diff --git a/.changeset/bright-falcons-chew.md b/.changeset/bright-falcons-chew.md
new file mode 100644
index 000000000..1c3e9a490
--- /dev/null
+++ b/.changeset/bright-falcons-chew.md
@@ -0,0 +1,5 @@
+---
+'@hey-api/types': patch
+---
+
+feat: add `ToArray`, `ToReadonlyArray`, and `AnyObject` types
diff --git a/.changeset/clever-toys-dress.md b/.changeset/clever-toys-dress.md
new file mode 100644
index 000000000..ad10ced8c
--- /dev/null
+++ b/.changeset/clever-toys-dress.md
@@ -0,0 +1,5 @@
+---
+'@hey-api/openapi-ts': patch
+---
+
+**cli**: clean up interface
diff --git a/.changeset/fluffy-pens-admire.md b/.changeset/fluffy-pens-admire.md
new file mode 100644
index 000000000..8f94228b9
--- /dev/null
+++ b/.changeset/fluffy-pens-admire.md
@@ -0,0 +1,5 @@
+---
+'@hey-api/codegen-core': patch
+---
+
+**config**: export `loadConfigFile` function (moved from `@hey-api/openapi-ts`)
diff --git a/.changeset/stupid-news-wash.md b/.changeset/stupid-news-wash.md
new file mode 100644
index 000000000..0e89c1920
--- /dev/null
+++ b/.changeset/stupid-news-wash.md
@@ -0,0 +1,5 @@
+---
+'@hey-api/openapi-ts': patch
+---
+
+**config**: move `loadConfigFile` function to `@hey-api/codegen-core`
diff --git a/.vscode/launch.json b/.vscode/launch.json
index aa4048fe8..eaea5c38c 100644
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -16,6 +16,7 @@
       "cwd": "${workspaceFolder}/dev",
       "runtimeExecutable": "node",
       "program": "${workspaceFolder}/packages/openapi-ts/dist/run.mjs",
+      "args": [],
       "env": {
         "DEBUG": "false"
       }
@@ -28,6 +29,7 @@
       "cwd": "${workspaceFolder}/dev",
       "runtimeExecutable": "node",
       "program": "${workspaceFolder}/packages/openapi-python/dist/run.mjs",
+      "args": [],
       "env": {
         "DEBUG": "false"
       }
diff --git a/packages/codegen-core/package.json b/packages/codegen-core/package.json
index 92bed14ca..253a45b9f 100644
--- a/packages/codegen-core/package.json
+++ b/packages/codegen-core/package.json
@@ -63,6 +63,7 @@
   "dependencies": {
     "@hey-api/types": "workspace:*",
     "ansi-colors": "4.1.3",
+    "c12": "3.3.3",
     "color-support": "1.1.3"
   },
   "peerDependencies": {
diff --git a/packages/codegen-core/src/__tests__/exports.test.ts b/packages/codegen-core/src/__tests__/exports.test.ts
index ca2c3cc5a..e6e2d7067 100644
--- a/packages/codegen-core/src/__tests__/exports.test.ts
+++ b/packages/codegen-core/src/__tests__/exports.test.ts
@@ -8,13 +8,16 @@ const constExports = [
   'File',
   'fromRef',
   'fromRefs',
+  'detectInteractiveSession',
   'isNode',
   'isNodeRef',
   'isRef',
   'isSymbol',
   'isSymbolRef',
+  'loadConfigFile',
   'log',
   'Logger',
+  'mergeConfigs',
   'nodeBrand',
   'Project',
   'ref',
diff --git a/packages/codegen-core/src/config/interactive.ts b/packages/codegen-core/src/config/interactive.ts
new file mode 100644
index 000000000..baf0570b0
--- /dev/null
+++ b/packages/codegen-core/src/config/interactive.ts
@@ -0,0 +1,14 @@
+/**
+ * Detect if the current session is interactive based on TTY status and environment variables.
+ * This is used as a fallback when the user doesn't explicitly set the interactive option.
+ * @internal
+ */
+export function detectInteractiveSession(): boolean {
+  return Boolean(
+    process.stdin.isTTY &&
+      process.stdout.isTTY &&
+      !process.env.CI &&
+      !process.env.NO_INTERACTIVE &&
+      !process.env.NO_INTERACTION,
+  );
+}
diff --git a/packages/codegen-core/src/config/load.ts b/packages/codegen-core/src/config/load.ts
new file mode 100644
index 000000000..00fb5b4cd
--- /dev/null
+++ b/packages/codegen-core/src/config/load.ts
@@ -0,0 +1,42 @@
+import type { Logger } from '@hey-api/codegen-core';
+import type { AnyObject, MaybeArray } from '@hey-api/types';
+
+import { mergeConfigs } from './merge';
+
+export async function loadConfigFile<T extends AnyObject>({
+  configFile,
+  logger,
+  name,
+  userConfig,
+}: {
+  configFile: string | undefined;
+  logger: Logger;
+  name: string;
+  userConfig: T;
+}): Promise<{
+  configFile: string | undefined;
+  configs: ReadonlyArray<T>;
+  foundConfig: boolean;
+}> {
+  const eventC12 = logger.timeEvent('c12');
+  // c12 is ESM-only since v3
+  const { loadConfig } = await import('c12');
+
+  const { config: fileConfig, configFile: loadedConfigFile } = await loadConfig<
+    MaybeArray<T>
+  >({
+    configFile,
+    name,
+  });
+  eventC12.timeEnd();
+
+  const fileConfigs = fileConfig instanceof Array ? fileConfig : [fileConfig];
+  const mergedConfigs = fileConfigs.map((config) =>
+    mergeConfigs<T>(config, userConfig),
+  );
+  const foundConfig = fileConfigs.some(
+    (config) => Object.keys(config).length > 0,
+  );
+
+  return { configFile: loadedConfigFile, configs: mergedConfigs, foundConfig };
+}
diff --git a/packages/codegen-core/src/config/merge.ts b/packages/codegen-core/src/config/merge.ts
new file mode 100644
index 000000000..2dbff0bc2
--- /dev/null
+++ b/packages/codegen-core/src/config/merge.ts
@@ -0,0 +1,28 @@
+import type { AnyObject } from '@hey-api/types';
+
+function isPlainObject(value: unknown): value is AnyObject {
+  return typeof value === 'object' && value !== null && !Array.isArray(value);
+}
+
+export function mergeConfigs<T extends AnyObject>(
+  configA: T | undefined,
+  configB: T | undefined,
+): T {
+  const a = (configA || {}) as AnyObject;
+  const b = (configB || {}) as AnyObject;
+
+  const result: AnyObject = { ...a };
+
+  for (const key of Object.keys(b)) {
+    const valueA = a[key];
+    const valueB = b[key];
+
+    if (isPlainObject(valueA) && isPlainObject(valueB)) {
+      result[key] = mergeConfigs(valueA, valueB);
+    } else {
+      result[key] = valueB;
+    }
+  }
+
+  return result as T;
+}
diff --git a/packages/codegen-core/src/index.ts b/packages/codegen-core/src/index.ts
index 924115f4a..87b1eaa4d 100644
--- a/packages/codegen-core/src/index.ts
+++ b/packages/codegen-core/src/index.ts
@@ -5,6 +5,9 @@ export type {
   ImportModule,
 } from './bindings';
 export { nodeBrand, symbolBrand } from './brands';
+export { detectInteractiveSession } from './config/interactive';
+export { loadConfigFile } from './config/load';
+export { mergeConfigs } from './config/merge';
 export type {
   IProjectRenderMeta as ProjectRenderMeta,
   ISymbolMeta as SymbolMeta,
diff --git a/packages/openapi-python/package.json b/packages/openapi-python/package.json
index df1af4f19..6dd1bf09d 100644
--- a/packages/openapi-python/package.json
+++ b/packages/openapi-python/package.json
@@ -77,7 +77,6 @@
     "@hey-api/json-schema-ref-parser": "1.2.2",
     "@hey-api/types": "workspace:*",
     "ansi-colors": "4.1.3",
-    "c12": "3.3.3",
     "color-support": "1.1.3",
     "commander": "14.0.2",
     "open": "11.0.0",
diff --git a/packages/openapi-python/src/cli.ts b/packages/openapi-python/src/cli.ts
deleted file mode 100644
index 675e2e9e3..000000000
--- a/packages/openapi-python/src/cli.ts
+++ /dev/null
@@ -1,120 +0,0 @@
-import type { OptionValues } from 'commander';
-import { Command } from 'commander';
-
-import { createClient } from '~/index';
-
-import pkg from '../package.json' assert { type: 'json' };
-
-const stringToBoolean = (
-  value: string | undefined,
-): boolean | string | undefined => {
-  if (value === 'true') return true;
-  if (value === 'false') return false;
-  return value;
-};
-
-const processParams = (
-  obj: OptionValues,
-  booleanKeys: ReadonlyArray<string>,
-): OptionValues => {
-  for (const key of booleanKeys) {
-    const value = obj[key];
-    if (typeof value === 'string') {
-      const parsedValue = stringToBoolean(value);
-      delete obj[key];
-      obj[key] = parsedValue;
-    }
-  }
-  return obj;
-};
-
-export const runCli = async (): Promise<void> => {
-  const params = new Command()
-    .name(Object.keys(pkg.bin)[0]!)
-    .usage('[options]')
-    .version(pkg.version)
-    .option('-c, --client <value>', 'HTTP client to generate')
-    .option('-d, --debug', 'Set log level to debug')
-    .option('--dry-run [value]', 'Skip writing files to disk?')
-    .option('-f, --file [value]', 'Path to the config file')
-    .option(
-      '-i, --input <value>',
-      'OpenAPI specification (path, url, or string content)',
-    )
-    .option('-l, --logs [value]', 'Logs folder')
-    .option('-o, --output <value>', 'Output folder')
-    .option('-p, --plugins [value...]', "List of plugins you'd like to use")
-    .option('-s, --silent', 'Set log level to silent')
-    .option(
-      '--no-log-file',
-      'Disable writing a log file. Works like --silent but without suppressing console output',
-    )
-    .option(
-      '-w, --watch [value]',
-      'Regenerate the client when the input file changes?',
-    )
-    .parse(process.argv)
-    .opts();
-
-  let userConfig: Record<string, unknown>;
-
-  try {
-    userConfig = processParams(params, ['dryRun', 'logFile']);
-
-    if (userConfig.file) {
-      userConfig.configFile = userConfig.file;
-      delete userConfig.file;
-    }
-
-    if (params.plugins === true) {
-      userConfig.plugins = [];
-    } else if (params.plugins) {
-      userConfig.plugins = params.plugins;
-    } else if (userConfig.client) {
-      userConfig.plugins = ['@hey-api/sdk'];
-    }
-
-    if (userConfig.client) {
-      (userConfig.plugins as Array<string>).push(userConfig.client as string);
-      delete userConfig.client;
-    }
-
-    userConfig.logs = userConfig.logs
-      ? {
-          path: userConfig.logs,
-        }
-      : {};
-
-    if (userConfig.debug) {
-      (userConfig.logs as Record<string, unknown>).level = 'debug';
-      delete userConfig.debug;
-    } else if (userConfig.silent) {
-      (userConfig.logs as Record<string, unknown>).level = 'silent';
-      delete userConfig.silent;
-    }
-
-    (userConfig.logs as Record<string, unknown>).file = userConfig.logFile;
-    delete userConfig.logFile;
-
-    if (typeof params.watch === 'string') {
-      userConfig.watch = Number.parseInt(params.watch, 10);
-    }
-
-    if (!Object.keys(userConfig.logs as Record<string, unknown>).length) {
-      delete userConfig.logs;
-    }
-
-    const context = await createClient(
-      userConfig as unknown as Required<Parameters<typeof createClient>>[0],
-    );
-    if (
-      !context[0]?.config.input.some(
-        (input) => input.watch && input.watch.enabled,
-      )
-    ) {
-      process.exit(0);
-    }
-  } catch {
-    process.exit(1);
-  }
-};
diff --git a/packages/openapi-python/src/cli/adapter.ts b/packages/openapi-python/src/cli/adapter.ts
new file mode 100644
index 000000000..64666ce28
--- /dev/null
+++ b/packages/openapi-python/src/cli/adapter.ts
@@ -0,0 +1,40 @@
+// import type { ToArray } from '@hey-api/types';
+
+import type { UserConfig } from '~/config/types';
+
+import type { CliOptions } from './schema';
+
+export const cliToConfig = (cli: CliOptions): Partial<UserConfig> => {
+  const config: Partial<UserConfig> = {};
+
+  if (cli.input) config.input = cli.input;
+  if (cli.output) config.output = cli.output;
+  if (cli.file) config.configFile = cli.file;
+  if (cli.dryRun !== undefined) config.dryRun = cli.dryRun;
+
+  // const plugins: ToArray<UserConfig['plugins']> = [];
+  // if (cli.plugins instanceof Array && cli.plugins.length > 0) {
+  //   plugins.push(...cli.plugins);
+  // }
+  // if (cli.client) plugins.push(cli.client);
+  // if (plugins.length > 0) config.plugins = plugins;
+
+  if (cli.debug || cli.silent || cli.logs || cli.logFile !== undefined) {
+    config.logs = {
+      ...(cli.logs && { path: cli.logs }),
+      ...(cli.debug && { level: 'debug' as const }),
+      ...(cli.silent && { level: 'silent' as const }),
+      ...(cli.logFile !== undefined && { file: cli.logFile }),
+    };
+  }
+
+  if (cli.watch !== undefined) {
+    if (typeof cli.watch === 'string') {
+      config.watch = Number.parseInt(cli.watch, 10);
+    } else {
+      config.watch = cli.watch;
+    }
+  }
+
+  return config;
+};
diff --git a/packages/openapi-python/src/cli/index.ts b/packages/openapi-python/src/cli/index.ts
new file mode 100644
index 000000000..d900f7bf9
--- /dev/null
+++ b/packages/openapi-python/src/cli/index.ts
@@ -0,0 +1,67 @@
+import { Command, CommanderError } from 'commander';
+
+import { createClient } from '~/index';
+
+import pkg from '../../package.json' assert { type: 'json' };
+import { cliToConfig } from './adapter';
+
+const binName = Object.keys(pkg.bin)[0]!;
+
+const program = new Command()
+  .name(binName)
+  .description('Generate Python code from OpenAPI specifications')
+  .version(pkg.version);
+
+program
+  .option(
+    '-i, --input <path...>',
+    'OpenAPI specification (path, URL, or string)',
+  )
+  .option('-o, --output <path...>', 'Output folder(s)')
+  .option('-c, --client <name>', 'HTTP client to generate')
+  .option('-p, --plugins [names...]', 'Plugins to use')
+  .option('-f, --file <path>', 'Path to config file')
+  .option('-d, --debug', 'Enable debug logging')
+  .option('-s, --silent', 'Suppress all output')
+  .option('-l, --logs <path>', 'Logs folder path')
+  .option('--no-log-file', 'Disable log file output')
+  .option('--dry-run', 'Skip writing files')
+  .option('-w, --watch [interval]', 'Watch for changes')
+  .action(async (options) => {
+    const config = cliToConfig(options);
+
+    const context = await createClient(
+      config as Parameters<typeof createClient>[0],
+    );
+
+    const hasActiveWatch = context[0]?.config.input.some(
+      (input) => input.watch?.enabled,
+    );
+
+    if (!hasActiveWatch) {
+      process.exit(0);
+    }
+  });
+
+export async function runCli(): Promise<void> {
+  try {
+    await program.parseAsync(process.argv);
+  } catch (error) {
+    if (error instanceof CommanderError && 'code' in error) {
+      if (error.code === 'commander.optionMissingArgument') {
+        console.error(
+          `\nMissing required argument. Run '${binName} --help' for usage.\n`,
+        );
+      } else if (error.code === 'commander.unknownOption') {
+        console.error(
+          `\nUnknown option. Run '${binName} --help' for available options.\n`,
+        );
+      }
+
+      process.exit(error.exitCode);
+    }
+
+    console.error('Unexpected error:', error);
+    process.exit(1);
+  }
+}
diff --git a/packages/openapi-python/src/cli/schema.ts b/packages/openapi-python/src/cli/schema.ts
new file mode 100644
index 000000000..f49160f37
--- /dev/null
+++ b/packages/openapi-python/src/cli/schema.ts
@@ -0,0 +1,17 @@
+import type { MaybeArray } from '@hey-api/types';
+
+// import type { PluginClientNames, PluginNames } from "~/plugins/types";
+
+export interface CliOptions {
+  // client?: PluginClientNames;
+  debug?: boolean;
+  dryRun?: boolean;
+  file?: string;
+  input?: MaybeArray<string>;
+  logFile?: boolean;
+  logs?: string;
+  output?: MaybeArray<string>;
+  // plugins?: ReadonlyArray<PluginNames>;
+  silent?: boolean;
+  watch?: boolean | string;
+}
diff --git a/packages/openapi-python/src/config/types.d.ts b/packages/openapi-python/src/config/types.d.ts
index 6692ab0b2..220745b6b 100644
--- a/packages/openapi-python/src/config/types.d.ts
+++ b/packages/openapi-python/src/config/types.d.ts
@@ -1,4 +1,4 @@
-// import { MaybeArray } from "@hey-api/types";
+import type { MaybeArray } from '@hey-api/types';
 
