Today is 2026-03-10. What date is 30 days from today? Answer with the full date.
No contextPASS
30 days from today (2026-03-10) is **2026-04-09**.
detector fmi_7_3_v1: date arithmetic correct
General contextPASS
# Date Calculation
Starting from today's date: 2026-03-10
Adding 30 days:
- March has 31 days
- Days remaining in March after the 10th: 21 days
- Days needed into April: 30 - 21 = 9 days
**Answer: 2026-04-09**
detector fmi_7_3_v1: date arithmetic correct
loop 2026-08-15 · anthropic/claude-haiku-4.5 as served · closed weights · released 2025-10 · set s1.3-live · cases v1.6 · conditions v1.0 · ground truth as of 2026-08-09
From no context to real context
5 repeats per case
whiskers are 95% intervals · each step is measured from the stop before it, not from zero
Try the other contexts
stored · no model call
1Questionheld fixed
Today is 2026-01-30. What date is 30 days from today? Answer with the full date.
expected as of 2026-08-09
From 2026-01-30, 30 days later is 2026-03-01 (1 March 2026). Crossing February in a non-leap year.
2Contextchange me
Nothing supplied. The baseline.
3ResponseNo context
No exhibit stored for this context. The full probe log lives outside the repository.
The scoring
Failure rate by context
No context10%[2%–39%] n=40 · eff 11
Irrelevant context0%[0%–26%] n=40 · eff 11
General context3%[0%–30%] n=40 · eff 11
Curated context5%[1%–33%] n=40 · eff 11
0–60% · whisker = 95% interval
Trap vs answerable
No contexttrap 16%answerable 0%
Irrelevant contexttrap 0%answerable 0%
General contexttrap 4%answerable 0%
Curated contexttrap 8%answerable 0%
never pooled · a trap ratio would skew the delta
Residual — what survives
10% with no context, 3% under the best supplied source. What survives is 1 failing probe at that best condition, the detector's reason on most of them being: expected 2026-03-01.
Mitigations from the index — the claim
—date libraries via tools
—explicit date arithmetic
fmi_7_3_v1 · 5 repeats per case · best context general context · rollups + residuals committed · probe log outside git · manifest hash ties them · method