From 2effb64ea4e196391fb70f210a2b685281e56969 Mon Sep 17 00:00:00 2001
From: Vladimir Pankov <m1dnyt3.911@gmail.com>
Date: Tue, 17 Feb 2026 14:07:21 +0200
Subject: [PATCH 01/12] Add Velocity transmission toggle and calculation logic.

---
 .../src/main/java/dev/slimevr/VRServer.kt     | 18 +++++
 .../main/java/dev/slimevr/config/VRConfig.kt  | 14 ++++
 .../java/dev/slimevr/config/VelocityConfig.kt | 10 +++
 .../processor/skeleton/HumanSkeleton.kt       |  1 +
 .../dev/slimevr/tracking/trackers/Tracker.kt  | 71 +++++++++++++++++++
 5 files changed, 114 insertions(+)
 create mode 100644 server/core/src/main/java/dev/slimevr/config/VelocityConfig.kt

diff --git a/server/core/src/main/java/dev/slimevr/VRServer.kt b/server/core/src/main/java/dev/slimevr/VRServer.kt
index f5e5cf6a71..1a0f7380ad 100644
--- a/server/core/src/main/java/dev/slimevr/VRServer.kt
+++ b/server/core/src/main/java/dev/slimevr/VRServer.kt
@@ -186,6 +186,21 @@ class VRServer @JvmOverloads constructor(
 		instance = this
 	}
 
+	/**
+	 * TODO: The design of this method is chosen for future expandability in case we want to have more complex velocity policies that depend on tracker properties or other config values.
+	 * Initiates the velocity policy application process for the specified [Tracker] (or all trackers if null).
+	 *
+	 * This method serves as the initiator.
+	 * The actual policy logic is not handled here,
+	 * but is delegated to [dev.slimevr.config.VRConfig.applyVelocityPolicy].
+	 */
+	private fun applyVelocityPolicyTo(tracker: Tracker?) {
+		val targets = tracker?.let { listOf(it) } ?: trackers
+		for (t in targets) {
+			configManager.vrConfig.applyVelocityPolicy(t)
+		}
+	}
+
 	fun hasBridge(bridgeClass: Class<out Bridge?>): Boolean {
 		for (bridge in bridges) {
 			if (bridgeClass.isAssignableFrom(bridge.javaClass)) {
@@ -231,6 +246,9 @@ class VRServer @JvmOverloads constructor(
 			refreshTrackersDriftCompensationEnabled()
 			configManager.vrConfig.writeTrackerConfig(tracker)
 			configManager.saveConfig()
+
+			// Requires a fresh TrackerConfig on Update, so executed after we save a new state.
+			applyVelocityPolicyTo(tracker)
 		}
 	}
 
diff --git a/server/core/src/main/java/dev/slimevr/config/VRConfig.kt b/server/core/src/main/java/dev/slimevr/config/VRConfig.kt
index 9ef33f5e00..dd100f55ef 100644
--- a/server/core/src/main/java/dev/slimevr/config/VRConfig.kt
+++ b/server/core/src/main/java/dev/slimevr/config/VRConfig.kt
@@ -58,6 +58,8 @@ class VRConfig {
 
 	val trackingChecklist: TrackingChecklistConfig = TrackingChecklistConfig()
 
+	var velocityConfig: VelocityConfig = VelocityConfig()
+
 	val vrcConfig: VRCConfig = VRCConfig()
 
 	init {
@@ -104,6 +106,17 @@ class VRConfig {
 		return config
 	}
 
+	/**
+	 * Applies the velocity policy to the given [Tracker].
+	 *
+	 * This method determines whether the tracker—be it a physical sensor or a computed virtual device—is
+	 * permitted to calculate and broadcast velocity data.
+	 * It resolves the active [VelocityConfig] value, updating [Tracker.allowVelocity] accordingly.
+	 */
+	fun applyVelocityPolicy(tracker: Tracker) {
+		tracker.allowVelocity = velocityConfig.sendDerivedVelocity
+	}
+
 	fun readTrackerConfig(tracker: Tracker) {
 		if (tracker.userEditable) {
 			val config = getTracker(tracker)
@@ -119,6 +132,7 @@ class VRConfig {
 					.readFilteringConfig(filters, tracker.getRotation())
 			}
 		}
+		applyVelocityPolicy(tracker)
 	}
 
 	fun writeTrackerConfig(tracker: Tracker?) {
diff --git a/server/core/src/main/java/dev/slimevr/config/VelocityConfig.kt b/server/core/src/main/java/dev/slimevr/config/VelocityConfig.kt
new file mode 100644
index 0000000000..a6516b1e24
--- /dev/null
+++ b/server/core/src/main/java/dev/slimevr/config/VelocityConfig.kt
@@ -0,0 +1,10 @@
+package dev.slimevr.config
+
+/**
+ * Allows to enable/disable sending of optional derived velocity data via Protobuf.
+ * Enables Natural Locomotion Support
+ * May create overprediction in certain titles causing excessive jitter when moving upper body.
+ */
+class VelocityConfig {
+	var sendDerivedVelocity: Boolean = false // Disables derived velocity for all trackers. Driver zeroes out velocity if nothing is returned in protobuf message.
+}
diff --git a/server/core/src/main/java/dev/slimevr/tracking/processor/skeleton/HumanSkeleton.kt b/server/core/src/main/java/dev/slimevr/tracking/processor/skeleton/HumanSkeleton.kt
index 2baef0bcd5..d64e8a4930 100644
--- a/server/core/src/main/java/dev/slimevr/tracking/processor/skeleton/HumanSkeleton.kt
+++ b/server/core/src/main/java/dev/slimevr/tracking/processor/skeleton/HumanSkeleton.kt
@@ -1171,6 +1171,7 @@ class HumanSkeleton(
 			it.position = trackerBone.getTailPosition()
 			it.setRotation(trackerBone.getGlobalRotation() * trackerBone.rotationOffset.inv())
 			it.dataTick()
+			it.updateDerivedVelocity(System.nanoTime())
 		}
 	}
 
diff --git a/server/core/src/main/java/dev/slimevr/tracking/trackers/Tracker.kt b/server/core/src/main/java/dev/slimevr/tracking/trackers/Tracker.kt
index a3d03ea10b..ae2a64edea 100644
--- a/server/core/src/main/java/dev/slimevr/tracking/trackers/Tracker.kt
+++ b/server/core/src/main/java/dev/slimevr/tracking/trackers/Tracker.kt
@@ -75,6 +75,11 @@ class Tracker @JvmOverloads constructor(
 	 */
 	val allowMounting: Boolean = false,
 
+	/**
+	 * If true, the tracker will send Derived Velocity.
+	 */
+	var allowVelocity: Boolean = false,
+
 	val isHmd: Boolean = false,
 
 	/**
@@ -111,7 +116,19 @@ class Tracker @JvmOverloads constructor(
 	// IMU: +z forward, +x left, +y up
 	// SlimeVR: +z backward, +x right, +y up
 	private var _acceleration = Vector3.NULL
+	private var _velocity = Vector3.NULL
 	private var _magVector = Vector3.NULL
+
+	/**
+	 * Velocity state server-side differentiation based on sent poses
+	 */
+	private data class VelocityState(
+		var prevTimeNs: Long = 0L,
+		var prevPos: Vector3 = Vector3(0f, 0f, 0f),
+	)
+
+	private var velocityState: VelocityState? = null
+
 	var position = Vector3.NULL
 	val resetsHandler: TrackerResetsHandler = TrackerResetsHandler(this)
 	val filteringHandler: TrackerFilteringHandler = TrackerFilteringHandler()
@@ -345,6 +362,42 @@ class Tracker @JvmOverloads constructor(
 		}
 	}
 
+	/**
+	 * Updates the derived velocity of the tracker by differentiating position over time.
+	 *
+	 * This method enforces the [allowVelocity] policy and checks for valid position data before
+	 * proceeding. If conditions are met, it calculates velocity based on the displacement since the
+	 * last update, applying a sanity check on the time delta to filter out noise and ensure data stability.
+	 *
+	 */
+	fun updateDerivedVelocity(nowNs: Long) {
+		if (!allowVelocity || !hasPosition) {
+			velocityState = null
+			_velocity = Vector3.NULL
+			return
+		}
+
+		val pos = position
+		val state = velocityState ?: VelocityState().also {
+			velocityState = it
+		}
+
+		if (state.prevTimeNs != 0L) {
+			val dt = (nowNs - state.prevTimeNs) * 1e-9
+			if (dt in 1e-4..0.25) {
+				_velocity = Vector3(
+					((pos.x - state.prevPos.x) / dt).toFloat(),
+					((pos.y - state.prevPos.y) / dt).toFloat(),
+					((pos.z - state.prevPos.z) / dt).toFloat(),
+				)
+			} else {
+				_velocity = Vector3.NULL
+			}
+		}
+		state.prevTimeNs = nowNs
+		state.prevPos = pos
+	}
+
 	/**
 	 * Gets the identity-adjusted tracker rotation after the resetsHandler's corrections
 	 * (identity reset, drift and identity mounting).
@@ -421,6 +474,24 @@ class Tracker @JvmOverloads constructor(
 		this._acceleration = vec
 	}
 
+	/**
+	 * Sets the derived velocity of the tracker.
+	 */
+	fun setVelocity(vec: Vector3) {
+		this._velocity = if (allowVelocity) vec else Vector3.NULL
+	}
+
+	/**
+	 * Gets the derived velocity of the tracker.
+	 */
+	fun getVelocity(): Vector3 = _velocity
+
+	/**
+	 * True if the tracker has valid velocity data.
+	 */
+	val hasVelocity: Boolean
+		get() = allowVelocity && _velocity != Vector3.NULL
+
 	/**
 	 * True if the raw rotation is coming directly from an IMU (no cameras or lighthouses)
 	 * For example, flex sensor trackers are not considered as IMU trackers (see TrackerDataType)

From 5b821ead4daeba32047523838437032ae49392d7 Mon Sep 17 00:00:00 2001
From: Vladimir Pankov <m1dnyt3.911@gmail.com>
Date: Tue, 17 Feb 2026 14:33:10 +0200
Subject: [PATCH 02/12] Add Velocity data send via ProtobufBridge. Update
 ProtobufMessages to latest definition from the Driver's main branch.

