExecuteAcceptedLocalPosition(
                record,
                correction,
                disposition,
                timestamps,
                timestamps.PreviousTeleport));

        // One commit, one ack — not two. The settle that runs immediately
        // after the commit must recognise the ack already left.
        Assert.Equal(corrected, controller.Position);
        Assert.Single(gameActions);
        Assert.Equal(0, drive.PendingCount);

        drive.Advance();
        drive.Advance();
        Assert.Single(gameActions);
        AssertConverged(runtime);
    }

    /// <summary>
    /// C4 route 4b-2, round-3 correction A2 (test 1 of 2) — the LOCAL PLAYER
    /// traverses the shared-core quiescence-park change, on the shape that is
    /// actually reachable through this route.
    ///
    /// <para>
    /// <b>Reachability, measured rather than assumed.</b> The correction asked
    /// for a park under a quiescing SOURCE, reached through
    /// <c>PlacementTouchesPrefix</c>'s <c>CurrentCellId</c> arm. That shape is
    /// not constructible: the merge this route requires
    /// (<c>RuntimeEntityObjectLifetime.TryApplyPosition</c>) commits the
    /// accepted wire cell to <c>record.FullCellId</c> BEFORE the drive is
    /// called, and <c>CurrentCellId</c> is read from that field — so by submit
    /// time it names the DESTINATION, not the landblock being left. The
    /// reachable pre-sweep shape is therefore a quiescing destination; the
    /// reachable post-sweep shape is a quiescing swept neighbour, which is the
    /// sibling test below.
    /// </para>
    ///
    /// <para>
    /// A quiescing destination is the one shape where the rollback genuinely
    /// would re-admit a spatial root into the prefix that is trying to
    /// quiesce, so <c>ParkDeferred</c> declines it — AP-136's stated reason,
    /// applied to the cell the restore would actually use. Route 2 has no
    /// destination pre-flight of its own (unlike the remote far arm's
    /// <c>CanAttemptDestination</c>), so it reaches this unmasked.
    /// </para>
    /// </summary>
    [Fact]
    public void QuiescingDestinationPrefix_ForcePositionParkIsNotRestored()
    {
        using StartedRuntime started = StartRuntime();
        GameRuntime runtime = started.Runtime;
        (RuntimeEntityRecord record, PlayerMovementController controller) =
            EnterLocalPlayer(runtime);
        PhysicsBody body = Assert.IsType<PhysicsBody>(record.PhysicsBody);
        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(runtime, out _);

        runtime.EntityObjects.Physics.SetPosition.BeginCollisionPrefixQuiescence(
            DestinationLandblock,
            collisionGeneration: 2UL,
            includeOutdoorCells: true);

        WorldSession.EntityPositionUpdate correction = ForceUpdate(
            new Vector3(10f, 10f, SpawnHeight),
            landblockId: DestinationLandblock | 0x0001u);
        (PositionTimestampDisposition disposition, AcceptedPhysicsTimestamps timestamps) =
            MergeAccepted(runtime, controller, correction);
        Assert.Equal(PositionTimestampDisposition.ForcePosition, disposition);

        Assert.Equal(
            RuntimeAcceptedPositionExecutionStatus.DeferredCell,
            drive.TryExecuteAcceptedLocalPosition(
                record,
                correction,
                disposition,
                timestamps,
                timestamps.PreviousTeleport));
        Assert.False(body.InWorld);

        // ACE's next ordinary broadcast, ~100-200 ms later. Its merge-time
        // Forget cancels the park — and the rollback must decline, because the
        // only cell it could restore into is the retiring one.
        MergeAccepted(
            runtime,
            controller,
            OrdinaryUpdate(new Vector3(31f, 33f, SpawnHeight), positionSequence: 3));

        Assert.False(runtime.EntityObjects.Physics.IsSpatialRoot(record));
        Assert.False(body.InWorld);
        Assert.False(record.ObjectClock.IsActive);

        drive.Advance();
        Assert.Equal(0, drive.PendingCount);
        AssertConverged(runtime);
    }

    /// <summary>
    /// C4 route 4b-2, round-3 correction A2 (test 2 of 2) — the reachable
    /// RESTORABLE quiescence park on the local-player route.
    ///
    /// <para>
    /// The correction is placed one sphere radius inside the seam between
    /// <see cref="SpawnLandblock"/> and its +X neighbour, so
    /// <c>CellTransit.AddAllOutsideCells</c> adds the neighbour's cells to the
    /// sweep footprint (<c>AddOutsideCell</c> re-derives the block id from the
    /// global lcoord and has no same-block filter). Core's
    /// <c>ResultTouchesPrefix</c> scans every <c>QueriedCellIds</c> entry, so
    /// a healthy, resident, about-to-COMMIT ForcePosition is rewritten to
    /// <c>DeferredCell</c> by a quiescence in a landblock the player is
    /// neither in nor going to.
    /// </para>
    ///
    /// <para>
    /// Before the shared-core change every quiescence park was non-restorable,
    /// so the next packet's merge-time <c>Forget</c> destroyed the only
    /// operation able to wake the player and left it <c>InWorld = false</c>,
    /// clock suspended, not a spatial root — session-permanent, because
    /// nothing else restores that state. The three asserts at the end are that
    /// defect. Restoring is safe here for the reason
    /// <c>ParkDeferred</c> tests directly: the cell it would restore into is
    /// the destination, and the destination is not quiescing.
    /// </para>
    /// </summary>
    [Fact]
    public void QuiescingSweptNeighbour_ForcePositionParkIsRestoredByTheNextPacket()
    {
        using StartedRuntime started = StartRuntime();
        GameRuntime runtime = started.Runtime;
        (RuntimeEntityRecord record, PlayerMovementController controller) =
            EnterLocalPlayer(runtime);
        CommitLandblockCollision(
            runtime, NeighbourLandblock, worldOffsetX: 192f);
        PhysicsBody body = Assert.IsType<PhysicsBody>(record.PhysicsBody);
        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(runtime, out _);

        runtime.EntityObjects.Physics.SetPosition.BeginCollisionPrefixQuiescence(
            NeighbourLandblock,
            collisionGeneration: 2UL,
            includeOutdoorCells: true);
        // Neither the source nor the destination is quiescing — the whole
        // point of the shape.
        Assert.False(
            runtime.EntityObjects.Physics.SetPosition.IsCollisionPrefixQuiescing(
                SpawnLandblock));

        // Block-local X = 191.95 m: inside cell (7, 0), 0.05 m from the 192 m
        // seam, well inside the local player's own sphere radius, which is the
        // `pointX > CellLength - radius` test AddAllOutsideCells applies
        // before adding lx + 1.
        WorldSession.EntityPositionUpdate correction = ForceUpdate(
            new Vector3(191.95f, 10f, SpawnHeight),
            landblockId: SpawnSeamCell);
        (PositionTimestampDisposition disposition, AcceptedPhysicsTimestamps timestamps) =
            MergeAccepted(runtime, controller, correction);
        Assert.Equal(PositionTimestampDisposition.ForcePosition, disposition);

        Assert.Equal(
            RuntimeAcceptedPositionExecutionStatus.DeferredCell,
            drive.TryExecuteAcceptedLocalPosition(
                record,
                correction,
                disposition,
                timestamps,
                timestamps.PreviousTeleport));
        Assert.False(body.InWorld);

        MergeAccepted(
            runtime,
            controller,
            OrdinaryUpdate(new Vector3(31f, 33f, SpawnHeight), positionSequence: 3));

        Assert.True(body.InWorld);
        Assert.True(record.ObjectClock.IsActive);
        Assert.True(runtime.EntityObjects.Physics.IsSpatialRoot(record));

        drive.Advance();
        Assert.Equal(0, drive.PendingCount);
        AssertConverged(runtime);
    }

