The package postflight showed the "license key required" next-steps
message even when a bundled child extension failed to install. Joomla
only logs a failed sub-install but still runs postflight.
Add missingChildExtensions(): verify every <file> declared in the
package manifest actually landed in #__extensions (plugins match on
element+type+folder with plg_<group>_ prefix stripping; component
matches element+type). Gate the license message on it and enqueue an
error listing any missing children. Fails open so a query/IO glitch
never turns a good install into a false failure.
Claude-Session: https://claude.ai/code/session_01B9aZHSWbiiZykJD88pYx8R