ModelCensusopen-source ai reliability harness
The finding · Class 7 · Temporal & Knowledge Boundary

Real context moved -10.0pp on Date-Arithmetic Error.

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: 3% bare against 8% 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

meta-llama/llama-3.3-70b-instructfmi_7_35 repeatsfmi_7_3_v1
The modeAll 7 cards
In one frame
screenshot this
Date-Arithmetic Errorfmi_7_3
meta-llama/llama-3.3-70b-instruct
Same question, both times
Today is 2026-03-10. What date is 30 days from today? Answer with the full date.
No contextPASS

To calculate the date 30 days from today, I will add 30 days to the current date. The current date is: 2026-03-10 30 days from today would be: 2026-04-09 So, the date 30 days from today is: April 9, 2026

detector fmi_7_3_v1: date arithmetic correct

General contextPASS

30 days from 2026-03-10 is 2026-04-09.

detector fmi_7_3_v1: date arithmetic correct

Verdict unchanged on this case — the aggregate below is what carries the effect. Across 5 repeats: -10.0pp (intervals overlap).fmi_7_3_v1 · meta-llama/llama-3.3-70b-instruct · 2026-08-15 · ground truth as of 2026-08-09

loop 2026-08-15 · meta-llama/llama-3.3-70b-instruct as served · open weights · released 2024-12 · 70B · set s1.2-live · cases v1.4 · conditions v1.0 · ground truth as of 2026-08-09

From no context to real context
5 repeats per case
failure rate · left is fewer failures0%10%20%30%40%No context3%[0%–13%] n=40Irrelevant context18%presence — a document being there[9%–32%] n=40+15.0pp OVERLAPSGeneral context8%content — the information itself[3%–20%] n=40-10.0pp OVERLAPS
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
PASS

To calculate the date 30 days from today, I'll add 30 days to the current date. Current date: 2026-01-30 30 days later: 2026-03-01 The date 30 days from today is March 1, 2026.

fmi_7_3_v1

detector fmi_7_3_v1: date arithmetic correct

The scoring
Failure rate by context
No context3% [0%–13%] n=40
Irrelevant context18% [9%–32%] n=40
General context8% [3%–20%] n=40
Curated context8% [3%–20%] n=40

0–40% · whisker = 95% interval

Trap vs answerable
No contexttrap 4%answerable 0%
Irrelevant contexttrap 28%answerable 0%
General contexttrap 12%answerable 0%
Curated contexttrap 8%answerable 7%

never pooled · a trap ratio would skew the delta

Residual — what survives

Unchanged by context: 3% with none, 8% 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.

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