Full Idea
The epistemic 1-intension for a sentence S is True at a scenario W iff (W and not-S) is a priori incoherent.
Gist of Idea
Truth in a scenario is the negation in that scenario being a priori incoherent
Source
David J.Chalmers (Epistemic Two-Dimensional Semantics [2004], p.180-4), quoted by Laura Schroeter - Two-Dimensional Semantics
Book Reference
'Stanford Online Encyclopaedia of Philosophy', ed/tr. Stanford University [plato.stanford.edu], p.25
A Reaction
See Two-Dimensional Semantics (in 'Language') and Chalmers for the background to this idea. I love the coherence view of justification, but get a bit nervous when people start defining truth in that way.