Web shell library: bootWebShell(el, seams?) mounts the whole client — loader machinery (statically held; a loader cannot load itself), pure-library module-table seeding, AppRoot (boot loading page → settled → full UI in one switch), and the SessionProvider/scopedSlots assembly closure. The vite application entry lives in apps/web and only calls bootWebShell. Contract: api-contracts v3 §9.3.

The optional seams parameter forwards the client loader's fetchBundle/executeBundle transport overrides (BootSeams); production callers omit it — it exists for test environments where <script> execution cannot reach the page context (jsdom).

Model Experience

None, as the entry shell boots the browser plugin tree; nothing here reaches a model request.

KV Cache effect

None; this package neither assembles nor sends a provider request.

Known Limitations and Deferred Work

One-shot rendering by design — the UI waits for loader.settled(); a single plugin failure keeps the loading page with a loud error, no partial availability (progressive rendering returns with its own project).
No HMR — the dev loop is tsdown watch + manual refresh for plugins; vite serves only the shell.
Narrow-window acceptance is deferred — the concession chain is implemented in ui-layout but the shell-level narrow-viewport walkthrough is a P-II acceptance item.