feat(physics): P5 commit 1 - port ConstraintManager leash distance constants (#167)

Add ConstraintDistance (outdoor/indoor start=10/5, max=50/20), byte-decoded
from the matching retail binary (GetStartConstraintDistance 0x0050ebc0,
GetMaxConstraintDistance 0x0050ec10 - both x87-return functions BN elided).
Deliberately omits the vestigial player-vs-remote branch the disassembly
shows loads identical constants either way. Pins the ACE-inversion (ACE's
start mapping is outdoor 5/indoor 10, the opposite of the binary - the
binary wins). Adds a full-chain conformance test proving an armed,
over-strained leash actually blocks jump_is_allowed (0x47), not just the
bare stub-property regression already covered.

See docs/research/2026-07-30-constraint-leash-constants.md.

src/AcDream.Core/Physics/Motion/ConstraintDistance.cs

@@ -0,0 +1,55 @@
+namespace AcDream.Core.Physics.Motion;
+
+/// <summary>
+/// Campaign P P5 (#167 / register TS-35) — retail
+/// <c>CPhysicsObj::GetStartConstraintDistance</c> (0x0050ebc0) and
+/// <c>GetMaxConstraintDistance</c> (0x0050ec10): the leash's start/max band,
+/// keyed by whether the object's OWN current cell is outdoor or indoor.
+///
+/// <para><b>Byte-decoded, not guessed</b> — BN elided both getters' return
+/// value as a bare <c>this-&gt;m_position;</c> expression (the classic x87
+/// FPU-return decompile artifact). The actual values were recovered by
+/// disassembling the matching binary's raw machine code (see
+/// <c>docs/research/2026-07-30-constraint-leash-constants.md</c> §1):
+/// outdoor start = <b>10.0</b>, indoor start = <b>5.0</b>; outdoor max =
+/// <b>50.0</b>, indoor max = <b>20.0</b>. Indoor is decided by the object's
+/// full cell id's low 16 bits: <c>&gt;= 0x0100</c> = EnvCell (indoor).</para>
+///
+/// <para><b>The retail player-vs-remote branch is INTENTIONALLY OMITTED.</b>
+/// The disassembly shows both getters branch on <c>this == player_object</c>
+/// AND load byte-identical constants either way — the branch is vestigial
+/// (both sides return the same four numbers). Porting that dead branch would
+/// only add a phantom "is this the player" parameter with zero behavioral
+/// effect, so this class keys purely on the object's own cell id.</para>
+///
+/// <para><b>ACE-inversion pin.</b> ACE's <c>PhysicsObj.GetStartConstraintDistance</c>
+/// (<c>PhysicsObj.cs:620</c>) maps outdoor → 5, indoor → 10 — the OPPOSITE of
+/// the binary. ACE's max mapping (outdoor 50 / indoor 20) matches. Do not
+/// "fix" this class to match ACE's start mapping; the disassembly is the
+/// oracle here (feedback_acme_oracle: binary wins over ACE on disagreement).
+/// </para>
+/// </summary>
+public static class ConstraintDistance
+{
+    private const float OutdoorStart = 10.0f;
+    private const float IndoorStart = 5.0f;
+    private const float OutdoorMax = 50.0f;
+    private const float IndoorMax = 20.0f;
+
+    /// <summary>Retail <c>cmp eax, 0x100; jae indoor</c> on the object's own
+    /// <c>m_position.objcell_id &amp; 0xFFFF</c> — low 16 bits ≥ 0x0100 is an
+    /// EnvCell (indoor); below that is an outdoor landblock cell index.</summary>
+    public static bool IsIndoorCell(uint objCellId) => (objCellId & 0xFFFFu) >= 0x0100u;
+
+    /// <summary>Retail <c>CPhysicsObj::GetStartConstraintDistance</c>
+    /// (0x0050ebc0) — the near edge of the leash's brake band, keyed by the
+    /// object's own current cell.</summary>
+    public static float GetStartConstraintDistance(uint objCellId) =>
+        IsIndoorCell(objCellId) ? IndoorStart : OutdoorStart;
+
+    /// <summary>Retail <c>CPhysicsObj::GetMaxConstraintDistance</c>
+    /// (0x0050ec10) — the far edge (full clamp), keyed by the object's own
+    /// current cell.</summary>
+    public static float GetMaxConstraintDistance(uint objCellId) =>
+        IsIndoorCell(objCellId) ? IndoorMax : OutdoorMax;
+}