 export interface UserConfig {
   /**
@@ -28,6 +28,7 @@ export interface UserConfig {
    * generate multiple outputs, one for each input.
    */
   // input: MaybeArray<UserInput | Required<UserInput>['path']>;
+  input: MaybeArray<string>;
   /**
    * Show an interactive error reporting tool when the program crashes? You
    * generally want to keep this disabled (default).
@@ -41,6 +42,11 @@ export interface UserConfig {
    * @default process.cwd()
    */
   // logs?: string | Logs;
+  logs?:
+    | string
+    | {
+        level?: 'debug' | 'info' | 'warn' | 'error' | 'silent';
+      };
   /**
    * Path to the output folder.
    *
@@ -48,6 +54,7 @@ export interface UserConfig {
    * generate multiple outputs, one for each input.
    */
   // output: MaybeArray<string | UserOutput>;
+  output: MaybeArray<string>;
   /**
    * Customize how the input is parsed and transformed before it's passed to
    * plugins.
@@ -68,4 +75,8 @@ export interface UserConfig {
   //       };
   //     }[PluginNames]
   // >;
+  /**
+   * @deprecated use `input.watch` instead
+   */
+  watch?: boolean | number;
 }
diff --git a/packages/openapi-python/src/index.ts b/packages/openapi-python/src/index.ts
index f2bc208d1..e7b9c61fc 100644
--- a/packages/openapi-python/src/index.ts
+++ b/packages/openapi-python/src/index.ts
@@ -79,11 +79,13 @@ colors.enabled = colorSupport().hasBasic;
 export { createClient } from '~/generate';
 
