persist

Merge generated into the file and publish it atomically, creating it if it isn't there.

Only what this launch had to INVENT belongs in generated: a value supplied by -D or the environment was put out of band on purpose, and writing it to disk would let the two disagree from the next launch on.

seed names settings the file should MENTION without setting: written as JSON null where neither side has it, which Props reads as unset — so the file spells the key without choosing a value.