pathing: route Descend->turn handoff through LandingRecovery hints

When a Descend segment is followed by another Descend (or Traverse/
Diagonal) with a different heading, PathSegmentBuilder.Classify
correctly assigned ExitTransition=LandingRecovery, but BuildHints fell
into the `if (turning)` branch first and returned hints with
RequireStableFooting=true. That gate forces GroundedSegmentController to
wait for IsSettledOnTargetBlock (footprint inside, won't leave next tick,
horizontal speed^2 <= 0.0016), so a multi-block diagonal Descend that
landed inside the target block while still carrying ~0.02 m/tick of
residual jump momentum oscillated in place for ~60 ticks (3 seconds)
until the speed decayed.

Move the LandingRecovery branch ahead of the turning branch so the
Descend-carry handoff uses RequireStableFooting=false and the
ShouldComplete shortcut (LandingRecovery + footprint inside target on
the ground) fires the moment the bot reaches the landing column.

Adds two regression tests covering the Descend->turning-Descend handoff
and a sanity guard that ordinary Traverse->turning-Traverse still uses
the turning branch.

Also lifts DiagnosticsTailSize from 64 to 200 and emits an automatic
"slow segment" tick dump from PathSegmentManager whenever a segment
takes >=25 ticks, which is what surfaced this stall.

Made-with: Cursor

MinecraftClient/Pathing/Execution/PathSegmentBuilder.cs

@@ -94,20 +94,21 @@ namespace MinecraftClient.Pathing.Execution
             bool nextImmediatelyJumps = nextNext is not null
                 && nextNext.MoveType is (MoveType.Parkour or MoveType.Ascend);
 
-            if (turning)
-            {
-                return new PathTransitionHints(
-                    DesiredHeadingX: next.HeadingX,
-                    DesiredHeadingZ: next.HeadingZ,
-                    MinExitSpeed: nextImmediatelyJumps ? 0.05 : 0.0,
-                    MaxExitSpeed: nextImmediatelyJumps ? 0.16 : 0.05,
-                    RequireStableFooting: !nextImmediatelyJumps,
-                    RequireGrounded: true,
-                    RequireJumpReady: nextImmediatelyJumps,
-                    AllowAirBrake: true,
-                    HorizonTicks: 12);
-            }
-
+            // LandingRecovery (current is Descend/Parkour/Fall) takes precedence
+            // over the turning branch even when heading changes between current
+            // and next. The turning branch demands RequireStableFooting=true,
+            // which forces the GroundedSegmentController completion gate to wait
+            // for IsSettledOnTargetBlock (footprint inside, won't leave next
+            // tick, horizontal speed^2 <= 0.0016). After a multi-block diagonal
+            // Descend the bot lands inside the target block already carrying
+            // ~0.02 m/tick of residual momentum that the planner can't shed
+            // cleanly: the per-tick yaw bias toward the next segment's heading
+            // pulls the bot off-axis, the bot slides off the target block, the
+            // template re-targets the centre, and so on for ~60 ticks until
+            // momentum decays. The LandingRecovery shortcut in
+            // GroundedSegmentController.ShouldComplete (!RequireStableFooting +
+            // footprint inside target) bypasses the speed gate cleanly the
+            // moment the bot reaches the landing column.
             if (exitTransition == PathTransitionType.LandingRecovery)
             {
                 return new PathTransitionHints(
@@ -122,6 +123,20 @@ namespace MinecraftClient.Pathing.Execution
                     HorizonTicks: 12);
             }
 
+            if (turning)
+            {
+                return new PathTransitionHints(
+                    DesiredHeadingX: next.HeadingX,
+                    DesiredHeadingZ: next.HeadingZ,
+                    MinExitSpeed: nextImmediatelyJumps ? 0.05 : 0.0,
+                    MaxExitSpeed: nextImmediatelyJumps ? 0.16 : 0.05,
+                    RequireStableFooting: !nextImmediatelyJumps,
+                    RequireGrounded: true,
+                    RequireJumpReady: nextImmediatelyJumps,
+                    AllowAirBrake: true,
+                    HorizonTicks: 12);
+            }
+
             return new PathTransitionHints(
                 DesiredHeadingX: next.HeadingX,
                 DesiredHeadingZ: next.HeadingZ,