 /**
- * Type helper for openapi-ts.config.ts, returns {@link MaybeArray<UserConfig>} object(s)
+ * Type helper for configuration object, returns {@link MaybeArray<UserConfig>} object(s)
  */
-export const defineConfig = async <T extends MaybeArray<UserConfig>>(
+export async function defineConfig<T extends MaybeArray<UserConfig>>(
   config: LazyOrAsync<T>,
-): Promise<T> => (typeof config === 'function' ? await config() : config);
+): Promise<T> {
+  return typeof config === 'function' ? await config() : config;
+}
 
 export { Logger } from '@hey-api/codegen-core';
 // export { defaultPaginationKeywords } from '~/config/parser';
diff --git a/packages/openapi-ts-tests/main/test/cli.test.ts b/packages/openapi-ts-tests/main/test/cli.test.ts
index 9bb58351e..5143df63e 100755
--- a/packages/openapi-ts-tests/main/test/cli.test.ts
+++ b/packages/openapi-ts-tests/main/test/cli.test.ts
@@ -15,7 +15,6 @@ describe('bin', () => {
       '--output',
       path.resolve(__dirname, '.gen'),
       '--dry-run',
-      'true',
     ]);
     expect(result.error).toBeFalsy();
     expect(result.status).toBe(0);
diff --git a/packages/openapi-ts/package.json b/packages/openapi-ts/package.json
index 840e8dfbf..fbf5a8227 100644
--- a/packages/openapi-ts/package.json
+++ b/packages/openapi-ts/package.json
@@ -93,7 +93,6 @@
     "@hey-api/json-schema-ref-parser": "1.2.2",
     "@hey-api/types": "workspace:*",
     "ansi-colors": "4.1.3",
-    "c12": "3.3.3",
     "color-support": "1.1.3",
     "commander": "14.0.2",
     "open": "11.0.0",
diff --git a/packages/openapi-ts/src/__tests__/cli.test.ts b/packages/openapi-ts/src/__tests__/cli.test.ts
index e5db904ee..29fb83a2c 100755
--- a/packages/openapi-ts/src/__tests__/cli.test.ts
+++ b/packages/openapi-ts/src/__tests__/cli.test.ts
@@ -53,11 +53,11 @@ describe('cli', () => {
       process.argv = originalArgv;
     }
     expect(spy).toHaveBeenCalledWith({
-      input: 'foo.json',
+      input: ['foo.json'],
       logs: {
         file: true,
       },
-      output: 'bar',
+      output: ['bar'],
     });
   });
 
@@ -77,7 +77,6 @@ describe('cli', () => {
       logs: {
         file: true,
       },
-      plugins: [],
     });
   });
 
@@ -102,7 +101,7 @@ describe('cli', () => {
     });
   });
 
-  it('with default plugins', async () => {
+  it('with client plugin', async () => {
     const originalArgv = process.argv.slice();
     try {
       process.argv = [
@@ -119,7 +118,7 @@ describe('cli', () => {
       logs: {
         file: true,
       },
-      plugins: ['@hey-api/typescript', '@hey-api/sdk', 'foo'],
+      plugins: ['foo'],
     });
   });
 
@@ -214,12 +213,12 @@ describe('cli', () => {
     expect(spy).toHaveBeenCalledWith({
       configFile: 'bar',
       dryRun: true,
-      input: 'baz',
+      input: ['baz'],
       logs: {
         file: true,
         path: 'qux',
       },
-      output: 'quux',
+      output: ['quux'],
       plugins: ['foo'],
       watch: true,
     });
diff --git a/packages/openapi-ts/src/__tests__/interactive.test.ts b/packages/openapi-ts/src/__tests__/interactive.test.ts
index 766ca3e6a..3f525cf7b 100644
--- a/packages/openapi-ts/src/__tests__/interactive.test.ts
+++ b/packages/openapi-ts/src/__tests__/interactive.test.ts
@@ -1,12 +1,15 @@
-import { Logger } from '@hey-api/codegen-core';
+import {
+  detectInteractiveSession,
+  Logger,
+  mergeConfigs,
+} from '@hey-api/codegen-core';
 import { afterEach, describe, expect, it } from 'vitest';
 
-import { detectInteractiveSession, initConfigs } from '~/config/init';
-import { mergeConfigs } from '~/config/merge';
+import { resolveJobs } from '~/config/init';
 
 describe('interactive config', () => {
   it('should use detectInteractiveSession when not provided', async () => {
-    const result = await initConfigs({
+    const result = await resolveJobs({
       logger: new Logger(),
       userConfigs: [
         {
@@ -17,11 +20,11 @@ describe('interactive config', () => {
     });
 
     // In test environment, TTY is typically not available, so it should be false
-    expect(result.results[0]?.config.interactive).toBe(false);
+    expect(result.jobs[0]?.config.interactive).toBe(false);
   });
 
   it('should respect user config when set to true', async () => {
-    const result = await initConfigs({
+    const result = await resolveJobs({
       logger: new Logger(),
       userConfigs: [
         {
@@ -32,11 +35,11 @@ describe('interactive config', () => {
       ],
     });
 
