BD Filename Template

Every serious ComfyUI user has a workflow that looks like four Text Concatenate nodes chained into a filename, with a separator you constantly forget. This node kills that. BD_FilenameTemplate takes one template string with %variable% placeholders, fills in the values you give it, and emits a single resolved STRING you wire straight into any save node's filename input.

It's the standalone, no-side-effect half of ComfyUI-BrainDead's save-context system: the BD Save Context node handles the persistent path templates for the pack's own save nodes, while this one is the lightweight resolver you can use anywhere - including ComfyUI's built-in SaveImage. Same templating, no context to register, no files touched.

How it works

You write a template, it substitutes variables. Forward slashes become subdirectories; empty variables collapse cleanly (so characters/%name%/%name%_v%version%%suffix% with an empty name doesn't leave you with //); undefined variables stay in the output as literal %var% text so typos surface instead of silently corrupting your file paths.

The built-in variables are %character%, %name%, %version%, %project%, %tag%, and %suffix% - the naming vocabulary the whole pack uses. Anything else goes in via custom_vars, one key=value per line.

The inputs that matter

• template - the only required one. Default: characters/%character%/%name%_v%version%%suffix%.
• version - just the number, no v prefix; the template adds the v (default 01).
• tag / suffix - the pack's convention: tag is a part name like face or topwear, suffix is a trailing bit like _albedo or _v2.
• custom_vars - multiline key=value extras, e.g. subfolder=PBR or resolution=4096.
• strict - when true, raises an error if the template references a variable you never defined. Great for catching a typo'd %sufix% in a template you're shipping to a team.

Outputs are filename (the resolved STRING) and status (a text log of what resolved and whether anything was left undefined).

What it looks like

template:  characters/%character%/%name%_v%version%%suffix%
character: letti
name:      topwear
version:   03
suffix:    _albedo
→  characters/letti/topwear_v03_albedo

Wire filename into any save node's filename/filename_prefix input and you're done.

Install

It's part of the BrainDead pack - install that once and this node (plus ~110 siblings) appears under 🧠BrainDead/Prompt:

cd ComfyUI/custom_nodes
git clone https://github.com/BizaNator/ComfyUI-BrainDead
cd ComfyUI-BrainDead
pip install -r requirements.txt

Or search "BrainDead" in ComfyUI Manager and restart. This node has zero extra dependencies - pure string work. Note the pack is written against ComfyUI's V3 extension API, so a reasonably current ComfyUI matters more than anything else here.

Troubleshooting

• %suffix% came out as literal text - you misspelled a variable or never set it. Either fill it in or set strict to catch it.
• A save landed in the wrong folder - check the trailing slashes in your template; %character%/ with an empty character collapses to a leading slash that resolves to your output root.
• You want a file naming, not a folder structure - just don't put slashes in the template.