Function featureFlagsPlugin

scripts/vite-plugin-feature-flags.ts:29–82

()

 * to prevent "module not found" errors.
 */
export default function featureFlagsPlugin(): Plugin {
  const features = getEnabledFeatures()

  const virtualModuleId = 'bun:bundle'
  const resolvedVirtualModuleId = '\0' + virtualModuleId

  return {
    name: 'feature-flags',

    // Resolve bun:bundle as a virtual module (prevents "module not found")
    resolveId(id) {
      if (id === virtualModuleId) {
        return resolvedVirtualModuleId
      }
    },

    // Provide a stub export for bun:bundle (unused at runtime after transform)
    load(id) {
      if (id === resolvedVirtualModuleId) {
        return 'export function feature(name) { return false; }'
      }
    },

    // Replace feature('X') calls with true/false literals at transform time,
    // and transpile `using` declarations for Node.js compatibility.
    transform(code, id) {
      // Skip node_modules
      if (id.includes('node_modules')) return null

      let modified = false

      // 1. Replace feature('X') calls with boolean literals
      let matchCount = 0
      let transformed = code.replace(FEATURE_CALL_RE, (match, flagName) => {
        matchCount++
        return features.has(flagName) ? 'true' : 'false'
      })
      if (matchCount > 0) modified = true

      // 2. Transpile `using _ = expr;` to `const _ = expr;` for Node.js compat.
      //    Node.js v22 does not support `using` declarations (Explicit Resource Management).
      //    Safe because: SLOW_OPERATION_LOGGING is not enabled, so slowLogging returns
      //    a no-op disposable whose [Symbol.dispose]() is empty.
      if (transformed.includes('using _')) {
        transformed = transformed.replace(/\busing\s+(_\w*)\s*=/g, 'const $1 =')
        modified = true
      }

      if (!modified) return null

      return { code: transformed, map: null }
    },
  }
}