-    expect(result.results[0]?.config.interactive).toBe(true);
+    expect(result.jobs[0]?.config.interactive).toBe(true);
   });
 
   it('should respect user config when set to false', async () => {
-    const result = await initConfigs({
+    const result = await resolveJobs({
       logger: new Logger(),
       userConfigs: [
         {
@@ -47,7 +50,7 @@ describe('interactive config', () => {
       ],
     });
 
-    expect(result.results[0]?.config.interactive).toBe(false);
+    expect(result.jobs[0]?.config.interactive).toBe(false);
   });
 
   it('should allow file config to set interactive when CLI does not provide it', () => {
@@ -76,7 +79,10 @@ describe('interactive config', () => {
     };
 
     // After fix: file config's interactive should be preserved
-    const mergedCorrect = mergeConfigs(fileConfig, cliConfigWithoutInteractive);
+    const mergedCorrect = mergeConfigs<Partial<typeof fileConfig>>(
+      fileConfig,
+      cliConfigWithoutInteractive,
+    );
     expect(mergedCorrect.interactive).toBe(false);
 
     // Before fix: CLI's auto-detected interactive would override file config
diff --git a/packages/openapi-ts/src/cli.ts b/packages/openapi-ts/src/cli.ts
deleted file mode 100644
index 75f528a46..000000000
--- a/packages/openapi-ts/src/cli.ts
+++ /dev/null
@@ -1,120 +0,0 @@
-import type { OptionValues } from 'commander';
-import { Command } from 'commander';
-
-import { createClient } from '~/index';
-
-import pkg from '../package.json' assert { type: 'json' };
-
-const stringToBoolean = (
-  value: string | undefined,
-): boolean | string | undefined => {
-  if (value === 'true') return true;
-  if (value === 'false') return false;
-  return value;
-};
-
-const processParams = (
-  obj: OptionValues,
-  booleanKeys: ReadonlyArray<string>,
-): OptionValues => {
-  for (const key of booleanKeys) {
-    const value = obj[key];
-    if (typeof value === 'string') {
-      const parsedValue = stringToBoolean(value);
-      delete obj[key];
-      obj[key] = parsedValue;
-    }
-  }
-  return obj;
-};
-
-export const runCli = async (): Promise<void> => {
-  const params = new Command()
-    .name(Object.keys(pkg.bin)[0]!)
-    .usage('[options]')
-    .version(pkg.version)
-    .option('-c, --client <value>', 'HTTP client to generate')
-    .option('-d, --debug', 'Set log level to debug')
-    .option('--dry-run [value]', 'Skip writing files to disk?')
-    .option('-f, --file [value]', 'Path to the config file')
-    .option(
-      '-i, --input <value>',
-      'OpenAPI specification (path, url, or string content)',
-    )
-    .option('-l, --logs [value]', 'Logs folder')
-    .option('-o, --output <value>', 'Output folder')
-    .option('-p, --plugins [value...]', "List of plugins you'd like to use")
-    .option('-s, --silent', 'Set log level to silent')
-    .option(
-      '--no-log-file',
-      'Disable writing a log file. Works like --silent but without suppressing console output',
-    )
-    .option(
-      '-w, --watch [value]',
-      'Regenerate the client when the input file changes?',
-    )
-    .parse(process.argv)
-    .opts();
-
-  let userConfig: Record<string, unknown>;
-
-  try {
-    userConfig = processParams(params, ['dryRun', 'logFile']);
-
-    if (userConfig.file) {
-      userConfig.configFile = userConfig.file;
-      delete userConfig.file;
-    }
-
-    if (params.plugins === true) {
-      userConfig.plugins = [];
-    } else if (params.plugins) {
-      userConfig.plugins = params.plugins;
-    } else if (userConfig.client) {
-      userConfig.plugins = ['@hey-api/typescript', '@hey-api/sdk'];
-    }
-
-    if (userConfig.client) {
-      (userConfig.plugins as Array<string>).push(userConfig.client as string);
-      delete userConfig.client;
-    }
-
-    userConfig.logs = userConfig.logs
-      ? {
-          path: userConfig.logs,
-        }
-      : {};
-
-    if (userConfig.debug) {
-      (userConfig.logs as Record<string, unknown>).level = 'debug';
-      delete userConfig.debug;
-    } else if (userConfig.silent) {
-      (userConfig.logs as Record<string, unknown>).level = 'silent';
-      delete userConfig.silent;
-    }
-
-    (userConfig.logs as Record<string, unknown>).file = userConfig.logFile;
-    delete userConfig.logFile;
-
-    if (typeof params.watch === 'string') {
-      userConfig.watch = Number.parseInt(params.watch, 10);
-    }
-
-    if (!Object.keys(userConfig.logs as Record<string, unknown>).length) {
-      delete userConfig.logs;
-    }
-
-    const context = await createClient(
-      userConfig as unknown as Required<Parameters<typeof createClient>>[0],
-    );
-    if (
-      !context[0]?.config.input.some(
-        (input) => input.watch && input.watch.enabled,
-      )
-    ) {
-      process.exit(0);
-    }
-  } catch {
-    process.exit(1);
-  }
-};
diff --git a/packages/openapi-ts/src/cli/adapter.ts b/packages/openapi-ts/src/cli/adapter.ts
new file mode 100644
index 000000000..222a088fa
--- /dev/null
+++ b/packages/openapi-ts/src/cli/adapter.ts
@@ -0,0 +1,40 @@
+import type { ToArray } from '@hey-api/types';
+
+import type { UserConfig } from '~/config/types';
+
+import type { CliOptions } from './schema';
+
+export const cliToConfig = (cli: CliOptions): Partial<UserConfig> => {
+  const config: Partial<UserConfig> = {};
+
+  if (cli.input) config.input = cli.input;
+  if (cli.output) config.output = cli.output;
+  if (cli.file) config.configFile = cli.file;
+  if (cli.dryRun !== undefined) config.dryRun = cli.dryRun;
+
+  const plugins: ToArray<UserConfig['plugins']> = [];
+  if (cli.plugins instanceof Array && cli.plugins.length > 0) {
+    plugins.push(...cli.plugins);
+  }
+  if (cli.client) plugins.push(cli.client);
+  if (plugins.length > 0) config.plugins = plugins;
+
+  if (cli.debug || cli.silent || cli.logs || cli.logFile !== undefined) {
+    config.logs = {
+      ...(cli.logs && { path: cli.logs }),
+      ...(cli.debug && { level: 'debug' as const }),
+      ...(cli.silent && { level: 'silent' as const }),
+      ...(cli.logFile !== undefined && { file: cli.logFile }),
+    };
+  }
+
+  if (cli.watch !== undefined) {
+    if (typeof cli.watch === 'string') {
+      config.watch = Number.parseInt(cli.watch, 10);
+    } else {
+      config.watch = cli.watch;
+    }
+  }
+
+  return config;
+};
diff --git a/packages/openapi-ts/src/cli/index.ts b/packages/openapi-ts/src/cli/index.ts
new file mode 100644
index 000000000..7c02bd893
--- /dev/null
+++ b/packages/openapi-ts/src/cli/index.ts
@@ -0,0 +1,67 @@
+import { Command, CommanderError } from 'commander';
+
+import { createClient } from '~/index';
+
+import pkg from '../../package.json' assert { type: 'json' };
+import { cliToConfig } from './adapter';
+
+const binName = Object.keys(pkg.bin)[0]!;
+
+const program = new Command()
+  .name(binName)
+  .description('Generate TypeScript code from OpenAPI specifications')
+  .version(pkg.version);
+
+program
+  .option(
+    '-i, --input <path...>',
+    'OpenAPI specification (path, URL, or string)',
+  )
+  .option('-o, --output <path...>', 'Output folder(s)')
+  .option('-c, --client <name>', 'HTTP client to generate')
+  .option('-p, --plugins [names...]', 'Plugins to use')
+  .option('-f, --file <path>', 'Path to config file')
+  .option('-d, --debug', 'Enable debug logging')
+  .option('-s, --silent', 'Suppress all output')
+  .option('-l, --logs <path>', 'Logs folder path')
+  .option('--no-log-file', 'Disable log file output')
+  .option('--dry-run', 'Skip writing files')
+  .option('-w, --watch [interval]', 'Watch for changes')
+  .action(async (options) => {
+    const config = cliToConfig(options);
+
+    const context = await createClient(
+      config as Parameters<typeof createClient>[0],
+    );
+
+    const hasActiveWatch = context[0]?.config.input.some(
+      (input) => input.watch?.enabled,
+    );
+
+    if (!hasActiveWatch) {
+      process.exit(0);
+    }
+  });
+
+export async function runCli(): Promise<void> {
+  try {
+    await program.parseAsync(process.argv);
+  } catch (error) {
+    if (error instanceof CommanderError && 'code' in error) {
+      if (error.code === 'commander.optionMissingArgument') {
+        console.error(
+          `\nMissing required argument. Run '${binName} --help' for usage.\n`,
+        );
+      } else if (error.code === 'commander.unknownOption') {
+        console.error(
+          `\nUnknown option. Run '${binName} --help' for available options.\n`,
+        );
+      }
+
+      process.exit(error.exitCode);
+    }
+
+    console.error('Unexpected error:', error);
+    process.exit(1);
+  }
+}
diff --git a/packages/openapi-ts/src/cli/schema.ts b/packages/openapi-ts/src/cli/schema.ts
new file mode 100644
index 000000000..0cd428a83
--- /dev/null
+++ b/packages/openapi-ts/src/cli/schema.ts
@@ -0,0 +1,17 @@
+import type { MaybeArray } from '@hey-api/types';
+
+import type { PluginClientNames, PluginNames } from '~/plugins/types';
+
+export interface CliOptions {
+  client?: PluginClientNames;
+  debug?: boolean;
+  dryRun?: boolean;
+  file?: string;
+  input?: MaybeArray<string>;
+  logFile?: boolean;
+  logs?: string;
+  output?: MaybeArray<string>;
+  plugins?: ReadonlyArray<PluginNames>;
+  silent?: boolean;
+  watch?: boolean | string;
+}
diff --git a/packages/openapi-ts/src/config/expand.ts b/packages/openapi-ts/src/config/expand.ts
new file mode 100644
index 000000000..0c78e1d75
--- /dev/null
+++ b/packages/openapi-ts/src/config/expand.ts
@@ -0,0 +1,54 @@
+import colors from 'ansi-colors';
+
+import { getInput } from './input';
+import type { UserConfig } from './types';
+
+export interface Job {
+  config: UserConfig;
+  index: number;
+}
+
+export function expandToJobs(
+  configs: ReadonlyArray<UserConfig>,
+): ReadonlyArray<Job> {
+  const jobs: Array<Job> = [];
+  let jobIndex = 0;
+
+  for (const config of configs) {
+    const inputs = getInput(config);
+    const outputs =
+      config.output instanceof Array ? config.output : [config.output];
+
+    if (outputs.length === 1) {
+      jobs.push({
+        config: {
+          ...config,
+          input: inputs,
+          output: outputs[0]!, // output array with single item
+        },
+        index: jobIndex++,
+      });
+    } else if (outputs.length > 1 && inputs.length !== outputs.length) {
+      // Warn and create job per output (all with same inputs)
+      console.warn(
+        `⚙️ ${colors.yellow('Warning:')} You provided ${colors.cyan(String(inputs.length))} ${colors.cyan(inputs.length === 1 ? 'input' : 'inputs')} and ${colors.yellow(String(outputs.length))} ${colors.yellow('outputs')}. This will produce identical output in multiple locations. You likely want to provide a single output or the same number of outputs as inputs.`,
+      );
+      for (const output of outputs) {
+        jobs.push({
+          config: { ...config, input: inputs, output },
+          index: jobIndex++,
+        });
+      }
+    } else if (outputs.length > 1) {
+      // Pair inputs with outputs by index
+      outputs.forEach((output, index) => {
+        jobs.push({
+          config: { ...config, input: inputs[index]!, output },
+          index: jobIndex++,
+        });
+      });
+    }
+  }
+
+  return jobs;
+}
diff --git a/packages/openapi-ts/src/config/init.ts b/packages/openapi-ts/src/config/init.ts
index 7068e3368..a668b35ed 100644
--- a/packages/openapi-ts/src/config/init.ts
+++ b/packages/openapi-ts/src/config/init.ts
@@ -1,184 +1,71 @@
-import path from 'node:path';
-
 import type { Logger } from '@hey-api/codegen-core';
-import type { ArrayOnly } from '@hey-api/types';
-import colors from 'ansi-colors';
-
-import { ConfigError } from '~/error';
+import { loadConfigFile } from '@hey-api/codegen-core';
 