---
 .../desktop/platform/ProtobufBridge.kt        |  42 +-
 .../desktop/platform/ProtobufMessages.java    | 445 ++++++++++++++++--
 2 files changed, 446 insertions(+), 41 deletions(-)

diff --git a/server/desktop/src/main/java/dev/slimevr/desktop/platform/ProtobufBridge.kt b/server/desktop/src/main/java/dev/slimevr/desktop/platform/ProtobufBridge.kt
index e6b60aaf52..9a116b5efd 100644
--- a/server/desktop/src/main/java/dev/slimevr/desktop/platform/ProtobufBridge.kt
+++ b/server/desktop/src/main/java/dev/slimevr/desktop/platform/ProtobufBridge.kt
@@ -82,6 +82,7 @@ abstract class ProtobufBridge(@JvmField protected val bridgeName: String) : ISte
 		target.position = source.position
 		target.setRotation(source.getRotation())
 		target.status = source.status
+		target.setVelocity(source.getVelocity())
 		target.batteryLevel = source.batteryLevel
 		target.batteryVoltage = source.batteryVoltage
 		target.dataTick()
@@ -103,23 +104,38 @@ abstract class ProtobufBridge(@JvmField protected val bridgeName: String) : ISte
 
 	@VRServerThread
 	protected fun writeTrackerUpdate(localTracker: Tracker?) {
-		val builder = ProtobufMessages.Position.newBuilder().setTrackerId(
-			localTracker!!.id,
-		)
-		if (localTracker.hasPosition) {
-			val pos = localTracker.position
+		val tracker = localTracker ?: return
+
+		val builder = ProtobufMessages.Position.newBuilder()
+			.setTrackerId(tracker.id)
+
+		if (tracker.hasPosition) {
+			val pos = tracker.position
 			builder.setX(pos.x)
 			builder.setY(pos.y)
 			builder.setZ(pos.z)
 		}
-		if (localTracker.hasRotation) {
-			val rot = localTracker.getRotation()
+
+		if (tracker.hasRotation) {
+			val rot = tracker.getRotation()
 			builder.setQx(rot.x)
 			builder.setQy(rot.y)
 			builder.setQz(rot.z)
 			builder.setQw(rot.w)
 		}
-		sendMessage(ProtobufMessage.newBuilder().setPosition(builder).build())
+
+		if (tracker.allowVelocity) {
+			val vel = tracker.getVelocity()
+			builder.setVx(vel.x)
+			builder.setVy(vel.y)
+			builder.setVz(vel.z)
+		}
+
+		sendMessage(
+			ProtobufMessage.newBuilder()
+				.setPosition(builder)
+				.build(),
+		)
 	}
 
 	@VRServerThread
@@ -169,6 +185,16 @@ abstract class ProtobufBridge(@JvmField protected val bridgeName: String) : ISte
 					),
 
 				)
+			if (positionMessage.hasVx()) {
+				tracker
+					.setVelocity(
+						Vector3(
+							positionMessage.vx,
+							positionMessage.vy,
+							positionMessage.vz,
+						),
+					)
+			}
 			tracker.dataTick()
 		}
 	}
diff --git a/server/desktop/src/main/java/dev/slimevr/desktop/platform/ProtobufMessages.java b/server/desktop/src/main/java/dev/slimevr/desktop/platform/ProtobufMessages.java
index ebb8e0f03c..703938ad6d 100644
--- a/server/desktop/src/main/java/dev/slimevr/desktop/platform/ProtobufMessages.java
+++ b/server/desktop/src/main/java/dev/slimevr/desktop/platform/ProtobufMessages.java
@@ -1052,6 +1052,48 @@ public interface PositionOrBuilder extends
 		 * @return The dataSource.
 		 */
 		dev.slimevr.desktop.platform.ProtobufMessages.Position.DataSource getDataSource();
+
+		/**
+		 * <code>optional float vx = 10;</code>
+		 * 
+		 * @return Whether the vx field is set.
+		 */
+		boolean hasVx();
+
+		/**
+		 * <code>optional float vx = 10;</code>
+		 * 
+		 * @return The vx.
+		 */
+		float getVx();
+
+		/**
+		 * <code>optional float vy = 11;</code>
+		 * 
+		 * @return Whether the vy field is set.
+		 */
+		boolean hasVy();
+
+		/**
+		 * <code>optional float vy = 11;</code>
+		 * 
+		 * @return The vy.
+		 */
+		float getVy();
+
+		/**
+		 * <code>optional float vz = 12;</code>
+		 * 
+		 * @return Whether the vz field is set.
+		 */
+		boolean hasVz();
+
+		/**
+		 * <code>optional float vz = 12;</code>
+		 * 
+		 * @return The vz.
+		 */
+		float getVz();
 	}
 
 	/**
@@ -1416,6 +1458,75 @@ public dev.slimevr.desktop.platform.ProtobufMessages.Position.DataSource getData
 				: result;
 		}
 
+		public static final int VX_FIELD_NUMBER = 10;
+		private float vx_ = 0F;
+
+		/**
+		 * <code>optional float vx = 10;</code>
+		 * 
+		 * @return Whether the vx field is set.
+		 */
+		@java.lang.Override
+		public boolean hasVx() {
+			return ((bitField0_ & 0x00000010) != 0);
+		}
+
+		/**
+		 * <code>optional float vx = 10;</code>
+		 * 
+		 * @return The vx.
+		 */
+		@java.lang.Override
+		public float getVx() {
+			return vx_;
+		}
+
+		public static final int VY_FIELD_NUMBER = 11;
+		private float vy_ = 0F;
+
+		/**
+		 * <code>optional float vy = 11;</code>
+		 * 
+		 * @return Whether the vy field is set.
+		 */
+		@java.lang.Override
+		public boolean hasVy() {
+			return ((bitField0_ & 0x00000020) != 0);
+		}
+
+		/**
+		 * <code>optional float vy = 11;</code>
+		 * 
+		 * @return The vy.
+		 */
+		@java.lang.Override
+		public float getVy() {
+			return vy_;
+		}
+
+		public static final int VZ_FIELD_NUMBER = 12;
+		private float vz_ = 0F;
+
+		/**
+		 * <code>optional float vz = 12;</code>
+		 * 
+		 * @return Whether the vz field is set.
+		 */
+		@java.lang.Override
+		public boolean hasVz() {
+			return ((bitField0_ & 0x00000040) != 0);
+		}
+
+		/**
+		 * <code>optional float vz = 12;</code>
+		 * 
+		 * @return The vz.
+		 */
+		@java.lang.Override
+		public float getVz() {
+			return vz_;
+		}
+
 		private byte memoizedIsInitialized = -1;
 
 		@java.lang.Override
@@ -1460,6 +1571,15 @@ public void writeTo(com.google.protobuf.CodedOutputStream output)
 			if (((bitField0_ & 0x00000008) != 0)) {
 				output.writeEnum(9, dataSource_);
 			}
+			if (((bitField0_ & 0x00000010) != 0)) {
+				output.writeFloat(10, vx_);
+			}
+			if (((bitField0_ & 0x00000020) != 0)) {
+				output.writeFloat(11, vy_);
+			}
+			if (((bitField0_ & 0x00000040) != 0)) {
+				output.writeFloat(12, vz_);
+			}
 			getUnknownFields().writeTo(output);
 		}
 
