Okay this was annoying. IO is blocking by default and it's not obvious. Working again.

gib-gab-gob/game.scm

@@ -20,9 +20,7 @@
      ((board-winner? board peer-mark) 'lost)
      (else 'play)))
   (define (signal-turn)
-    (format #t "signal-turn start\n")
     (syscaller-free-fiber (λ () (put-message state+ (%state))))
-    (format #t "signal-turn end\n")
     #f)
   (define (switch-turn!)
     (let ((new-turn (not ($ %my-turn?))))
@@ -36,8 +34,7 @@
     (if (not ($ %my-turn?))
         (begin
           (board-choose! board peer-mark x y)
-          (switch-turn!)
-          (format #t "I have logged the peer's turn.\n"))
+          (switch-turn!))
         (error "It's my turn!"))]
    ;; TODO: These need to go somewhere else so the peer can't move or init for us!
    [(try-transition) 'playing]
@@ -54,10 +51,8 @@
     (if ($ %my-turn?)
         (begin
           (board-assert-vacant board x y)
-          (format #t "tell peer about it\n")
           (on (<- peer 'peer-turn! x y)
               (λ (_)
-                (format #t "peer promise resolve, then switch and return\n")
                 (board-choose! board mark x y)
                 (switch-turn!)
                 (%state))

gib-gab-gob/ui/console.scm

@@ -4,6 +4,7 @@
   #:use-module (gib-gab-gob board)
   #:use-module (ice-9 rdelim)
   #:use-module (ice-9 exceptions)
+  #:use-module (ice-9 suspendable-ports)
   #:use-module (srfi srfi-9)
   #:use-module (srfi srfi-1)
   #:use-module (fibers)
@@ -15,6 +16,12 @@
   #:use-module (goblins ocapn netlayer onion)
   #:export (make-initiator make-joiner))
 
+;; https://www.gnu.org/software/guile/manual/guile.html#Non_002dBlocking-I_002fO
+(let* ((input (current-input-port))
+       (flags (fcntl input F_GETFL)))
+  (fcntl input F_SETFL (logior O_NONBLOCK flags)))
+(install-suspendable-ports!)
+
 (random-state-from-platform)
 
 ;; Module for simple console-based UI (no curses)