06. Persistence, Boot, and Recovery

Frothy persists the overlay image, not the current execution.

That means local scopes, in-flight evaluation, and native runtime pointers do not survive persistence. Top-level overlay state does.

The Three Persistence Operations

save
restore
dangerous.wipe

• save snapshots the current overlay image
• restore replaces the current live overlay with the saved overlay
• dangerous.wipe clears both the live overlay and the stored overlay and returns the runtime to the base image

boot

If the top-level slot boot holds Code after restore, the runtime executes it under top-level recovery before entering the prompt.

boot is fn [
  led.on:
]

That makes boot the right place for small, explicit startup behavior.

Safe Boot

Safe boot is the recovery valve when saved state is broken. On the maintained interactive path, press Ctrl-C during the safe-boot window to skip restore and boot, return to the prompt, inspect the current state, and repair or wipe it.

Base Image Recovery

Base-image names are the recovery anchor. If you shadow a base name in the overlay and later call dangerous.wipe, the boot-rebuilt base value wins.

That rule is what lets Frothy keep rebinding flexible without making recovery fragile.

A Good Habit

Do not save every experiment. Save when the overlay represents a coherent working state that you would actually want to reconnect to.

Next: Projects, build, and flash .