As to why i think it's not possible is due to the fact that most of the kiln jobs uses clay as material but the resulting item is of one of the ceramic materials and i think workflow looks for an job that uses the material one specified and expect the item made to be of the same material.
No, it is slightly more intelligent than that - if it knows the specific input material, it tries to deduce what the output would be; that code might be missing the necessary rules for clay stuff though. For instance, in the current release it does that correctly for all kinds of 'extract from plant' jobs, but Brew Drink was somehow forgotten
As I recall the clay reactions are custom reactions, and there is enough information to predict the result. The problem is that the "make clay bricks" reaction has a BOULDER (
[REAGENT:clay:1:BOULDER:NONE:NONE:NONE]) input with a material selection mask to select only boulders that have a FIRED_MAT specification. Workflow doesn't really understand material selection masks, except on an ad hoc basis, and does not know what to make of FIRED_MAT specifically. If you specify a specific boulder type to be used (with the
job item-material command), then workflow will be able to determine the output product. What it cannot do is synthesize the set of all possible outputs, with a filtered wildcard input, and monitor stocks of that set. It could, in theory; it just doesn't.
It would be nice if we could use material selectors like FIRED_MAT as masks for workflow, but I'm certainly not up to the required code changes, not at the moment at least.