@@ -1506,6 +1626,18 @@ public int getSerializedSize() {
 				size += com.google.protobuf.CodedOutputStream
 					.computeEnumSize(9, dataSource_);
 			}
+			if (((bitField0_ & 0x00000010) != 0)) {
+				size += com.google.protobuf.CodedOutputStream
+					.computeFloatSize(10, vx_);
+			}
+			if (((bitField0_ & 0x00000020) != 0)) {
+				size += com.google.protobuf.CodedOutputStream
+					.computeFloatSize(11, vy_);
+			}
+			if (((bitField0_ & 0x00000040) != 0)) {
+				size += com.google.protobuf.CodedOutputStream
+					.computeFloatSize(12, vz_);
+			}
 			size += getUnknownFields().getSerializedSize();
 			memoizedSize = size;
 			return size;
@@ -1600,6 +1732,42 @@ public boolean equals(final java.lang.Object obj) {
 				if (dataSource_ != other.dataSource_)
 					return false;
 			}
+			if (hasVx() != other.hasVx())
+				return false;
+			if (hasVx()) {
+				if (
+					java.lang.Float.floatToIntBits(getVx())
+						!= java.lang.Float
+							.floatToIntBits(
+								other.getVx()
+							)
+				)
+					return false;
+			}
+			if (hasVy() != other.hasVy())
+				return false;
+			if (hasVy()) {
+				if (
+					java.lang.Float.floatToIntBits(getVy())
+						!= java.lang.Float
+							.floatToIntBits(
+								other.getVy()
+							)
+				)
+					return false;
+			}
+			if (hasVz() != other.hasVz())
+				return false;
+			if (hasVz()) {
+				if (
+					java.lang.Float.floatToIntBits(getVz())
+						!= java.lang.Float
+							.floatToIntBits(
+								other.getVz()
+							)
+				)
+					return false;
+			}
 			if (!getUnknownFields().equals(other.getUnknownFields()))
 				return false;
 			return true;
@@ -1666,6 +1834,30 @@ public int hashCode() {
 				hash = (37 * hash) + DATA_SOURCE_FIELD_NUMBER;
 				hash = (53 * hash) + dataSource_;
 			}
+			if (hasVx()) {
+				hash = (37 * hash) + VX_FIELD_NUMBER;
+				hash = (53 * hash)
+					+ java.lang.Float
+						.floatToIntBits(
+							getVx()
+						);
+			}
+			if (hasVy()) {
+				hash = (37 * hash) + VY_FIELD_NUMBER;
+				hash = (53 * hash)
+					+ java.lang.Float
+						.floatToIntBits(
+							getVy()
+						);
+			}
+			if (hasVz()) {
+				hash = (37 * hash) + VZ_FIELD_NUMBER;
+				hash = (53 * hash)
+					+ java.lang.Float
+						.floatToIntBits(
+							getVz()
+						);
+			}
 			hash = (29 * hash) + getUnknownFields().hashCode();
 			memoizedHashCode = hash;
 			return hash;
@@ -1841,6 +2033,9 @@ public Builder clear() {
 				qz_ = 0F;
 				qw_ = 0F;
 				dataSource_ = 0;
+				vx_ = 0F;
+				vy_ = 0F;
+				vz_ = 0F;
 				return this;
 			}
 
@@ -1911,6 +2106,18 @@ private void buildPartial0(
 					result.dataSource_ = dataSource_;
 					to_bitField0_ |= 0x00000008;
 				}
+				if (((from_bitField0_ & 0x00000200) != 0)) {
+					result.vx_ = vx_;
+					to_bitField0_ |= 0x00000010;
+				}
+				if (((from_bitField0_ & 0x00000400) != 0)) {
+					result.vy_ = vy_;
+					to_bitField0_ |= 0x00000020;
+				}
+				if (((from_bitField0_ & 0x00000800) != 0)) {
+					result.vz_ = vz_;
+					to_bitField0_ |= 0x00000040;
+				}
 				result.bitField0_ |= to_bitField0_;
 			}
 
@@ -1960,6 +2167,15 @@ public Builder mergeFrom(dev.slimevr.desktop.platform.ProtobufMessages.Position
 				if (other.hasDataSource()) {
 					setDataSourceValue(other.getDataSourceValue());
 				}
+				if (other.hasVx()) {
+					setVx(other.getVx());
+				}
+				if (other.hasVy()) {
+					setVy(other.getVy());
+				}
+				if (other.hasVz()) {
+					setVz(other.getVz());
+				}
 				this.mergeUnknownFields(other.getUnknownFields());
 				onChanged();
 				return this;
@@ -2032,6 +2248,21 @@ public Builder mergeFrom(
 								bitField0_ |= 0x00000100;
 								break;
 							} // case 72
+							case 85: {
+								vx_ = input.readFloat();
+								bitField0_ |= 0x00000200;
+								break;
+							} // case 85
+							case 93: {
+								vy_ = input.readFloat();
+								bitField0_ |= 0x00000400;
+								break;
+							} // case 93
+							case 101: {
+								vz_ = input.readFloat();
+								bitField0_ |= 0x00000800;
+								break;
+							} // case 101
 							default: {
 								if (!super.parseUnknownField(input, extensionRegistry, tag)) {
 									done = true; // was an endgroup tag
@@ -2464,6 +2695,150 @@ public Builder clearDataSource() {
 				return this;
 			}
 
+			private float vx_;
+
+			/**
+			 * <code>optional float vx = 10;</code>
+			 * 
+			 * @return Whether the vx field is set.
+			 */
+			@java.lang.Override
+			public boolean hasVx() {
+				return ((bitField0_ & 0x00000200) != 0);
+			}
+
+			/**
+			 * <code>optional float vx = 10;</code>
+			 * 
+			 * @return The vx.
+			 */
+			@java.lang.Override
+			public float getVx() {
+				return vx_;
+			}
+
+			/**
+			 * <code>optional float vx = 10;</code>
+			 * 
+			 * @param value The vx to set.
+			 * @return This builder for chaining.
+			 */
+			public Builder setVx(float value) {
+
+				vx_ = value;
+				bitField0_ |= 0x00000200;
+				onChanged();
+				return this;
+			}
+
+			/**
+			 * <code>optional float vx = 10;</code>
+			 * 
+			 * @return This builder for chaining.
+			 */
+			public Builder clearVx() {
+				bitField0_ = (bitField0_ & ~0x00000200);
+				vx_ = 0F;
+				onChanged();
+				return this;
+			}
+
+			private float vy_;
+
+			/**
+			 * <code>optional float vy = 11;</code>
+			 * 
+			 * @return Whether the vy field is set.
+			 */
+			@java.lang.Override
+			public boolean hasVy() {
+				return ((bitField0_ & 0x00000400) != 0);
+			}
+
+			/**
+			 * <code>optional float vy = 11;</code>
+			 * 
+			 * @return The vy.
+			 */
+			@java.lang.Override
+			public float getVy() {
+				return vy_;
+			}
+
+			/**
+			 * <code>optional float vy = 11;</code>
+			 * 
+			 * @param value The vy to set.
+			 * @return This builder for chaining.
+			 */
+			public Builder setVy(float value) {
+
+				vy_ = value;
+				bitField0_ |= 0x00000400;
+				onChanged();
+				return this;
+			}
+
+			/**
+			 * <code>optional float vy = 11;</code>
+			 * 
+			 * @return This builder for chaining.
+			 */
+			public Builder clearVy() {
+				bitField0_ = (bitField0_ & ~0x00000400);
+				vy_ = 0F;
+				onChanged();
+				return this;
+			}
+
+			private float vz_;
+
+			/**
+			 * <code>optional float vz = 12;</code>
+			 * 
+			 * @return Whether the vz field is set.
+			 */
+			@java.lang.Override
+			public boolean hasVz() {
+				return ((bitField0_ & 0x00000800) != 0);
+			}
+
+			/**
+			 * <code>optional float vz = 12;</code>
+			 * 
+			 * @return The vz.
+			 */
+			@java.lang.Override
+			public float getVz() {
+				return vz_;
+			}
+
+			/**
+			 * <code>optional float vz = 12;</code>
+			 * 
+			 * @param value The vz to set.
+			 * @return This builder for chaining.
+			 */
+			public Builder setVz(float value) {
+
+				vz_ = value;
+				bitField0_ |= 0x00000800;
+				onChanged();
+				return this;
+			}
+
+			/**
+			 * <code>optional float vz = 12;</code>
+			 * 
+			 * @return This builder for chaining.
+			 */
+			public Builder clearVz() {
+				bitField0_ = (bitField0_ & ~0x00000800);
+				vz_ = 0F;
+				onChanged();
+				return this;
+			}
+
 			// @@protoc_insertion_point(builder_scope:messages.Position)
 		}
 