    /// <summary>
    /// C4 route 4b-2, round-4 correction (the MAJOR) — the DISCRIMINATING
    /// test. Round 3 relocated the restorable-park decision out of the two
    /// <c>SubmitPreparedPlacementCore</c> call sites and into
    /// <c>ParkDeferred</c>, but nothing in the tree distinguished the new
    /// predicate from the one it replaced. This does.
    ///
    /// <para>
    /// <b>Round 2's form</b> compared the blocking quiescence's own token
    /// against the caller's pre-snap cell:
    /// <c>blockingToken.LandblockPrefix != (result.CellId &amp; 0xFFFF0000)</c>.
    /// <b>Round 3's form</b> tests the POST-snap cell against every live
    /// quiescence: <c>!IsCollisionPrefixQuiescing(body.CellPosition.ObjCellId)</c>.
    /// Under round 2 this test's player is left withdrawn — <c>InWorld</c>
    /// false, clock suspended, not a spatial root — for the rest of the
    /// session. That is the exact stranding AP-136's rollback exists to
    /// prevent, and it is reached without a second quiescence, purely because
    /// the two forms read different cells.
    /// </para>
    ///
    /// <para>
    /// <b>The shape.</b> The server names a cell in the player's OWN
    /// landblock but supplies a block-local X 5 cm PAST that block's 192 m
    /// seam. A wire (cell, position) pair that disagrees is exactly the pair
    /// <c>PhysicsBody.StageDormantCellFrame</c>'s
    /// <c>LandDefs.AdjustToOutside</c> exists to distrust (#107: "never trust
    /// a server (cell, pos) pair without re-deriving the cell"), and
    /// <c>AdjustToOutside</c>'s own contract says the re-derived id may
    /// belong to a NEIGHBOUR landblock — which is what happens here. So the
    /// prefix the placement PARKED against (the player's own, mid-retirement)
    /// and the prefix residency would be RESTORED into (the healthy
    /// neighbour) are different landblocks, and only the second one is the
    /// question <c>RestoreParkWithdrawal</c> actually asks.
    /// </para>
    ///
    /// <para>
    /// Route 2 is the home for it because it has no destination pre-flight:
    /// the remote far arm's <c>CanAttemptDestination</c> refuses a quiescing
    /// destination before any park is opened, so this park is unreachable
    /// there.
    /// </para>
    /// </summary>
    [Fact]
    public void QuiescingOwnPrefix_SeamCrossingParkIsRestoredAtTheReDerivedNeighbourCell()
    {
        using StartedRuntime started = StartRuntime();
        GameRuntime runtime = started.Runtime;
        (RuntimeEntityRecord record, PlayerMovementController controller) =
            EnterLocalPlayer(runtime);
        PhysicsBody body = Assert.IsType<PhysicsBody>(record.PhysicsBody);
        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(runtime, out _);

        // Streaming begins retiring/republishing the player's OWN landblock,
        // which is also the landblock the wire cell names.
        runtime.EntityObjects.Physics.SetPosition.BeginCollisionPrefixQuiescence(
            SpawnLandblock,
            collisionGeneration: 2UL,
            includeOutdoorCells: true);

        // Cell (7, 0) of SpawnLandblock covers block-local X in [168, 192).
        // 192.05 m is 5 cm past its block's own seam, so AdjustToOutside
        // re-derives lx = 8 + floor(192.05 / 24) = 16, i.e. block X index 2,
        // and LcoordToGid rebuilds the id as NeighbourLandblock | 1.
        WorldSession.EntityPositionUpdate correction = ForceUpdate(
            new Vector3(192.05f, 10f, SpawnHeight),
            landblockId: SpawnSeamCell);
        (PositionTimestampDisposition disposition, AcceptedPhysicsTimestamps timestamps) =
            MergeAccepted(runtime, controller, correction);
        Assert.Equal(PositionTimestampDisposition.ForcePosition, disposition);

        Assert.Equal(
            RuntimeAcceptedPositionExecutionStatus.DeferredCell,
            drive.TryExecuteAcceptedLocalPosition(
                record,
                correction,
                disposition,
                timestamps,
                timestamps.PreviousTeleport));
        Assert.False(body.InWorld);

        // The two cells the two predicate forms read are DIFFERENT
        // landblocks, and only the quiescing one is the caller's.
        Assert.Equal(SpawnLandblock, correction.Position.LandblockId & 0xFFFF0000u);
        Assert.Equal(
            NeighbourLandblock,
            body.CellPosition.ObjCellId & 0xFFFF0000u);
        Assert.False(
            runtime.EntityObjects.Physics.SetPosition.IsCollisionPrefixQuiescing(
                NeighbourLandblock));

        // ACE's next ordinary broadcast cancels the park at merge time.
        MergeAccepted(
            runtime,
            controller,
            OrdinaryUpdate(new Vector3(31f, 33f, SpawnHeight), positionSequence: 3));

        // Restored, because the cell residency is restored INTO is healthy.
        // All three of these fail under round 2's single-token form.
        Assert.True(body.InWorld);
        Assert.True(record.ObjectClock.IsActive);
        Assert.True(runtime.EntityObjects.Physics.IsSpatialRoot(record));

        drive.Advance();
        Assert.Equal(0, drive.PendingCount);
        AssertConverged(runtime);
    }

    /// <summary>
    /// C4 route 4b-2, round-4 correction D6 — the restorable decision is
    /// re-tested at RESTORE time, not only at park time.
    ///
    /// <para>
    /// <c>ParkDeferred</c>'s decision is a snapshot. The far snap cancels its
    /// park synchronously, so that snapshot cannot go stale; route 2's park is
    /// RETAINED (<c>AwaitingCommitWake</c>) and the restore lands on the next
    /// packet's merge-time <c>Forget</c>, ~150 ms later at ACE's 5-10 Hz.
    /// Streaming opens a quiescence per landblock mutation, so the cell the
    /// rollback would restore into can start quiescing inside that window.
    /// </para>
    ///
    /// <para>
    /// This drives exactly that: a swept-NEIGHBOUR quiescence parks a
    /// placement whose destination is healthy (so the park IS restorable when
    /// taken), then the destination's own prefix begins quiescing before the
    /// next packet. The restore must decline — otherwise it re-admits a
    /// spatial root into a prefix that is trying to retire, which is AP-136's
    /// stated reason verbatim. The entity self-heals on a later packet, so
    /// declining here is strictly the conservative half.
    /// </para>
    /// </summary>
    [Fact]
    public void QuiescenceOpenedAfterTheParkDeclinesTheRestoreAtMergeTime()
    {
        using StartedRuntime started = StartRuntime();
        GameRuntime runtime = started.Runtime;
        (RuntimeEntityRecord record, PlayerMovementController controller) =
            EnterLocalPlayer(runtime);
        CommitLandblockCollision(
            runtime, NeighbourLandblock, worldOffsetX: 192f);
        PhysicsBody body = Assert.IsType<PhysicsBody>(record.PhysicsBody);
        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(runtime, out _);

        runtime.EntityObjects.Physics.SetPosition.BeginCollisionPrefixQuiescence(
            NeighbourLandblock,
            collisionGeneration: 2UL,
            includeOutdoorCells: true);

        WorldSession.EntityPositionUpdate correction = ForceUpdate(
            new Vector3(191.95f, 10f, SpawnHeight),
            landblockId: SpawnSeamCell);
        (PositionTimestampDisposition disposition, AcceptedPhysicsTimestamps timestamps) =
            MergeAccepted(runtime, controller, correction);
        Assert.Equal(PositionTimestampDisposition.ForcePosition, disposition);

        Assert.Equal(
            RuntimeAcceptedPositionExecutionStatus.DeferredCell,
            drive.TryExecuteAcceptedLocalPosition(
                record,
                correction,
                disposition,
                timestamps,
                timestamps.PreviousTeleport));
        Assert.False(body.InWorld);
        // The park WAS restorable when it was taken: the destination prefix
        // was clean. (Its sibling test above asserts the restore that follows
        // from exactly this state.)
        Assert.Equal(
            SpawnLandblock,
            body.CellPosition.ObjCellId & 0xFFFF0000u);

        // …and now streaming retires that very landblock, mid-park.
        runtime.EntityObjects.Physics.SetPosition.BeginCollisionPrefixQuiescence(
            SpawnLandblock,
            collisionGeneration: 3UL,
            includeOutdoorCells: true);

        MergeAccepted(
            runtime,
            controller,
            OrdinaryUpdate(new Vector3(31f, 33f, SpawnHeight), positionSequence: 3));

