Float debug print

Dimension math in ComfyUI goes wrong quietly. You wire up Divide → Multiply → some ratio node, and the width that comes out the other end is 767 instead of 768, and nothing tells you where it drifted. Float debug print is the node for that: give it a float and a text label, and it prints label: value to the console the moment the graph runs. It's a dead end by design - nothing comes out the other side - so you tap the value you're suspicious of and read the terminal.

How it works

It takes a FLOAT plus a Prefix string and writes both to standard output during execution. The prefix exists so that when you've got three or four of these scattered across a graph, the log tells you which is which instead of showing three anonymous numbers in a row. Being an output node, it runs independently the moment its input is available - no downstream connection required.

The inputs and outputs that matter

• Prefix (STRING, default empty) - a label printed before the value, so latent width beats a bare 767.99998 in the log.
• Value (FLOAT, default 1, steps of 0.01) - the number to print.
• No outputs - this is a terminal sink, not a pass-through.

Where it fits

Reach for it right before a computed float feeds into something expensive or precision-sensitive: an image resize, a latent scale factor, a conditioning area calculation. Tap the value here, run the graph, and confirm it's actually 1.5 and not 1.4999999999 before you burn a generation on the wrong number - floating point math accumulates small errors exactly like that across a long Derfuu chain (Divide → Multiply → Sum, say), and this is the cheapest way to catch it. If you'd rather see the value sitting on the node itself on the canvas instead of scrolling a console, or you need to inspect a type other than float, Derfuu's To text (Debug) shows any type in a widget and passes it through - often the friendlier tool when you're not sure yet what type you're even looking at.

How to install it

ComfyUI Manager: search Derfuu_ComfyUI_ModdedNodes, install, restart. Manually:

cd ComfyUI/custom_nodes
git clone https://github.com/Derfuu/Derfuu_ComfyUI_ModdedNodes

then restart. No dependencies, no models - plain Python.

Common issues & troubleshooting

Nothing shows up. It prints to the console where ComfyUI is running, not anywhere in the browser UI. If you're on a desktop launcher or a remote/hosted instance, you need the terminal or server log open to see it. It also only fires when the node actually executes - a branch that got pruned prints nothing.

Wrong type going in. The input is typed FLOAT. Feeding an INT usually still works since ints widen to floats without complaint, but a STRING or a TUPLE won't connect - use String debug print or Tuple debug print for those instead.

It's a dead end and you needed the value to keep moving. There's no output by design. If you need to inspect and keep wiring downstream, use To text (Debug), which passes its input through untouched.

Node red after a pack update. Derfuu has a history of deleting deprecated nodes on updates instead of leaving a legacy-labeled version around, which has broken downloaded workflows before. If a debug node in an old graph won't load, it may no longer exist under that name - reconnect a fresh copy. A ModuleNotFoundError about Derfuu_ComfyUI_ModdedNodes_legacy means a duplicated folder; keep exactly one, named Derfuu_ComfyUI_ModdedNodes.