  We investigate the gauge-invariant observables constructed by smearing the
graviton and inflaton fields by compactly supported tensors at linear order in
general single-field inflation. These observables correspond to gauge-invariant
quantities that can be measured locally. In particular, we show that these
observables are equivalent to (smeared) local gauge-invariant observables such
as the linearised Weyl tensor, which have better infrared properties than the
graviton and inflaton fields. Special cases include the equivalence between the
compactly supported gauge-invariant graviton observable and the smeared
linearised Weyl tensor in Minkowski and de Sitter spaces. Our results indicate
that the infrared divergences in the tensor and scalar perturbations in
single-field inflation have the same status as in de Sitter space and are both
a gauge artefact, in a certain technical sense, at tree level.
