Disable HEAD method fetching if unavailable

docs/openapi-ts/configuration/input.md

@@ -164,5 +164,19 @@ npx @hey-api/openapi-ts \
 
 :::
 
+If your server doesn't support `HEAD` requests for incremental checks, you can pass an object to `input.watch` and disable them explicitly:
+
+```js
+export default {
+  input: {
+    path: 'https://api.example.com/openapi.json',
+    watch: {
+      enabled: true,
+      isHeadMethodSupported: false,
+    },
+  },
+};
+```
+
 <!--@include: ../../partials/examples.md-->
 <!--@include: ../../partials/sponsors.md-->

packages/openapi-ts/src/createClient.ts

@@ -250,9 +250,19 @@ export const createClient = async ({
 }): Promise<Context | undefined> => {
   const watches: ReadonlyArray<WatchValues> =
     _watches ||
-    Array.from({ length: config.input.length }, () => ({
-      headers: new Headers(),
-    }));
+    Array.from({ length: config.input.length }, (_, index) => {
+      const watchValues: WatchValues = {
+        headers: new Headers(),
+      };
+
+      const isHeadMethodSupported =
+        config.input[index]?.watch.isHeadMethodSupported;
+      if (isHeadMethodSupported !== undefined) {
+        watchValues.isHeadMethodSupported = isHeadMethodSupported;
+      }
+
+      return watchValues;
+    });
 
   const inputPaths = config.input.map((input) => compileInputPath(input));
 

packages/openapi-ts/src/types/input.d.ts

@@ -181,6 +181,12 @@ export type Watch = {
    * @default 1000
    */
   interval?: number;
+  /**
+   * Does the remote server support `HEAD` requests for change detection?
+   * Set this to `false` if you know the endpoint does not implement `HEAD`
+   * to avoid unnecessary requests during watch mode.
+   */
+  isHeadMethodSupported?: boolean;
   /**
    * How long will we wait before the request times out?
    *