tests/AcDream.Core.Tests/Physics/Motion/ConstraintDistanceTests.cs

@@ -0,0 +1,72 @@
+using AcDream.Core.Physics.Motion;
+using Xunit;
+
+namespace AcDream.Core.Tests.Physics.Motion;
+
+/// <summary>
+/// Campaign P P5 (#167 / TS-35) golden values for
+/// <see cref="ConstraintDistance"/> — byte-decoded from the matching retail
+/// binary (docs/research/2026-07-30-constraint-leash-constants.md §1), not
+/// guessed and not copied from ACE (whose start mapping is INVERTED).
+/// </summary>
+public sealed class ConstraintDistanceTests
+{
+    // Outdoor landblock cell indices are 0x0001-0x00FF (low16 < 0x0100).
+    private const uint OutdoorCell = 0x12340007u;
+    // EnvCell (indoor) indices are 0x0100+ .
+    private const uint IndoorCell = 0x12340105u;
+
+    [Fact]
+    public void GetStartConstraintDistance_Outdoor_Is10NotAcesInverted5()
+    {
+        // ACE PhysicsObj.cs:620 maps outdoor start -> 5. The disassembly
+        // (0x0050ebc0) says 10. The binary wins.
+        Assert.Equal(10.0f, ConstraintDistance.GetStartConstraintDistance(OutdoorCell));
+    }
+
+    [Fact]
+    public void GetStartConstraintDistance_Indoor_Is5()
+    {
+        Assert.Equal(5.0f, ConstraintDistance.GetStartConstraintDistance(IndoorCell));
+    }
+
+    [Fact]
+    public void GetMaxConstraintDistance_Outdoor_Is50()
+    {
+        Assert.Equal(50.0f, ConstraintDistance.GetMaxConstraintDistance(OutdoorCell));
+    }
+
+    [Fact]
+    public void GetMaxConstraintDistance_Indoor_Is20()
+    {
+        Assert.Equal(20.0f, ConstraintDistance.GetMaxConstraintDistance(IndoorCell));
+    }
+
+    [Theory]
+    [InlineData(0x00FFu, false)]
+    [InlineData(0x0100u, true)]
+    [InlineData(0x0000u, false)]
+    [InlineData(0xFFFFu, true)]
+    public void IsIndoorCell_BoundaryIsLow16Ox0100(uint objCellId, bool expectedIndoor)
+    {
+        Assert.Equal(expectedIndoor, ConstraintDistance.IsIndoorCell(objCellId));
+    }
+
+    // The disassembly's "this == player_object" branch loads IDENTICAL
+    // constants on both sides (research doc §1, "vestigial" finding) — there
+    // is deliberately no player/remote parameter on this API. Pin that the
+    // SAME cell always yields the SAME band regardless of which kind of
+    // object (player or remote) is asking, by construction (no such
+    // parameter exists to differentiate them).
+    [Fact]
+    public void NoPlayerVsRemoteSplit_SameCellAlwaysYieldsSameBand()
+    {
+        float startA = ConstraintDistance.GetStartConstraintDistance(OutdoorCell);
+        float startB = ConstraintDistance.GetStartConstraintDistance(OutdoorCell);
+        float maxA = ConstraintDistance.GetMaxConstraintDistance(OutdoorCell);
+        float maxB = ConstraintDistance.GetMaxConstraintDistance(OutdoorCell);
+
+        Assert.Equal(startA, startB);
+        Assert.Equal(maxA, maxB);
+    }
+}

tests/AcDream.Core.Tests/Physics/MotionInterpreterJumpFamilyTests.cs

@@ -1,6 +1,7 @@
 using System.Numerics;
 using AcDream.Core.Physics;
 using AcDream.Core.Physics.Motion;
+using AcDream.Core.Tests.Physics.Motion;
 using Xunit;
 
 namespace AcDream.Core.Tests.Physics;
@@ -694,6 +695,47 @@ public sealed class MotionInterpreterJumpFamilyTests
         Assert.Equal(WeenieError.GeneralMovementFailure, result);
     }
 
+    // Campaign P P5 (#167 / TS-35): the FULL production chain — ConstraintManager
+    // armed via ConstraintDistance's byte-decoded constants, the leash's linear
+    // taper (ConstraintManager.AdjustOffset) driving ConstraintPosOffset past 90%
+    // of max, then PhysicsBody.IsFullyConstrained pushed from the read (exactly
+    // as PlayerMovementController's/RuntimeRemotePhysicsUpdater's per-tick pump
+    // does) — not just the bare-stub-property test above. Proves the leash
+    // actually blocks a jump once armed and over-strained, end to end.
+    [Fact]
+    public void JumpIsAllowed_LeashArmedAndOverstrained_ReturnsGeneralMovementFailure()
+    {
+        var world = new System.Collections.Generic.Dictionary<uint, R5Host>();
+        var host = new R5Host(10u, world);
+        const uint outdoorCell = 0x12340007u; // low16 < 0x0100 -> outdoor
+        host.Position = new Position(outdoorCell, Vector3.Zero, Quaternion.Identity);
+
+        float start = ConstraintDistance.GetStartConstraintDistance(outdoorCell);
+        float max = ConstraintDistance.GetMaxConstraintDistance(outdoorCell);
+        Assert.Equal(10.0f, start);
+        Assert.Equal(50.0f, max);
+
+        // Arm anchored to the object's own current position (matches the
+        // production arm sites: offset starts at 0 since anchor == self).
+        host.PositionManager.ConstrainTo(host.Position, start, max);
+        Assert.False(host.PositionManager.IsFullyConstrained());
+
+        // Drive one large per-tick offset (a single tick's step length, per
+        // ConstraintManager's retail semantics) past 90% of max (45 m).
+        var frame = new MotionDeltaFrame { Origin = new Vector3(46f, 0f, 0f) };
+        host.PositionManager.AdjustOffset(frame, quantum: 1.0 / 30.0);
+        Assert.True(host.PositionManager.IsFullyConstrained());
+
+        var body = MakeGrounded();
+        // The per-tick pump's push (PlayerMovementController / RuntimeRemotePhysicsUpdater):
+        body.IsFullyConstrained = host.PositionManager.IsFullyConstrained();
+        var interp = MakeInterp(body);
+
+        var result = interp.jump_is_allowed(0.5f, out _);
+
+        Assert.Equal(WeenieError.GeneralMovementFailure, result); // 0x47
+    }
+
     [Fact]
     public void JumpIsAllowed_PendingHeadNonzeroError_ShortCircuitsChain()
     {