chore: import upstream snapshot with attribution

tsdown.config.ts

@@ -0,0 +1,145 @@
+import { createRequire } from 'node:module';
+import { readFileSync } from 'fs';
+
+import { defineConfig } from 'tsdown';
+
+const require = createRequire(import.meta.url);
+const semver = require('semver') as typeof import('semver');
+
+// Read package.json for version constants
+const packageJson = JSON.parse(readFileSync('./package.json', 'utf8'));
+
+// Normalize the package.json engines range into comparator sets that the zero-dependency
+// CLI entrypoint can evaluate before importing any other modules.
+const enginesNode: string = packageJson.engines?.node ?? '>=20.0.0';
+let nodeEngineComparatorSets: Array<
+  Array<{ operator: '' | '=' | '>' | '>=' | '<' | '<='; version: string }>
+>;
+try {
+  nodeEngineComparatorSets = new semver.Range(enginesNode).set.map((comparatorSet) =>
+    comparatorSet.map((comparator) => ({
+      operator: comparator.operator,
+      version: comparator.semver.version,
+    })),
+  );
+} catch {
+  console.warn(
+    `[tsdown] Warning: Could not parse engines.node "${enginesNode}". Defaulting to >=20.0.0.`,
+  );
+  nodeEngineComparatorSets = [[{ operator: '>=', version: '20.0.0' }]];
+}
+
+// Build-time constants injected into all builds
+// These replace the __PROMPTFOO_*__ placeholders in source files
+// Note: tsdown define requires all values to be strings
+const versionDefines = {
+  __PROMPTFOO_VERSION__: JSON.stringify(packageJson.version),
+  __PROMPTFOO_POSTHOG_KEY__: JSON.stringify(process.env.PROMPTFOO_POSTHOG_KEY || ''),
+  __PROMPTFOO_NODE_ENGINE_RANGE__: JSON.stringify(enginesNode),
+  __PROMPTFOO_NODE_ENGINE_COMPARATOR_SETS__: JSON.stringify(nodeEngineComparatorSets),
+};
+
+// All configs use clean: false. Use `npm run build:clean` for explicit cleaning.
+// This prevents race conditions when multiple configs share the same outDir.
+export default defineConfig([
+  // Server (ESM only) - stable path for workflows
+  {
+    entry: { 'server/index': 'src/server/index.ts' },
+    format: ['esm'],
+    target: 'node20',
+    outDir: 'dist/src',
+    shims: true,
+    sourcemap: true,
+    clean: false,
+    fixedExtension: false, // Use .js extension for ESM since package.json has type: module
+    inlineOnly: false, // Disable warning about bundling dependencies
+    define: {
+      ...versionDefines,
+      BUILD_FORMAT: '"esm"',
+      'process.env.BUILD_FORMAT': '"esm"',
+    },
+    external: [
+      // Externalize all bare module imports so Node resolves CJS deps natively
+      /^[a-z@][^:]*/,
+    ],
+  },
+  // CLI binary (ESM only)
+  {
+    entry: ['src/entrypoint.ts', 'src/main.ts'],
+    format: ['esm'],
+    target: 'node20',
+    outDir: 'dist/src',
+    clean: false,
+    shims: true, // Provides __dirname, __filename shims automatically
+    sourcemap: true,
+    fixedExtension: false, // Use .js extension for ESM since package.json has type: module
+    inlineOnly: false, // Disable warning about bundling dependencies
+    define: {
+      ...versionDefines,
+      BUILD_FORMAT: '"esm"',
+      'process.env.BUILD_FORMAT': '"esm"',
+    },
+    outputOptions: {
+      banner: '#!/usr/bin/env node',
+    },
+    external: [
+      // Externalize all bare module imports so Node resolves CJS deps natively
+      /^[a-z@][^:]*/,
+      // Ensure critical native deps remain external
+      '@huggingface/transformers',
+      'playwright',
+      'sharp',
+      '@swc/core',
+      'esbuild',
+      'fsevents',
+    ],
+  },
+  // Library ESM build
+  {
+    entry: {
+      contracts: 'src/contracts.ts',
+      index: 'src/index.ts',
+    },
+    format: ['esm'],
+    target: 'node20',
+    outDir: 'dist/src',
+    treeshake: true,
+    sourcemap: true,
+    shims: true, // Ensure library ESM build has shims
+    clean: false,
+    fixedExtension: false, // Use .js extension for ESM since package.json has type: module
+    inlineOnly: false, // Disable warning about bundling dependencies
+    define: {
+      ...versionDefines,
+      BUILD_FORMAT: '"esm"',
+      'process.env.BUILD_FORMAT': '"esm"',
+    },
+    external: [
+      // Externalize all bare module imports so Node resolves CJS deps natively
+      /^[a-z@][^:]*/,
+    ],
+  },
+  // Library CJS build for compatibility
+  {
+    entry: {
+      contracts: 'src/contracts.ts',
+      index: 'src/index.ts',
+    },
+    format: ['cjs'],
+    target: 'node20',
+    outDir: 'dist/src',
+    sourcemap: true,
+    clean: false,
+    fixedExtension: true, // Use .cjs extension for CJS output
+    inlineOnly: false, // Disable warning about bundling dependencies
+    define: {
+      ...versionDefines,
+      BUILD_FORMAT: '"cjs"',
+      'process.env.BUILD_FORMAT': '"cjs"',
+    },
+    external: [
+      // Externalize all bare module imports so Node resolves CJS deps natively
+      /^[a-z@][^:]*/,
+    ],
+  },
+]);