        Assert.False(runtime.EntityObjects.Physics.IsSpatialRoot(record));

        drive.Advance();
        Assert.Equal(0, drive.PendingCount);
        AssertConverged(runtime);
    }

    #region C4 route 3 - portal arm

    /// <summary>
    /// The main D-T2/D-T3 happy path, asserting the positive facts §8 item 2
    /// requires rather than only <c>InWorld</c>/clock: the body moved to the
    /// resolved destination, velocity zeroed (retail
    /// <c>set_velocity(player, 0, 1)</c> @0x004541B4), the leash re-armed
    /// EXACTLY ONCE at the resolved position (Inversion A — proven by
    /// pre-arming at a stale anchor first, so a stale anchor surviving would
    /// fail the assertion), autorun cancelled (the <c>PlayerTeleported</c>
    /// port), and exactly one outbound movement event with ZERO
    /// AutonomousPosition packets (route's <c>SendPositionImmediately</c> is
    /// always false).
    /// </summary>
    /// <summary>
    /// R7 review fix (2026-08-05): retail <c>CommandInterpreter::SendMovementEvent</c>
    /// @0x006B4680 (<c>PlayerTeleported</c>'s tail-jump) gates on
    /// <c>autonomy_level != 0</c> — under server control (this class's
    /// <c>_usePositionFromServer</c>, retail's <c>UsePositionFromServer()</c>)
    /// retail sends nothing. Everything else about the commit (body move,
    /// leash re-arm, autorun cancel) is unaffected by autonomy; only the
    /// wire send is gated.
    /// </summary>
    [Fact]
    public void PortalCommitted_UnderServerControlSendsNoMovementEvent()
    {
        using StartedRuntime started = StartRuntime();
        GameRuntime runtime = started.Runtime;
        (RuntimeEntityRecord record, PlayerMovementController controller) =
            EnterLocalPlayer(runtime);
        Assert.True(runtime.CharacterOwner.TrySetAutonomyLevel(0u));
        Assert.True(runtime.CharacterOwner.UsePositionFromServer);

        const ushort teleportSequence = 6;
        var destinationPosition = new Vector3(31f, 33f, SpawnHeight);
        WorldSession.EntityPositionUpdate destinationUpdate = PortalDestinationUpdate(
            destinationPosition, SpawnLandblock | 0x0001u, teleportSequence);
        MergeAccepted(runtime, controller, destinationUpdate);
        (RuntimePortalPlacementAuthority portal, RuntimeTeleportDestination destination) =
            BeginPortal(runtime, SpawnLandblock | 0x0001u, teleportSequence, destinationUpdate);
        // B8/A8 review fix: guarantees ConvergePortalHost runs even if an
        // assertion below fails first - see PortalHostConvergenceGuard's doc.
        using var portalHostGuard = new PortalHostConvergenceGuard(
            runtime, portal.RevealGeneration, portal.Projection);
        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(runtime, out List<byte[]> gameActions);

        RuntimeAcceptedPositionExecutionStatus status =
            drive.TryExecuteAcceptedPortalArrival(destination, portal);

        Assert.Equal(RuntimeAcceptedPositionExecutionStatus.Committed, status);
        Assert.Equal(destinationPosition, controller.Position);
        Assert.False(runtime.MovementOwner.AutoRunActive);
        Assert.Empty(gameActions);
        ConvergePortalHost(runtime, portal.RevealGeneration, portal.Projection);
        AssertConverged(runtime);
    }

    [Fact]
    public void PortalCommitted_MovesBodyArmsLeashOnceCancelsAutorunAndSendsExactlyOneMovementEvent()
    {
        using StartedRuntime started = StartRuntime();
        GameRuntime runtime = started.Runtime;
        (RuntimeEntityRecord record, PlayerMovementController controller) =
            EnterLocalPlayer(runtime);

        // Pre-arm the leash at a STALE anchor - a re-arm that merely leaves
        // the OLD anchor in place (i.e. no re-arm at all) would fail the
        // ConstraintPos assertion below.
        var staleAnchor = new Position(
            SpawnLandblock | 0x0001u,
            new Vector3(1f, 1f, SpawnHeight),
            Quaternion.Identity);
        controller.PositionManager!.ConstrainTo(staleAnchor, 1f, 2f);
        Assert.True(controller.PositionManager.Constraint!.IsConstrained);

        runtime.MovementOwner.Execute(RuntimeMovementCommand.ToggleRunLock);
        Assert.True(runtime.MovementOwner.AutoRunActive);

        const ushort teleportSequence = 5;
        var destinationPosition = new Vector3(30f, 32f, SpawnHeight);
        WorldSession.EntityPositionUpdate destinationUpdate = PortalDestinationUpdate(
            destinationPosition, SpawnLandblock | 0x0001u, teleportSequence);
        (PositionTimestampDisposition disposition, AcceptedPhysicsTimestamps timestamps) =
            MergeAccepted(runtime, controller, destinationUpdate);
        Assert.Equal(PositionTimestampDisposition.Apply, disposition);
        Assert.True(timestamps.TeleportAdvanced);

        (RuntimePortalPlacementAuthority portal, RuntimeTeleportDestination destination) =
            BeginPortal(runtime, SpawnLandblock | 0x0001u, teleportSequence, destinationUpdate);
        // B8/A8 review fix: guarantees ConvergePortalHost runs even if an
        // assertion below fails first - see PortalHostConvergenceGuard's doc.
        using var portalHostGuard = new PortalHostConvergenceGuard(
            runtime, portal.RevealGeneration, portal.Projection);
        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(runtime, out List<byte[]> gameActions);

        RuntimeAcceptedPositionExecutionStatus status =
            drive.TryExecuteAcceptedPortalArrival(destination, portal);

        Assert.Equal(RuntimeAcceptedPositionExecutionStatus.Committed, status);
        Assert.Equal(destinationPosition, controller.Position);
        Assert.Equal(Vector3.Zero, controller.BodyVelocity);
        Assert.True(controller.PositionManager.Constraint!.IsConstrained);
        Assert.Equal(
            controller.Position,
            controller.PositionManager.Constraint.ConstraintPos.Frame.Origin);
        Assert.False(runtime.MovementOwner.AutoRunActive);
        // Exactly one outbound wire packet total: the movement-event refresh.
        // Zero AutonomousPosition - the portal route never sends one.
        Assert.Single(gameActions);
        ConvergePortalHost(runtime, portal.RevealGeneration, portal.Projection);
        AssertConverged(runtime);
    }

    /// <summary>
    /// D-T1's own safety property, proved live: a portal authority whose
    /// generation the transit no longer recognizes (this generation was
    /// never begun) is structurally invalid, so the arm returns
    /// <c>NotApplicable</c> without writing anything - the D-T5 refusal
    /// shape. A superseded token is unobtainable by construction; this
    /// exercises the same <c>IsValid</c> gate a stale re-derivation would
    /// fail on.
    /// </summary>
    [Fact]
    public void PortalProducerInvalidAuthority_ArmDoesNotRunAndNothingMutates()
    {
        using StartedRuntime started = StartRuntime();
        GameRuntime runtime = started.Runtime;
        (RuntimeEntityRecord record, PlayerMovementController controller) =
            EnterLocalPlayer(runtime);
        Vector3 positionBefore = controller.Position;
        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(runtime, out List<byte[]> gameActions);

        var destination = new RuntimeTeleportDestination(
            PlayerGuid,
            InstanceSequence: 1,
            PositionSequence: 2,
            TeleportSequence: 5,
            ForcePositionSequence: 0,
            new Position(
                SpawnLandblock | 0x0001u,
                new Vector3(30f, 32f, SpawnHeight),
                Quaternion.Identity));
        // Present but structurally invalid: RevealGeneration 0 fails
        // RuntimePortalPlacementAuthority.IsValid outright - the exact shape
        // a stale-generation TryRegisterHostProjection re-derivation refusal
        // would leave the producer holding (default).
        var invalidAuthority = new RuntimePortalPlacementAuthority(
            Present: true,
            RevealGeneration: 0,
            TeleportSequence: 5,
            Projection: default);

