feat: add launch_context_async() + JS contextOptions escape hatch (#141)

Python: add async counterpart to launch_context(). Forwards all kwargs to
browser.new_context() — enables storage_state, permissions, extra_http_headers,
etc. without needing a persistent profile folder.

JS: launchContext() and launchPersistentContext() silently dropped unknown
options. New contextOptions field in LaunchContextOptions is spread into
newContext() to forward arbitrary Playwright context options (e.g.
storageState, permissions, geolocation).

CHANGELOG.md

@@ -6,6 +6,11 @@ Changes are tagged: **[wrapper]** for Python/JS wrapper, **[binary]** for Chromi
 
 ---
 
+## [Unreleased]
+
+- **[wrapper]** Python: add `launch_context_async()` — async counterpart to `launch_context()`. Returns a BrowserContext with all kwargs forwarded to `browser.new_context()`, enabling `storage_state`, `permissions`, `extra_http_headers`, etc. without a persistent profile folder. Closes #141.
+- **[wrapper]** JS: `launchContext()` and `launchPersistentContext()` silently dropped unknown options (including `storageState`). New `contextOptions` escape hatch forwards arbitrary options to Playwright's `newContext()`.
+
 ## [0.3.24] — 2026-04-10
 
 - **[wrapper]** Native SOCKS5 proxy support — pass `proxy="socks5://user:pass@host:port"` directly. Credentials handled natively by Chrome. Works across all launch functions, Python + JS.

README.md

@@ -316,6 +316,38 @@ page.goto("https://protected-site.com")
 context.close()
 ```
 
+Extra kwargs are forwarded to Playwright's `browser.new_context()` — use this for `storage_state`, `permissions`, `extra_http_headers`, etc. without needing a persistent profile folder:
+
+```python
+from cloakbrowser import launch_context
+
+# Restore a saved session (cookies, localStorage) from a JSON file
+context = launch_context(storage_state="state.json")
+page = context.new_page()
+page.goto("https://example.com")
+# Save state back for next run
+context.storage_state(path="state.json")
+context.close()
+```
+
+### `launch_context_async()`
+
+Async counterpart to `launch_context()`. Same signature and kwargs forwarding:
+
+```python
+import asyncio
+from cloakbrowser import launch_context_async
+
+async def main():
+    ctx = await launch_context_async(storage_state="state.json")
+    page = await ctx.new_page()
+    await page.goto("https://example.com")
+    await ctx.storage_state(path="state.json")
+    await ctx.close()
+
+asyncio.run(main())
+```
+
 ### `launch_persistent_context()`
 
 Same as `launch_context()`, but with a persistent user profile. Cookies, localStorage, and cache persist across sessions.

cloakbrowser/__init__.py

@@ -11,7 +11,7 @@ Usage:
     browser.close()
 """
 
-from .browser import launch, launch_async, launch_context, launch_persistent_context, launch_persistent_context_async, ProxySettings, build_args, maybe_resolve_geoip
+from .browser import launch, launch_async, launch_context, launch_context_async, launch_persistent_context, launch_persistent_context_async, ProxySettings, build_args, maybe_resolve_geoip
 from .config import CHROMIUM_VERSION, get_default_stealth_args
 from .download import binary_info, check_for_update, clear_cache, ensure_binary
 from ._version import __version__
@@ -32,6 +32,7 @@ __all__ = [
     "launch",
     "launch_async",
     "launch_context",
+    "launch_context_async",
     "launch_persistent_context",
     "launch_persistent_context_async",
     "ensure_binary",

cloakbrowser/browser.py

@@ -585,6 +585,130 @@ def launch_context(
     return context
 
 
+async def launch_context_async(
+    headless: bool = True,
+    proxy: str | ProxySettings | None = None,
+    args: list[str] | None = None,
+    stealth_args: bool = True,
+    user_agent: str | None = None,
+    viewport: dict | None = _VIEWPORT_UNSET,
+    locale: str | None = None,
+    timezone: str | None = None,
+    color_scheme: Literal["light", "dark", "no-preference"] | None = None,
+    geoip: bool = False,
+    backend: str | None = None,
+    humanize: bool = False,
+    human_preset: HumanPreset = "default",
+    human_config: HumanConfigOverrides | None = None,
+    **kwargs: Any,
+) -> Any:
+    """Async version of launch_context().
