Flat pre, call flop and turn with overpair; river fold is correct versus a polarized shove.
Flop 2h-3h-2d: HJ fires small into 7.5BB. With 77 we have an overpair and a very strong hand on this low, paired board. The small c-bet gives us excellent odds (3.8:1, need ~21%); calling is the standard response. Raising is mostly unnecessary and would mostly isolate us against stronger hands.
Turn 6s: SPR is now around 1.35, so stacks are very shallow. HJ bets 7BB into 16.5BB. We’re getting about 2.4:1 and need roughly 30% equity; 77 still has plenty of showdown value versus a range that includes a lot of bluffs and weaker pairs. Calling is preferred; jamming would be overplaying our hand and folding would be too tight.
River Ac: HJ shoves 22.3BB into 45.8BB. This is a polarized, value-heavy shove after betting flop and turn. Our 77 is now a bluff-catcher versus a range that’s heavily weighted to Ax and full houses. We’re getting about 2.1:1 and need ~33% equity, but our actual equity versus this polarized range is much lower, so folding is correct.