fix: persist widget build cache across restarts

[mehdiraized]

What

Persist widget build artifacts to disk and restore them on demand instead of rebuilding every widget after every server/app restart.

This change updates the widget runner to:

• cache each built widget dist/ output under the app data directory, keyed by the widget source hash
• restore the widget server from that cached build on the next request after restart
• invalidate old cache entries automatically when widget files change
• validate the shared base template more strictly before reusing it
• rebuild the base template if a previous install was incomplete

Why

Today widget builds only live in memory and temporary directories, so every restart forces all widgets to rebuild from scratch.

That has two user-facing problems:

• dashboards spend time in Building widget... on every app launch even when nothing changed
• partially installed or corrupted base templates can be reused, which can lead to intermittent ERR_MODULE_NOT_FOUND failures during widget builds

Persisting build output fixes the repeated rebuild behavior, and tightening template validation makes the build pipeline more reliable.

Test plan

• Tests pass locally
• Tested manually

Manual verification:

• started the app/server against a real widget database
• requested a widget route and confirmed the first request built the widget normally
• restarted the server and requested the same widget again
• confirmed the widget was restored from cache instead of rebuilt
• confirmed the runner logged Restored cached widget ... on the second run

---

Note

Medium Risk
Introduces disk-backed caching and restore logic for widget build artifacts, changing build/serve lifecycle and filesystem interactions; failures could lead to stale/invalid builds being served or unexpected rebuild loops.

Overview
Adds a persistent widget build cache under the app data directory, keyed by a hash of widget source files plus template/cache versions, and updates the build pipeline to copy dist/ into that cache and serve from it instead of a temp sandbox.

ensureWidget now attempts to restore and serve a cached build on demand after restarts, falling back to a rebuild and purging the cache entry if restore fails; runtime/sandbox cleanup is centralized via disposeWidgetRuntime.

Base template reuse is tightened with stricter validation (required UI files and packages) and automatic reinstallation if the template directory is incomplete.

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[homanp]

@mehdiraized mind looking at the PR comments?

[mehdiraized]

@mehdiraized mind looking at the PR comments?

Sure, I’ll check the Cursor comments and make any needed changes, then update the PR.