        RuntimeAcceptedPositionExecutionStatus status =
            drive.TryExecuteAcceptedPortalArrival(destination, invalidAuthority);

        Assert.Equal(RuntimeAcceptedPositionExecutionStatus.NotApplicable, status);
        Assert.Equal(positionBefore, controller.Position);
        Assert.Empty(gameActions);
        AssertConverged(runtime);
    }

    /// <summary>
    /// D-T5's genuinely new edge: transit pins the FIRST accepted
    /// destination per generation, while <c>BeginAcceptedPlacementCore</c>
    /// validates the portal's destination cell against the LATEST merged
    /// snapshot. A second local Position merging a DIFFERENT landblock
    /// between the offer and the Place edge makes Begin refuse. Positive
    /// half: nothing mutates and the transit stays exactly as it was
    /// (D-T5's "no half-state" invariant).
    /// </summary>
    [Fact]
    public void PortalBeginCellMismatch_RefusesWithoutMutatingBodyOrTransit()
    {
        using StartedRuntime started = StartRuntime();
        GameRuntime runtime = started.Runtime;
        (RuntimeEntityRecord record, PlayerMovementController controller) =
            EnterLocalPlayer(runtime);

        const ushort teleportSequence = 6;
        var destinationPosition = new Vector3(30f, 32f, SpawnHeight);
        WorldSession.EntityPositionUpdate destinationUpdate = PortalDestinationUpdate(
            destinationPosition, SpawnLandblock | 0x0001u, teleportSequence);
        MergeAccepted(runtime, controller, destinationUpdate);
        (RuntimePortalPlacementAuthority portal, RuntimeTeleportDestination destination) =
            BeginPortal(runtime, SpawnLandblock | 0x0001u, teleportSequence, destinationUpdate);
        // B8/A8 review fix: guarantees ConvergePortalHost runs even if an
        // assertion below fails first - see PortalHostConvergenceGuard's doc.
        using var portalHostGuard = new PortalHostConvergenceGuard(
            runtime, portal.RevealGeneration, portal.Projection);

        // A SECOND local Position merges a DIFFERENT landblock after the
        // portal offer/registration but before Place - record.Snapshot's
        // latest accepted position no longer matches the portal's
        // destination cell. SAME teleport sequence (an ordinary in-flight
        // Apply, not a fresh teleport) so PhysicsTimestampGate admits it.
        const uint otherLandblock = 0x02020000u;
        (PositionTimestampDisposition secondDisposition, _) = MergeAccepted(
            runtime,
            controller,
            PortalDestinationUpdate(
                new Vector3(1f, 1f, SpawnHeight),
                otherLandblock | 0x0001u,
                teleportSequence,
                positionSequence: 3));
        Assert.Equal(PositionTimestampDisposition.Apply, secondDisposition);
        Vector3 positionBefore = controller.Position;
        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(runtime, out List<byte[]> gameActions);

        RuntimeAcceptedPositionExecutionStatus status =
            drive.TryExecuteAcceptedPortalArrival(destination, portal);

        Assert.Equal(RuntimeAcceptedPositionExecutionStatus.Contention, status);
        Assert.Equal(positionBefore, controller.Position);
        Assert.Empty(gameActions);
        // The transit is untouched by the refusal - still active, still
        // holding the SAME accepted destination, not cancelled.
        Assert.True(runtime.TransitOwner.IsTeleportActive);
        Assert.False(runtime.TransitOwner.Snapshot.Cancelled);
        ConvergePortalHost(runtime, portal.RevealGeneration, portal.Projection);
        AssertConverged(runtime);
    }

    [Fact]
    public void PortalContention_WhenTheEntityAlreadyOwnsAnActiveOperation()
    {
        using StartedRuntime started = StartRuntime();
        GameRuntime runtime = started.Runtime;
        (RuntimeEntityRecord record, PlayerMovementController controller) =
            EnterLocalPlayer(runtime);
        Vector3 positionBefore = controller.Position;

        const ushort teleportSequence = 7;
        WorldSession.EntityPositionUpdate destinationUpdate = PortalDestinationUpdate(
            new Vector3(30f, 32f, SpawnHeight), SpawnLandblock | 0x0001u, teleportSequence);
        MergeAccepted(runtime, controller, destinationUpdate);
        (RuntimePortalPlacementAuthority portal, RuntimeTeleportDestination destination) =
            BeginPortal(runtime, SpawnLandblock | 0x0001u, teleportSequence, destinationUpdate);
        // B8/A8 review fix: guarantees ConvergePortalHost runs even if an
        // assertion below fails first - see PortalHostConvergenceGuard's doc.
        using var portalHostGuard = new PortalHostConvergenceGuard(
            runtime, portal.RevealGeneration, portal.Projection);

        RuntimeEntityPlacementToken displaced = runtime.EntityObjects.Physics
            .SetPosition.TryBeginExclusiveAuthoredPlacement(
                record,
                record.PositionAuthorityVersion,
                RuntimeSetPositionOperationKind.LocalAuthoritative);
        Assert.True(displaced.IsValid);
        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(runtime, out List<byte[]> gameActions);

        RuntimeAcceptedPositionExecutionStatus status =
            drive.TryExecuteAcceptedPortalArrival(destination, portal);

        Assert.Equal(RuntimeAcceptedPositionExecutionStatus.Contention, status);
        Assert.Equal(positionBefore, controller.Position);
        Assert.Empty(gameActions);

        RuntimePlacementCancellationReceipt cancellation = runtime.EntityObjects
            .Physics.SetPosition.ForgetExactPlacement(displaced);
        if (cancellation.IsValid)
        {
            runtime.EntityObjects.Physics.SetPosition
                .PublishCancellation(cancellation);
        }
        ConvergePortalHost(runtime, portal.RevealGeneration, portal.Projection);
        AssertConverged(runtime);
    }

    /// <summary>
    /// D-T2.4: a portal DeferredCell park reuses the SAME retained-operation
    /// machinery the force arm uses, but on wake it commits WITHOUT the force
    /// funnel's re-issue decision (trap T7 - <see cref="_newestForce"/> is
    /// never touched) and WITHOUT a double commit however many times
    /// <see cref="RuntimeAcceptedPositionDriveController.Advance"/> is
    /// pumped afterward.
    ///
    /// <para>Root-cause note (closed): an earlier revision of this test
    /// asserted the wrong post-commit position (the FORCE arm's
    /// cross-landblock +192/+192 delta) and asserted zero outbound game
    /// actions after a commit that legitimately sends one. Because both
    /// were WRONG, the assertion failure fired before this method's own
    /// <c>ConvergePortalHost</c> cleanup call ever ran, which left the
    /// portal's host projection unconverged - and <c>StartedRuntime</c>'s
    /// `using`-triggered <c>Dispose()</c> then threw "hosts=1, pending=1"
    /// while unwinding, MASKING the real (first) failure as a teardown
    /// defect. The actual cause: an accepted Position merge with
    /// <c>TeleportAdvanced</c> (this is one - #283) rebases
    /// <c>RuntimePhysicsState</c>'s world-frame center onto the DESTINATION
    /// landblock immediately, before the placement itself ever resolves -
    /// exactly as <c>ObserveLocalWorldFrame</c>'s doc comment states ("only
    /// an accepted teleport moves it afterward"). So by the time this
    /// deferred park's retry runs, the destination landblock IS the frame
    /// center and the correct expected offset is zero, not the FORCE
    /// arm's stale-frame cross-landblock delta. No production code
    /// changed to fix this; both fixes were test-assertion corrections.</para>
    /// </summary>
    [Fact]
    public void PortalDeferredCell_ParksThenCommitsExactlyOnceOnTheCollisionGenerationWake()
    {
        using StartedRuntime started = StartRuntime();
        GameRuntime runtime = started.Runtime;
        (RuntimeEntityRecord record, PlayerMovementController controller) =
            EnterLocalPlayer(runtime);
        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(runtime, out List<byte[]> gameActions);

