  Symmetry topological field theory (SymTFT) gives a holographic correspondence
between systems with a global symmetry and a higher-dimensional topological
field theory. In this framework, classification of gapped phases of matter in
spacetime dimension 1+1D correspond to classifications of mechanisms to confine
the SymTFT by condensing anyons. In this work, we extend these results to
characterize gapless symmetry-protected topological states: symmetry-enriched
gapless phases or critical points that exhibit edge modes protected by symmetry
and topology. We establish a one-to-one correspondence between 1+1D bosonic
gSPTs, and partially-confined boundaries of 2+1D SymTFTs. From general physical
considerations, we determine the set of data and consistency conditions
required to define a 1+1D gSPT, and show that this data precisely matches that
of symmetry-preserving partial confinement (or partially gapped boundaries) of
2+1D quantum double models. We illustrate this correspondence through a
dimensional reduction (thin-slab) construction, which enables a
physically-intuitive derivation of how properties of the gSPT such as edge
modes, emergent anomalies, and stability to perturbations arise from the SymTFT
perspective.ditions required to define a 1+1D gSPT and show that they fully
determine the physics of the gSPT including edge modes and emergent anomaly.