-import { getInput } from './input';
-import { getLogs } from './logs';
-import { mergeConfigs } from './merge';
-import { getOutput } from './output';
+import { expandToJobs } from './expand';
 import { getProjectDependencies } from './packages';
-import { getParser } from './parser';
-import { getPlugins } from './plugins';
-import type { Config, UserConfig } from './types';
-
-type ConfigResult = {
-  config: Config;
-  errors: ReadonlyArray<Error>;
-  jobIndex: number;
-};
+import type { ResolvedJob } from './resolve';
+import { resolveConfig } from './resolve';
+import type { UserConfig } from './types';
+import { validateJobs } from './validate';
 
 export type Configs = {
   dependencies: Record<string, string>;
-  results: ReadonlyArray<ConfigResult>;
+  jobs: ReadonlyArray<ResolvedJob>;
+  /**
+   * @deprecated Use `jobs` instead.
+   */
+  results: ReadonlyArray<ResolvedJob>;
 };
 
-/**
- * Detect if the current session is interactive based on TTY status and environment variables.
- * This is used as a fallback when the user doesn't explicitly set the interactive option.
- * @internal
- */
-export const detectInteractiveSession = (): boolean =>
-  Boolean(
-    process.stdin.isTTY &&
-      process.stdout.isTTY &&
-      !process.env.CI &&
-      !process.env.NO_INTERACTIVE &&
-      !process.env.NO_INTERACTION,
-  );
-
 /**
  * @internal
  */
-export const initConfigs = async ({
+export async function resolveJobs({
   logger,
   userConfigs,
 }: {
   logger: Logger;
   userConfigs: ReadonlyArray<UserConfig>;
-}): Promise<Configs> => {
+}): Promise<Configs> {
   const configs: Array<UserConfig> = [];
   let dependencies: Record<string, string> = {};
 
   const eventLoad = logger.timeEvent('load');
   for (const userConfig of userConfigs) {
-    let configurationFile: string | undefined = undefined;
-    if (userConfig?.configFile) {
+    let configFile: string | undefined;
+    if (userConfig.configFile) {
       const parts = userConfig.configFile.split('.');
-      configurationFile = parts.slice(0, parts.length - 1).join('.');
+      configFile = parts.slice(0, parts.length - 1).join('.');
     }
 
-    const eventC12 = logger.timeEvent('c12');
-    // c12 is ESM-only since v3
-    const { loadConfig } = await import('c12');
-    const { config: configFromFile, configFile: loadedConfigFile } =
-      await loadConfig<UserConfig>({
-        configFile: configurationFile,
-        name: 'openapi-ts',
-      });
-    eventC12.timeEnd();
+    const loaded = await loadConfigFile<UserConfig>({
+      configFile,
+      logger,
+      name: 'openapi-ts',
+      userConfig,
+    });
 
     if (!Object.keys(dependencies).length) {
       // TODO: handle dependencies for multiple configs properly?
       dependencies = getProjectDependencies(
-        Object.keys(configFromFile).length ? loadedConfigFile : undefined,
+        loaded.foundConfig ? loaded.configFile : undefined,
       );
     }
 