        const uint deferredLandblock = 0x02020000u;
        var deferredPosition = new Vector3(10f, 10f, SpawnHeight);
        const ushort teleportSequence = 8;
        WorldSession.EntityPositionUpdate destinationUpdate = PortalDestinationUpdate(
            deferredPosition, deferredLandblock | 0x0001u, teleportSequence);
        (PositionTimestampDisposition disposition, AcceptedPhysicsTimestamps mergeTimestamps) =
            MergeAccepted(runtime, controller, destinationUpdate);
        Assert.Equal(PositionTimestampDisposition.Apply, disposition);
        // #283: RuntimePhysicsState.ObserveLocalWorldFrame rebases the world
        // frame center to the DESTINATION landblock the instant an accepted
        // Position merges with TeleportAdvanced (RuntimeEntityObjectLifetime
        // .TryApplyPosition calls it with teleportAdvanced: timestamps
        // .TeleportAdvanced) - by design, "only an accepted teleport moves
        // it afterward" (RuntimePhysicsState.cs doc comment). This merge IS
        // that accepted teleport, so by the time the placement itself runs,
        // TryGetWorldFrameOffset(deferredLandblock) is already (0,0) - the
        // frame is centered ON the destination, not still on SpawnLandblock.
        Assert.True(mergeTimestamps.TeleportAdvanced);
        (RuntimePortalPlacementAuthority portal, RuntimeTeleportDestination destination) =
            BeginPortal(runtime, deferredLandblock | 0x0001u, teleportSequence, destinationUpdate);
        // B8/A8 review fix: guarantees ConvergePortalHost runs even if an
        // assertion below fails first - see PortalHostConvergenceGuard's doc.
        using var portalHostGuard = new PortalHostConvergenceGuard(
            runtime, portal.RevealGeneration, portal.Projection);

        RuntimeAcceptedPositionExecutionStatus parked =
            drive.TryExecuteAcceptedPortalArrival(destination, portal);

        Assert.Equal(RuntimeAcceptedPositionExecutionStatus.DeferredCell, parked);
        Assert.Empty(gameActions);
        Assert.Equal(1, drive.PendingCount);

        drive.Advance();
        Assert.Equal(1, drive.PendingCount);

        CommitLandblockCollision(runtime, deferredLandblock);
        DrainPlacementFifo(runtime);
        drive.Advance();

        Assert.Equal(0, drive.PendingCount);
        // Zero offset, not +192/+192: the accepted-teleport merge above
        // already rebased the world frame onto deferredLandblock (#283),
        // so the placement resolves in a frame ALREADY centered on the
        // destination. Asserting the old cross-landblock delta here would
        // be asserting a stale frame the merge already retired.
        Assert.Equal(deferredPosition, controller.Position);

        // The committed portal placement sends its ONE outbound movement
        // event exactly like PortalCommitted_* asserts (D-T3's
        // PlayerTeleported port; never an AutonomousPosition -
        // SendPositionImmediately is always false for the portal route).
        Assert.Single(gameActions);

        // No re-issue path exists for a portal pending (trap T7): further
        // pumps are pure no-ops, never a second commit or a stray ack.
        drive.Advance();
        drive.Advance();
        Assert.Single(gameActions);
        ConvergePortalHost(runtime, portal.RevealGeneration, portal.Projection);
        AssertConverged(runtime);
    }

    /// <summary>
    /// A2/D-T2.4 review fix (2026-08-05): the wake path must re-validate
    /// the portal authority before committing, so a park that resolves
    /// AFTER something has made the authority stale (transit ended or was
    /// superseded) does not run the reconcile/ack suffix — architecture
    /// review A2's FIFO-wedge shape ("a Place receipt whose Token.Portal
    /// still names the ended reveal"). The stub predicate below always
    /// reports stale, standing in for that condition without needing to
    /// actually end the transit mid-park.
    /// </summary>
    [Fact]
    public void PortalDeferredCell_WakeAbandonsInsteadOfReconcilingWhenAuthorityWentStale()
    {
        using StartedRuntime started = StartRuntime();
        GameRuntime runtime = started.Runtime;
        (RuntimeEntityRecord record, PlayerMovementController controller) =
            EnterLocalPlayer(runtime);
        RuntimeAcceptedPositionDriveController drive =
            CreateAcceptedPositionDrive(
                runtime,
                out List<byte[]> gameActions,
                isPortalAuthorityCurrent: static _ => false);

        const uint deferredLandblock = 0x02020000u;
        var deferredPosition = new Vector3(10f, 10f, SpawnHeight);
        const ushort teleportSequence = 9;
        WorldSession.EntityPositionUpdate destinationUpdate = PortalDestinationUpdate(
            deferredPosition, deferredLandblock | 0x0001u, teleportSequence);
        MergeAccepted(runtime, controller, destinationUpdate);
        (RuntimePortalPlacementAuthority portal, RuntimeTeleportDestination destination) =
            BeginPortal(runtime, deferredLandblock | 0x0001u, teleportSequence, destinationUpdate);
        // B8/A8 review fix: guarantees ConvergePortalHost runs even if an
        // assertion below fails first - see PortalHostConvergenceGuard's doc.
        using var portalHostGuard = new PortalHostConvergenceGuard(
            runtime, portal.RevealGeneration, portal.Projection);

        RuntimeAcceptedPositionExecutionStatus parked =
            drive.TryExecuteAcceptedPortalArrival(destination, portal);
        Assert.Equal(RuntimeAcceptedPositionExecutionStatus.DeferredCell, parked);
        Assert.Equal(1, drive.PendingCount);

        CommitLandblockCollision(runtime, deferredLandblock);
        DrainPlacementFifo(runtime);
        drive.Advance();

        // The park resolved (PendingCount converges to zero either way —
        // the wake always retires its retained operation) but because the
        // stub reports the authority stale, NO reconcile/ack ran: zero
        // outbound movement events, autorun untouched. The underlying body
        // commit (RetryDeferred) is a SEPARATE, asynchronous mechanism this
        // class cannot prevent (see the class doc on
        // IsPortalAuthorityCurrent) — it still lands.
        Assert.Equal(0, drive.PendingCount);
        Assert.Empty(gameActions);
        Assert.Equal(deferredPosition, controller.Position);

        ConvergePortalHost(runtime, portal.RevealGeneration, portal.Projection);
        AssertConverged(runtime);
    }

    private static WorldSession.EntityPositionUpdate PortalDestinationUpdate(
        Vector3 position,
        uint landblockId,
        ushort teleportSequence,
        ushort positionSequence = 2) =>
        new(
            PlayerGuid,
            new CreateObject.ServerPosition(
                landblockId,
                position.X,
                position.Y,
                position.Z,
                1f,
                0f,
                0f,
                0f),
            Velocity: null,
            PlacementId: null,
            IsGrounded: true,
            InstanceSequence: 1,
            PositionSequence: positionSequence,
            TeleportSequence: teleportSequence,
            ForcePositionSequence: 0);

    /// <summary>
    /// Mirrors <see cref="RuntimePlacementPresentationSinkTests.Fixture.BeginPortal"/>'s
    /// shape against <see cref="GameRuntime.TransitOwner"/> directly - F751 →
    /// offer → begin reveal → register the host token exactly like the
    /// graphical/headless producers (D-T1).
    /// </summary>
    private static (RuntimePortalPlacementAuthority Portal, RuntimeTeleportDestination Destination)
        BeginPortal(
            GameRuntime runtime,
            uint destinationCell,
            ushort teleportSequence,
            in WorldSession.EntityPositionUpdate destinationUpdate)
    {
        RuntimeWorldTransitState transit = runtime.TransitOwner;
        Assert.True(transit.TryQueueTeleportStart(teleportSequence));
        Assert.True(transit.ActivateQueuedTeleport());
        var destination = new RuntimeTeleportDestination(
            PlayerGuid,
            InstanceSequence: 1,
            PositionSequence: destinationUpdate.PositionSequence,
            TeleportSequence: teleportSequence,
            ForcePositionSequence: 0,
            new Position(
                destinationCell,
                new Vector3(
                    destinationUpdate.Position.PositionX,
                    destinationUpdate.Position.PositionY,
                    destinationUpdate.Position.PositionZ),
                Quaternion.Identity));
        Assert.True(transit.OfferTeleportDestination(
            destination,
            teleportTimestampAdvanced: true));
        Assert.True(transit.TryBeginPortalReveal(
            teleportSequence,
            destinationCell,
            out long generation));
        Assert.True(transit.TryRegisterHostProjection(
            generation,
            destinationCell,
            out RuntimeWorldHostProjectionToken host));
        return (
            new RuntimePortalPlacementAuthority(true, generation, teleportSequence, host),
            destination);
    }

