RecompileFrontendAssets  

Flag this asset set as needing a rebuild, without touching the compiled files or their manifest revisions.

The rebuild itself is deferred to the next request (see {\Flarum\Frontend\recompileIfDirty}): a request that toggles an extension booted before that extension's extenders were applied, so rebuilding here would bake the old sources — e.g. locale bundles without a newly-enabled extension's keys — into the manifest, and with the revision then matching, nothing would ever rebuild them. Deferring also means nothing is deleted or unset in the meantime: already-served asset URLs keep resolving, and the asset revision token doesn't flicker, so connected clients aren't prompted to reload for a rebuild that may not change anything they load.

Rebuild this asset set in place if it has been flagged dirty, then clear the flag. Runs early in a freshly-booted request — one whose container reflects the current extension state — so the rebuilt output is correct.

Rebuild the compiled assets in place.

Unlike {\Flarum\Frontend\flush}, nothing is deleted up front: each compiler renders its output and only overwrites the file (and its manifest revision) when the result actually differs. That means there is never a window where an already-served asset URL points at a missing file, and never a gap in the revision manifest that would flicker the asset revision token and fire a spurious "new version available" prompt on connected clients. A rebuild that produces identical output is a complete no-op. {\Flarum\Frontend\Event\AssetsRecompiled} is dispatched once the rebuild has finished, so consumers (e.g. the realtime broadcaster) read a settled revision.