Sonder Driver Bridge

Sonder Driver Bridge is where a Driver lane in Sonder Editor actually becomes usable pixels. Sonder Driver Selector answers "is there a driver this run?" without decoding anything; this node takes that lightweight reference and does the real work - decoding the driver lane's frames for the current render window and handing them to your generation workflow, frame-indexed and window-rebased so driver and output stay in lockstep on the timeline.

This is the node behind the IC-LoRA motion-transfer demo in the pack's launch material: an OpenPose clip on a Driver lane, and the generated video follows it frame for frame. The Bridge is what makes "the driver segment starts at this local output frame" a number your graph can actually use.

How it works

Its only input is driver_ref, wired from a Sonder Driver Selector - nothing else. The outputs are the three things a driver-consuming node (like an IC-LoRA or a pose conditioner) needs:

• driver_images - the decoded driver frames as an IMAGE batch, rebased to the editor's output window so they align with the frames you're generating.
• driver_idx - the local output frame where the driver segment starts. If there's no driver, it falls back to a deterministic index rather than a random one, so downstream conditioning doesn't get a moving target.
• driver_strength - the driver conditioning strength. Emits 0 when no driver is active, which is your signal that the conditioning should be bypassed this run.

The failure modes are deliberately explicit. Missing lanes or clips don't crash the graph - you get a black fallback image batch, which composes cleanly into conditioning. But if a driver is declared active and its media fails to decode, that's raised as a node error instead of silently handing you garbage frames. You'd rather see "this clip is corrupt" than feed a black frame into your generator and wonder why the pose vanished.

Install and wiring pattern

Part of the Sonder pack: ComfyUI Manager search Sonder Editor, or git clone https://github.com/SonderSaid/ComfyUI-Sonder-Editor.git into custom_nodes, pip install -r requirements.txt, restart. Classic node, loads on any build that runs the pack.

The intended wiring, straight from the README: the Selector sits outside the driver branch, has_driver drives a lazy Sonder Switch or Cluster, and the Bridge lives inside the driver branch consuming the driver_ref. When has_driver is 0 the Bridge still runs but emits the black fallback and a 0 strength - the graph keeps its shape, nothing needs rewiring per scene.

One thing to remember: the Bridge decodes media, so it costs real time and RAM on long clips. The Selector's whole trick is letting your Switch skip the decode entirely on scenes without a driver. If you're lazy-routing with has_driver and the Bridge still runs, check your wiring - you want it inside the branch, not glued directly to the Selector.