    /// <summary>
    /// Test-only host-side convergence: cancels the reveal generation and
    /// drains the 4-stage host acknowledgement suffix
    /// (<see cref="RuntimeWorldTransitState.RequireTerminalHostProjection"/>'s
    /// SimulationReleaseProjected + DestinationReservationReleased +
    /// TerminalProjected) so <see cref="RuntimeWorldTransitState.ResetSession"/>
    /// does not throw during <c>StartedRuntime.Dispose()</c> teardown. A REAL
    /// host (graphical/headless) always runs this suffix itself
    /// (<c>LocalPlayerTeleportController.ResetTransit</c> /
    /// <c>RuntimeLiveEntitySessionController.TryCompletePortal</c>'s
    /// <c>Complete</c> path); this fixture stands in for that host exactly
    /// like <c>DrainPlacementFifo</c> stands in for the placement
    /// subscription.
    /// </summary>
    private static void ConvergePortalHost(
        GameRuntime runtime,
        long generation,
        RuntimeWorldHostProjectionToken projection)
    {
        RuntimeWorldTransitState transit = runtime.TransitOwner;
        if (!transit.Snapshot.Cancelled && !transit.Snapshot.Completed)
            transit.Cancel(generation);
        transit.AcknowledgeHostProjection(new RuntimeWorldHostAcknowledgement(
            projection, RuntimeWorldHostAcknowledgementStage.SimulationReleaseProjected));
        transit.AcknowledgeHostProjection(new RuntimeWorldHostAcknowledgement(
            projection, RuntimeWorldHostAcknowledgementStage.DestinationReservationReleased));
        transit.AcknowledgeHostProjection(new RuntimeWorldHostAcknowledgement(
            projection, RuntimeWorldHostAcknowledgementStage.TerminalProjected));
        transit.EndTeleport();
    }

    /// <summary>
    /// B8/A8 review fix (2026-08-05): a plain trailing-statement call to
    /// <see cref="ConvergePortalHost"/> is masked whenever an assertion
    /// EARLIER in the same test body fails first - the real failure never
    /// reaches xUnit because <c>StartedRuntime.Dispose()</c>'s own
    /// <c>RuntimeWorldTransitState.ResetSession</c> throws a SECOND,
    /// unrelated-looking "hosts=1, pending=1" exception while unwinding,
    /// which is the one that actually surfaces. A <c>using var</c> local of
    /// this guard, declared immediately after <see cref="BeginPortal"/>
    /// returns, disposes on EVERY exit path (normal return AND exception
    /// unwind) via C#'s own <c>using</c> semantics - equivalent to a
    /// try/finally wrapping the rest of the method without the nesting.
    /// <see cref="ConvergePortalHost"/> is idempotent against an already-
    /// converged host (every step it performs is a no-op past the first
    /// successful run), so a test that ALSO calls it explicitly on its own
    /// success path is safe to leave as-is; this guard exists purely to
    /// guarantee the call still happens when that explicit call is never
    /// reached.
    /// </summary>
    private readonly struct PortalHostConvergenceGuard : IDisposable
    {
        private readonly GameRuntime _runtime;
        private readonly long _generation;
        private readonly RuntimeWorldHostProjectionToken _projection;

        public PortalHostConvergenceGuard(
            GameRuntime runtime,
            long generation,
            RuntimeWorldHostProjectionToken projection)
        {
            _runtime = runtime;
            _generation = generation;
            _projection = projection;
        }

        public void Dispose() =>
            ConvergePortalHost(_runtime, _generation, _projection);
    }

    #endregion

    private static void AssertConverged(GameRuntime runtime)
    {
        RuntimeEntityObjectOwnershipSnapshot ownership =
            runtime.EntityObjects.CaptureOwnership();
        Assert.Equal(0, ownership.AcceptedPositionDrivePendingCount);
    }

    /// <summary>
    /// Performs the SAME upstream merge production runs BEFORE this route
    /// ever sees a Position
    /// (<see cref="RuntimeEntityObjectLifetime.TryApplyPosition"/>, called by
    /// <c>LiveEntityInboundAuthorityGate.TryAcceptPosition</c> in App and
    /// directly in <c>RuntimeLiveEntitySessionController.OnPositionUpdated</c>
    /// in headless) — this is what actually admits the disposition via the
    /// REAL <c>PhysicsTimestampGate</c> and substitutes the controller's
    /// current heading into <c>record.Snapshot</c> for a ForcePosition
    /// (contract §1c), rather than hand-rolling a disposition/timestamps pair
    /// the seam's caller could never actually observe.
    /// </summary>
    private static (PositionTimestampDisposition Disposition, AcceptedPhysicsTimestamps Timestamps)
        MergeAccepted(
            GameRuntime runtime,
            PlayerMovementController controller,
            in WorldSession.EntityPositionUpdate update)
    {
        Assert.True(runtime.EntityObjects.TryApplyPosition(
            update,
            isLocalPlayer: true,
            forcePositionRotation: controller.BodyOrientation,
            currentLocalVelocity: controller.BodyVelocity,
            acknowledgeProjection: null,
            out PositionTimestampDisposition disposition,
            out _,
            out AcceptedPhysicsTimestamps timestamps));
        return (disposition, timestamps);
    }

    /// <summary>
    /// A wire Position whose FORCE_POSITION_TS strictly advances, so the REAL
    /// <see cref="PhysicsTimestampGate.TryAcceptPositionEvent"/> admits it as
    /// <see cref="PositionTimestampDisposition.ForcePosition"/> (retail
    /// <c>SmartBox::HandleReceivedPosition</c> @0x00453FD0's FORCE_POSITION
    /// branch: fresh FORCE_POSITION_TS with an exactly-equal TELEPORT_TS).
    /// The spawn seeds FORCE_POSITION_TS 0 / POSITION_TS 1, so the defaults
    /// are the FIRST such packet; a session's SECOND force must raise
    /// <paramref name="forcePositionSequence"/> again.
    /// </summary>
    private static WorldSession.EntityPositionUpdate ForceUpdate(
        Vector3 position,
        uint landblockId = SpawnLandblock | 0x0001u,
        ushort positionSequence = 2,
        ushort forcePositionSequence = 1) =>
        new(
            PlayerGuid,
            new CreateObject.ServerPosition(
                landblockId,
                position.X,
                position.Y,
                position.Z,
                1f,
                0f,
                0f,
                0f),
            Velocity: null,
            PlacementId: null,
            IsGrounded: true,
            InstanceSequence: 1,
            PositionSequence: positionSequence,
            TeleportSequence: 0,
            ForcePositionSequence: forcePositionSequence);

    /// <summary>
    /// An ORDINARY server position echo: FORCE_POSITION_TS does NOT advance,
    /// POSITION_TS strictly does, so the same real gate admits it as
    /// <see cref="PositionTimestampDisposition.Apply"/>. Neither host ever
    /// dispatches this disposition to the drive — it merges (advancing
    /// <c>PositionAuthorityVersion</c> and Forgetting any in-flight placement)
    /// entirely behind the drive's back, which is exactly what makes it the
    /// N2 case.
    /// </summary>
    private static WorldSession.EntityPositionUpdate OrdinaryUpdate(
        Vector3 position,
        ushort positionSequence,
        ushort forcePositionSequence = 1,
        uint landblockId = SpawnLandblock | 0x0001u) =>
        ForceUpdate(
            position,
            landblockId,
            positionSequence,
            forcePositionSequence);

    private static AcceptedPhysicsTimestamps Timestamps(ushort teleport) =>
        new(
            Instance: 1,
            ServerControlledMove: 1,
            Teleport: teleport,
            ForcePosition: 1,
            TeleportAdvanced: false,
            PreviousTeleport: teleport);

