Proposal for new PNG chunk for civitai specific metadata

At the moment, civitai only parses metadata correctly for its own generator and for automatic1111 if the civitai helper extension is installed.

For other platforms, the parsing either fails completely (for complex ComfyUI workflow) or do not parse the resources correctly (for example, even though the model hashes are embedded in the PNG produced by tensor.art, it is not being parsed).

What I am proposing is that civitai should support a new PNG optional chunk, let's call it CIVT. This chunk will contain the bare minimum amount of metadata, which is essentially the metadata produced by Automatic1111 with the civitai helper extension: Prompt, Negative Prompt, CFG, Sampler, Steps, Seed, and a list of resource hashes.

Then civitai, or 3rd party developers, can write extension for other platforms such as ComfyUI, Fooocus, Forge, SDNext, etc. to generate this extra CIVT chunk, without having to touch the tEXt chunk which can continue to contain their proprietary workflow metadata. Thus allowing maximum flexibility yet maintaining compatibility.

This will require almost no change or work on civitai's part. Civitai only has to change its current parser to look for this CIVT chunk and then parse it, as it is currently parsing the tEXt chunk. And of course announce this to the world once it is implemented.