This is the text of the fare rule:
CANCELLATIONS
BEFORE DEPARTURE
CANCELLATIONS PERMITTED.
AFTER DEPARTURE
CANCELLATIONS PERMITTED.
NOTE - TEXT BELOW NOT VALIDATED FOR AUTOPRICING.
REF DIFF BETWEEN FARE PAID AND APPLICABLE OW FARE
FOR THE SECTOR FLOWN.
IN CASE OF NO-SHOW TICKET IS NON REFUNDABLE.
CHANGES
ANY TIME
CHANGES PERMITTED.
NOTE - TEXT BELOW NOT VALIDATED FOR AUTOPRICING.
UPGRADING PERMITTED TO M-/ Y-/ D-/ C- FARES
THEN THE DIFFERENCE BETWEEN ORIGINAL FARE AND
NEW FARE MUST BE PAID
-----------------------------------------------
CHANGE IS FREE OF CHARGE AT THE AIRPORT THE DAY
OF DEPARTURE FOR AN EARLIER FLIGHT IN ANY OF
FOLLOWING BKG CLASSES K / H / L / M / Y
NAME CHANGES NOT PERMITTED.
So, yes, it's full-refundable, as long as you don't "no show".
As far as I'm concerned, I asked the lounge agent to call the gate agent to de-board me and retrieve my bag. As my bag was offloaded (and back in my hands before the original flight departure time), my assumption is the gate agent marked me as "no show", and didn't cancel me.
I can see this turning into a battle. My dealings with SN have not been good so far. In terms of time-to-respond, by far the worst of any airline I've dealt with in the last 5 years.