1 files changed, 277 insertions, 0 deletions
diff --git a/src/cdp/daemon-transport.ts b/src/cdp/daemon-transport.ts
new file mode 100644
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+++ b/src/cdp/daemon-transport.ts
@@ -0,0 +1,277 @@
+/**
+ * DaemonTransport — CdpTransport backed by a Unix socket to the browser daemon.
+ *
+ * Satisfies the exact CdpTransport interface so BrowserClient, CdpSession, and
+ * all domain tools work without changes. Internally uses newline-delimited JSON
+ * over a Unix domain socket instead of a WebSocket to Chrome.
+ *
+ * References:
+ *   - CdpTransport interface: src/cdp/transport.ts
+ *   - net.createConnection IPC: https://nodejs.org/docs/latest-v22.x/api/net.html#netcreateconnection
+ *   - readline.createInterface: https://nodejs.org/docs/latest-v22.x/api/readline.html#readlinecreateinterfaceoptions
+ */
+
+import { createConnection, type Socket } from "node:net";
+import { createInterface } from "node:readline";
+import { type Result, err, ok } from "../util/result";
+import { type CdpError, cdpError } from "../cdp/errors";
+import type { CdpTransport } from "../cdp/transport";
+import type { CdpEvent } from "../cdp/types";
+import {
+  DAEMON_SOCKET_PATH,
+  type WireRequest,
+  type WireControl,
+  deserialize,
+  serialize,
+} from "../daemon/protocol";
+
+// ── Types ──────────────────────────────────────────────────────────────────────
+
+type EventQueue = {
+  readonly push: (e: CdpEvent) => void;
+  readonly end: () => void;
+  readonly iter: AsyncIterable<CdpEvent>;
+};
+
+// ── Helpers ────────────────────────────────────────────────────────────────────
+
+const makeEventQueue = (): EventQueue => {
+  const buf: CdpEvent[] = [];
+  const waiters: Array<(v: IteratorResult<CdpEvent>) => void> = [];
+  let ended = false;
+  return {
+    push(e) {
+      if (ended) return;
+      const w = waiters.shift();
+      if (w) w({ value: e, done: false });
+      else buf.push(e);
+    },
+    end() {
+      ended = true;
+      for (const w of waiters.splice(0)) w({ value: undefined as unknown as CdpEvent, done: true });
+    },
+    iter: {
+      [Symbol.asyncIterator]() {
+        return {
+          next: (): Promise<IteratorResult<CdpEvent>> =>
+            new Promise((resolve) => {
+              const next = buf.shift();
+              if (next) resolve({ value: next, done: false });
+              else if (ended) resolve({ value: undefined as unknown as CdpEvent, done: true });
+              else waiters.push(resolve);
+            }),
+        };
+      },
+    },
+  };
+};
+
+// ── Implementation ─────────────────────────────────────────────────────────────
+
+export const createDaemonTransport = (clientId: string): CdpTransport => {
+  let socket: Socket | null = null;
+  let rl: ReturnType<typeof createInterface> | null = null;
+  let queue = makeEventQueue();
+  const closeListeners = new Set<() => void>();
+  const pending = new Map<number, {
+    resolve: (v: Result<unknown, CdpError>) => void;
+    timer: ReturnType<typeof setTimeout>;
+    method: string;
+  }>();
+  let registered = false;
+  let nextRequestId = 1;
+
+  const cleanup = (reason: string): void => {
+    for (const [, p] of pending) {
+      clearTimeout(p.timer);
+      p.resolve(err(cdpError("transport_closed", reason, p.method)));
+    }
+    pending.clear();
+    queue.end();
+    queue = makeEventQueue();
+    registered = false;
+
+    if (rl) { rl.close(); rl = null; }
+    if (socket) { try { socket.destroy(); } catch {} socket = null; }
+
+    for (const cb of closeListeners) cb();
+  };
+
+  // ── Connect ────────────────────────────────────────────────────────────
+
+  const connect = (_url: string, opts?: { timeoutMs?: number }): Promise<Result<void, CdpError>> => {
+    // url is ignored — we always connect to the daemon socket
+    const timeoutMs = opts?.timeoutMs ?? 10_000;
+
+    if (socket && !socket.destroyed && registered) {
+      return Promise.resolve(ok(undefined));
+    }
+
+    return new Promise((resolve) => {
+      let settled = false;
+      const settle = (r: Result<void, CdpError>): void => {
+        if (settled) return;
+        settled = true;
+        resolve(r);
+      };
+
+      try {
+        socket = createConnection(DAEMON_SOCKET_PATH);
+      } catch (e) {
+        settle(err(cdpError("transport_closed", e instanceof Error ? e.message : String(e))));
+        return;
+      }
+
+      const connectTimer = setTimeout(() => {
+        cleanup("Connection timeout");
+        settle(err(cdpError("timeout", `Daemon connection timed out after ${timeoutMs}ms`)));
+      }, timeoutMs);
+
+      socket.on("connect", () => {
+        clearTimeout(connectTimer);
