Ah! Well done. That might explain the purpose of postActions (where they are at the end, not the start, of the rule).

So, this works too, and may be useful when you want to use & immediately change a value

"branchB_1": ["(B1: #fishColor#) [fishColor:magenta]"],

"branchB_2": ["(B2: #fishColor#)"],

i felt all clever for finishing out my metaphor only to finally figure out that actions (constants, defined sets) don't flow by symbol, they're just a wall you stick somewhere in your final flattened grammar and then everything after that follows that definition #tracery