-    const mergedConfigs =
-      configFromFile instanceof Array
-        ? configFromFile.map((config) => mergeConfigs(config, userConfig))
-        : [mergeConfigs(configFromFile, userConfig)];
-
-    for (const mergedConfig of mergedConfigs) {
-      const input = getInput(mergedConfig);
-
-      if (mergedConfig.output instanceof Array) {
-        const countInputs = input.length;
-        const countOutputs = mergedConfig.output.length;
-        if (countOutputs > 1) {
-          if (countInputs !== countOutputs) {
-            console.warn(
-              `⚙️ ${colors.yellow('Warning:')} You provided ${colors.cyan(String(countInputs))} ${colors.cyan(countInputs === 1 ? 'input' : 'inputs')} and ${colors.yellow(String(countOutputs))} ${colors.yellow('outputs')}. This is probably not what you want as it will produce identical output in multiple locations. You most likely want to provide a single output or the same number of outputs as inputs.`,
-            );
-            for (const output of mergedConfig.output) {
-              configs.push({ ...mergedConfig, input, output });
-            }
-          } else {
-            mergedConfig.output.forEach((output, index) => {
-              configs.push({ ...mergedConfig, input: input[index]!, output });
-            });
-          }
-        } else {
-          configs.push({
-            ...mergedConfig,
-            input,
-            output: mergedConfig.output[0] ?? '',
-          });
-        }
-      } else {
-        configs.push({ ...mergedConfig, input });
-      }
-    }
+    configs.push(...loaded.configs);
   }
   eventLoad.timeEnd();
 
-  const results: Array<ArrayOnly<ConfigResult>> = [];
-
   const eventBuild = logger.timeEvent('build');
-  for (const userConfig of configs) {
-    const logs = getLogs(userConfig);
-    const input = getInput(userConfig);
-    const output = getOutput(userConfig);
-    const parser = getParser(userConfig);
-
-    const errors: Array<Error> = [];
-
-    if (!input.length) {
-      errors.push(
-        new ConfigError(
-          'missing input - which OpenAPI specification should we use to generate your output?',
-        ),
-      );
-    }
-
-    if (!output.path) {
-      errors.push(
-        new ConfigError(
-          'missing output - where should we generate your output?',
-        ),
-      );
-    }
-
-    output.path = path.resolve(process.cwd(), output.path);
-
-    let plugins: Pick<Config, 'plugins' | 'pluginOrder'>;
-
-    try {
-      plugins = getPlugins({ dependencies, userConfig });
-    } catch (error) {
-      errors.push(error);
-      plugins = {
-        pluginOrder: [],
-        plugins: {},
-      };
-    }
-
-    const config: Config = {
-      configFile: userConfig.configFile ?? '',
-      dryRun: userConfig.dryRun ?? false,
-      input,
-      interactive: userConfig.interactive ?? detectInteractiveSession(),
-      logs,
-      output,
-      parser,
-      pluginOrder: plugins.pluginOrder,
-      plugins: plugins.plugins,
-    };
-
-    const jobIndex = results.length;
-
-    if (logs.level === 'debug') {
-      const jobPrefix = colors.gray(`[Job ${jobIndex + 1}] `);
-      console.warn(`${jobPrefix}${colors.cyan('config:')}`, config);
-    }
-
-    results.push({ config, errors, jobIndex });
-  }
+  const jobs = validateJobs(expandToJobs(configs));
+  const resolvedJobs = jobs.map((validated) =>
+    resolveConfig(validated, dependencies),
+  );
   eventBuild.timeEnd();
 
-  return { dependencies, results };
-};
+  return {
+    dependencies,
+    jobs: resolvedJobs,
+    results: resolvedJobs,
+  };
+}
diff --git a/packages/openapi-ts/src/config/merge.ts b/packages/openapi-ts/src/config/merge.ts
deleted file mode 100644
index a4ce11067..000000000
--- a/packages/openapi-ts/src/config/merge.ts
+++ /dev/null
@@ -1,32 +0,0 @@
-import type { UserConfig } from './types';
-
-const mergeObjects = (
-  objA: Record<string, unknown> | undefined,
-  objB: Record<string, unknown> | undefined,
-): Record<string, unknown> => {
-  const a = objA || {};
-  const b = objB || {};
-  return {
-    ...a,
-    ...b,
-  };
-};
-
-export const mergeConfigs = (
-  configA: UserConfig | undefined,
-  configB: UserConfig | undefined,
-): UserConfig => {
-  const a: Partial<UserConfig> = configA || {};
-  const b: Partial<UserConfig> = configB || {};
-  const merged: UserConfig = {
-    ...(a as UserConfig),
-    ...(b as UserConfig),
-  };
-  if (typeof merged.logs === 'object') {
-    merged.logs = mergeObjects(
-      a.logs as Record<string, unknown>,
-      b.logs as Record<string, unknown>,
-    );
-  }
-  return merged;
-};
diff --git a/packages/openapi-ts/src/config/resolve.ts b/packages/openapi-ts/src/config/resolve.ts
new file mode 100644
index 000000000..19352320e
--- /dev/null
+++ b/packages/openapi-ts/src/config/resolve.ts
@@ -0,0 +1,65 @@
+import path from 'node:path';
+
+import { detectInteractiveSession } from '@hey-api/codegen-core';
+import colors from 'ansi-colors';
+
+import { getInput } from './input';
+import { getLogs } from './logs';
+import { getOutput } from './output';
+import { getParser } from './parser';
+import { getPlugins } from './plugins';
+import type { Config } from './types';
+import type { ValidationResult } from './validate';
+
+export type ResolvedJob = {
+  config: Config;
+  errors: Array<Error>;
+  index: number;
+};
+
+export const resolveConfig = (
+  validated: ValidationResult,
+  dependencies: Record<string, string>,
+): ResolvedJob => {
+  const logs = getLogs(validated.job.config);
+  const input = getInput(validated.job.config);
+  const output = getOutput(validated.job.config);
+  const parser = getParser(validated.job.config);
+
+  output.path = path.resolve(process.cwd(), output.path);
+
+  let plugins: Pick<Config, 'plugins' | 'pluginOrder'>;
+
+  try {
+    plugins = getPlugins({ dependencies, userConfig: validated.job.config });
+  } catch (error) {
+    validated.errors.push(error);
+    plugins = {
+      pluginOrder: [],
+      plugins: {},
+    };
+  }
+
+  const config: Config = {
+    configFile: validated.job.config.configFile ?? '',
+    dryRun: validated.job.config.dryRun ?? false,
+    input,
+    interactive: validated.job.config.interactive ?? detectInteractiveSession(),
+    logs,
+    output,
+    parser,
+    pluginOrder: plugins.pluginOrder,
+    plugins: plugins.plugins,
+  };
+
+  if (logs.level === 'debug') {
+    const jobPrefix = colors.gray(`[Job ${validated.job.index}] `);
+    console.warn(`${jobPrefix}${colors.cyan('config:')}`, config);
+  }
+
+  return {
+    config,
+    errors: validated.errors,
+    index: validated.job.index,
+  };
+};
diff --git a/packages/openapi-ts/src/config/types.d.ts b/packages/openapi-ts/src/config/types.d.ts
index 940423b18..c6568a935 100644
--- a/packages/openapi-ts/src/config/types.d.ts
+++ b/packages/openapi-ts/src/config/types.d.ts
@@ -9,7 +9,7 @@ import type { Parser, UserParser } from '~/types/parser';
 
 import type { Output, UserOutput } from './output';
 