+        rl = createInterface({ input: socket!, crlfDelay: Infinity });
+
+        rl.on("line", (line: string) => {
+          const msg = deserialize(line);
+          if (!msg) return;
+
+          if (msg.type === "control" && msg.action === "registered" && msg.clientId === clientId) {
+            registered = true;
+            settle(ok(undefined));
+            return;
+          }
+
+          if (msg.type === "control" && msg.action === "shutdown") {
+            cleanup(`Daemon shutting down: ${msg.reason ?? "unknown"}`);
+            return;
+          }
+
+          if (!registered) return;
+
+          if (msg.type === "response") {
+            const p = pending.get(msg.id);
+            if (!p) return;
+            pending.delete(msg.id);
+            clearTimeout(p.timer);
+
+            if (msg.error) {
+              p.resolve(err(cdpError(
+                msg.error.message.includes("Session with given id not found")
+                  ? "session_not_found"
+                  : "remote_error",
+                msg.error.message,
+                p.method,
+              )));
+            } else {
+              p.resolve(ok(msg.result));
+            }
+            return;
+          }
+
+          if (msg.type === "event") {
+            queue.push({
+              method: msg.method,
+              params: msg.params,
+              ...(msg.sessionId !== undefined ? { sessionId: msg.sessionId } : {}),
+            });
+            return;
+          }
+        });
+
+        socket!.on("error", () => {
+          // Errors are surfaced via 'close'
+        });
+
+        socket!.on("close", () => {
+          clearTimeout(connectTimer);
+          cleanup("Daemon socket closed");
+          // If connect hasn't settled yet, settle with error
+          settle(err(cdpError("transport_closed", "Daemon socket closed before registration")));
+        });
+
+        // Send registration
+        const regMsg: WireControl = { type: "control", action: "register", clientId };
+        socket!.write(serialize(regMsg) + "\n");
+      });
+
+      socket.on("error", (e: NodeJS.ErrnoException) => {
+        clearTimeout(connectTimer);
+        const msg = e.code === "ENOENT"
+          ? "Daemon not running — socket not found"
+          : e.message;
+        settle(err(cdpError("transport_closed", msg)));
+      });
+    });
+  };
+
+  // ── Close ──────────────────────────────────────────────────────────────
+
+  const close = async (): Promise<void> => {
+    if (registered && socket && !socket.destroyed) {
+      const dereg: WireControl = { type: "control", action: "deregister", clientId };
+      try { socket.write(serialize(dereg) + "\n"); } catch {}
+    }
+    cleanup("close() called");
+  };
+
+  // ── Request ────────────────────────────────────────────────────────────
+
+  const request = (
+    method: string,
+    params: Record<string, unknown>,
+    opts?: { sessionId?: string | null; timeoutMs?: number },
+  ): Promise<Result<unknown, CdpError>> => {
+    const timeoutMs = opts?.timeoutMs ?? 15_000;
+    const sessionId = opts?.sessionId ?? null;
+
+    if (!socket || socket.destroyed || !registered) {
+      return Promise.resolve(err(cdpError("transport_closed", "Daemon not connected", method)));
+    }
+
+    const id = nextRequestId++;
+    const req: WireRequest = {
+      type: "request",
+      id,
+      method,
+      params,
+      ...(sessionId !== null && sessionId !== undefined ? { sessionId } : {}),
+    };
+
+    return new Promise((resolve) => {
+      const timer = setTimeout(() => {
+        pending.delete(id);
+        resolve(err(cdpError("timeout", `Daemon timeout after ${timeoutMs}ms: ${method}`, method)));
+      }, timeoutMs);
+
+      pending.set(id, { resolve, timer, method });
+
+      try {
+        socket!.write(serialize(req) + "\n");
+      } catch (e) {
+        clearTimeout(timer);
+        pending.delete(id);
+        resolve(err(cdpError("transport_closed", e instanceof Error ? e.message : String(e), method)));
+      }
+    });
+  };
+
+  // ── Events ─────────────────────────────────────────────────────────────
+
+  const events = (): AsyncIterable<CdpEvent> => queue.iter;
+
+  // ── State ──────────────────────────────────────────────────────────────
+
+  const state = (): "open" | "closed" | "connecting" => {
+    if (!socket) return "closed";
+    if (!registered) return "connecting";
+    if (socket.destroyed) return "closed";
+    return "open";
+  };
+
+  const onClose = (cb: () => void): (() => void) => {
+    closeListeners.add(cb);
+    return () => closeListeners.delete(cb);
+  };
+
+  return { connect, close, request, events, state, onClose };
+};