Shopify CLI grows dev store creation, aligns sizes with Brotli

The week's through-line is the CLI making the day-to-day loop less manual. `app dev` gained the ability to create a dev store directly from its store picker [1][2]. Developers who hit "no store available" no longer need to leave the CLI, open the Partner Dashboard, and return: the picker now offers a create route. Alongside that, `app dev --use-localhost` stopped aborting when the localhost certificate wasn't present on macOS and now prompts to generate it [3][4]. A small quality-of-life fix, but it removes a hard stop in a common setup path.

Two changes target extension size behavior. The CLI now reports compressed bundle size using Brotli, aligning with how Shopify actually compresses extensions, so the number developers see locally should match what the platform evaluates [5]. In the same area, the CLI supports the `bundle_size_exception` capability, which lets eligible apps request an exception to the standard size limit [6][7]. Together they make the size check both more accurate and more flexible. The merge notes call it a move to "report extension compressed bundle size using Brotli" [5].

Configuration-only extensions, which previously ran silently during `app dev`, now get a default dev-session message [8]. Since they have no preview or build output, developers were left guessing whether anything happened; the new message makes the session state explicit. Elsewhere, the CLI fixed the development store help text so `app dev`'s new capabilities are described correctly, clearing up confusion about what the flag does [9][10].

Underneath the user-facing work, the team added unit tests for the `hrtime` utilities [11][12], which measure high-resolution time used for performance tracking in the dev session. Test coverage here is unglamorous but foundational, since timing bugs in dev tooling tend to surface as mysterious slowdowns and are hard to chase without solid tests. The theme tooling also moved forward with bumps to `theme-check-node` 3.29.0 and `theme-language-server-node` 2.22.2, keeping theme developers on current language tooling [13].

A quiet week otherwise, but directionally clear: Shopify CLI is consolidating the full create-to-test loop in one command and making its extension checks behave like production. If you build on Shopify, try the new `app dev` store creation flow and re-run your extension size checks against the Brotli-aligned output before your next release.