#extensions 6 articles

• A CDN-hosted extension bundle may only import modules its App Catalog manifest declaresgotchas / spfxReplacing an extension's stable-named bundle on the CDN without a new .sppkg works only while its define([...]) lists modules already in the installed manifest's scriptResources — one new value import and the extension…
• A command set's commands are fixed in its manifestgotchas / spfxtitle, iconImageUrl, visible and disabled change at runtime, new commands need a new .sppkg; ship one entry that opens your own menu, or reserve hidden slots (and keep their titles honest)
• List and library pages run a stale extension bundle from Cache Storage for daysgotchas / spfxStable (unhashed) bundle URL = list and library pages can run a days-old copy from the Lists app's own Cache Storage (Lists-odsp-web-prod_*), whatever Cache-Control says; keep the stable file a tiny loader and load…
• ListViewCommandSet button never appears — raiseOnChange() does not re-run onListViewUpdatedgotchas / spfxTwo independent causes: uploading a new .sppkg registers the extension on no site by itself (register it at runtime, or deploy it tenant-wide with the all-sites tick), and raiseOnChange() re-reads command.visible…
• Your Application Customizer runs again inside SharePoint dialog iframesgotchas / spfxA floating button rendered twice, the copy pinned to the dialog's corner; refuse nested browsing contexts before anything else (+ un-render path and why a body MutationObserver needs a definitive „no“)
• Your Application Customizer's floating UI disappears when navigating the sitegotchas / spfxThe button vanishes as you click around the site; visibilitychange never fires on in-page nav, so re-render on navigatedEvent (+ a MutationObserver backstop that stops re-reading configuration after a definitive…