    /// <summary>
    /// Spawns the local player, drives its initial-Create residence to
    /// completion, and returns the resulting canonical record + live
    /// controller — the fixture every test above needs before a
    /// ForcePosition can be route-2-eligible at all.
    /// </summary>
    private static (RuntimeEntityRecord Record, PlayerMovementController Controller)
        EnterLocalPlayer(GameRuntime runtime)
    {
        runtime.PlayerIdentity.ServerGuid = PlayerGuid;
        CommitLandblockCollision(runtime, SpawnLandblock);
        RuntimeFirstEntryDriveController firstEntry = CreateFirstEntryDrive(runtime);
        using var session = new WorldSession(
            new IPEndPoint(IPAddress.Loopback, 9000),
            new FixtureTransport());
        var sessionController = new RuntimeLiveEntitySessionController(
            runtime,
            session,
            worldProjection: new FixtureWorldProjection(firstEntry));
        LiveEntitySessionSink sink = sessionController.CreateSink();

        sink.Spawned(Spawn(PlayerGuid));
        DrainFirstEntry(runtime, firstEntry);

        RuntimeEntityRecord record = Assert.IsType<RuntimeEntityRecord>(
            GetActive(runtime, PlayerGuid));
        PlayerMovementController controller = Assert.IsType<PlayerMovementController>(
            runtime.MovementOwner.Controller);
        return (record, controller);
    }

    private static RuntimeEntityRecord GetActive(GameRuntime runtime, uint guid)
    {
        Assert.True(runtime.EntityObjects.Entities.TryGetActive(
            guid, out RuntimeEntityRecord record));
        return record;
    }

    /// <summary>
    /// Constructs the drive controller with a LIVE (deliberately never
    /// disposed within this factory — it must outlive the whole test)
    /// fixture <see cref="WorldSession"/> whose captured outbound game
    /// actions the caller can assert against.
    /// </summary>
    private static RuntimeAcceptedPositionDriveController CreateAcceptedPositionDrive(
        GameRuntime runtime,
        out List<byte[]> gameActions,
        Func<RuntimePortalPlacementAuthority, bool>? isPortalAuthorityCurrent = null)
    {
        var captured = new List<byte[]>();
        gameActions = captured;
        var liveSession = new WorldSession(
            new IPEndPoint(IPAddress.Loopback, 9001),
            new FixtureTransport())
        {
            GameActionCapture = body => captured.Add(body),
        };
        return new RuntimeAcceptedPositionDriveController(
            runtime.EntityObjects,
            runtime.Clock,
            new UnusedCollisionSource(),
            new LocalPlayerOutboundController((_, _, _, _, _, _) => { }),
            () => runtime.Generation,
            () => runtime.PlayerIdentity.ServerGuid,
            () => runtime.MovementOwner.Controller,
            () => runtime.CharacterOwner.UsePositionFromServer,
            () => liveSession,
            // C4 route 3: the portal arm's PlayerTeleported port needs the
            // autorun latch owner. Unused on the force arm this factory has
            // always served, so every existing route-2 test is unaffected.
            () => runtime.MovementOwner,
            // A2/D-T2.4 review fix (2026-08-05): defaults to null (existing
            // callers unaffected - every retained portal pending is treated
            // as current, today's unconditional behaviour).
            isPortalAuthorityCurrent);
    }

    /// <summary>
    /// A flat landblock whose terrain surface sits exactly at
    /// <see cref="SpawnHeight"/> — every fixture position in this file uses
    /// that Z so <c>CommitCanonical</c>'s contact resolve genuinely finds
    /// ground (retail <c>CommandInterpreter::SendPositionEvent</c>'s own
    /// admission gate requires Contact+OnWalkable —
    /// <c>PlayerMovementController.CanSendPositionEvent</c> — so an airborne
    /// fixture body would silently suppress every ack this suite asserts).
    /// </summary>
    private static void CommitLandblockCollision(
        GameRuntime runtime,
        uint landblockId,
        float worldOffsetX = 0f)
    {
        // Mirrors HeadlessSessionHostTests.AddFlatLandblock's exact
        // proven-working shape (every heightmap byte and every table entry
        // participate) rather than a sparse table — a resolve near a
        // landblock edge samples neighbouring grid entries too.
        var heights = new byte[81];
        Array.Fill(heights, (byte)SpawnHeight);
        var heightTable = new float[256];
        for (int index = 0; index < heightTable.Length; index++)
            heightTable[index] = index;
        runtime.EntityObjects.Physics.SetPosition.BeginCollisionGeneration(
            landblockId, 1UL);
        runtime.EntityObjects.Physics.Engine.AddLandblock(
            landblockId,
            new TerrainSurface(heights, heightTable),
            Array.Empty<CellSurface>(),
            Array.Empty<PortalPlane>(),
            worldOffsetX,
            worldOffsetY: 0f);
        runtime.EntityObjects.Physics.SetPosition.CommitCollisionGeneration(
            landblockId, 1UL, ready: true);
        runtime.EntityObjects.Physics.ObserveLocalWorldFrame(
            landblockId | 0x0001u,
            teleportAdvanced: false);
    }

    private static RuntimeFirstEntryDriveController CreateFirstEntryDrive(
        GameRuntime runtime) =>
        new(
            runtime.EntityObjects,
            runtime.Clock,
            new UnusedCollisionSource(),
            () => PlayerMovementConstructionOptions.Fallback,
            static _ => new RuntimeLocalPlayerPhysicsActivationPreparation(
                Radius: 0.48f,
                Height: 1.835f,
                RuntimeLocalPlayerShadowDisposition.ProvenShapeless));

    private static void DrainFirstEntry(
        GameRuntime runtime,
        RuntimeFirstEntryDriveController drive)
    {
        for (int attempt = 0; attempt < 8 && drive.PendingCount != 0; attempt++)
        {
            drive.DriveAll();
            DrainPlacementFifo(runtime);
        }
        Assert.Equal(0, drive.PendingCount);
    }

    private static void DrainPlacementFifo(GameRuntime runtime)
    {
        while (runtime.EntityObjects.Physics.SetPosition.TryPeekProjection(
                out RuntimePlacementProjectionSnapshot head))
        {
            if (!runtime.EntityObjects.Physics.SetPosition
                    .AcknowledgeProjection(head.Token))
            {
                break;
            }
        }
    }

    private static WorldSession.EntitySpawn Spawn(uint guid)
    {
        var position = new CreateObject.ServerPosition(
            SpawnLandblock | 0x0001u,
            10f,
            10f,
            5f,
            1f,
            0f,
            0f,
            0f);
        var timestamps = new PhysicsTimestamps(
            Position: 1,
            Movement: 1,
            State: 1,
            Vector: 1,
            Teleport: 0,
            ServerControlledMove: 1,
            ForcePosition: 0,
            ObjDesc: 1,
            Instance: 1);
        var physics = new PhysicsSpawnData(
            RawState: (uint)PhysicsStateFlags.ReportCollisions,
            Position: position,
            Movement: null,
            AnimationFrame: null,
            SetupTableId: null,
            MotionTableId: null,
            SoundTableId: null,
            PhysicsScriptTableId: null,
            Parent: null,
            Children: null,
            Scale: null,
            Friction: null,
            Elasticity: null,
            Translucency: null,
            Velocity: null,
            Acceleration: null,
            AngularVelocity: null,
            DefaultScriptType: null,
            DefaultScriptIntensity: null,
            Timestamps: timestamps);
        return new WorldSession.EntitySpawn(
            guid,
            position,
            null,
            [],
            [],
            [],
            null,
            null,
            "direct entity",
            null,
            null,
            null,
            PhysicsState: physics.RawState,
            InstanceSequence: 1,
            MovementSequence: 1,
            ServerControlSequence: 1,
            PositionSequence: 1,
            Physics: physics);
    }

    private sealed class UnusedCollisionSource
        : AcDream.Content.IPreparedCollisionSource
    {
        public AcDream.Content.PreparedAssetPresence ProbeCollision(
            AcDream.Content.Pak.PakAssetType type,
            uint sourceFileId) =>
            AcDream.Content.PreparedAssetPresence.Available;

        public AcDream.Content.PreparedCollisionReadResult<
            FlatSetupCollision> ReadSetupCollision(
                uint sourceFileId,
                CancellationToken cancellationToken = default) =>
            AcDream.Content.PreparedCollisionReadResult<
                FlatSetupCollision>.Missing;

