feat(client): add support for defaultQuery option

src/core.ts

@@ -73,6 +73,8 @@ export abstract class APIClient {
     };
   }
 
+  protected abstract defaultQuery(): DefaultQuery | undefined;
+
   /**
    * Override this to add your own headers validation:
    */
@@ -260,6 +262,11 @@ export abstract class APIClient {
         new URL(path)
       : new URL(this.baseURL + (this.baseURL.endsWith('/') && path.startsWith('/') ? path.slice(1) : path));
 
+    const defaultQuery = this.defaultQuery();
+    if (!isEmptyObj(defaultQuery)) {
+      query = { ...defaultQuery, ...query } as Req;
+    }
+
     if (query) {
       url.search = qs.stringify(query, this.qsOptions());
     }
@@ -516,6 +523,7 @@ type HTTPMethod = 'get' | 'post' | 'put' | 'patch' | 'delete';
 
 export type RequestClient = { fetch: Fetch };
 export type Headers = Record<string, string | null | undefined>;
+export type DefaultQuery = Record<string, string | undefined>;
 export type KeysEnum<T> = { [P in keyof Required<T>]: true };
 
 export type RequestOptions<Req extends {} = Record<string, unknown> | Readable> = {

src/index.ts

@@ -17,6 +17,7 @@ type Config = {
   httpAgent?: Agent;
   maxRetries?: number;
   defaultHeaders?: Core.Headers;
+  defaultQuery?: Core.DefaultQuery;
   authToken?: string | null;
 };
 
@@ -48,6 +49,10 @@ export class Anthropic extends Core.APIClient {
 
   completions: API.Completions = new API.Completions(this);
 
+  protected override defaultQuery(): Core.DefaultQuery | undefined {
+    return this._options.defaultQuery;
+  }
+
   protected override defaultHeaders(): Core.Headers {
     return {
       ...super.defaultHeaders(),

tests/index.test.ts

@@ -24,6 +24,35 @@ describe('instantiate client', () => {
     expect((req.headers as Headers)['X-My-Default-Header']).toEqual('2');
   });
 
+  describe('defaultQuery', () => {
+    test('with null query params given', () => {
+      const client = new Anthropic({
+        baseURL: 'http://localhost:5000/',
+        defaultQuery: { apiVersion: 'foo' },
+        apiKey: 'my api key',
+      });
+      expect(client.buildURL('/foo', null)).toEqual('http://localhost:5000/foo?apiVersion=foo');
+    });
+
+    test('multiple default query params', () => {
+      const client = new Anthropic({
+        baseURL: 'http://localhost:5000/',
+        defaultQuery: { apiVersion: 'foo', hello: 'world' },
+        apiKey: 'my api key',
+      });
+      expect(client.buildURL('/foo', null)).toEqual('http://localhost:5000/foo?apiVersion=foo&hello=world');
+    });
+
+    test('overriding with `undefined`', () => {
+      const client = new Anthropic({
+        baseURL: 'http://localhost:5000/',
+        defaultQuery: { hello: 'world' },
+        apiKey: 'my api key',
+      });
+      expect(client.buildURL('/foo', { hello: undefined })).toEqual('http://localhost:5000/foo');
+    });
+  });
+
   describe('baseUrl', () => {
     test('trailing slash', () => {
       const client = new Anthropic({ baseURL: 'http://localhost:5000/custom/path/', apiKey: 'my api key' });