You did well for your first booking. There have been many instances of JAL cancelling flights or rescheduling flights to make connections invalid and in those cases, after being contacted by the AS JAL liaison, JAL will open space on other JAL flights. Your case is different. In your case AS flights were canceled by AS. JAL technically does not have responsibility to rebook here, but maybe at AS's urging they will. What should have happened is AS should have booked you on alternate flights to meet your original JAL flight, or, as what the agent tried to do, rebook for a different flight with space available. Unfortunately, your AS agent tried to book you on a JAL flight that did not have confirmed space available and also canceled your original flight. This really is AS's mistake and if this were a fair world AS would fix it. I don't know what they will do here. My guess is they will ask JAL to fix the AS blunder and if JAL does not agree that AS likely will tell you they cannot fix it. I would push back hard and escalate up the supervisory chain if they do you dirty like that, asking to speak with a supervisor and explain how AS made the mistake of canceling your original JAL F flight without your permission and they need to fix it. If they do not then this definitely warrants filing a DOT complaint. Please update us on the outcome.

One recommended procedure is to not call the regular reservation line, which has a pool of agents, some of which are not well trained on handling issues with partner reservations. Call the partner desk phone number (should be found in this thread somewhere) during regular AS Seattle business hours for best results.