@@ -9023,7 +9398,7 @@ public static com.google.protobuf.Descriptors.FileDescriptor getDescriptor() {
 				+
 				"ngPong\"#\n\007Version\022\030\n\020protocol_version\030\001 "
 				+
-				"\001(\005\"\223\002\n\010Position\022\022\n\ntracker_id\030\001 \001(\005\022\016\n\001"
+				"\001(\005\"\333\002\n\010Position\022\022\n\ntracker_id\030\001 \001(\005\022\016\n\001"
 				+
 				"x\030\002 \001(\002H\000\210\001\001\022\016\n\001y\030\003 \001(\002H\001\210\001\001\022\016\n\001z\030\004 \001(\002H"
 				+
@@ -9031,67 +9406,71 @@ public static com.google.protobuf.Descriptors.FileDescriptor getDescriptor() {
 				+
 				"\022\n\n\002qw\030\010 \001(\002\0227\n\013data_source\030\t \001(\0162\035.mess"
 				+
-				"ages.Position.DataSourceH\003\210\001\001\"8\n\nDataSou"
+				"ages.Position.DataSourceH\003\210\001\001\022\017\n\002vx\030\n \001("
+				+
+				"\002H\004\210\001\001\022\017\n\002vy\030\013 \001(\002H\005\210\001\001\022\017\n\002vz\030\014 \001(\002H\006\210\001\001"
+				+
+				"\"8\n\nDataSource\022\010\n\004NONE\020\000\022\007\n\003IMU\020\001\022\r\n\tPRE"
 				+
-				"rce\022\010\n\004NONE\020\000\022\007\n\003IMU\020\001\022\r\n\tPRECISION\020\002\022\010\n"
+				"CISION\020\002\022\010\n\004FULL\020\003B\004\n\002_xB\004\n\002_yB\004\n\002_zB\016\n\014"
 				+
-				"\004FULL\020\003B\004\n\002_xB\004\n\002_yB\004\n\002_zB\016\n\014_data_sourc"
+				"_data_sourceB\005\n\003_vxB\005\n\003_vyB\005\n\003_vz\"\227\001\n\nUs"
 				+
-				"e\"\227\001\n\nUserAction\022\014\n\004name\030\001 \001(\t\022C\n\020action"
+				"erAction\022\014\n\004name\030\001 \001(\t\022C\n\020action_argumen"
 				+
-				"_arguments\030\002 \003(\0132).messages.UserAction.A"
+				"ts\030\002 \003(\0132).messages.UserAction.ActionArg"
 				+
-				"ctionArgumentsEntry\0326\n\024ActionArgumentsEn"
+				"umentsEntry\0326\n\024ActionArgumentsEntry\022\013\n\003k"
 				+
-				"try\022\013\n\003key\030\001 \001(\t\022\r\n\005value\030\002 \001(\t:\0028\001\"|\n\014T"
+				"ey\030\001 \001(\t\022\r\n\005value\030\002 \001(\t:\0028\001\"|\n\014TrackerAd"
 				+
-				"rackerAdded\022\022\n\ntracker_id\030\001 \001(\005\022\026\n\016track"
+				"ded\022\022\n\ntracker_id\030\001 \001(\005\022\026\n\016tracker_seria"
 				+
-				"er_serial\030\002 \001(\t\022\024\n\014tracker_name\030\003 \001(\t\022\024\n"
+				"l\030\002 \001(\t\022\024\n\014tracker_name\030\003 \001(\t\022\024\n\014tracker"
 				+
-				"\014tracker_role\030\004 \001(\005\022\024\n\014manufacturer\030\005 \001("
+				"_role\030\004 \001(\005\022\024\n\014manufacturer\030\005 \001(\t\"\374\002\n\rTr"
 				+
-				"\t\"\374\002\n\rTrackerStatus\022\022\n\ntracker_id\030\001 \001(\005\022"
+				"ackerStatus\022\022\n\ntracker_id\030\001 \001(\005\022.\n\006statu"
 				+
-				".\n\006status\030\002 \001(\0162\036.messages.TrackerStatus"
+				"s\030\002 \001(\0162\036.messages.TrackerStatus.Status\022"
 				+
-				".Status\0221\n\005extra\030\003 \003(\0132\".messages.Tracke"
+				"1\n\005extra\030\003 \003(\0132\".messages.TrackerStatus."
 				+
-				"rStatus.ExtraEntry\022;\n\nconfidence\030\004 \001(\0162\""
+				"ExtraEntry\022;\n\nconfidence\030\004 \001(\0162\".message"
 				+
-				".messages.TrackerStatus.ConfidenceH\000\210\001\001\032"
+				"s.TrackerStatus.ConfidenceH\000\210\001\001\032,\n\nExtra"
 				+
-				",\n\nExtraEntry\022\013\n\003key\030\001 \001(\t\022\r\n\005value\030\002 \001("
+				"Entry\022\013\n\003key\030\001 \001(\t\022\r\n\005value\030\002 \001(\t:\0028\001\"E\n"
 				+
-				"\t:\0028\001\"E\n\006Status\022\020\n\014DISCONNECTED\020\000\022\006\n\002OK\020"
+				"\006Status\022\020\n\014DISCONNECTED\020\000\022\006\n\002OK\020\001\022\010\n\004BUS"
 				+
-				"\001\022\010\n\004BUSY\020\002\022\t\n\005ERROR\020\003\022\014\n\010OCCLUDED\020\004\"3\n\n"
+				"Y\020\002\022\t\n\005ERROR\020\003\022\014\n\010OCCLUDED\020\004\"3\n\nConfiden"
 				+
-				"Confidence\022\006\n\002NO\020\000\022\007\n\003LOW\020\001\022\n\n\006MEDIUM\020\005\022"
+				"ce\022\006\n\002NO\020\000\022\007\n\003LOW\020\001\022\n\n\006MEDIUM\020\005\022\010\n\004HIGH\020"
 				+
-				"\010\n\004HIGH\020\nB\r\n\013_confidence\"I\n\007Battery\022\022\n\nt"
+				"\nB\r\n\013_confidence\"I\n\007Battery\022\022\n\ntracker_i"
 				+
-				"racker_id\030\001 \001(\005\022\025\n\rbattery_level\030\002 \001(\002\022\023"
+				"d\030\001 \001(\005\022\025\n\rbattery_level\030\002 \001(\002\022\023\n\013is_cha"
 				+
-				"\n\013is_charging\030\003 \001(\010\"\241\002\n\017ProtobufMessage\022"
+				"rging\030\003 \001(\010\"\241\002\n\017ProtobufMessage\022&\n\010posit"
 				+
-				"&\n\010position\030\001 \001(\0132\022.messages.PositionH\000\022"
+				"ion\030\001 \001(\0132\022.messages.PositionH\000\022+\n\013user_"
 				+
-				"+\n\013user_action\030\002 \001(\0132\024.messages.UserActi"
+				"action\030\002 \001(\0132\024.messages.UserActionH\000\022/\n\r"
 				+
-				"onH\000\022/\n\rtracker_added\030\003 \001(\0132\026.messages.T"
+				"tracker_added\030\003 \001(\0132\026.messages.TrackerAd"
 				+
-				"rackerAddedH\000\0221\n\016tracker_status\030\004 \001(\0132\027."
+				"dedH\000\0221\n\016tracker_status\030\004 \001(\0132\027.messages"
 				+
-				"messages.TrackerStatusH\000\022$\n\007battery\030\005 \001("
+				".TrackerStatusH\000\022$\n\007battery\030\005 \001(\0132\021.mess"
 				+
-				"\0132\021.messages.BatteryH\000\022$\n\007version\030\006 \001(\0132"
+				"ages.BatteryH\000\022$\n\007version\030\006 \001(\0132\021.messag"
 				+
-				"\021.messages.VersionH\000B\t\n\007messageB2\n\034dev.s"
+				"es.VersionH\000B\t\n\007messageB2\n\034dev.slimevr.d"
 				+
-				"limevr.desktop.platformB\020ProtobufMessage"
+				"esktop.platformB\020ProtobufMessagesH\003b\006pro"
 				+
-				"sH\003b\006proto3"
+				"to3"
 		};
 		descriptor = com.google.protobuf.Descriptors.FileDescriptor
 			.internalBuildGeneratedFileFrom(
@@ -9113,7 +9492,7 @@ public static com.google.protobuf.Descriptors.FileDescriptor getDescriptor() {
 		internal_static_messages_Position_fieldAccessorTable = new com.google.protobuf.GeneratedMessage.FieldAccessorTable(
 			internal_static_messages_Position_descriptor,
 			new java.lang.String[] { "TrackerId", "X", "Y", "Z", "Qx", "Qy", "Qz", "Qw",
-				"DataSource", }
+				"DataSource", "Vx", "Vy", "Vz", }
 		);
 		internal_static_messages_UserAction_descriptor = getDescriptor().getMessageTypes().get(3);
 		internal_static_messages_UserAction_fieldAccessorTable = new com.google.protobuf.GeneratedMessage.FieldAccessorTable(

From f58d4b3169265f7be6004d9af0c643d9f74de0a7 Mon Sep 17 00:00:00 2001
From: Vladimir Pankov <m1dnyt3.911@gmail.com>
Date: Fri, 20 Mar 2026 23:56:42 +0200
Subject: [PATCH 03/12] Added velocity transmission toggle to GUI and RPC (NaLo
 support)

---
 gui/public/i18n/en/translation.ftl            |  3 ++
 .../settings/pages/GeneralSettings.tsx        | 42 +++++++++++++++++++
 package.json                                  |  4 +-
 .../main/java/dev/slimevr/config/VRConfig.kt  | 10 +----
 .../java/dev/slimevr/config/VelocityConfig.kt | 11 ++++-
 .../rpc/settings/RPCSettingsBuilder.kt        | 12 ++++++
 .../rpc/settings/RPCSettingsHandler.kt        |  6 +++
 solarxr-protocol                              |  2 +-
 8 files changed, 78 insertions(+), 12 deletions(-)

