feat: add browser routing cache

examples/browser-routing.ts

@@ -0,0 +1,13 @@
+import Kernel from '@onkernel/sdk';
+
+async function main() {
+  const kernel = new Kernel();
+
+  const browser = await kernel.browsers.create({});
+  const response = await kernel.browsers.fetch(browser.session_id, 'https://example.com', { method: 'GET' });
+  console.log('status', response.status);
+
+  await kernel.browsers.deleteByID(browser.session_id);
+}
+
+void main();

src/client.ts

@@ -20,6 +20,11 @@ import * as Uploads from './core/uploads';
 import * as API from './resources/index';
 import { APIPromise } from './core/api-promise';
 import { AppListParams, AppListResponse, AppListResponsesOffsetPagination, Apps } from './resources/apps';
+import {
+  BrowserRouteCache,
+  browserRoutingSubresourcesFromEnv,
+  createRoutingFetch,
+} from './lib/browser-routing';
 import {
   BrowserPool,
   BrowserPoolAcquireParams,
@@ -247,9 +252,11 @@ export class Kernel {
   fetchOptions: MergedRequestInit | undefined;
 
   private fetch: Fetch;
+  private rawFetch: Fetch;
   #encoder: Opts.RequestEncoder;
   protected idempotencyHeader?: string;
   private _options: ClientOptions;
+  public browserRouteCache: BrowserRouteCache;
 
   /**
    * API Client for interfacing with the Kernel API.
@@ -312,7 +319,13 @@ export class Kernel {
       defaultLogLevel;
     this.fetchOptions = options.fetchOptions;
     this.maxRetries = options.maxRetries ?? 2;
-    this.fetch = options.fetch ?? Shims.getDefaultFetch();
+    this.rawFetch = options.fetch ?? Shims.getDefaultFetch();
+    this.browserRouteCache = new BrowserRouteCache();
+    this.fetch = createRoutingFetch(this.rawFetch, {
+      apiBaseURL: this.baseURL,
+      subresources: browserRoutingSubresourcesFromEnv(),
+      cache: this.browserRouteCache,
+    });
     this.#encoder = Opts.FallbackEncoder;
 
     this._options = options;
@@ -332,11 +345,17 @@ export class Kernel {
       timeout: this.timeout,
       logger: this.logger,
       logLevel: this.logLevel,
-      fetch: this.fetch,
+      fetch: this.rawFetch,
       fetchOptions: this.fetchOptions,
       apiKey: this.apiKey,
       ...options,
     });
+    client.browserRouteCache = this.browserRouteCache;
+    client.fetch = createRoutingFetch(client.rawFetch, {
+      apiBaseURL: client.baseURL,
+      subresources: browserRoutingSubresourcesFromEnv(),
+      cache: client.browserRouteCache,
+    });
     return client;
   }
 

src/index.ts

@@ -5,6 +5,8 @@ export { Kernel as default } from './client';
 export { type Uploadable, toFile } from './core/uploads';
 export { APIPromise } from './core/api-promise';
 export { Kernel, type ClientOptions } from './client';
+export { type BrowserFetchInit } from './lib/browser-fetch';
+export { BrowserRouteCache, type BrowserRoute } from './lib/browser-routing';
 export { PagePromise } from './core/pagination';
 export {
   KernelError,

