sync: update documentation sources (2026-06-24 00:51 UTC)

Author: github-actions[bot]

roblox/en-us/reference/cloud/openapi.json

@@ -7,14 +7,77 @@ type: class
 memory_category: BaseParts
 summary: |
   Aligns two `Class.BasePart|BaseParts` with an animate-able kinematic or
-  force-based joint.
+  force-based joint that supports physical simulation (ragdoll, arm strength).
+  The default joint type for R15 avatar rigs.
 description: |
-  An `AnimationConstraint` constrains its `Class.Attachment|Attachments` so that
-  they're offset by `Class.AnimationConstraint.Transform|Transform`.
+  #### Replaces Motor6D for Avatar rigs
+
+  As part of the
+  [Avatar Joint Upgrade](https://devforum.roblox.com/t/avatar-joint-upgrade-for-physically-simulated-character-movement-is-now-live/4298561),
+  `AnimationConstraint` is the **replacement for `Class.Motor6D`** in R15 player
+  character rigs. When
+  `Class.StarterPlayer.AvatarJointUpgrade|AvatarJointUpgrade` is enabled (the
+  default for new experiences), player characters spawn with
+  AnimationConstraints instead of Motor6Ds. Unlike Motor6D, AnimationConstraint
+  supports both kinematic animation and force-based physical simulation —
+  enabling ragdoll physics, arm strength, and other physically simulated
+  character movement without rebuilding the rig.
+
+  #### Migrating from Motor6D
+
+  If you have existing code that uses Motor6D for character rigs, note these key
+  differences. See also the
+  [Phase 2 migration recommendations](https://devforum.roblox.com/t/avatar-joint-upgrade-aju-phase-2-rollout-updated-migration-recommendations/4656414).
+
+  - **Finding joints**: Use `:FindFirstChildWhichIsA("AnimationConstraint")`
+    instead of `:FindFirstChildOfClass("Motor6D")`. For code that must support
+    both old and new rigs, check for AnimationConstraint first, then fall back
+    to Motor6D.
+  - **C0, C1, Part0, Part1**: These properties exist on AnimationConstraint as
+    **read-only** aliases for backwards compatibility. They map to
+    `Attachment0.CFrame`, `Attachment1.CFrame`, `Attachment0.Parent`, and
+    `Attachment1.Parent` respectively. Do not attempt to write to them.
+  - **Do not modify RigAttachment.CFrame directly** — this disrupts animation
+    retargeting and causes performance issues.
+  - **Transform**: Works identically to `Class.Motor6D.Transform` — the
+    `Class.Animator` writes to it each frame. Layer procedural animations by
+    multiplying into `Transform` during `Class.RunService.PreSimulation`, which
+    stacks with active animation tracks without breaking retargeting.
+  - **IsKinematic**: When `true` (default), behavior is equivalent to Motor6D.
+    Set to `false` to enable force-based physical simulation.
+  - **Type checks**: `animConstraint:IsA("Motor6D")` returns `false`. Update any
+    `IsA("Motor6D")` guards to also accept `"AnimationConstraint"`.
+  - **Server replication**: Instead of setting C0 on the server, use client-side
+    animation evaluation and synchronize data through custom Attributes or
+    `Class.UnreliableRemoteEvent`.
 
-  For backwards compatibility with `Class.Motor6D`, `AnimationConstraint`
-  exposes read-only `C0`, `C1`, `Part0`, and `Part1` properties to help adopt
-  the `Class.StarterPlayer.AvatarJointUpgrade|AvatarJointUpgrade`.
+  ##### Example: Procedural neck rotation
+
+  ```lua
+  -- Before (Motor6D): writing to C0 directly
+  local originalC0 = neck.C0
+  RunService.RenderStepped:Connect(function()
+      neck.C0 = originalC0 * computeNeckRotation()
+  end)
+
+  -- After (AnimationConstraint): multiplying into Transform during PreSimulation
+  RunService.PreSimulation:Connect(function()
+      if not animator.EvaluationThrottled then
+          neck.Transform = computeNeckRotation() * neck.Transform
+      end
+  end)
+  ```
+
+  #### Description
+
+  An `AnimationConstraint` constrains its `Class.Attachment|Attachments` so that
+  they're offset by `Class.AnimationConstraint.Transform|Transform`. When
+  `Class.AnimationConstraint.IsKinematic|IsKinematic` is `true`, the parts
+  follow the transform perfectly (identical to Motor6D behavior). When `false`,
+  the constraint applies forces and torques limited by
+  `Class.AnimationConstraint.MaxForce|MaxForce` and
+  `Class.AnimationConstraint.MaxTorque|MaxTorque`, enabling physically simulated
+  character movement.
 code_samples: []
 inherits:
   - Constraint

