refactor: iterate viteConfig.environments directly instead of re-invoking plugin config hook

[teneburu]

Refactor environment discovery to iterate viteConfig.environments directly

Removes the fragile findPlugin / hasPlugin pattern that re-invoked the plugin's config hook to discover environment entry paths. Instead, reads viteConfig.environments directly — the same source of truth Vite already provides.

Why

The old approach called the plugin's config hook a second time at runtime to reconstruct environment configuration. This broke when another plugin (like @vitejs/plugin-rsc) modified the same environments during its own config hook — the re-invocation could produce a different result or fail outright.

The new approach iterates viteConfig.environments directly, which is always available after Vite resolves its config. No plugin introspection needed.

Changes

• development.ts (environment config) — loadEntryModulePaths() now walks viteConfig.environments directly, instead of re-invoking the plugin's config hook on a synthetic object. Removes the findPlugin/hasPlugin introspection helpers and the ViteEnvironmentsConfig interface. Because the new path reads already-resolved config, it also strips Vite's internal \0 null-byte prefix from virtual module IDs. The file deletes ~90 lines total. Returns null (not {}) when no environments match — the caller handles both identically.

• development.ts (runner reuse) — loadEntries() uses isRunnableDevEnvironment(envConfig).runner where available, falling back to createServerModuleRunner(). Avoids creating a duplicate ModuleRunner when @vitejs/plugin-rsc later accesses envConfig.runner via its lazy getter for cross-environment imports.

• plugin.ts — Generalizes rollupOptions.input from { index?: string } to Record<string, string>. Iterates all input entries, not just the one named index. Required when Vite environments register entries under non-standard names.

• development.test.ts — Adds environments field to the mock config so loadEntryModulePaths is exercised as intended.

Verification

• All 86 tests pass (78 runtime + 8 typecheck)
• tsc build produces no errors
• No breaking changes — iterates environments that always exist in Vite 8, falls back gracefully (returns null) when none match

[changeset-bot]

🦋 Changeset detected

Latest commit: 6098208

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@fastify/vite	Patch

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