The Monorepo UI Package Dependency Trap

I was working on my monorepo and noticed something odd. My Epicenter app needed to install bits-ui and @lucide/svelte even though I was already importing these through my shared UI package.

Wait, shouldn’t the UI package provide these dependencies?

Here’s what I found: the UI package had these dependencies in devDependencies instead of dependencies. That’s the trap.

The Problem

When you structure a UI package like this:

{
  "name": "@repo/ui",
  "devDependencies": {
    "bits-ui": "catalog:",
    "@lucide/svelte": "^0.525.0",
    "clsx": "catalog:",
    "tailwind-merge": "catalog:"
  }
}

Those packages are only installed when developing the UI package itself. Apps that consume @repo/ui don’t get them.

So every app ends up looking like this:

{
  "name": "my-app",
  "dependencies": {
    "@repo/ui": "workspace:*",
    "bits-ui": "catalog:",      // Duplicate!
    "@lucide/svelte": "^0.525.0" // Duplicate!
  }
}

The Fix

Move runtime dependencies to dependencies in your UI package:

{
  "name": "@repo/ui",
  "dependencies": {
    "bits-ui": "catalog:",
    "@lucide/svelte": "^0.525.0",
    "clsx": "catalog:",
    "tailwind-merge": "catalog:"
  },
  "devDependencies": {
    // Only build tools and types here
    "typescript": "^5.7.3",
    "svelte-check": "catalog:"
  }
}

Now your apps can be cleaner:

{
  "name": "my-app",
  "dependencies": {
    "@repo/ui": "workspace:*"
    // That's it! UI deps come along automatically
  }
}

The Lesson

In monorepo UI packages, ask yourself: “Does the consuming app need this at runtime?”

If yes → dependencies
If no → devDependencies

Common runtime dependencies for UI packages:

• Component libraries (bits-ui, radix-ui)
• Icon libraries (@lucide/svelte)
• Runtime utilities (clsx, tailwind-merge)
• Styling tools used at runtime (tailwind-variants)

Common dev dependencies:

• Type definitions (@types/*)
• Build tools (vite, rollup)
• Linters and formatters
• Testing libraries

I had 3 apps all installing the same UI dependencies. Now they just install @repo/ui and get everything they need. Less duplication, clearer dependency tree, easier maintenance.

The fix took 2 minutes. Finding the problem took me way longer than I’d like to admit.