MinecraftClient/Pathing/Execution/PathSegmentManager.cs

@@ -51,10 +51,12 @@ namespace MinecraftClient.Pathing.Execution
         /// </summary>
         public static bool DiagnosticsEnabled { get; set; }
 
-        private const int DiagnosticsTailSize = 64;
+        private const int DiagnosticsTailSize = 200;
+        private const int SlowSegmentDumpTickThreshold = 25;
         private readonly Queue<string> _diagnosticsTail = new(DiagnosticsTailSize + 1);
         private PathResult? _lastPlan;
         private int _lastObservedSegmentIndex = -1;
+        private int _ticksSinceSegmentStart;
 
         public bool IsNavigating =>
             (_executor is not null && !_executor.IsComplete)
@@ -89,6 +91,7 @@ namespace MinecraftClient.Pathing.Execution
             var segments = PathSegmentBuilder.FromPath(result.Path);
             _executor = new PathExecutor(segments, _debugLog, _observer);
             _lastObservedSegmentIndex = -1;
+            _ticksSinceSegmentStart = 0;
             _infoLog?.Invoke($"[PathMgr] Navigation started: {segments.Count} segments");
         }
 
@@ -197,11 +200,32 @@ namespace MinecraftClient.Pathing.Execution
             // without relying on the bounded tail buffer. Resets on plan install.
             if (segIdx != _lastObservedSegmentIndex)
             {
+                if (_lastObservedSegmentIndex >= 0
+                    && _ticksSinceSegmentStart >= SlowSegmentDumpTickThreshold)
+                {
+                    _infoLog?.Invoke(
+                        $"[PathDiag] Slow segment {_lastObservedSegmentIndex}/{_executor.TotalSegments} took {_ticksSinceSegmentStart} ticks, dumping last {Math.Min(_diagnosticsTail.Count, _ticksSinceSegmentStart)} ticks:");
+                    int toDump = Math.Min(_diagnosticsTail.Count, _ticksSinceSegmentStart);
+                    int skipCount = _diagnosticsTail.Count - toDump;
+                    int i = 0;
+                    foreach (string line in _diagnosticsTail)
+                    {
+                        if (i++ < skipCount)
+                            continue;
+                        _infoLog?.Invoke($"[PathDiag]   t-{toDump - (i - skipCount)}: {line}");
+                    }
+                }
+
                 _lastObservedSegmentIndex = segIdx;
+                _ticksSinceSegmentStart = 0;
                 _infoLog?.Invoke(
                     $"[PathDiag] seg->{segIdx}/{_executor.TotalSegments} pos=({pos.X:F2},{pos.Y:F2},{pos.Z:F2}) yaw={physics.Yaw:F1} vy={physics.DeltaMovement.Y:F3} og={physics.OnGround} " +
                     (seg is null ? "none" : $"{seg.MoveType} ({seg.Start.X:F1},{seg.Start.Y:F1},{seg.Start.Z:F1})->({seg.End.X:F1},{seg.End.Y:F1},{seg.End.Z:F1}) exit={seg.ExitTransition}"));
             }
+            else
+            {
+                _ticksSinceSegmentStart++;
+            }
 
             _diagnosticsTail.Enqueue(
                 $"pos=({pos.X:F2},{pos.Y:F2},{pos.Z:F2}) yaw={physics.Yaw:F1} vy={physics.DeltaMovement.Y:F3} vx={physics.DeltaMovement.X:F3} vz={physics.DeltaMovement.Z:F3} og={physics.OnGround} {segStr}");
@@ -428,6 +452,7 @@ namespace MinecraftClient.Pathing.Execution
             _lastPlan = result;
             _diagnosticsTail.Clear();
             _lastObservedSegmentIndex = -1;
+            _ticksSinceSegmentStart = 0;
             if (isInitial)
             {
                 _executor = new PathExecutor(segments, _debugLog, _observer);