Real context moved 0.0pp on Date-Arithmetic Error.
Gets date arithmetic wrong.
~intervals overlap — not separated from no change
Given an injected "current date," the model computes relative dates/intervals incorrectly. The rule
Today is 2026-01-30. What date is 30 days from today? Answer with the full date.
Today's date is **2026-01-30**. Adding 30 days: - January has 31 days, so from January 30, there is 1 day remaining in January (January 31). - That leaves 29 more days into February. - February 2026 has 28 days (2026 is not a leap year), so 29 days into February goes 1 day into March. **March 1, 2026**
detector fmi_7_3_v1: date arithmetic correct
## Calculating 30 Days from Today Starting date: **January 30, 2026** - January has 31 days, so from January 30, there is **1 day remaining** in January (January 31) - That leaves 29 more days into February - February 2026 is not a leap year, so February has 28 days - 29 days into February goes **1 day past** the end of February, landing on **March 1** **30 days from January 30, 2026 is March 1, 2026.**
detector fmi_7_3_v1: date arithmetic correct
loop 2026-09-09 · anthropic/claude-sonnet-4.6 as served · closed weights · released 2026-02 · set s1.4-live · cases v1.7 · conditions v1.0 · ground truth as of 2026-08-09
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.
Nothing supplied. The baseline.
Today's date is **2026-01-30**. Adding 30 days: - January has 31 days, so from January 30, there is 1 day remaining in January (January 31). - That leaves 29 more days into February. - February 2026 has 28 days (2026 is not a leap year), so 29 days into February goes 1 day into March. **March 1, 2026**
fmi_7_3_v1
detector fmi_7_3_v1: date arithmetic correct
0–40% · whisker = 95% interval
never pooled · a trap ratio would skew the delta
Unchanged by context: 0% with none, 0% with the strongest supplied source. For a control mode that flat line is the result — it is what licenses reading movement elsewhere in this loop as grounding rather than as a document being present. Nothing survives at the best condition on the cases measured here.
- date libraries via tools
- explicit date arithmetic
fmi_7_3_v1 · 5 repeats per case · best context curated context · rollups + residuals committed · probe log outside git · manifest hash ties them · method