diff --git a/gui/public/i18n/en/translation.ftl b/gui/public/i18n/en/translation.ftl
index dffb2a281c..6fe99de31a 100644
--- a/gui/public/i18n/en/translation.ftl
+++ b/gui/public/i18n/en/translation.ftl
@@ -635,6 +635,9 @@ settings-general-fk_settings-enforce_joint_constraints-correct_constraints-descr
 settings-general-fk_settings-ik = Position data
 settings-general-fk_settings-ik-use_position = Use Position data
 settings-general-fk_settings-ik-use_position-description = Enables the use of position data from trackers that provide it. When enabling this make sure to full reset and recalibrate in game.
+settings-general-fk_settings-velocity_settings = Velocity Settings
+settings-general-fk_settings-velocity_settings-description = Send derived velocity data to SteamVR. Required for Natural Locomotion support.
+settings-general-fk_settings-velocity_settings-send_derived_velocity = Send derived velocity to driver
 settings-general-fk_settings-arm_fk = Arm tracking
 settings-general-fk_settings-arm_fk-description = Force arms to be tracked from the headset (HMD) even if positional hand data is available.
 settings-general-fk_settings-arm_fk-force_arms = Force arms from HMD
diff --git a/gui/src/components/settings/pages/GeneralSettings.tsx b/gui/src/components/settings/pages/GeneralSettings.tsx
index 11197c65b4..115480777d 100644
--- a/gui/src/components/settings/pages/GeneralSettings.tsx
+++ b/gui/src/components/settings/pages/GeneralSettings.tsx
@@ -15,6 +15,7 @@ import {
   SteamVRTrackersSettingT,
   TapDetectionSettingsT,
   HIDSettingsT,
+  VelocitySettingsT,
   BodyPart,
 } from 'solarxr-protocol';
 import { useConfig } from '@/hooks/config';
@@ -114,6 +115,9 @@ export type SettingsForm = {
   hidSettings: {
     trackersOverHID: boolean;
   };
+  velocitySettings: {
+    sendDerivedVelocity: boolean;
+  };
 };
 
 const defaultValues: SettingsForm = {
@@ -173,6 +177,7 @@ const defaultValues: SettingsForm = {
   resetsSettings: defaultResetSettings,
   stayAligned: defaultStayAlignedSettings,
   hidSettings: { trackersOverHID: false },
+  velocitySettings: { sendDerivedVelocity: false },
 };
 
 const settingsAtom = atom(new SettingsResponseT());
@@ -350,6 +355,11 @@ export function GeneralSettings() {
     hidSettings.trackersOverHid = values.hidSettings.trackersOverHID;
     settingsReq.hidSettings = hidSettings;
 
+    const velocitySettings = new VelocitySettingsT();
+    velocitySettings.sendDerivedVelocity =
+      values.velocitySettings.sendDerivedVelocity;
+    settings.velocitySettings = velocitySettings;
+
     if (values.resetsSettings) {
       settingsReq.resetsSettings = loadResetSettings(values.resetsSettings);
     }
@@ -483,6 +493,12 @@ export function GeneralSettings() {
       };
     }
 
+    if (settings.velocitySettings) {
+      formData.velocitySettings = {
+        sendDerivedVelocity: settings.velocitySettings.sendDerivedVelocity,
+      };
+    }
+
     reset({ ...getValues(), ...formData });
   }, [settings]);
 
@@ -1053,6 +1069,32 @@ export function GeneralSettings() {
               />
             </div>
 
+            <div className="flex flex-col pt-2 pb-1">
+              <Typography variant="section-title">
+                {l10n.getString(
+                  'settings-general-fk_settings-velocity_settings'
+                )}
+              </Typography>
+              <div className="pt-2">
+                <Typography>
+                  {l10n.getString(
+                    'settings-general-fk_settings-velocity_settings-description'
+                  )}
+                </Typography>
+              </div>
+            </div>
+            <div className="grid sm:grid-cols-1 pb-3">
+              <CheckBox
+                variant="toggle"
+                outlined
+                control={control}
+                name="velocitySettings.sendDerivedVelocity"
+                label={l10n.getString(
+                  'settings-general-fk_settings-velocity_settings-send_derived_velocity'
+                )}
+              />
+            </div>
+
             {config?.debug && (
               <>
                 <div className="flex flex-col pt-2 pb-3">
diff --git a/package.json b/package.json
index 4b500ef7c1..6fb1460219 100644
--- a/package.json
+++ b/package.json
@@ -17,7 +17,7 @@
     "preinstall": "npx only-allow pnpm"
   },
   "devDependencies": {
-    "husky": "^9.1.6",
-    "lint-staged": "^15.2.10"
+    "husky": "^9.1.7",
+    "lint-staged": "^15.5.2"
   }
 }
diff --git a/server/core/src/main/java/dev/slimevr/config/VRConfig.kt b/server/core/src/main/java/dev/slimevr/config/VRConfig.kt
index dd100f55ef..5aa36e64f9 100644
--- a/server/core/src/main/java/dev/slimevr/config/VRConfig.kt
+++ b/server/core/src/main/java/dev/slimevr/config/VRConfig.kt
@@ -58,7 +58,7 @@ class VRConfig {
 
 	val trackingChecklist: TrackingChecklistConfig = TrackingChecklistConfig()
 
-	var velocityConfig: VelocityConfig = VelocityConfig()
+	val velocityConfig: VelocityConfig = VelocityConfig()
 
 	val vrcConfig: VRCConfig = VRCConfig()
 
@@ -106,13 +106,7 @@ class VRConfig {
 		return config
 	}
 
-	/**
-	 * Applies the velocity policy to the given [Tracker].
-	 *
-	 * This method determines whether the tracker—be it a physical sensor or a computed virtual device—is
-	 * permitted to calculate and broadcast velocity data.
-	 * It resolves the active [VelocityConfig] value, updating [Tracker.allowVelocity] accordingly.
-	 */
+	/** Resolves value from global config and applies to tracker. */
 	fun applyVelocityPolicy(tracker: Tracker) {
 		tracker.allowVelocity = velocityConfig.sendDerivedVelocity
 	}
diff --git a/server/core/src/main/java/dev/slimevr/config/VelocityConfig.kt b/server/core/src/main/java/dev/slimevr/config/VelocityConfig.kt
index a6516b1e24..204b951e32 100644
--- a/server/core/src/main/java/dev/slimevr/config/VelocityConfig.kt
+++ b/server/core/src/main/java/dev/slimevr/config/VelocityConfig.kt
@@ -1,10 +1,19 @@
 package dev.slimevr.config
 
+import dev.slimevr.VRServer
+
 /**
  * Allows to enable/disable sending of optional derived velocity data via Protobuf.
  * Enables Natural Locomotion Support
  * May create overprediction in certain titles causing excessive jitter when moving upper body.
  */
 class VelocityConfig {
-	var sendDerivedVelocity: Boolean = false // Disables derived velocity for all trackers. Driver zeroes out velocity if nothing is returned in protobuf message.
+	// Disables derived velocity for all trackers. Driver zeroes out velocity if nothing is returned in protobuf message.
+	var sendDerivedVelocity: Boolean = false
+
+	fun updateTrackersVelocityPolicy() {
+		for (t in VRServer.instance.allTrackers) {
+			t.allowVelocity = sendDerivedVelocity
+		}
+	}
 }
diff --git a/server/core/src/main/java/dev/slimevr/protocol/rpc/settings/RPCSettingsBuilder.kt b/server/core/src/main/java/dev/slimevr/protocol/rpc/settings/RPCSettingsBuilder.kt
index bc6dd73098..cf2feca96b 100644
--- a/server/core/src/main/java/dev/slimevr/protocol/rpc/settings/RPCSettingsBuilder.kt
+++ b/server/core/src/main/java/dev/slimevr/protocol/rpc/settings/RPCSettingsBuilder.kt
@@ -15,6 +15,7 @@ import dev.slimevr.config.StayAlignedConfig
 import dev.slimevr.config.TapDetectionConfig
 import dev.slimevr.config.VMCConfig
 import dev.slimevr.config.VRCOSCConfig
+import dev.slimevr.config.VelocityConfig
 import dev.slimevr.filtering.TrackerFilters.Companion.getByConfigkey
 import dev.slimevr.tracking.processor.HumanPoseManager
 import dev.slimevr.tracking.processor.config.SkeletonConfigToggles
@@ -34,6 +35,7 @@ import solarxr_protocol.rpc.SteamVRTrackersSetting
 import solarxr_protocol.rpc.TapDetectionSettings
 import solarxr_protocol.rpc.VMCOSCSettings
 import solarxr_protocol.rpc.VRCOSCSettings
+import solarxr_protocol.rpc.VelocitySettings
 import solarxr_protocol.rpc.settings.LegTweaksSettings
 import solarxr_protocol.rpc.settings.ModelRatios
 import solarxr_protocol.rpc.settings.ModelSettings
@@ -427,6 +429,7 @@ fun createSettingsResponse(fbb: FlatBufferBuilder, server: VRServer): Int {
 			),
 			createHIDSettings(fbb, server.configManager.vrConfig.hidConfig),
 			0,
+			createVelocitySettings(fbb, server.configManager.vrConfig.velocityConfig),
 		)
 }
 
@@ -462,3 +465,12 @@ fun createHIDSettings(
 		fbb,
 		config.trackersOverHID,
 	)
+
+fun createVelocitySettings(
+	fbb: FlatBufferBuilder,
+	config: VelocityConfig,
+): Int = VelocitySettings
+	.createVelocitySettings(
+		fbb,
+		config.sendDerivedVelocity,
+	)
diff --git a/server/core/src/main/java/dev/slimevr/protocol/rpc/settings/RPCSettingsHandler.kt b/server/core/src/main/java/dev/slimevr/protocol/rpc/settings/RPCSettingsHandler.kt
index 8cbb87c139..3777a4041e 100644
--- a/server/core/src/main/java/dev/slimevr/protocol/rpc/settings/RPCSettingsHandler.kt
+++ b/server/core/src/main/java/dev/slimevr/protocol/rpc/settings/RPCSettingsHandler.kt
@@ -367,6 +367,12 @@ class RPCSettingsHandler(var rpcHandler: RPCHandler, var api: ProtocolAPI) {
 			config.trackersOverHID = requestConfig.trackersOverHid()
 		}
 
+		if (req.velocitySettings() != null) {
+			val velocityConfig = api.server.configManager.vrConfig.velocityConfig
+			velocityConfig.sendDerivedVelocity = req.velocitySettings().sendDerivedVelocity()
+			velocityConfig.updateTrackersVelocityPolicy()
+		}
+
 		api.server.configManager.saveConfig()
 	}
 
diff --git a/solarxr-protocol b/solarxr-protocol
index 5d572629c9..9e83ea846e 160000
--- a/solarxr-protocol
+++ b/solarxr-protocol
@@ -1 +1 @@
-Subproject commit 5d572629c94f895574162225ec69443705ce35af
+Subproject commit 9e83ea846e846dbc27615c59b0598bb288b1e7f8

From da666d3b144e3d04c7e26e5360d48ef10fe2b5df Mon Sep 17 00:00:00 2001
From: Vladimir Pankov <m1dnyt3.911@gmail.com>
Date: Tue, 21 Apr 2026 17:10:13 +0300
Subject: [PATCH 04/12] Remove applyVelocityPolicyTo(), Replace System.nanoTime
 with Timesource, Replace allowVelocity with hasVelocity in ProtobufBridge.

