The finding · Class 7 · Temporal & Knowledge Boundary

Real context moved -12.5pp on Date-Arithmetic Error.

Gets date arithmetic wrong.

Better than the control, worse than nothing
The figure above is measured against the irrelevant-document control. Against no context at all this card is worse: 18% bare against 20% with the best supplied source. What the source repaired is damage the presence of a document did.

~intervals overlap — not separated from no change

Given an injected "current date," the model computes relative dates/intervals incorrectly. The rule

mistralai/mistral-small-3.2-24b-instructfmi_7_35 repeatsfmi_7_3_v1

The mode All 10 cards

loop 2026-09-10 · mistralai/mistral-small-3.2-24b-instruct as served · open weights · released 2025-06 · 24B · set s1.4-live · cases v1.7 · 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 context18% [5%–47%] n=40 · eff 11

Irrelevant context33% [13%–62%] n=40 · eff 11

General context23% [7%–52%] n=40 · eff 11

Curated context20% [6%–50%] n=40 · eff 11

0–80% · whisker = 95% interval

Trap vs answerable

No contexttrap 24%answerable 7%

Irrelevant contexttrap 36%answerable 27%

General contexttrap 16%answerable 33%

Curated contexttrap 20%answerable 20%

never pooled · a trap ratio would skew the delta

Residual — what survives

Supplying context did not reduce this failure, it increased it: 18% with no context against 23% under the strongest supplied source. What survives is therefore not a remainder but a substitution — the failures under context are 8 probes the detector still rejected, dominated by: expected 2026-08-23.

Mitigations from the index — the claim

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