src/lib/browser-fetch.ts

@@ -0,0 +1,180 @@
+import type { RequestInfo, RequestInit } from '../internal/builtin-types';
+import { KernelError } from '../core/error';
+import { buildHeaders } from '../internal/headers';
+import type { FinalRequestOptions, RequestOptions } from '../internal/request-options';
+import type { HTTPMethod } from '../internal/types';
+import { joinURL } from './join-url';
+import type { Kernel } from '../client';
+
+export interface BrowserFetchInit extends RequestInit {
+  timeout_ms?: number;
+}
+
+export async function browserFetch(
+  client: Kernel,
+  sessionId: string,
+  input: RequestInfo | URL,
+  init?: BrowserFetchInit,
+): Promise<Response> {
+  const route = client.browserRouteCache.get(sessionId);
+  if (!route) {
+    throw new KernelError(
+      `browser route cache does not contain session ${sessionId}; create, retrieve, or list the browser before calling browser.fetch`,
+    );
+  }
+
+  const { url: targetURL, method, headers, body, signal, duplex, timeout_ms } = splitFetchArgs(input, init);
+  assertHTTPURL(targetURL);
+
+  const query: Record<string, unknown> = { url: targetURL, jwt: route.jwt };
+  if (timeout_ms !== undefined) {
+    query['timeout_ms'] = timeout_ms;
+  }
+
+  const accept = headers.get('accept');
+  const requestOptions: FinalRequestOptions = {
+    method: normalizeMethod(method),
+    path: joinURL(route.baseURL, '/curl/raw'),
+    query,
+    body: body as RequestOptions['body'],
+    headers: buildHeaders([
+      { Authorization: null },
+      accept ? { Accept: accept } : { Accept: '*/*' },
+      headersToRequestOptionsHeaders(headers),
+    ]),
+    signal: signal ?? null,
+    __binaryResponse: true,
+  };
+  if (duplex) {
+    requestOptions.fetchOptions = { duplex } as NonNullable<RequestOptions['fetchOptions']>;
+  }
+
+  return client.request(requestOptions).asResponse();
+}
+
+function normalizeMethod(method: string): HTTPMethod {
+  const methodLower = method.toLowerCase();
+  const allowed = new Set(['get', 'post', 'put', 'patch', 'delete']);
+  if (!allowed.has(methodLower)) {
+    throw new KernelError(`browser.fetch unsupported HTTP method: ${method}`);
+  }
+  return methodLower as HTTPMethod;
+}
+
+function splitFetchArgs(
+  input: RequestInfo | URL,
+  init?: BrowserFetchInit,
+): {
+  url: string;
+  method: string;
+  headers: Headers;
+  body?: RequestInit['body'];
+  signal?: AbortSignal | null;
+  duplex?: RequestInit['duplex'];
+  timeout_ms?: number;
+} {
+  const timeoutFromInit = init && 'timeout_ms' in init ? init['timeout_ms'] : undefined;
+
+  if (input instanceof Request) {
+    const headers = new Headers(input.headers);
+    if (init?.headers) {
+      const extra = new Headers(init.headers);
+      extra.forEach((value, key) => {
+        headers.set(key, value);
+      });
+    }
+
+    const out: {
+      url: string;
+      method: string;
+      headers: Headers;
+      body?: RequestInit['body'];
+      signal?: AbortSignal | null;
+      duplex?: RequestInit['duplex'];
+      timeout_ms?: number;
+    } = {
+      url: input.url,
+      method: (init?.method ?? input.method)?.toUpperCase() || 'GET',
+      headers,
+    };
+    const body = init?.body ?? input.body;
+    if (body !== undefined && body !== null) {
+      out.body = body;
+    }
+    const signal = init?.signal ?? input.signal;
+    if (signal !== undefined) {
+      out.signal = signal;
+    }
+    if (init?.duplex !== undefined) {
+      out.duplex = init.duplex;
+    }
+    if (timeoutFromInit !== undefined) {
+      out.timeout_ms = timeoutFromInit;
+    }
+    return out;
+  }
+
+  const out: {
+    url: string;
+    method: string;
+    headers: Headers;
+    body?: RequestInit['body'];
+    signal?: AbortSignal | null;
+    duplex?: RequestInit['duplex'];
+    timeout_ms?: number;
+  } = {
+    url: input instanceof URL ? input.href : String(input),
+    method: (init?.method ?? 'GET').toUpperCase(),
+    headers: new Headers(init?.headers),
+  };
+  if (init?.body !== undefined) {
+    out.body = init.body;
+  }
+  if (init?.signal !== undefined) {
+    out.signal = init.signal;
+  }
+  if (init?.duplex !== undefined) {
+    out.duplex = init.duplex;
+  }
+  if (timeoutFromInit !== undefined) {
+    out.timeout_ms = timeoutFromInit;
+  }
+  return out;
+}
+
+function assertHTTPURL(url: string): void {
+  let parsed: URL;
+  try {
+    parsed = new URL(url);
+  } catch {
+    throw new KernelError(`browser.fetch target must be an absolute URL; received: ${url}`);
+  }
+
+  if (parsed.protocol !== 'http:' && parsed.protocol !== 'https:') {
+    throw new KernelError(`browser.fetch only supports http(s) URLs; received: ${parsed.protocol}`);
+  }
+}
+
+function headersToRequestOptionsHeaders(headers: Headers): Record<string, string | null | undefined> {
+  const out: Record<string, string | null | undefined> = {};
+
+  headers.forEach((value, key) => {
+    switch (key.toLowerCase()) {
+      case 'accept':
+      case 'content-length':
+      case 'connection':
+      case 'keep-alive':
+      case 'proxy-authenticate':
+      case 'proxy-authorization':
+      case 'te':
+      case 'trailers':
+      case 'transfer-encoding':
+      case 'upgrade':
+        return;
+      default:
+        out[key] = value;
+    }
+  });
+
+  return out;
+}