slotted-actions-animationlisted

# Slotted Actions Animation ## Trigger Use this skill when the user: - Wants to create or edit animation from Python in Blender 5.x - Mentions `Action`, `slot`, `channelbag`, `keyframe_insert`, `fcurves` - Has older 4.x animation code (`action.fcurves.new(...)`) that no longer works in 5.x - Asks how to insert keyframes programmatically and have them persist ## What changed and why Blender **4.4** introduced the **Slotted Actions** data model to support non-linear, multi-target animation. The old model was a flat list of F-curves owned directly by the Action, which made it impossible for one Action to drive two different IDs (e.g. an armature pose and the armature's custom property channels at the same time) without overwriting each other. Two version boundaries matter: - **Blender 4.4 / 4.5 LTS**: the slotted data model (`action.slots`, `action.layers`, `strip.channelbag`) is present **alongside** the legacy flat API (`action.fcurves`, `action.groups`, `action.id_root`), which still works as a proxy. The helper `bpy_extras.anim_utils.action_get_channelbag_for_slot(action, slot)` exists; `action_ensure_channelbag_for_slot` does **not**. - **Blender 5.0+**: the legacy flat API was **removed** (`action.fcurves` raises `AttributeError`). The new helper `bpy_extras.anim_utils.action_ensure_channelbag_for_slot(action, slot)` is added. The slotted model: ``` Action Slots[] # one per ID being driven Layers[] # animation layers, blendable Strips[]