main is red: statistics simulation study crashes and 58 validated-statistics assertions fail #263

Current main (4c05aaa, 2026-10-23) fails three checks on its own push run, so every PR based on it is blocked. Neither failure involves files changed by the PR that surfaced them.

1. Statistics standards and evidence — the seeded simulation study crashes

ERROR: LoadError: MethodError: no method matching Dict(::Type{Int64}, ::Type{Dict{String, BigFloat}})
 [1] main(args::Vector{String})
   @ Main scripts/statistics/simulation_study.jl:104

Line 104 constructs Dict(Int, Dict{String,BigFloat})(...) — Julia parses that as a call to Dict with two type arguments, not as a parameterised constructor. It needs braces:

maxima = Dict{Int, Dict{String, BigFloat}}(

That is the whole error; the rest of the job (KYAML gate, I-JSON/JCS gate) is green.

2. Julia tests — 58 failed, 6 errored on the validated-statistics layer

First failure cluster (from the check-run annotations):

Property: high-precision storage round-trips at achieved precision:
Test Failed at test/unit/test_statistics_properties.jl:235
  Expression: occursin("rounded", display)
   Evaluated: occursin("rounded", "0.000000 (approximate, 1024-bit, 6dp)")

The display string no longer contains the word the property test asserts, across several precisions (test_statistics_ui.jl also contributes failures). Introduced with the validated-statistics layer (#257); the same failure appears on every push since.

3. Occupancy disagreement test

Fails on the same push run; see the run for detail.

Evidence

• Push run for 4c05aaa: failed checks are Julia tests, Statistics standards and evidence, Occupancy disagreement test.
• PR bench(null_calibration): replicate #193 at 1,000 sims and measure the alternatives #262 (benchmark-only, no Julia source touched) reproduces exactly the same failures on its rebased head, which is how this was found.

Fixing these is outside the scope of #262; this issue exists so that the block is visible and has a destination, and so the one-line Dict{…} fix is not buried in an unrelated PR.