until just now; up to this very moment
Emphasizes that a state or action continued right up to the present instant, often with a sense of sudden change or realization. Used adverbially.
He had been silent until just now, but suddenly started talking.
I hadn't noticed until this very moment, but there's a scratch here.
A fixed emphatic expression formed by reduplicating 今 (now) with the particle が and まで (until). The exact historical derivation is uncertain, but it likely arose as a colloquial intensifier.