+
+    Launch stealth browser and return a BrowserContext with common options pre-set.
+    All extra kwargs are forwarded to ``browser.new_context()`` — use this for
+    ``storage_state``, ``permissions``, ``extra_http_headers``, etc. without needing
+    a persistent profile folder.
+
+    Args:
+        headless: Run in headless mode (default True).
+        proxy: Proxy URL string or Playwright proxy dict (see launch() for details).
+        args: Additional Chromium CLI arguments.
+        stealth_args: Include default stealth fingerprint args (default True).
+        user_agent: Custom user agent string.
+        viewport: Viewport size dict, e.g. {"width": 1920, "height": 1080}.
+            Pass None to disable viewport emulation (use OS window size).
+        locale: Browser locale, e.g. "en-US".
+        timezone: IANA timezone (e.g. 'America/New_York').
+        color_scheme: Color scheme preference — 'light', 'dark', or 'no-preference'.
+        geoip: Auto-detect timezone/locale from proxy IP (default False).
+        backend: Playwright backend — 'playwright' (default) or 'patchright'.
+        humanize: Enable human-like mouse, keyboard, scroll behavior (default False).
+        human_preset: Humanize preset — 'default' or 'careful' (default 'default').
+        human_config: Custom humanize config mapping to override preset values.
+        **kwargs: Passed to browser.new_context() — e.g. storage_state, permissions.
+
+    Returns:
+        Playwright BrowserContext object (async API).
+        Call ``await .close()`` when done — this also closes the underlying browser.
+
+    Example:
+        >>> import asyncio
+        >>> from cloakbrowser import launch_context_async
+        >>>
+        >>> async def main():
+        ...     # Load saved session (cookies, localStorage)
+        ...     ctx = await launch_context_async(
+        ...         headless=True,
+        ...         storage_state="state.json",
+        ...     )
+        ...     page = await ctx.new_page()
+        ...     await page.goto("https://example.com")
+        ...     # Save state back
+        ...     await ctx.storage_state(path="state.json")
+        ...     await ctx.close()
+        >>>
+        >>> asyncio.run(main())
+    """
+    timezone = _resolve_timezone(timezone, kwargs)
+
+    # Resolve geoip BEFORE launch_async() to avoid double-resolution and ensure
+    # resolved values flow to binary flags
+    timezone, locale, exit_ip = maybe_resolve_geoip(geoip, proxy, timezone, locale)
+    if exit_ip and not (args and any(a.startswith("--fingerprint-webrtc-ip") for a in args)):
+        args = list(args or [])
+        args.append(f"--fingerprint-webrtc-ip={exit_ip}")
+    # --fingerprint-timezone is process-wide (reads CommandLine in renderer),
+    # so it applies to ALL contexts, not just the default one.
+    # locale and timezone are set via binary flags only — no CDP emulation.
+    browser = await launch_async(headless=headless, proxy=proxy, args=args, stealth_args=stealth_args,
+                                 timezone=timezone, locale=locale, backend=backend)
+
+    context_kwargs: dict[str, Any] = {}
+    if user_agent:
+        context_kwargs["user_agent"] = user_agent
+    if viewport is _VIEWPORT_UNSET:
+        context_kwargs["viewport"] = DEFAULT_VIEWPORT
+    elif viewport is None:
+        context_kwargs["no_viewport"] = True
+    else:
+        context_kwargs["viewport"] = viewport
+    if color_scheme:
+        context_kwargs["color_scheme"] = color_scheme
+    context_kwargs.update(kwargs)
+
+    # Catch BaseException (not just Exception) so that asyncio.CancelledError
+    # triggers browser cleanup — otherwise the underlying Chromium process
+    # leaks when the awaiting task is cancelled.