---
 .../core/src/main/java/dev/slimevr/VRServer.kt  | 17 +----------------
 .../processor/skeleton/HumanSkeleton.kt         |  2 +-
 .../dev/slimevr/tracking/trackers/Tracker.kt    | 14 +++++++++-----
 .../slimevr/desktop/platform/ProtobufBridge.kt  |  2 +-
 4 files changed, 12 insertions(+), 23 deletions(-)

diff --git a/server/core/src/main/java/dev/slimevr/VRServer.kt b/server/core/src/main/java/dev/slimevr/VRServer.kt
index 1a0f7380ad..cd3339f97e 100644
--- a/server/core/src/main/java/dev/slimevr/VRServer.kt
+++ b/server/core/src/main/java/dev/slimevr/VRServer.kt
@@ -186,21 +186,6 @@ class VRServer @JvmOverloads constructor(
 		instance = this
 	}
 
-	/**
-	 * TODO: The design of this method is chosen for future expandability in case we want to have more complex velocity policies that depend on tracker properties or other config values.
-	 * Initiates the velocity policy application process for the specified [Tracker] (or all trackers if null).
-	 *
-	 * This method serves as the initiator.
-	 * The actual policy logic is not handled here,
-	 * but is delegated to [dev.slimevr.config.VRConfig.applyVelocityPolicy].
-	 */
-	private fun applyVelocityPolicyTo(tracker: Tracker?) {
-		val targets = tracker?.let { listOf(it) } ?: trackers
-		for (t in targets) {
-			configManager.vrConfig.applyVelocityPolicy(t)
-		}
-	}
-
 	fun hasBridge(bridgeClass: Class<out Bridge?>): Boolean {
 		for (bridge in bridges) {
 			if (bridgeClass.isAssignableFrom(bridge.javaClass)) {
@@ -248,7 +233,7 @@ class VRServer @JvmOverloads constructor(
 			configManager.saveConfig()
 
 			// Requires a fresh TrackerConfig on Update, so executed after we save a new state.
-			applyVelocityPolicyTo(tracker)
+			tracker?.let { configManager.vrConfig.applyVelocityPolicy(it) }
 		}
 	}
 
diff --git a/server/core/src/main/java/dev/slimevr/tracking/processor/skeleton/HumanSkeleton.kt b/server/core/src/main/java/dev/slimevr/tracking/processor/skeleton/HumanSkeleton.kt
index d64e8a4930..da16526691 100644
--- a/server/core/src/main/java/dev/slimevr/tracking/processor/skeleton/HumanSkeleton.kt
+++ b/server/core/src/main/java/dev/slimevr/tracking/processor/skeleton/HumanSkeleton.kt
@@ -1171,7 +1171,7 @@ class HumanSkeleton(
 			it.position = trackerBone.getTailPosition()
 			it.setRotation(trackerBone.getGlobalRotation() * trackerBone.rotationOffset.inv())
 			it.dataTick()
-			it.updateDerivedVelocity(System.nanoTime())
+			it.updateDerivedVelocity()
 		}
 	}
 
diff --git a/server/core/src/main/java/dev/slimevr/tracking/trackers/Tracker.kt b/server/core/src/main/java/dev/slimevr/tracking/trackers/Tracker.kt
index ae2a64edea..00d79d5fa7 100644
--- a/server/core/src/main/java/dev/slimevr/tracking/trackers/Tracker.kt
+++ b/server/core/src/main/java/dev/slimevr/tracking/trackers/Tracker.kt
@@ -12,6 +12,9 @@ import io.eiren.util.BufferedTimer
 import io.github.axisangles.ktmath.Quaternion
 import io.github.axisangles.ktmath.Vector3
 import kotlin.properties.Delegates
+import kotlin.time.DurationUnit
+import kotlin.time.TimeMark
+import kotlin.time.TimeSource
 
 const val TIMEOUT_MS = 2_000L
 const val DISCONNECT_MS = 3_000L + TIMEOUT_MS
@@ -123,7 +126,7 @@ class Tracker @JvmOverloads constructor(
 	 * Velocity state server-side differentiation based on sent poses
 	 */
 	private data class VelocityState(
-		var prevTimeNs: Long = 0L,
+		var prevMark: TimeMark? = null,
 		var prevPos: Vector3 = Vector3(0f, 0f, 0f),
 	)
 
@@ -370,7 +373,7 @@ class Tracker @JvmOverloads constructor(
 	 * last update, applying a sanity check on the time delta to filter out noise and ensure data stability.
 	 *
 	 */
-	fun updateDerivedVelocity(nowNs: Long) {
+	fun updateDerivedVelocity() {
 		if (!allowVelocity || !hasPosition) {
 			velocityState = null
 			_velocity = Vector3.NULL
@@ -382,8 +385,9 @@ class Tracker @JvmOverloads constructor(
 			velocityState = it
 		}
 
-		if (state.prevTimeNs != 0L) {
-			val dt = (nowNs - state.prevTimeNs) * 1e-9
+		val prevMark = state.prevMark
+		if (prevMark != null) {
+			val dt = prevMark.elapsedNow().toDouble(DurationUnit.SECONDS)
 			if (dt in 1e-4..0.25) {
 				_velocity = Vector3(
 					((pos.x - state.prevPos.x) / dt).toFloat(),
@@ -394,7 +398,7 @@ class Tracker @JvmOverloads constructor(
 				_velocity = Vector3.NULL
 			}
 		}
-		state.prevTimeNs = nowNs
+		state.prevMark = TimeSource.Monotonic.markNow()
 		state.prevPos = pos
 	}
 
diff --git a/server/desktop/src/main/java/dev/slimevr/desktop/platform/ProtobufBridge.kt b/server/desktop/src/main/java/dev/slimevr/desktop/platform/ProtobufBridge.kt
index 9a116b5efd..d20d8f9e13 100644
--- a/server/desktop/src/main/java/dev/slimevr/desktop/platform/ProtobufBridge.kt
+++ b/server/desktop/src/main/java/dev/slimevr/desktop/platform/ProtobufBridge.kt
@@ -124,7 +124,7 @@ abstract class ProtobufBridge(@JvmField protected val bridgeName: String) : ISte
 			builder.setQw(rot.w)
 		}
 
-		if (tracker.allowVelocity) {
+		if (tracker.hasVelocity) {
 			val vel = tracker.getVelocity()
 			builder.setVx(vel.x)
 			builder.setVy(vel.y)

From e39202686fb95e93515b1fa811847750dd79fb1b Mon Sep 17 00:00:00 2001
From: Vladimir Pankov <m1dnyt3.911@gmail.com>
Date: Tue, 21 Apr 2026 18:18:51 +0300
Subject: [PATCH 05/12] Add build stubs for solarxr-protocol schema additions
 pending #1811

# Conflicts:
#	server/core/src/main/java/dev/slimevr/protocol/rpc/settings/RPCSettingsBuilder.kt
---
 .../dev/slimevr/protocol/rpc/settings/RPCSettingsHandler.kt     | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/server/core/src/main/java/dev/slimevr/protocol/rpc/settings/RPCSettingsHandler.kt b/server/core/src/main/java/dev/slimevr/protocol/rpc/settings/RPCSettingsHandler.kt
index 3777a4041e..5e0e588bdd 100644
--- a/server/core/src/main/java/dev/slimevr/protocol/rpc/settings/RPCSettingsHandler.kt
+++ b/server/core/src/main/java/dev/slimevr/protocol/rpc/settings/RPCSettingsHandler.kt
@@ -390,7 +390,7 @@ class RPCSettingsHandler(var rpcHandler: RPCHandler, var api: ProtocolAPI) {
 			val settings = SettingsResponse
 				.createSettingsResponse(
 					fbb,
-					createSteamVRSettings(fbb, bridge), 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+					createSteamVRSettings(fbb, bridge), 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 				)
 			val outbound =
 				rpcHandler.createRPCMessage(fbb, RpcMessage.SettingsResponse, settings)

From d47dd3a423a8f22b1cc4fb41005552c945d80164 Mon Sep 17 00:00:00 2001
From: Vladimir Pankov <m1dnyt3.911@gmail.com>
Date: Tue, 21 Apr 2026 18:32:00 +0300
Subject: [PATCH 06/12] Add FBT jitter warning to velocity settings description


