slicc-cdp-client

Shared Chrome DevTools Protocol connection for the playwright-cli and curlwright binaries.

The crates.io name is slicc-cdp-client. The Rust library name stays cdp_client:

cdp-client = { package = "slicc-cdp-client", version = "1" }

One browser WebSocket. Target.attachToTarget uses {targetId, flatten: true}. Later page commands send that sessionId at the top level. There is no /devtools/page/<id> socket.

Fetch interception

cdp_client::fetch pauses requests on one target session. Interception::attach(&mut cdp, target_id, &patterns) checks the target, attaches, and sends Fetch.enable; dropping it, or finish(), sends Fetch.disable and detaches. Interception::on_session does the same on a session you already hold and leaves it attached. cdp::detach also forgets that session's paused requests.

• Pattern::request(glob) and Pattern::response(glob) are CDP urlPatterns (*, ?, \ to escape) at the Request or Response stage, with an optional resource_type.
• next(timeout) returns a Paused: method, url, url_fragment, full_url(), headers, post_data, and at the response stage status, response_headers and location(), which resolves Location against the request URL and keeps its fragment.
• decide(&paused, &Decision) sends Continue(Overrides) (continueRequest with URL, method, body or headers), ContinueResponse(ResponseOverrides), Fulfill(Fulfill) (fulfillRequest: status, headers, body; Fulfill::signed_in() is a short "Signed in, you can close this tab" page) or Fail(ErrorReason) (failRequest). response_body(&paused) is Fetch.getResponseBody, decoded.
• navigation(guard, event) reads a Page.frameNavigated event as url plus urlFragment, for a redirect made by script.
• Cdp::set_decider(session, Some(Box<dyn FnMut(&Paused) -> Decision>)) answers pauses inline, even while another call waits for its reply, so a synchronous Page.navigate doesn't deadlock. A decision CDP rejects is retried as a plain continue and kept in take_fetch_errors().

Seven and the vault are never intercepted. protected::Protected implements protectedOrigins from the slicc-browsers crate with a WHATWG URL parser and passes every vector in its protected.json. A paused request whose URL, or whose Location, is protected is continued unchanged at once and never reaches next or a decider. enable refuses a pattern that names a protected host, and any call without a session (browser-wide Fetch.enable). Interception::attach refuses a target on a protected origin, or a blank popup whose opener is protected or gone. A decision can't redirect to a protected URL, by url, Location or Refresh. Cdp::protect_origins(&[...]) adds extra origins.

use cdp_client::fetch::{Decision, Fulfill, Interception, Pattern};
let mut seen = Interception::attach(&mut cdp, &target_id, &[Pattern::response("https://idp.example/authorize*")])?;
let session = seen.session_id().to_string();
seen.notify("Page.navigate", serde_json::json!({ "url": authorize_url }), Some(&session));
if let Some(paused) = seen.next(std::time::Duration::from_secs(120))? {
    let redirect = paused.location();
    seen.decide(&paused, &Decision::Fulfill(Fulfill::signed_in()))?;
}

Host builds use native-tls for wss:// and for https:// discovery, on macOS, Linux, and Windows. Rust 1.83 or newer. The wasm32-wasip1 build has no TLS. This crate does not launch Chrome. Callers pass a DevTools WebSocket URL or an http:// discovery URL.

cargo install slicc-cdp installs the playwright-cli command. cargo install curlwright installs curlwright. @ai-ecoverse/slicc-cdp on npm ships their WASI builds for SLICC.