        public AcDream.Content.PreparedCollisionReadResult<
            FlatGfxObjCollisionAsset> ReadGfxObjCollision(
                uint sourceFileId,
                CancellationToken cancellationToken = default) =>
            throw new NotSupportedException();

        public AcDream.Content.PreparedCollisionReadResult<
            FlatCellStructureCollisionAsset> ReadCellStructureCollision(
                uint sourceFileId,
                CancellationToken cancellationToken = default) =>
            throw new NotSupportedException();

        public AcDream.Content.PreparedCollisionReadResult<
            FlatEnvCellTopology> ReadEnvCellTopology(
                uint sourceFileId,
                CancellationToken cancellationToken = default) =>
            throw new NotSupportedException();

        public AcDream.Content.PreparedCollisionSourceStats CollisionStats =>
            default;

        public void Dispose()
        {
        }
    }

    private sealed class FixtureTransport : IWorldSessionTransport
    {
        public void Send(ReadOnlySpan<byte> datagram)
        {
        }

        public void Send(
            IPEndPoint remote,
            ReadOnlySpan<byte> datagram)
        {
        }

        public int Receive(
            Span<byte> destination,
            TimeSpan timeout,
            out IPEndPoint? from)
        {
            from = null;
            return -1;
        }

        public ValueTask<NetReceiveResult> ReceiveAsync(
            Memory<byte> destination,
            CancellationToken cancellationToken) =>
            ValueTask.FromException<NetReceiveResult>(
                new OperationCanceledException(cancellationToken));

        public void Dispose()
        {
        }
    }

    private sealed class FixtureWorldProjection : IRuntimeDirectWorldProjection
    {
        private readonly RuntimeFirstEntryDriveController _firstEntry;

        internal FixtureWorldProjection(RuntimeFirstEntryDriveController firstEntry) =>
            _firstEntry = firstEntry;

        public void ProjectSpawn(RuntimeEntityRecord record, bool isLocalPlayer) =>
            _firstEntry.DriveAll();

        public void ProjectPosition(
            RuntimeEntityRecord record,
            bool isLocalPlayer,
            PositionTimestampDisposition disposition)
        {
        }

        public void CenterOnAcceptedForcePosition(RuntimeEntityRecord record)
        {
        }

        public void BeginTeleport()
        {
        }

        public RuntimeDestinationReadiness PrepareDestination(
            long revealGeneration,
            RuntimeTeleportDestination destination,
            RuntimeWorldHostProjectionToken portal) =>
            new(
                revealGeneration,
                destination.CellId,
                IsIndoor: false,
                IsUnhydratable: false,
                RequiredRenderRadius: 1,
                IsRenderNeighborhoodReady: true,
                AreCompositeTexturesReady: true,
                IsCollisionReady: true);
    }

    /// <summary>
    /// C3c: initial-residence admission requires a live session generation
    /// (RuntimeInitialCreateResidenceState.CanAcceptCreate), so this test
    /// starts one through the same fixture-session shape
    /// DirectGameRuntimeCommandAdapterTests / RuntimeLiveEntitySessionControllerTests use.
    /// </summary>
    private sealed class StartedRuntime : IDisposable
    {
        internal required GameRuntime Runtime { get; init; }
        internal required LiveSessionHost Live { get; init; }

        public void Dispose()
        {
            _ = Live.Stop(Runtime.Generation);
            Runtime.Dispose();
        }
    }

    private static StartedRuntime StartRuntime()
    {
        var operations = new FixtureGameplayOperations();
        var sessionOperations = new FixtureSessionOperations();
        var runtime = new GameRuntime(new GameRuntimeDependencies(
            operations,
            operations,
            operations,
            operations,
            SessionOperations: sessionOperations));
        operations.Bind(runtime);
        var resetHost = new FixtureResetHost();
        var options = new LiveSessionConnectOptions(
            true,
            "127.0.0.1",
            9000,
            "account",
            "password");
        var live = new LiveSessionHost(
            runtime.Session,
            new LiveSessionHostBindings(
                new LiveSessionRoutingFactories(
                    _ => new FixtureEventRoute(),
                    _ => new FixtureCommandRoute()),
                generation => runtime.ResetGeneration(generation, resetHost),
                new LiveSessionSelectionBindings(
                    id => runtime.PlayerIdentity.ServerGuid = id,
                    _ => { },
                    runtime.CommunicationOwner.Chat.SetLocalPlayerGuid,
                    _ => { },
                    _ => { },
                    runtime.ActionOwner.Combat.Clear),
                new LiveSessionEnteredWorldBindings(
                    _ => { },
                    () => { },
                    () => { },
                    _ => { },
                    () => { }),
                (_, _, _) => { },
                () => { }),
            options);
        LiveSessionStartResult startResult = live.Start(options);
        Assert.Equal(LiveSessionStartStatus.Connected, startResult.Status);
        Assert.NotEqual(0UL, runtime.Generation.Value);
        return new StartedRuntime { Runtime = runtime, Live = live };
    }

    private sealed class FixtureSessionOperations : ILiveSessionOperations
    {
        public IPEndPoint ResolveEndpoint(string host, int port) =>
            new(IPAddress.Loopback, port);

        public WorldSession CreateSession(IPEndPoint endpoint) =>
            new(endpoint, new FixtureTransport());

        public void Connect(WorldSession session, string user, string password)
        {
        }

        public CharacterList.Parsed GetCharacters(WorldSession session) =>
            new(
                0u,
                [new CharacterList.Character(PlayerGuid, "Direct", 0u)],
                [],
                11,
                "account",
                true,
                true);

        public void EnterWorld(WorldSession session, int activeCharacterIndex)
        {
        }

        public void Tick(WorldSession session)
        {
        }

        public void DisposeSession(WorldSession session) =>
            session.Dispose();
    }

    private sealed class FixtureEventRoute : ILiveSessionEventRouting
    {
        public void Attach()
        {
        }

        public void Dispose()
        {
        }
    }

    private sealed class FixtureCommandRoute : ILiveSessionCommandRouting
    {
        public void Activate()
        {
        }

        public void Dispose()
        {
        }
    }

    private sealed class FixtureResetHost : IRuntimeGenerationResetHost
    {
        public void RetireEntityProjection(RuntimeEntityRecord entity)
        {
        }

        public void DrainEntityProjectionBoundary()
        {
        }

        public void CompleteEntityProjectionRetirement()
        {
        }
    }

    private sealed class FixtureGameplayOperations
        : IRuntimeCombatAttackOperations,
          IRuntimeCombatTargetOperations,
          IRuntimeCombatModeOperations,
          IRuntimeSpellCastOperations
    {
        private GameRuntime? _runtime;

        public void Bind(GameRuntime runtime) => _runtime = runtime;
        public bool CanStartAttack() => false;
        public void PrepareAttackRequest()
        {
        }

        public bool SendAttack(AttackHeight height, float power) => false;
        public void SendCancelAttack()
        {
        }

        public bool IsDualWield => false;
        public bool PlayerReadyForAttack => false;
        public bool AutoRepeatAttack => false;
        public bool AutoTarget => false;
        public uint? SelectClosestTarget() => null;
        public bool IsInWorld => _runtime?.Session.IsInWorld == true;
        public IReadOnlyList<ClientObject> GetOrderedEquipment() => [];
        public void NotifyExplicitCombatModeRequest()
        {
        }

        public void SendChangeCombatMode(CombatMode mode)
        {
        }

        public uint LocalPlayerId =>
            _runtime?.PlayerIdentity.ServerGuid ?? 0u;
        public bool CanSend => false;
        public bool HasRequiredComponents(uint spellId) => false;

        public bool IsTargetCompatible(
            uint targetId,
            SpellMetadata spell,
            bool showMessage) => false;

        public void StopCompletely()
        {
        }

        public void SendUntargeted(uint spellId)
        {
        }

        public void SendTargeted(uint targetId, uint spellId)
        {
        }

        public void DisplayMessage(string message)
        {
        }

        public void IncrementBusy()
        {
        }
    }
}