Lily
Posted on Jul 19
• Originally published at dev.to
This is another entry in my "Claude Code environment" series. Last time, in Multi-slot launchd retry design, I wrote about the "idempotent morning/noon/night triple-fire" pattern. This time I'm applying it to something concrete: the "disposable migration job" I set up ahead of Fable 5's end of life (2026-07-07), and I'm publishing the full implementation.
It rewrites the model field in settings.json with jq, fires a desktop notification, and finally removes its own registration with launchctl unload and disappears. The design wraps launch, execution, and self-destruction into a single script. This isn't specific to model migration — it's a general-purpose pattern for "a job that changes a setting exactly once on a specific day and then vanishes," so I'll show all of the actual code.
