  Given a grid diagram for a knot or link K in $S^3$, we construct a spectrum
whose homology is the knot Floer homology of K. We conjecture that the homotopy
type of the spectrum is an invariant of K. Our construction does not use
holomorphic geometry, but rather builds on the combinatorial definition of grid
homology. We inductively define models for the moduli spaces of
pseudo-holomorphic strips and disk bubbles, and patch them together into a
framed flow category. The inductive step relies on the vanishing of an
obstruction class that takes values in a complex of positive domains with
partitions.