-export interface UserConfig {
+export type UserConfig = {
   /**
    * Path to the config file. Set this value if you don't use the default
    * config file name, or it's not located in the project root.
@@ -81,7 +81,7 @@ export interface UserConfig {
    * @deprecated use `input.watch` instead
    */
   watch?: boolean | number | Watch;
-}
+};
 
 export type Config = Omit<
   Required<UserConfig>,
diff --git a/packages/openapi-ts/src/config/validate.ts b/packages/openapi-ts/src/config/validate.ts
new file mode 100644
index 000000000..2be89f161
--- /dev/null
+++ b/packages/openapi-ts/src/config/validate.ts
@@ -0,0 +1,39 @@
+import { ConfigError } from '~/error';
+
+import type { Job } from './expand';
+import { getInput } from './input';
+import { getOutput } from './output';
+
+export interface ValidationResult {
+  errors: Array<ConfigError>;
+  job: Job;
+}
+
+export function validateJobs(
+  jobs: ReadonlyArray<Job>,
+): ReadonlyArray<ValidationResult> {
+  return jobs.map((job) => {
+    const errors: Array<ConfigError> = [];
+    const { config } = job;
+
+    const inputs = getInput(config);
+    if (!inputs.length) {
+      errors.push(
+        new ConfigError(
+          'missing input - which OpenAPI specification should we use to generate your output?',
+        ),
+      );
+    }
+
+    const output = getOutput(config);
+    if (!output.path) {
+      errors.push(
+        new ConfigError(
+          'missing output - where should we generate your output?',
+        ),
+      );
+    }
+
+    return { errors, job };
+  });
+}
diff --git a/packages/openapi-ts/src/generate.ts b/packages/openapi-ts/src/generate.ts
index 6aba3be51..bdbb3907c 100644
--- a/packages/openapi-ts/src/generate.ts
+++ b/packages/openapi-ts/src/generate.ts
@@ -3,7 +3,7 @@ import type { LazyOrAsync, MaybeArray } from '@hey-api/types';
 
 import { checkNodeVersion } from '~/config/engine';
 import type { Configs } from '~/config/init';
-import { initConfigs } from '~/config/init';
+import { resolveJobs } from '~/config/init';
 import { getLogs } from '~/config/logs';
 import type { UserConfig } from '~/config/types';
 import { createClient as pCreateClient } from '~/createClient';
@@ -23,10 +23,10 @@ import { printCliIntro } from '~/utils/cli';
  *
  * @param userConfig User provided {@link UserConfig} configuration(s).
  */
-export const createClient = async (
+export async function createClient(
   userConfig?: LazyOrAsync<MaybeArray<UserConfig>>,
   logger = new Logger(),
-): Promise<ReadonlyArray<Context>> => {
+): Promise<ReadonlyArray<Context>> {
   const resolvedConfig =
     typeof userConfig === 'function' ? await userConfig() : userConfig;
   const userConfigs = resolvedConfig
@@ -42,7 +42,7 @@ export const createClient = async (
     rawLogs = getLogs({ logs: rawLogs });
   }
 
-  let configs: Configs | undefined;
+  let jobs: Configs['jobs'] = [];
 
   try {
     checkNodeVersion();
@@ -50,61 +50,51 @@ export const createClient = async (
     const eventCreateClient = logger.timeEvent('createClient');
 
     const eventConfig = logger.timeEvent('config');
-    configs = await initConfigs({ logger, userConfigs });
-    const printIntro = configs.results.some(
-      (result) => result.config.logs.level !== 'silent',
-    );
-    if (printIntro) {
-      printCliIntro();
-    }
+    const resolved = await resolveJobs({ logger, userConfigs });
+    const dependencies = resolved.dependencies;
+    jobs = resolved.jobs;
+    const printIntro = jobs.some((job) => job.config.logs.level !== 'silent');
+    if (printIntro) printCliIntro();
     eventConfig.timeEnd();
 
-    const allConfigErrors = configs.results.flatMap((result) =>
-      result.errors.map((error) => ({ error, jobIndex: result.jobIndex })),
+    const configErrors = jobs.flatMap((job) =>
+      job.errors.map((error) => ({ error, jobIndex: job.index })),
     );
-    if (allConfigErrors.length) {
-      throw new ConfigValidationError(allConfigErrors);
+    if (configErrors.length > 0) {
+      throw new ConfigValidationError(configErrors);
     }
 
-    const clients = await Promise.all(
-      configs.results.map(async (result) => {
+    const outputs = await Promise.all(
+      jobs.map(async (job) => {
         try {
           return await pCreateClient({
-            config: result.config,
-            dependencies: configs!.dependencies,
-            jobIndex: result.jobIndex,
+            config: job.config,
+            dependencies,
+            jobIndex: job.index,
             logger,
           });
         } catch (error) {
           throw new JobError('', {
             error,
-            jobIndex: result.jobIndex,
+            jobIndex: job.index,
           });
         }
       }),
     );
-    const result = clients.filter((client) =>
-      Boolean(client),
-    ) as ReadonlyArray<Context>;
+    const contexts = outputs.filter((ctx): ctx is Context => ctx !== undefined);
 
     eventCreateClient.timeEnd();
 
-    const printLogs = configs.results.some(
-      (result) => result.config.logs.level === 'debug',
-    );
-    logger.report(printLogs);
+    logger.report(jobs.some((job) => job.config.logs.level === 'debug'));
 
-    return result;
+    return contexts;
   } catch (error) {
-    const results = configs?.results ?? [];
-
     const logs =
-      results.find((result) => result.config.logs.level !== 'silent')?.config
-        .logs ??
-      results[0]?.config.logs ??
+      jobs.find((job) => job.config.logs.level !== 'silent')?.config.logs ??
+      jobs[0]?.config.logs ??
       rawLogs;
     const dryRun =
-      results.some((result) => result.config.dryRun) ??
+      jobs.some((job) => job.config.dryRun) ??
       userConfigs.some((config) => config.dryRun) ??
       false;
     const logPath =
@@ -114,7 +104,7 @@ export const createClient = async (
     if (!logs || logs.level !== 'silent') {
       printCrashReport({ error, logPath });
       const isInteractive =
-        results.some((result) => result.config.interactive) ??
+        jobs.some((job) => job.config.interactive) ??
         userConfigs.some((config) => config.interactive) ??
         false;
       if (await shouldReportCrash({ error, isInteractive })) {
@@ -124,4 +114,4 @@ export const createClient = async (
 
     throw error;
   }
-};
+}
diff --git a/packages/openapi-ts/src/index.ts b/packages/openapi-ts/src/index.ts
index 63ea62111..f2bf9a14e 100644
--- a/packages/openapi-ts/src/index.ts
+++ b/packages/openapi-ts/src/index.ts
@@ -79,11 +79,13 @@ colors.enabled = colorSupport().hasBasic;
 export { createClient } from '~/generate';
 
 /**
- * Type helper for openapi-ts.config.ts, returns {@link MaybeArray<UserConfig>} object(s)
+ * Type helper for configuration object, returns {@link MaybeArray<UserConfig>} object(s)
  */
-export const defineConfig = async <T extends MaybeArray<UserConfig>>(
+export async function defineConfig<T extends MaybeArray<UserConfig>>(
   config: LazyOrAsync<T>,
-): Promise<T> => (typeof config === 'function' ? await config() : config);
+): Promise<T> {
+  return typeof config === 'function' ? await config() : config;
+}
 
 export { Logger } from '@hey-api/codegen-core';
 export { defaultPaginationKeywords } from '~/config/parser';
diff --git a/packages/openapi-ts/src/internal.ts b/packages/openapi-ts/src/internal.ts
index ec80d9485..5ed164152 100644
--- a/packages/openapi-ts/src/internal.ts
+++ b/packages/openapi-ts/src/internal.ts
@@ -1,3 +1,3 @@
-export { initConfigs } from './config/init';
+export { resolveJobs as initConfigs } from './config/init';
 export { getSpec } from './getSpec';
 export { parseOpenApiSpec } from './openApi';
diff --git a/packages/types/src/index.ts b/packages/types/src/index.ts
index 01ab8a619..2a866c98d 100644
--- a/packages/types/src/index.ts
+++ b/packages/types/src/index.ts
@@ -1,8 +1,13 @@
+/**
+ * An object with string keys and unknown values.
+ */
+export type AnyObject = Record<string, unknown>;
+
 /**
  * Converts all top-level ReadonlyArray properties to Array (shallow).
  */
 export type ArrayOnly<T> = {
-  [K in keyof T]: T[K] extends ReadonlyArray<infer U> ? Array<U> : T[K];
+  [K in keyof T]: ToArray<T[K]>;
 };
 