+    try:
+        context = await browser.new_context(**context_kwargs)
+    except BaseException:
+        try:
+            await browser.close()
+        except BaseException:
+            pass
+        raise
+
+    # Patch close() to also close the browser (and its Playwright instance)
+    _original_ctx_close = context.close
+
+    async def _close_context_with_cleanup() -> None:
+        try:
+            await _original_ctx_close()
+        finally:
+            await browser.close()
+
+    context.close = _close_context_with_cleanup
+
+    # Human-like behavioral patching (async variant)
+    if humanize:
+        from .human import patch_context_async
+        from .human.config import resolve_config
+        cfg = resolve_config(human_preset, human_config)
+        patch_context_async(context, cfg)
+
+    return context
+
+
 # ---------------------------------------------------------------------------
 # Backend resolution
 # ---------------------------------------------------------------------------

js/src/playwright.ts

@@ -3,7 +3,7 @@
  * Mirrors Python cloakbrowser/browser.py.
  */
 
-import type { Browser, BrowserContext } from "playwright-core";
+import type { Browser, BrowserContext, BrowserContextOptions } from "playwright-core";
 import type { LaunchOptions, LaunchContextOptions, LaunchPersistentContextOptions } from "./types.js";
 import { DEFAULT_VIEWPORT, IGNORE_DEFAULT_ARGS } from "./config.js";
 import { buildArgs } from "./args.js";
@@ -21,6 +21,29 @@ export function resolveTimezone<T extends { timezone?: string; timezoneId?: stri
   return options;
 }
 
+/**
+ * Strip `locale` and `timezoneId` from user-provided contextOptions — both route
+ * through detectable CDP emulation. The wrapper's top-level `locale`/`timezone`
+ * fields use binary flags instead (undetectable). Warn so users notice.
+ */
+function filterStealthCtxOptions(ctx?: BrowserContextOptions): Partial<BrowserContextOptions> {
+  if (!ctx) return {};
+  const { locale, timezoneId, ...rest } = ctx;
+  if (locale !== undefined) {
+    console.warn(
+      "[cloakbrowser] contextOptions.locale ignored — use top-level `locale` " +
+      "instead (routes through binary flag, avoids detectable CDP emulation)."
+    );
+  }
+  if (timezoneId !== undefined) {
+    console.warn(
+      "[cloakbrowser] contextOptions.timezoneId ignored — use top-level `timezone` " +
+      "instead (routes through binary flag, avoids detectable CDP emulation)."
+    );
+  }
+  return rest;
+}
+
 /**
  * Launch stealth Chromium browser via Playwright.
  *
@@ -104,6 +127,9 @@ export async function launchContext(
   let context: BrowserContext;
   try {
     context = await browser.newContext({
+      // contextOptions first — explicit wrapper fields below override it.
+      // filterStealthCtxOptions strips locale/timezoneId to prevent CDP detection.
+      ...filterStealthCtxOptions(options.contextOptions),
       ...(options.userAgent ? { userAgent: options.userAgent } : {}),
       viewport: options.viewport === undefined ? DEFAULT_VIEWPORT : options.viewport,
       ...(options.colorScheme ? { colorScheme: options.colorScheme } : {}),
@@ -178,6 +204,9 @@ export async function launchPersistentContext(
     args,
     ignoreDefaultArgs: IGNORE_DEFAULT_ARGS,
     ...(proxyOption ? { proxy: proxyOption } : {}),
+    // contextOptions before explicit wrapper fields so explicit wins.
+    // filterStealthCtxOptions strips locale/timezoneId to prevent CDP detection.
