Simple Trigger Node

ComfyUI doesn't run nodes left-to-right. It runs them in dependency order - a node executes when its inputs are ready - and for most workflows that's exactly right. But sometimes it's exactly wrong. The classic case this node exists for: you want a vision model to caption an image, then load a big checkpoint, then generate. Without any constraint, ComfyUI can happily load the checkpoint first, pin several GB of VRAM, and then your LLM either squeaks by or OOMs. Simple Trigger Node is the pack's way of saying "not until I say so."

The mechanism is almost insultingly simple: it's a pass-through. The input port passes straight through to the output port unchanged - the node does nothing to the value - but it only fires once the trigger port's upstream has finished. Because output depends on both input and trigger, everything downstream of this node waits for the trigger signal. That's the whole trick.

Inputs and outputs

• input - anything (the node accepts any type). Passed through unchanged.
• trigger - anything, and this is the one you don't wire to your data. Per the tooltip it's meant to be "not connected anywhere" - you connect it to a node that signals when, e.g. the LLM's output or a slow upstream node. Whatever you connect here gates the output.
• output - whatever came in on input, once the trigger fires.

How to use it

The README's example is the good one: put the Trigger Node before a Load Checkpoint, wire the checkpoint's model output through the trigger's input, and connect the LLM's text output to the trigger's trigger port. Result: the checkpoint doesn't load until the LLM has finished captioning - no more loading a 7GB model just to sit idle while a small LLM runs.

LLM text ──► trigger  ──┐
                        ├─► Load Checkpoint ─► ... generation
(any)  ────► input  ────┘

Yes, you can also just connect the LLM output directly into the checkpoint loader - but ComfyUI's execution scheduling doesn't always respect data dependencies the way you'd hope, which is why the author built this as an explicit alternative to ComfyUI's On_Trigger mode. The node's own description calls that mode "non-working." This is the workaround.

Install

Part of KLL535/ComfyUI_Simple_Qwen3-VL-gguf:

cd ComfyUI/custom_nodes
git clone https://github.com/KLL535/ComfyUI_Simple_Qwen3-VL-gguf

or ComfyUI Manager (search ComfyUI_Simple_Qwen3-VL-gguf), restart, F5.

One honest limitation: it's a one-shot gate, not a state machine. It sequences execution, but it won't loop, hold state across runs, or conditionally skip a branch. For memory-sequencing - the thing it's built for - it works. If you need real conditional logic, ComfyUI's built-in control-flow nodes are a better fit.