Feature request: configurable paths and ports for daemon, Chrome CDP and stream server (for OS-sandboxed use)

[ro-hansolo]

We run agent-browser (v0.41.1) inside an OS sandbox (macOS Seatbelt, Windows filtering) that allows only listed loopback ports and one socket folder. Today some of the locations agent-browser picks cannot be set from outside, so we cannot stay inside the allowed set. Here is what we checked in the v0.41.1 source (tag v0.41.1, commit 5868f7c).

Already available:

• Socket folder: AGENT_BROWSER_SOCKET_DIR (cli/src/connection.rs:103-106). It uses an existing folder as-is (no chmod), which is what we need.

Missing:

1. Windows daemon port. The daemon port is derived from the session name, 49152 + hash % 16383 (cli/src/connection.rs:411-431). There is no env var or flag to set it. If that port is taken, the daemon silently falls back to an OS-assigned ephemeral port (cli/src/native/daemon.rs:364-372), which a sandbox cannot allow in advance.

2. Chrome's remote-debugging (CDP) port. Chrome is always started with --remote-debugging-port=0 (cli/src/native/cdp/chrome.rs:467), and the port is read back from DevToolsActivePort in the profile directory (chrome.rs:946-968). There is no option to choose the port.

3. Stream server port. AGENT_BROWSER_STREAM_PORT exists (cli/src/native/daemon.rs:110), so this is already available. However, when that port is taken the server falls back to an ephemeral port (cli/src/native/stream/mod.rs:318-322, called with allow_port_fallback = true from daemon.rs).

Requests:

• A way to set the daemon's TCP port on Windows, e.g. AGENT_BROWSER_DAEMON_PORT.
• A way to set Chrome's remote-debugging port, e.g. AGENT_BROWSER_CDP_PORT or a passthrough that replaces --remote-debugging-port=0. The port would then be read from the given value, not from DevToolsActivePort.
• When a fixed port was requested and is taken, fail with a clear error instead of falling back to an ephemeral port, for the daemon (daemon.rs:364-372) and the stream server (stream/mod.rs:318-322). Keep the fallback as the default if you prefer, but make it opt-out.

Related existing issues: #1155 (Unix socket blocked in a sandbox), #1791 and #1796 (--remote-debugging-port=0 on WSL2; #1796 pre-binds a fixed port and is closed), #2136 (Windows derived port taken by another program; it fixes the readiness check but adds no way to set the port).

Happy to test a branch on Windows and macOS.