Compatibility and versioning

There are four independent version numbers:

Version	Where	Current	Changes when
Shellaro	the app	0.7.0	every release
Manifest schema	`schemaVersion`	1	the manifest changes incompatibly
Extension API	`apiVersion`	1	the API changes incompatibly
Pack / Lab format	`pack.json` / `lab.json` `schemaVersion`	1	those formats change incompatibly

Rules

Within API version 1, Shellaro may add optional methods, events, item fields and permissions. Nothing is removed or changed incompatibly without a new apiVersion.
An extension declares the API version it was written for. Shellaro refuses an extension that needs a newer API ("Update Shellaro to use it") instead of running it half-working.
engines.shellaro is checked before install and at every load. A package that does not fit is listed as incompatible and cannot be installed; an installed one that stops fitting (after a Shellaro update) shows as Incompatible and does not run.
Unknown manifest fields are warnings, not errors, so a newer CLI can add optional fields. Unknown permissions are errors: a package must not assume a capability this Shellaro does not have.
Prefer >=0.7.0 for Command and Lab Packs (formats are stable) and >=0.7.0 <0.8.0 for extensions until you have tested the next minor version.

Version numbers of packages

Semantic versions. Updates install when the source has a higher version that fits Shellaro. Pre-releases (1.3.0-beta.1) sort before the release and only satisfy ranges that name a pre-release of the same version, as in npm. Installing an older version than the installed one is possible from a file, with a warning in the review.