+    ...filterStealthCtxOptions(options.contextOptions),
     ...(options.userAgent ? { userAgent: options.userAgent } : {}),
     viewport: options.viewport === undefined ? DEFAULT_VIEWPORT : options.viewport,
     ...(options.colorScheme ? { colorScheme: options.colorScheme } : {}),

js/src/types.ts

@@ -2,6 +2,7 @@
  * Shared types for cloakbrowser launch wrappers.
  */
 
+import type { BrowserContextOptions } from "playwright-core";
 import type { HumanConfig, HumanPreset } from "./human/config.js";
 
 export interface LaunchOptions {
@@ -45,6 +46,15 @@ export interface LaunchContextOptions extends LaunchOptions {
   timezoneId?: string;
   /** Color scheme preference — 'light', 'dark', or 'no-preference'. */
   colorScheme?: "light" | "dark" | "no-preference";
+  /**
+   * Extra options forwarded directly to Playwright's `browser.newContext()` —
+   * e.g. `storageState`, `permissions`, `geolocation`, `extraHTTPHeaders`,
+   * `httpCredentials`. Use this for context-level options not surfaced as
+   * top-level fields. `locale` and `timezoneId` are stripped here to avoid
+   * detectable CDP emulation — use the top-level `locale` and `timezone`
+   * wrapper fields instead (they route through undetectable binary flags).
+   */
+  contextOptions?: BrowserContextOptions;
 }
 
 export interface LaunchPersistentContextOptions extends LaunchContextOptions {

js/tests/launch.test.ts

@@ -130,6 +130,60 @@ describe("launchContext (unit)", () => {
     // Browser also closed
     expect(mockBrowser.close).toHaveBeenCalledOnce();
   });
+
+  it("forwards contextOptions to newContext (storageState, etc.)", async () => {
+    const { launchContext } = await import("../src/playwright.js");
+    await launchContext({
+      contextOptions: {
+        storageState: "state.json",
+        permissions: ["geolocation"],
+      },
+    });
+
+    const ctxArgs = mockBrowser.newContext.mock.calls[0][0];
+    expect(ctxArgs.storageState).toBe("state.json");
+    expect(ctxArgs.permissions).toEqual(["geolocation"]);
+  });
+
+  it("explicit top-level fields win over contextOptions on collision", async () => {
+    const { launchContext } = await import("../src/playwright.js");
+    await launchContext({
+      userAgent: "Explicit/1.0",
+      viewport: { width: 1280, height: 720 },
+      colorScheme: "dark",
+      contextOptions: {
+        userAgent: "ShouldBeOverridden/9.9",
+        viewport: { width: 9999, height: 9999 },
+        colorScheme: "light",
+      },
+    });
+
+    const ctxArgs = mockBrowser.newContext.mock.calls[0][0];
+    expect(ctxArgs.userAgent).toBe("Explicit/1.0");
+    expect(ctxArgs.viewport).toEqual({ width: 1280, height: 720 });
+    expect(ctxArgs.colorScheme).toBe("dark");
+  });
+
+  it("strips locale and timezoneId from contextOptions (stealth-sensitive)", async () => {
+    const warnSpy = vi.spyOn(console, "warn").mockImplementation(() => {});
+    const { launchContext } = await import("../src/playwright.js");
+    await launchContext({
+      contextOptions: {
+        storageState: "state.json",
+        locale: "de-DE",
+        timezoneId: "Europe/Berlin",
+      },
+    });
+
+    const ctxArgs = mockBrowser.newContext.mock.calls[0][0];
+    // Stealth-sensitive keys stripped — they would reintroduce detectable CDP emulation.
