Flow Control (Sidecar Bypass)

Flow Control (Sidecar Bypass) is a remote control for bypassing nodes, and the whole point is that it sits outside your data path. You get four toggle switches on one small node, each wired to a different upstream node in your graph, and flipping a switch bypasses that node without you ever opening its properties or hunting for its little bypass button. If you constantly A/B test "does this LoRA / this upscale / this ControlNet actually help?" this is the node that makes the comparison a one-click affair.

How it works

The clever part is that BypassControl does nothing on the Python side - its execute returns an empty result. All the work happens in the frontend JavaScript that ships with the pack. When you connect input_1 to some upstream node, the extension watches that connection and toggles the upstream node's execution mode between always (normal) and bypass based on the active_1 switch. Flip the switch, the target node's mode changes, done.

The node has no outputs and is marked as an output node, which is the honest reflection of what it is: a control panel, not a data component. Per channel you get:

• input_N - the wire you drag to the node you want to control. The connection direction is the mechanism; the actual data doesn't flow through here.
• active_N - the on/off toggle (labelled "Active" / "BYPASS" in the UI).
• label_N - rename the channel so the node actually tells you what each switch does, instead of "Group 1".

Four channels covers your typical comparison set: base prompt, one LoRA, one ControlNet, one sampler tweak.

Installing

This is one of the 26 nodes in ComfyUI-Flow-Assistor - install once via ComfyUI Manager (search "Flow Assistor") or:

cd ComfyUI/custom_nodes
git clone https://github.com/Merserk/ComfyUI-Flow-Assistor.git

Restart to load the frontend extension. Current ComfyUI required (V3-only pack), no extra Python deps. If the switches don't seem to do anything, that's almost always the frontend extension not having loaded - a hard restart of ComfyUI (and often a browser refresh) fixes it.

Where people get burned

Two habits to avoid. First: don't expect the input_N ports to carry data - nothing flows through them, so don't route your pipeline through this node hoping for a pass-through. Second: the switch is a global graph edit, not per-run state. If you save the workflow with a node bypassed, it loads bypassed; if you share the JSON, you're sharing your test configuration. That's usually what you want, but it has caught people who forgot a channel was flipped mid-experiment and then "fixed" unrelated things. Also note it bypasses the upstream node feeding the port, not the port itself - drag the wire from the node you actually want to silence.