Sensor Switch Model

The most common thing a ComfyUI user switches is the model. Checkpoint A for one style, checkpoint B for another, and a graph that's otherwise identical. This node is a two-way switch for MODEL objects with the sensor family's signature behavior: route whichever input is actually connected, fall back to the boolean when both are.

The clean use case: load two checkpoints, wire one model_true, the other model_false, and switch between them without touching a single other node. Or keep it simpler - one checkpoint that you sometimes replace by bypassing - and let the sensor handle the rest. Because both inputs are optional, the node also won't error out mid-build when an input isn't hooked up yet.

Inputs and outputs

• switch - boolean, default true.
• model_true / model_false - optional MODEL inputs.
• model - single MODEL output.

Selection logic, same as the whole family: one connected input wins outright; both connected → switch on picks model_true, off picks model_false; neither → None instead of a crash. Drop the output into a KSampler's model port and everything downstream just works.

Pair it with the Clip switch

Here's the part people realize late: a checkpoint loads a model and a CLIP (and a VAE). If you're switching between checkpoints, you almost always want to switch the CLIP at the same time, since the text encoder is model-specific. The pack ships both a Sensor Switch Model and a Sensor Switch Clip, so the standard pattern is one of each, both toggled together (or both fed from the same two checkpoints). It's a small thing, but it's exactly the kind of wiring that turns a ten-minute graph edit into a two-second toggle.

The standard caveat

Same as its siblings: ComfyUI can pass data through a bypassed node, so when both inputs are wired the sensor won't reliably auto-detect a bypass - set switch manually for that. The auto-detect is for genuinely disconnected inputs, and the "don't crash on missing input" behavior is what makes the node pleasant to build with.

Installing it

Manager search "ComfyUI-Fossiel-QoL-Nodes", or:

cd ComfyUI/custom_nodes
git clone https://github.com/Fossiel/ComfyUI-Fossiel-QoL-Nodes
pip install -r ComfyUI-Fossiel-QoL-Nodes/requirements.txt

Restart, find Sensor Switch Model under Fossiel/QoL. Pure routing, no downloads - if you're already using the pack's Sensor Switch Clip, this is its natural partner.