+    expect(ctxArgs.locale).toBeUndefined();
+    expect(ctxArgs.timezoneId).toBeUndefined();
+    // Benign keys preserved
+    expect(ctxArgs.storageState).toBe("state.json");
+    // Warning was logged for both stripped keys
+    expect(warnSpy).toHaveBeenCalledTimes(2);
+  });
 });
 
 describe("launchPersistentContext (unit)", () => {
@@ -207,4 +261,53 @@ describe("launchPersistentContext (unit)", () => {
     expect(args.userAgent).toBe("Custom/1.0");
     expect(args.colorScheme).toBe("dark");
   });
+
+  it("forwards contextOptions to launchPersistentContext", async () => {
+    const { launchPersistentContext } = await import("../src/playwright.js");
+    await launchPersistentContext({
+      userDataDir: "/tmp/profile",
+      contextOptions: {
+        permissions: ["geolocation"],
+        extraHTTPHeaders: { "X-Custom": "1" },
+      },
+    });
+
+    const args = mockChromium.launchPersistentContext.mock.calls[0][1];
+    expect(args.permissions).toEqual(["geolocation"]);
+    expect(args.extraHTTPHeaders).toEqual({ "X-Custom": "1" });
+  });
+
+  it("explicit top-level fields win over contextOptions in persistent context", async () => {
+    const { launchPersistentContext } = await import("../src/playwright.js");
+    await launchPersistentContext({
+      userDataDir: "/tmp/profile",
+      userAgent: "Explicit/1.0",
+      viewport: { width: 1280, height: 720 },
+      contextOptions: {
+        userAgent: "ShouldBeOverridden/9.9",
+        viewport: { width: 9999, height: 9999 },
+      },
+    });
+
+    const args = mockChromium.launchPersistentContext.mock.calls[0][1];
+    expect(args.userAgent).toBe("Explicit/1.0");
+    expect(args.viewport).toEqual({ width: 1280, height: 720 });
+  });
+
+  it("strips locale and timezoneId from contextOptions (persistent context)", async () => {
+    const warnSpy = vi.spyOn(console, "warn").mockImplementation(() => {});
+    const { launchPersistentContext } = await import("../src/playwright.js");
+    await launchPersistentContext({
+      userDataDir: "/tmp/profile",
+      contextOptions: {
+        locale: "de-DE",
+        timezoneId: "Europe/Berlin",
+      },
+    });
+
+    const args = mockChromium.launchPersistentContext.mock.calls[0][1];
+    expect(args.locale).toBeUndefined();
+    expect(args.timezoneId).toBeUndefined();
+    expect(warnSpy).toHaveBeenCalledTimes(2);
+  });
 });

tests/test_launch_context.py

@@ -1,6 +1,6 @@
 """Unit tests for launch_context() — context kwargs, viewport defaults, close cleanup."""
 
-from unittest.mock import MagicMock, call, patch
+from unittest.mock import AsyncMock, MagicMock, call, patch
 
 import pytest
 
@@ -207,3 +207,125 @@ def test_kwargs_passthrough(mock_launch, _mock_bin):
     # Verify kwarg did NOT leak to launch()
     launch_kwargs = mock_launch.call_args[1]
     assert "record_video_dir" not in launch_kwargs
+
+
+# ---------------------------------------------------------------------------
+# Async: launch_context_async()
+# ---------------------------------------------------------------------------
+
+
+def _make_mock_async_browser():
+    """Create a mock async browser whose new_context() returns a mock context."""
+    browser = AsyncMock()
+    context = AsyncMock()
+    browser.new_context.return_value = context
+    return browser, context
+
+
+@pytest.mark.asyncio
+@patch("cloakbrowser.browser.ensure_binary", return_value="/fake/chrome")
+@patch("cloakbrowser.browser.launch_async")
+async def test_async_storage_state_forwarded(mock_launch_async, _mock_bin):
+    """storage_state kwarg forwarded to browser.new_context() in async path.
+
+    This is the motivating use case from issue #141.
