fix: don't append custom collection prefixes to the shared collection list - #533

📚 Description

getRuntimeCollections (src/context.ts:28-45) does not return a list, it returns the shared one and then writes to it:

const resolved = runtimeOptions.fallbackToApi
  ? collectionNames                 // <- the module-level constant itself
  : typeof this.options.serverBundle === 'string'
    ? collectionNames               // <- same
    : this.options.serverBundle
      ? this.options.serverBundle.collections?.map(...) || []   // <- fresh array
      : []

for (const collection of this.options.customCollections || []) {
  if (collection.prefix && !resolved.includes(collection.prefix))
    resolved.push(collection.prefix)
}

Three branches, and only the third builds its own array. The other two hand back collectionNames from src/collection-names.ts, which is generated, module-level, and read by IconUsageScanner (src/core/scan.ts:21), discoverInstalledCollections (src/core/collections.ts:133-161), _resolveServerBundle (src/context.ts:104), and by anyone importing it from @nuxt/icon/utils. The push appends every custom collection prefix to it permanently.

fallbackToApi defaults to true, so the default configuration takes a leaking branch, and module.ts:110 calls this on every setup.

Two consequences:

Across apps in one process. Building or preparing two Nuxt apps in the same Node process (a test suite, a monorepo script, a programmatic build() loop) leaks the first app's custom prefixes into the second's appConfig.icon.collections. That list is what useResolvedName uses to disambiguate a dashed name, so app B starts resolving my-icons-logo to my-icons:logo for a collection it does not have.

Inside a single build. module.ts:110 runs during setup, and _resolveServerBundle runs later from the nitro:config hook. With serverBundle: 'remote' (or 'auto' on an edge preset) the second one reads the already-polluted collectionNames, so a custom collection is emitted twice in nuxt-icon-server-bundle.mjs: once as createRemoteCollection('https://cdn.jsdelivr.net/npm/@iconify-json/my-icons/icons.json') for a package that does not exist, and once as the real inline data.

The fix copies the list in the two branches that return the shared one. The .map() branch already produced a fresh array, so appending is now local in all three.

Test

test/runtime-collections.test.ts covers both consequences, using the same fake-Nuxt style as test/client-bundle.test.ts. Both fail without the source change, each on the leaked value rather than on an error:

AssertionError: expected [ 'academicons', 'akar-icons', ...(219) ] to not include 'my-icons'
 ❯ test/runtime-collections.test.ts:35:59

AssertionError: expected [ 'my-icons', ...(1) ] to deeply equal [ { prefix: 'my-icons', ...(1) } ]
 ❯ test/runtime-collections.test.ts:50:19

I reverted src/context.ts to its committed state to confirm that, then restored it. pnpm test:unit is 29 passed, pnpm lint and pnpm typecheck are clean.