 Conflicts:

	server/core/src/main/java/dev/slimevr/protocol/rpc/settings/RPCSettingsBuilder.kt
---
 gui/public/i18n/en/translation.ftl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gui/public/i18n/en/translation.ftl b/gui/public/i18n/en/translation.ftl
index 6fe99de31a..fd804a0ec6 100644
--- a/gui/public/i18n/en/translation.ftl
+++ b/gui/public/i18n/en/translation.ftl
@@ -636,7 +636,7 @@ settings-general-fk_settings-ik = Position data
 settings-general-fk_settings-ik-use_position = Use Position data
 settings-general-fk_settings-ik-use_position-description = Enables the use of position data from trackers that provide it. When enabling this make sure to full reset and recalibrate in game.
 settings-general-fk_settings-velocity_settings = Velocity Settings
-settings-general-fk_settings-velocity_settings-description = Send derived velocity data to SteamVR. Required for Natural Locomotion support.
+settings-general-fk_settings-velocity_settings-description = Send derived velocity data to SteamVR. Required for Natural Locomotion support. May cause jitter in FBT.
 settings-general-fk_settings-velocity_settings-send_derived_velocity = Send derived velocity to driver
 settings-general-fk_settings-arm_fk = Arm tracking
 settings-general-fk_settings-arm_fk-description = Force arms to be tracked from the headset (HMD) even if positional hand data is available.

From 70a98a35f7654c7da35aa1eb87553fb72c6d433a Mon Sep 17 00:00:00 2001
From: Vladimir Pankov <m1dnyt3.911@gmail.com>
Date: Wed, 22 Apr 2026 18:18:52 +0300
Subject: [PATCH 07/12] Fix RPC velocity toggle state being sent to response
 instead of request

---
 gui/src/components/settings/pages/GeneralSettings.tsx | 2 +-
 package.json                                          | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/gui/src/components/settings/pages/GeneralSettings.tsx b/gui/src/components/settings/pages/GeneralSettings.tsx
index 115480777d..a90e725afc 100644
--- a/gui/src/components/settings/pages/GeneralSettings.tsx
+++ b/gui/src/components/settings/pages/GeneralSettings.tsx
@@ -358,7 +358,7 @@ export function GeneralSettings() {
     const velocitySettings = new VelocitySettingsT();
     velocitySettings.sendDerivedVelocity =
       values.velocitySettings.sendDerivedVelocity;
-    settings.velocitySettings = velocitySettings;
+    settingsReq.velocitySettings = velocitySettings;
 
     if (values.resetsSettings) {
       settingsReq.resetsSettings = loadResetSettings(values.resetsSettings);
diff --git a/package.json b/package.json
index 6fb1460219..4b500ef7c1 100644
--- a/package.json
+++ b/package.json
@@ -17,7 +17,7 @@
     "preinstall": "npx only-allow pnpm"
   },
   "devDependencies": {
-    "husky": "^9.1.7",
-    "lint-staged": "^15.5.2"
+    "husky": "^9.1.6",
+    "lint-staged": "^15.2.10"
   }
 }

From 18522536fe993d9e4fdaefb85f431a9571b144a8 Mon Sep 17 00:00:00 2001
From: Vladimir Pankov <m1dnyt3.911@gmail.com>
Date: Fri, 24 Apr 2026 13:14:54 +0300
Subject: [PATCH 08/12] Review: Inlined velocity policy, non-nullable
 velocityState, markNow timing fix, non-nullable writeTrackerUpdate param

---
 .../src/main/java/dev/slimevr/VRServer.kt     |  3 ---
 .../main/java/dev/slimevr/config/VRConfig.kt  |  7 +----
 .../dev/slimevr/tracking/trackers/Tracker.kt  | 27 ++++++++++---------
 .../desktop/platform/ProtobufBridge.kt        | 18 ++++++-------
 4 files changed, 23 insertions(+), 32 deletions(-)

diff --git a/server/core/src/main/java/dev/slimevr/VRServer.kt b/server/core/src/main/java/dev/slimevr/VRServer.kt
index cd3339f97e..f5e5cf6a71 100644
--- a/server/core/src/main/java/dev/slimevr/VRServer.kt
+++ b/server/core/src/main/java/dev/slimevr/VRServer.kt
@@ -231,9 +231,6 @@ class VRServer @JvmOverloads constructor(
 			refreshTrackersDriftCompensationEnabled()
 			configManager.vrConfig.writeTrackerConfig(tracker)
 			configManager.saveConfig()
-
-			// Requires a fresh TrackerConfig on Update, so executed after we save a new state.
-			tracker?.let { configManager.vrConfig.applyVelocityPolicy(it) }
 		}
 	}
 
diff --git a/server/core/src/main/java/dev/slimevr/config/VRConfig.kt b/server/core/src/main/java/dev/slimevr/config/VRConfig.kt
index 5aa36e64f9..903750aa8a 100644
--- a/server/core/src/main/java/dev/slimevr/config/VRConfig.kt
+++ b/server/core/src/main/java/dev/slimevr/config/VRConfig.kt
@@ -106,11 +106,6 @@ class VRConfig {
 		return config
 	}
 
-	/** Resolves value from global config and applies to tracker. */
-	fun applyVelocityPolicy(tracker: Tracker) {
-		tracker.allowVelocity = velocityConfig.sendDerivedVelocity
-	}
-
 	fun readTrackerConfig(tracker: Tracker) {
 		if (tracker.userEditable) {
 			val config = getTracker(tracker)
@@ -126,7 +121,7 @@ class VRConfig {
 					.readFilteringConfig(filters, tracker.getRotation())
 			}
 		}
-		applyVelocityPolicy(tracker)
+		tracker.allowVelocity = velocityConfig.sendDerivedVelocity
 	}
 
 	fun writeTrackerConfig(tracker: Tracker?) {
diff --git a/server/core/src/main/java/dev/slimevr/tracking/trackers/Tracker.kt b/server/core/src/main/java/dev/slimevr/tracking/trackers/Tracker.kt
index 00d79d5fa7..b8c69e803f 100644
--- a/server/core/src/main/java/dev/slimevr/tracking/trackers/Tracker.kt
+++ b/server/core/src/main/java/dev/slimevr/tracking/trackers/Tracker.kt
@@ -12,8 +12,9 @@ import io.eiren.util.BufferedTimer
 import io.github.axisangles.ktmath.Quaternion
 import io.github.axisangles.ktmath.Vector3
 import kotlin.properties.Delegates
+import kotlin.time.Duration.Companion.microseconds
+import kotlin.time.Duration.Companion.milliseconds
 import kotlin.time.DurationUnit
-import kotlin.time.TimeMark
 import kotlin.time.TimeSource
 
 const val TIMEOUT_MS = 2_000L
@@ -126,11 +127,11 @@ class Tracker @JvmOverloads constructor(
 	 * Velocity state server-side differentiation based on sent poses
 	 */
 	private data class VelocityState(
-		var prevMark: TimeMark? = null,
+		var prevMark: TimeSource.Monotonic.ValueTimeMark? = null,
 		var prevPos: Vector3 = Vector3(0f, 0f, 0f),
 	)
 
-	private var velocityState: VelocityState? = null
+	private var velocityState: VelocityState = VelocityState()
 
 	var position = Vector3.NULL
 	val resetsHandler: TrackerResetsHandler = TrackerResetsHandler(this)
@@ -375,30 +376,30 @@ class Tracker @JvmOverloads constructor(
 	 */
 	fun updateDerivedVelocity() {
 		if (!allowVelocity || !hasPosition) {
-			velocityState = null
+			velocityState.prevMark = null
 			_velocity = Vector3.NULL
 			return
 		}
 
 		val pos = position
-		val state = velocityState ?: VelocityState().also {
-			velocityState = it
-		}
+		val state = velocityState
+		val now = TimeSource.Monotonic.markNow()
 
 		val prevMark = state.prevMark
 		if (prevMark != null) {
-			val dt = prevMark.elapsedNow().toDouble(DurationUnit.SECONDS)
-			if (dt in 1e-4..0.25) {
+			val dt = now - prevMark
+			if (dt in 100.microseconds..250.milliseconds) {
+				val dtSeconds = dt.toDouble(DurationUnit.SECONDS)
 				_velocity = Vector3(
-					((pos.x - state.prevPos.x) / dt).toFloat(),
-					((pos.y - state.prevPos.y) / dt).toFloat(),
-					((pos.z - state.prevPos.z) / dt).toFloat(),
+					((pos.x - state.prevPos.x) / dtSeconds).toFloat(),
+					((pos.y - state.prevPos.y) / dtSeconds).toFloat(),
+					((pos.z - state.prevPos.z) / dtSeconds).toFloat(),
 				)
 			} else {
 				_velocity = Vector3.NULL
 			}
 		}
-		state.prevMark = TimeSource.Monotonic.markNow()
+		state.prevMark = now
 		state.prevPos = pos
 	}
 
diff --git a/server/desktop/src/main/java/dev/slimevr/desktop/platform/ProtobufBridge.kt b/server/desktop/src/main/java/dev/slimevr/desktop/platform/ProtobufBridge.kt
index d20d8f9e13..5cc8a33603 100644
--- a/server/desktop/src/main/java/dev/slimevr/desktop/platform/ProtobufBridge.kt
+++ b/server/desktop/src/main/java/dev/slimevr/desktop/platform/ProtobufBridge.kt
@@ -103,29 +103,27 @@ abstract class ProtobufBridge(@JvmField protected val bridgeName: String) : ISte
 	}
 