+    """
+    browser, context = _make_mock_async_browser()
+    mock_launch_async.return_value = browser
+
+    from cloakbrowser.browser import launch_context_async
+    await launch_context_async(storage_state="state.json")
+
+    ctx_kwargs = browser.new_context.call_args
+    assert ctx_kwargs[1]["storage_state"] == "state.json"
+
+
+@pytest.mark.asyncio
+@patch("cloakbrowser.browser.ensure_binary", return_value="/fake/chrome")
+@patch("cloakbrowser.browser.launch_async")
+async def test_async_default_viewport(mock_launch_async, _mock_bin):
+    """DEFAULT_VIEWPORT applied when no viewport given (async)."""
+    browser, context = _make_mock_async_browser()
+    mock_launch_async.return_value = browser
+
+    from cloakbrowser.browser import launch_context_async
+    await launch_context_async()
+
+    ctx_kwargs = browser.new_context.call_args
+    assert ctx_kwargs[1]["viewport"] == DEFAULT_VIEWPORT
+
+
+@pytest.mark.asyncio
+@patch("cloakbrowser.browser.ensure_binary", return_value="/fake/chrome")
+@patch("cloakbrowser.browser.launch_async")
+async def test_async_locale_flows_to_binary_not_cdp(mock_launch_async, _mock_bin):
+    """locale flows to launch_async() for --lang flag, NOT to new_context() CDP."""
+    browser, context = _make_mock_async_browser()
+    mock_launch_async.return_value = browser
+
+    from cloakbrowser.browser import launch_context_async
+    await launch_context_async(locale="de-DE", timezone="Europe/Berlin")
+
+    # Binary flags
+    assert mock_launch_async.call_args[1]["locale"] == "de-DE"
+    assert mock_launch_async.call_args[1]["timezone"] == "Europe/Berlin"
+    # Not in context — would trigger detectable CDP emulation
+    ctx_kwargs = browser.new_context.call_args
+    assert "locale" not in ctx_kwargs[1]
+    assert "timezone_id" not in ctx_kwargs[1]
+
+
+@pytest.mark.asyncio
+@patch("cloakbrowser.browser.ensure_binary", return_value="/fake/chrome")
+@patch("cloakbrowser.browser.launch_async")
+async def test_async_close_closes_browser(mock_launch_async, _mock_bin):
+    """await ctx.close() also closes the underlying browser."""
+    browser, context = _make_mock_async_browser()
+    original_ctx_close = context.close
+    mock_launch_async.return_value = browser
+
+    from cloakbrowser.browser import launch_context_async
+    ctx = await launch_context_async()
+
+    await ctx.close()
+    original_ctx_close.assert_called_once()
+    browser.close.assert_called_once()
+
+
+@pytest.mark.asyncio
+@patch("cloakbrowser.browser.ensure_binary", return_value="/fake/chrome")
+@patch("cloakbrowser.browser.launch_async")
+async def test_async_error_closes_browser(mock_launch_async, _mock_bin):
+    """If new_context() raises in async path, browser is still closed."""
+    browser = AsyncMock()
+    browser.new_context.side_effect = RuntimeError("context creation failed")
+    mock_launch_async.return_value = browser
+
+    from cloakbrowser.browser import launch_context_async
+    with pytest.raises(RuntimeError, match="context creation failed"):
+        await launch_context_async()
+
+    browser.close.assert_called_once()
+
+
+@pytest.mark.asyncio
+@patch("cloakbrowser.browser.ensure_binary", return_value="/fake/chrome")
+@patch("cloakbrowser.browser.launch_async")
+async def test_async_cancellation_closes_browser(mock_launch_async, _mock_bin):
+    """asyncio.CancelledError during new_context() still closes browser.
+
+    CancelledError derives from BaseException (not Exception) in Python 3.8+,
+    so the cleanup must catch BaseException to prevent browser process leaks
+    when the awaiting task is cancelled.
+    """
+    import asyncio
+
+    browser = AsyncMock()
+    browser.new_context.side_effect = asyncio.CancelledError()
+    mock_launch_async.return_value = browser
+
+    from cloakbrowser.browser import launch_context_async
+    with pytest.raises(asyncio.CancelledError):
+        await launch_context_async()
+
+    browser.close.assert_called_once()