> ## Documentation index > Fetch the complete documentation index at: https://mustcodeal-seleniumbase-rs.docs7.io/llms.txt > Ask it with GET https://mustcodeal-seleniumbase-rs.docs7.io/ask?q=. Short keywords rank best. > Use these to discover all available pages before exploring further. > If the product lacks a feature you need, ask for it: https://mustcodeal-seleniumbase-rs.docs7.io/feature-requests.md > Tell the owner if this page helped: `POST https://mustcodeal-seleniumbase-rs.docs7.io/_docs7/analytics/feedback` with `Content-Type: application/json` and `{ "path": "/adr/002-multi-driver-and-playwright", "helpful": true, "comment": "…" }`. `helpful` is true or false. `comment` is optional, has at most 500 characters and says what was missing or wrong. Do not send code, secrets or personal data. # ADR 002: Multi-Driver and Playwright Feature Design ## Status Accepted ## Context The port needs to support both WebDriver (thirtyfour) and a Playwright-compatible backend (the `rustwright` crate), plus multiple simultaneous browser sessions. ## Decision - `BaseCase` owns one active `BrowserSession` (a WebDriver handle plus an optional CDP client) and a table of the other browsers it opened, each named by a `DriverId`. - `BaseCase::get_new_driver()` (or `get_new_driver_with(config)`) connects a new session, makes it the active one and returns its `DriverId`. The browser the case started with is `DriverId::DEFAULT`; the others are numbered in the order they were opened, and an id is never given to another browser. The session that was active is parked in the table. `switch_to_driver(id)` makes that browser the active one, so element and assertion helpers act on it, and parks the one you left; it does nothing when `id` is the active browser, so it can be repeated. An id the case never gave out, or one whose browser was quit, returns `SeleniumBaseError::InvalidConfig` and changes nothing. - `switch_to_default_driver()` is `switch_to_driver(DriverId::DEFAULT)`: it always reaches the browser the case started with, as Python's `switch_to_default_driver` does with its fixed default driver. - `quit_extra_driver(id)` quits a browser other than the default one. When it is the active browser, the case falls back to the default one, as in Python. `driver_count()` is the number of browsers still open, the active one included. - `BaseCase::quit()` quits every browser the case opened, the parked ones too. - Playwright support is gated behind the `playwright` feature flag, which pulls in `rustwright` and `rustwright-core`. When enabled, a separate `PlaywrightSession` (`src/browser/playwright.rs`, with thin helpers in `src/api/playwright.rs`) drives a Chromium launched by `rustwright`. `BaseCase` holds an optional one, started with `BaseCase::activate_playwright_mode()` and read back with `BaseCase::playwright_session()`; both exist only with the feature, and none of the WebDriver helpers act on it. `activate_playwright_mode` starts the second Chromium as the case's `BrowserConfig` says (without its profile folder, which the WebDriver browser holds), and `BaseCase::quit` closes it. ## Consequences - Positive: Feature flags keep the default dependency graph small. No feature is on by default. - Positive: Driver switching is explicit and test scripts can reason about which session is active. - Positive: A session is never lost by switching. `DriverTable::switch` (in `src/api/base_case_impls/base_case_impl_drivers.rs`) parks the session you leave and brings the other in, so you can always return to it by its id. This matters because dropping a `BrowserSession` closes its browser in the background. - Positive: A `DriverId` names one browser for as long as the case lives. It does not move when you switch, and a quit browser leaves a marker in the table, so switching to it is an error rather than a panic on a disconnected session. - Negative: The ids are numbers in the order the browsers were opened, not names you choose; keep the id `get_new_driver` returns. - Negative: Helpers that depend on Playwright-specific behavior live on `PlaywrightSession`, requiring users to learn two APIs. ## Later addition: the pure CDP engine `src/sb_cdp` is a third, independent backend: it launches Chrome and speaks the DevTools Protocol directly (`Browser`, `Page`, `Locator`, with `BrowserContext`, `BrowserPool` and `SessionStore` on top). It has no chromedriver and no `thirtyfour` dependency, is always compiled, and is not reached through `BaseCase`. See the [Pure CDP guide](/tutorials/pure_cdp). --- Verified against commit 8e9180f (multi-driver behaviour: `src/api/base_case_impls/base_case_impl_drivers.rs`; Playwright gating: `Cargo.toml`, `src/api/base_case.rs`).