NoIntegerCocycleException

No valid Z-lift of the chosen cocycle exists for the chosen prime -- either the underlying cohomology class is genuinely torsion (no real/integer lift can exist at any prime -- an RP²-type class is the standard example), or prime was too small relative to the true integer cocycle's own magnitudes for the mod-prime reduction to be injective on the relevant range (retry with a larger prime). Thrown rather than silently coordinatizing against a mod-prime mirage -- see .claude/WORKLOG-mainstream-feature-gap-analysis.md item 2's own framing: "∂(ℤ-lift) = 0 must be a runtime check, not assumed."