## Plan.digest()


SHA-256 of everything else in the saved plan, as JSON reads it back


Usage

``` python
Plan.digest()
```


(keys sorted, values through `str` where JSON has no type).

The preconditions vouch for the world the actions and context were computed from; the digest binds the three together, so a saved plan edited in one place - an action dropped, a `target_state` or `bookmark_commit` changed - is refused at apply rather than applied under checks that describe another plan. It detects edits, it does not authenticate: whoever can write the file can recompute it.