diff --git a/packages/cli/.config/esbuild.cli.mts b/packages/cli/.config/esbuild.cli.mts
index af30ac0f6..2d91f06bb 100644
--- a/packages/cli/.config/esbuild.cli.mts
+++ b/packages/cli/.config/esbuild.cli.mts
@@ -14,7 +14,7 @@ import { IMPORT_META_URL_BANNER } from 'build-infra/lib/esbuild-helpers'
 import { unicodeTransformPlugin } from 'build-infra/lib/esbuild-plugin-unicode-transform'
 
 import {
-  createDefineEntries,
+  createBaseConfig,
   envVarReplacementPlugin,
   getInlinedEnvVars,
   runBuild,
@@ -58,33 +58,27 @@ function resolveSocketLibExternal(socketLibPath: string, packageName: string) {
 }
 
 
+const baseConfig = createBaseConfig(inlinedEnvVars)
+
 const config: BuildOptions = {
+  ...baseConfig,
+  banner: {
+    js: `#!/usr/bin/env node\n"use strict";\n${IMPORT_META_URL_BANNER.js}`,
+  },
+  define: {
+    ...baseConfig.define,
+    'import.meta.url': '__importMetaUrl',
+  },
   entryPoints: [path.join(rootPath, 'src/cli-dispatch.mts')],
-  bundle: true,
-  outfile: path.join(rootPath, 'build/cli.js'),
-  platform: 'node',
-  target: 'node18',
-  format: 'cjs',
+  keepNames: true,
+  // .cs files used by node-gyp on Windows.
+  loader: { '.cs': 'empty' },
   logOverride: {
     'commonjs-variable-in-esm': 'silent',
     'require-resolve-not-external': 'silent',
   },
-  // .cs files used by node-gyp on Windows.
-  loader: { '.cs': 'empty' },
-  sourcemap: false,
-  minify: false,
-  keepNames: true,
-  write: false,
   metafile: true,
-  define: {
-    'process.env.NODE_ENV': '"production"',
-    'import.meta.url': '__importMetaUrl',
-    ...createDefineEntries(inlinedEnvVars),
-  },
-  banner: {
-    js: `#!/usr/bin/env node\n"use strict";\n${IMPORT_META_URL_BANNER.js}`,
-  },
-
+  outfile: path.join(rootPath, 'build/cli.js'),
   plugins: [
     unicodeTransformPlugin(),
     // Environment variable replacement must run AFTER unicode transform.
diff --git a/packages/cli/scripts/esbuild-utils.mts b/packages/cli/scripts/esbuild-utils.mts
index 1408ea32d..8450a4f67 100644
--- a/packages/cli/scripts/esbuild-utils.mts
+++ b/packages/cli/scripts/esbuild-utils.mts
@@ -15,42 +15,56 @@ import { EnvironmentVariables } from './environment-variables.mts'
 
 const logger = getDefaultLogger()
 
+/**
+ * Settings every Socket CLI esbuild config shares.
+ *
+ * Kept in one place so the target Node version, module format, minify
+ * default, etc. can't drift between the index loader and the main CLI
+ * bundle. Callers spread this and add variant-specific fields
+ * (entry points, output, banner, plugins, extra defines).
+ */
+export function createBaseConfig(
+  inlinedEnvVars: Record<string, string>,
+): BuildOptions {
+  return {
+    bundle: true,
+    define: {
+      'process.env.NODE_ENV': '"production"',
+      ...createDefineEntries(inlinedEnvVars),
+    },
+    format: 'cjs',
+    minify: false,
+    platform: 'node',
+    // We don't ship minified bundles and we don't ship sourcemaps for prod.
+    sourcemap: false,
+    target: 'node25',
+    // Plugin writes are handled by `runBuild` so every caller's env-var
+    // replacement can mutate output buffers before they hit disk.
+    write: false,
+  }
+}
+
 /**
  * Create a standard index loader config.
- * @param {Object} options - Configuration options
- * @param {string} options.entryPoint - Path to entry point file
- * @param {string} options.outfile - Path to output file
- * @returns {Object} esbuild configuration object
  */
-export function createIndexConfig({ entryPoint, outfile }: { entryPoint: string; outfile: string }) {
-  // Get inlined environment variables for build-time constant replacement.
+export function createIndexConfig({
+  entryPoint,
+  outfile,
+}: {
+  entryPoint: string
+  outfile: string
+}): BuildOptions {
   const inlinedEnvVars = getInlinedEnvVars()
 
-  const config: BuildOptions = {
+  return {
+    ...createBaseConfig(inlinedEnvVars),
     banner: {
       js: '#!/usr/bin/env node',
     },
-    bundle: true,
     entryPoints: [entryPoint],
-    format: 'cjs',
-    minify: false,
     outfile,
-    platform: 'node',
-    // Source maps off for entry point production build.
-    sourcemap: false,
-    target: 'node18',
-    // Define environment variables for inlining.
-    define: {
-      'process.env.NODE_ENV': '"production"',
-      ...createDefineEntries(inlinedEnvVars),
-    },
-    // Add plugin for post-bundle env var replacement.
     plugins: [envVarReplacementPlugin(inlinedEnvVars)],
-    // Plugin needs to transform output.
-    write: false,
   }
-
-  return config
 }
 
 /**