roblox/en-us/reference/engine/classes/AnimationConstraint.yaml

@@ -112,6 +112,13 @@ methods:
         summary: |
           A table of arguments for 2D preview generation. Type:
           `avatarGeneration2dPreviewParams: {SessionId: string, FileId: string, TextPrompt: string?}`
+      - name: progressCallback
+        type: Function?
+        default:
+        summary: |
+          Optional callback function that will be invoked periodically with a
+          progressInfo table with the overall progress (from 0 to 1). Type:
+          `(progressInfo: { Progress: number }) -> ()`
     returns:
       - type: string
         summary: |
@@ -159,6 +166,13 @@ methods:
         summary: |
           A table of arguments for generating an avatar. Type:
           `avatarGenerationParams: {SessionId: string, PreviewId: string}`
+      - name: progressCallback
+        type: Function?
+        default:
+        summary: |
+          Optional callback function that will be invoked periodically with a
+          progressInfo table with the overall progress (from 0 to 1). Type:
+          `(progressInfo: { Progress: number }) -> ()`
     returns:
       - type: string
         summary: |

roblox/en-us/reference/engine/classes/AvatarCreationService.yaml

@@ -5,7 +5,10 @@
 name: DigitsRigDescription
 type: class
 memory_category: Animation
-summary: ''
+summary: |
+  Maps the 15 phalanx joints of one hand (5 fingers, 3 joints each) and exposes
+  forward- and inverse-kinematics helpers for controlling finger poses at
+  runtime.
 description: |
   Enables interoperability of animations across hand rigs and drives the hand
   finger solver. Each `DigitsRigDescription` maps the 15 phalanx joints of one

roblox/en-us/reference/engine/classes/DigitsRigDescription.yaml

@@ -358,4 +358,23 @@ events:
     security: None
     capabilities:
       - UI
+  - name: GuiButton.SecondaryActivated
+    summary: |
+      Fires when the button's "secondary" input is activated.
+    description: |
+      Fires when a right-click press-and-release is detected on desktop, long
+      press is detected on mobile, or **Y**/triangle is activated in UI
+      navigation mode on console. This event is not available yet.
+    code_samples: []
+    parameters:
+      - name: inputObject
+        type: InputObject
+        default:
+        summary: |
+          The input object representing the alternate activation action.
+    tags: []
+    deprecation_message: ''
+    security: None
+    capabilities:
+      - UI
 callbacks: []

roblox/en-us/reference/engine/classes/GuiButton.yaml

@@ -5,7 +5,10 @@
 name: HumanoidRigDescription
 type: class
 memory_category: Animation
-summary: ''
+summary: |
+  Stores the joint mapping, T-pose, and per-joint properties for a 22-joint
+  bipedal character rig. Joints may be `Class.AnimationConstraint`,
+  `Class.Motor6D`, or `Class.Bone` instances.
 description: |
   Stores the joint mapping, reference T-pose and per-joint properties for a
   bipedal `Humanoid` character rig. Each of the 22 joints in the rig hierarchy

roblox/en-us/reference/engine/classes/HumanoidRigDescription.yaml

@@ -6,16 +6,36 @@ name: Motor6D
 type: class
 memory_category: BaseParts
 summary: |
-  Creates an animatable joint between two `Class.BasePart|BaseParts`.
+  Creates an animatable joint between two `Class.BasePart|BaseParts`. Superseded
+  by `Class.AnimationConstraint` for avatar/character rigs. Motor6D is no longer
+  used by default for player characters when
+  `Class.StarterPlayer.AvatarJointUpgrade|AvatarJointUpgrade` is enabled.
 description: |
+  #### Description
+
   **Motor6D** joins two `Class.BasePart|BaseParts`
   (`Class.JointInstance.Part0|Part0` and `Class.JointInstance.Part1|Part1`)
   together in an animatable way. The `Class.Motor6D.Transform|Transform`
   property determines the offset between these parts. This can be set manually
   using `Class.RunService.PreSimulation` or through an `Class.Animator`.
 
   Models whose parts are joined by `Class.Motor6D` are usually referred to as
-  **rigs**, typically for `Class.Humanoid|Humanoids`.
+  **rigs**, typically for `Class.Humanoid|Humanoids`. Motor6D remains
+  appropriate for non-avatar mechanical rigs (doors, turrets, vehicles) where
+  physical simulation is not needed.
+
+  #### Transitioning to AnimationConstraint for Avatar rigs
+
+  As of the
+  [Avatar Joint Upgrade](https://devforum.roblox.com/t/avatar-joint-upgrade-for-physically-simulated-character-movement-is-now-live/4298561),
+  R15 player characters spawn with
+  `Class.AnimationConstraint|AnimationConstraints` instead of Motor6Ds when
+  `Class.StarterPlayer.AvatarJointUpgrade|AvatarJointUpgrade` is enabled (the
+  default for new experiences). Code that assumes character joints are Motor6Ds
+  — such as `character:FindFirstChildOfClass("Motor6D")` or
+  `joint:IsA("Motor6D")` — will not find joints on upgraded characters. Use
+  `Class.AnimationConstraint` for new avatar rig code. See the migration notes
+  on the `Class.AnimationConstraint` page.
 code_samples: []
 inherits:
   - Motor

roblox/en-us/reference/engine/classes/Motor6D.yaml

@@ -47,7 +47,8 @@ properties:
       shadow's edges appear softer.
 
       Note that the scale factor of this `Datatype.UDim` property is relative to
-      the parent's width or height, whichever is shorter.
+      the parent's width or height, whichever is shorter. This property must
+      also be non-negative; a negative value will be treated as `0`.
     code_samples: []
     type: UDim
     tags: []