huskies: merge 1214 bug find_free_port can return a reserved/occupied port (2200), flaking its test and merge gates

server/src/chat/transport/matrix/new_project.rs

@@ -1440,12 +1440,18 @@ fn interpret_docker_run_error(stderr: &str, image: &str) -> String {
     }
 }
 
+/// Host ports reserved for the sled SSH range and never handed out as a
+/// newly allocated `ssh_port`, even when momentarily bindable during a scan.
+const RESERVED_SSH_PORTS: std::ops::RangeInclusive<u16> = 2200..=2202;
+
 /// Scan `start..start+range` for a bindable TCP port on 127.0.0.1.
 ///
 /// Returns `Some(port)` for the first port that can be bound, or `None` if all
-/// ports in the range are occupied.
+/// ports in the range are occupied. Ports in [`RESERVED_SSH_PORTS`] are never
+/// returned, even if bindable at scan time.
 fn find_free_port_in_range(start: u16, range: u16) -> Option<u16> {
     (start..start.saturating_add(range))
+        .filter(|port| !RESERVED_SSH_PORTS.contains(port))
         .find(|&port| std::net::TcpListener::bind(("127.0.0.1", port)).is_ok())
 }
 
@@ -1720,6 +1726,21 @@ mod tests {
         assert_eq!(find_free_port_in_range(port, 1), None);
     }
 
+    #[test]
+    fn find_free_port_skips_reserved_ssh_range() {
+        // The reserved 2200-2202 sled SSH range must never be handed out as
+        // a newly allocated ssh_port, even when those ports are bindable at
+        // scan time. Loop many times to rule out a flaky, timing-dependent
+        // pass rather than trusting a single lucky draw.
+        for _ in 0..100 {
+            let port = find_free_port(2200).expect("expected Some(port) in scan range");
+            assert!(
+                !RESERVED_SSH_PORTS.contains(&port),
+                "returned port {port} falls within the reserved 2200-2202 SSH range"
+            );
+        }
+    }
+
     #[test]
     fn detect_stack_go_mod() {
         let dir = tempfile::tempdir().unwrap();