 /**
@@ -42,5 +47,16 @@ export type MaybePromise<T> = T | Promise<T>;
  * Converts all top-level Array properties to ReadonlyArray (shallow).
  */
 export type ReadonlyArrayOnly<T> = {
-  [K in keyof T]: T[K] extends Array<infer U> ? ReadonlyArray<U> : T[K];
+  [K in keyof T]: ToReadonlyArray<T[K]>;
 };
+
+/**
+ * Converts ReadonlyArray<T> to Array<T>, preserving unions.
+ */
+export type ToArray<T> = T extends ReadonlyArray<infer U> ? Array<U> : T;
+
+/**
+ * Converts Array<T> to ReadonlyArray<T>, preserving unions.
+ */
+export type ToReadonlyArray<T> =
+  T extends ReadonlyArray<infer U> ? ReadonlyArray<U> : T;
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 04b8bcda9..083800e11 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -1253,6 +1253,9 @@ importers:
       ansi-colors:
         specifier: 4.1.3
         version: 4.1.3
+      c12:
+        specifier: 3.3.3
+        version: 3.3.3(magicast@0.3.5)
       color-support:
         specifier: 1.1.3
         version: 1.1.3
@@ -1346,9 +1349,6 @@ importers:
       ansi-colors:
         specifier: 4.1.3
         version: 4.1.3
-      c12:
-        specifier: 3.3.3
-        version: 3.3.3(magicast@0.3.5)
       color-support:
         specifier: 1.1.3
         version: 1.1.3
@@ -1401,9 +1401,6 @@ importers:
       ansi-colors:
         specifier: 4.1.3
         version: 4.1.3
-      c12:
-        specifier: 3.3.3
-        version: 3.3.3(magicast@0.3.5)
       color-support:
         specifier: 1.1.3
         version: 1.1.3
@@ -7908,14 +7905,6 @@ packages:
       magicast:
         optional: true
 
-  c12@3.3.2:
-    resolution: {integrity: sha512-QkikB2X5voO1okL3QsES0N690Sn/K9WokXqUsDQsWy5SnYb+psYQFGA10iy1bZHj3fjISKsI67Q90gruvWWM3A==}
-    peerDependencies:
-      magicast: '*'
-    peerDependenciesMeta:
-      magicast:
-        optional: true
-
   c12@3.3.3:
     resolution: {integrity: sha512-750hTRvgBy5kcMNPdh95Qo+XUBeGo8C7nsKSmedDmaQI+E0r82DwHeM6vBewDe4rGFbnxoa4V9pw+sPh5+Iz8Q==}
     peerDependencies:
@@ -14693,7 +14682,7 @@ snapshots:
       '@vitejs/plugin-basic-ssl': 1.2.0(vite@7.2.2(@types/node@22.10.5)(jiti@2.6.1)(less@4.2.2)(sass@1.85.0)(terser@5.43.1)(yaml@2.8.2))
       ansi-colors: 4.1.3
       autoprefixer: 10.4.20(postcss@8.5.2)
-      babel-loader: 9.2.1(@babel/core@7.26.9)(webpack@5.98.0)
+      babel-loader: 9.2.1(@babel/core@7.26.9)(webpack@5.98.0(esbuild@0.25.0))
       browserslist: 4.25.4
       copy-webpack-plugin: 12.0.2(webpack@5.98.0)
       css-loader: 7.1.2(webpack@5.98.0)
@@ -14713,7 +14702,7 @@ snapshots:
       picomatch: 4.0.2
       piscina: 4.8.0
       postcss: 8.5.2
-      postcss-loader: 8.1.1(postcss@8.5.2)(typescript@5.8.3)(webpack@5.98.0)
+      postcss-loader: 8.1.1(postcss@8.5.2)(typescript@5.8.3)(webpack@5.98.0(esbuild@0.25.0))
       resolve-url-loader: 5.0.0
       rxjs: 7.8.1
       sass: 1.85.0
@@ -14781,7 +14770,7 @@ snapshots:
       '@vitejs/plugin-basic-ssl': 1.2.0(vite@7.2.2(@types/node@22.10.5)(jiti@2.6.1)(less@4.2.2)(sass@1.85.0)(terser@5.39.0)(yaml@2.8.2))
       ansi-colors: 4.1.3
       autoprefixer: 10.4.20(postcss@8.5.2)
-      babel-loader: 9.2.1(@babel/core@7.26.9)(webpack@5.98.0)
+      babel-loader: 9.2.1(@babel/core@7.26.9)(webpack@5.98.0(esbuild@0.25.0))
       browserslist: 4.25.4
       copy-webpack-plugin: 12.0.2(webpack@5.98.0)
       css-loader: 7.1.2(webpack@5.98.0)
@@ -14801,7 +14790,7 @@ snapshots:
       picomatch: 4.0.2
       piscina: 4.8.0
       postcss: 8.5.2
-      postcss-loader: 8.1.1(postcss@8.5.2)(typescript@5.8.3)(webpack@5.98.0)
+      postcss-loader: 8.1.1(postcss@8.5.2)(typescript@5.8.3)(webpack@5.98.0(esbuild@0.25.0))
       resolve-url-loader: 5.0.0
       rxjs: 7.8.1
       sass: 1.85.0
@@ -14889,7 +14878,7 @@ snapshots:
       picomatch: 4.0.2
       piscina: 4.8.0
       postcss: 8.5.2
-      postcss-loader: 8.1.1(postcss@8.5.2)(typescript@5.8.3)(webpack@5.98.0)
+      postcss-loader: 8.1.1(postcss@8.5.2)(typescript@5.8.3)(webpack@5.98.0(esbuild@0.25.0))
       resolve-url-loader: 5.0.0
       rxjs: 7.8.1
       sass: 1.85.0
@@ -19166,7 +19155,7 @@ snapshots:
   '@nuxt/test-utils@3.21.0(@vue/test-utils@2.4.6)(jsdom@23.0.0)(magicast@0.3.5)(typescript@5.9.3)(vitest@3.2.4(@types/debug@4.1.12)(@types/node@22.10.5)(jiti@2.6.1)(jsdom@23.0.0)(less@4.2.2)(sass@1.85.0)(terser@5.43.1)(yaml@2.8.2))':
     dependencies:
       '@nuxt/kit': 3.20.2(magicast@0.3.5)
-      c12: 3.3.2(magicast@0.3.5)
+      c12: 3.3.3(magicast@0.3.5)
       consola: 3.4.2
       defu: 6.1.4
       destr: 2.0.5
@@ -22379,7 +22368,7 @@ snapshots:
       schema-utils: 4.3.2
       webpack: 5.98.0(esbuild@0.25.0)
 
-  babel-loader@9.2.1(@babel/core@7.26.9)(webpack@5.98.0):
+  babel-loader@9.2.1(@babel/core@7.26.9)(webpack@5.98.0(esbuild@0.25.0)):
     dependencies:
       '@babel/core': 7.26.9
       find-cache-dir: 4.0.0
@@ -22596,23 +22585,6 @@ snapshots:
     optionalDependencies:
       magicast: 0.3.5
 
-  c12@3.3.2(magicast@0.3.5):
-    dependencies:
-      chokidar: 4.0.3
-      confbox: 0.2.2
-      defu: 6.1.4
-      dotenv: 17.2.3
-      exsolve: 1.0.8
-      giget: 2.0.0
-      jiti: 2.6.1
-      ohash: 2.0.11
-      pathe: 2.0.3
-      perfect-debounce: 2.0.0
-      pkg-types: 2.3.0
-      rc9: 2.1.2
-    optionalDependencies:
-      magicast: 0.3.5
-
   c12@3.3.3(magicast@0.3.5):
     dependencies:
       chokidar: 5.0.0
@@ -27869,7 +27841,7 @@ snapshots:
       ts-node: 10.9.2(@types/node@22.10.5)(typescript@5.9.3)
     optional: true
 
-  postcss-loader@8.1.1(postcss@8.5.2)(typescript@5.8.3)(webpack@5.98.0):
+  postcss-loader@8.1.1(postcss@8.5.2)(typescript@5.8.3)(webpack@5.98.0(esbuild@0.25.0)):
     dependencies:
       cosmiconfig: 9.0.0(typescript@5.8.3)
       jiti: 1.21.7