 	@VRServerThread
-	protected fun writeTrackerUpdate(localTracker: Tracker?) {
-		val tracker = localTracker ?: return
-
+	protected fun writeTrackerUpdate(localTracker: Tracker) {
 		val builder = ProtobufMessages.Position.newBuilder()
-			.setTrackerId(tracker.id)
+			.setTrackerId(localTracker.id)
 
-		if (tracker.hasPosition) {
-			val pos = tracker.position
+		if (localTracker.hasPosition) {
+			val pos = localTracker.position
 			builder.setX(pos.x)
 			builder.setY(pos.y)
 			builder.setZ(pos.z)
 		}
 
-		if (tracker.hasRotation) {
-			val rot = tracker.getRotation()
+		if (localTracker.hasRotation) {
+			val rot = localTracker.getRotation()
 			builder.setQx(rot.x)
 			builder.setQy(rot.y)
 			builder.setQz(rot.z)
 			builder.setQw(rot.w)
 		}
 
-		if (tracker.hasVelocity) {
-			val vel = tracker.getVelocity()
+		if (localTracker.hasVelocity) {
+			val vel = localTracker.getVelocity()
 			builder.setVx(vel.x)
 			builder.setVy(vel.y)
 			builder.setVz(vel.z)

From d9c4ccf17f988ec004f1c796caf7a7f77e512317 Mon Sep 17 00:00:00 2001
From: Vladimir Pankov <m1dnyt3.911@gmail.com>
Date: Fri, 24 Apr 2026 15:09:45 +0300
Subject: [PATCH 09/12] Review: velocityState direct use and change to val

---
 .../java/dev/slimevr/tracking/trackers/Tracker.kt | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/server/core/src/main/java/dev/slimevr/tracking/trackers/Tracker.kt b/server/core/src/main/java/dev/slimevr/tracking/trackers/Tracker.kt
index b8c69e803f..324e7e7dbe 100644
--- a/server/core/src/main/java/dev/slimevr/tracking/trackers/Tracker.kt
+++ b/server/core/src/main/java/dev/slimevr/tracking/trackers/Tracker.kt
@@ -131,7 +131,7 @@ class Tracker @JvmOverloads constructor(
 		var prevPos: Vector3 = Vector3(0f, 0f, 0f),
 	)
 
-	private var velocityState: VelocityState = VelocityState()
+	private val velocityState = VelocityState()
 
 	var position = Vector3.NULL
 	val resetsHandler: TrackerResetsHandler = TrackerResetsHandler(this)
@@ -382,25 +382,24 @@ class Tracker @JvmOverloads constructor(
 		}
 
 		val pos = position
-		val state = velocityState
 		val now = TimeSource.Monotonic.markNow()
 
-		val prevMark = state.prevMark
+		val prevMark = velocityState.prevMark
 		if (prevMark != null) {
 			val dt = now - prevMark
 			if (dt in 100.microseconds..250.milliseconds) {
 				val dtSeconds = dt.toDouble(DurationUnit.SECONDS)
 				_velocity = Vector3(
-					((pos.x - state.prevPos.x) / dtSeconds).toFloat(),
-					((pos.y - state.prevPos.y) / dtSeconds).toFloat(),
-					((pos.z - state.prevPos.z) / dtSeconds).toFloat(),
+					((pos.x - velocityState.prevPos.x) / dtSeconds).toFloat(),
+					((pos.y - velocityState.prevPos.y) / dtSeconds).toFloat(),
+					((pos.z - velocityState.prevPos.z) / dtSeconds).toFloat(),
 				)
 			} else {
 				_velocity = Vector3.NULL
 			}
 		}
-		state.prevMark = now
-		state.prevPos = pos
+		velocityState.prevMark = now
+		velocityState.prevPos = pos
 	}
 
 	/**

From 822a831f3d75c5bb261b8f6f6902d85858073177 Mon Sep 17 00:00:00 2001
From: Vladimir Pankov <m1dnyt3.911@gmail.com>
Date: Fri, 24 Apr 2026 16:00:00 +0300
Subject: [PATCH 10/12] Solar: sync with the updated head

---
 solarxr-protocol | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/solarxr-protocol b/solarxr-protocol
index 9e83ea846e..ee4d7c1a5f 160000
--- a/solarxr-protocol
+++ b/solarxr-protocol
@@ -1 +1 @@
-Subproject commit 9e83ea846e846dbc27615c59b0598bb288b1e7f8
+Subproject commit ee4d7c1a5f23a368fef0da1069fbc2c8bb62eca6

From a9bfa5e293dc2d9975e01b6021539ba670ffd00b Mon Sep 17 00:00:00 2001
From: Vladimir Pankov <m1dnyt3.911@gmail.com>
Date: Mon, 27 Apr 2026 13:23:02 +0300
Subject: [PATCH 11/12] Update solarxr to track main.

---
 solarxr-protocol | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/solarxr-protocol b/solarxr-protocol
index ee4d7c1a5f..aa384c0f8b 160000
--- a/solarxr-protocol
+++ b/solarxr-protocol
@@ -1 +1 @@
-Subproject commit ee4d7c1a5f23a368fef0da1069fbc2c8bb62eca6
+Subproject commit aa384c0f8b0c1c8c8146295ff595ea034d348399

From 4fd5c9a1bb80ccc825d711cb9050a111f1f07a2c Mon Sep 17 00:00:00 2001
From: Vladimir Pankov <m1dnyt3.911@gmail.com>
Date: Tue, 28 Apr 2026 11:58:39 +0300
Subject: [PATCH 12/12] Review: rename updateTrackersVelocityPolicy and
 rephrase updateDerivedVelocity KDoc

---
 .../src/main/java/dev/slimevr/config/VelocityConfig.kt   | 2 +-
 .../slimevr/protocol/rpc/settings/RPCSettingsHandler.kt  | 2 +-
 .../main/java/dev/slimevr/tracking/trackers/Tracker.kt   | 9 +++------
 3 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/server/core/src/main/java/dev/slimevr/config/VelocityConfig.kt b/server/core/src/main/java/dev/slimevr/config/VelocityConfig.kt
index 204b951e32..82a6d1f673 100644
--- a/server/core/src/main/java/dev/slimevr/config/VelocityConfig.kt
+++ b/server/core/src/main/java/dev/slimevr/config/VelocityConfig.kt
@@ -11,7 +11,7 @@ class VelocityConfig {
 	// Disables derived velocity for all trackers. Driver zeroes out velocity if nothing is returned in protobuf message.
 	var sendDerivedVelocity: Boolean = false
 
-	fun updateTrackersVelocityPolicy() {
+	fun updateTrackersVelocitySettings() {
 		for (t in VRServer.instance.allTrackers) {
 			t.allowVelocity = sendDerivedVelocity
 		}
diff --git a/server/core/src/main/java/dev/slimevr/protocol/rpc/settings/RPCSettingsHandler.kt b/server/core/src/main/java/dev/slimevr/protocol/rpc/settings/RPCSettingsHandler.kt
index 5e0e588bdd..207fc1fe38 100644
--- a/server/core/src/main/java/dev/slimevr/protocol/rpc/settings/RPCSettingsHandler.kt
+++ b/server/core/src/main/java/dev/slimevr/protocol/rpc/settings/RPCSettingsHandler.kt
@@ -370,7 +370,7 @@ class RPCSettingsHandler(var rpcHandler: RPCHandler, var api: ProtocolAPI) {
 		if (req.velocitySettings() != null) {
 			val velocityConfig = api.server.configManager.vrConfig.velocityConfig
 			velocityConfig.sendDerivedVelocity = req.velocitySettings().sendDerivedVelocity()
-			velocityConfig.updateTrackersVelocityPolicy()
+			velocityConfig.updateTrackersVelocitySettings()
 		}
 
 		api.server.configManager.saveConfig()
diff --git a/server/core/src/main/java/dev/slimevr/tracking/trackers/Tracker.kt b/server/core/src/main/java/dev/slimevr/tracking/trackers/Tracker.kt
index 324e7e7dbe..4262b2abe9 100644
--- a/server/core/src/main/java/dev/slimevr/tracking/trackers/Tracker.kt
+++ b/server/core/src/main/java/dev/slimevr/tracking/trackers/Tracker.kt
@@ -367,12 +367,9 @@ class Tracker @JvmOverloads constructor(
 	}
 
 	/**
-	 * Updates the derived velocity of the tracker by differentiating position over time.
-	 *
-	 * This method enforces the [allowVelocity] policy and checks for valid position data before
-	 * proceeding. If conditions are met, it calculates velocity based on the displacement since the
-	 * last update, applying a sanity check on the time delta to filter out noise and ensure data stability.
-	 *
+	 * If derived velocity is enabled, updates the derived velocity of the tracker,
+	 * calculating it based on the position displacement since the last update,
+	 * applying a sanity check on the time delta to filter out noise and ensure data stability.
 	 */
 	fun updateDerivedVelocity() {
 		if (!allowVelocity || !hasPosition) {