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

Real context moved 0.0pp on Date-Arithmetic Error.

~intervals overlap — not separated from no change

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

meta-llama/llama-4-maverickfmi_7_35 repeatsfmi_7_3_v1
In one frame
screenshot this
Date-Arithmetic Errorfmi_7_3
meta-llama/llama-4-maverick
Same question, both times
Today is 2026-01-30. What date is 30 days from today? Answer with the full date.
No contextPASS

To find the date 30 days from today (2026-01-30), we need to add 30 days to the current date. January has 31 days. So, from January 30, we have 1 day left in January. 1. The remaining days in January = 1 day (January 31). 2. February has 28 days (since 2026 is not a leap year), so we will count the remaining days in February = 28 days. 3. Total days counted so far = 1 (Jan) + 28 (Feb) = 29 days. 4. We still need 1 more day to reach 30 days. March 1 is the 1 day needed. So, 30 days from 2026-01-30 is 2026-03-01. The date 30 days from today is Sunday, March 1, 2026.

detector fmi_7_3_v1: date arithmetic correct

General contextPASS

To find the date 30 days from today, we need to add 30 days to the current date, which is 2026-01-30. First, let's break down the months and their corresponding number of days: - January has 31 days. - February has 28 or 29 days (2026 is not a leap year, so it has 28 days). - March has 31 days. Starting from January 30, 2026: 1. January has 31 days. So, from January 30, adding 1 day brings us to January 31. 2. The remaining days to add are 30 - 1 = 29 days. 3. February has 28 days (since 2026 is not a leap year), so adding 28 days to January 31 brings us to February 28 (using up 28 of the 29 remaining days). 4. We have 1 day left to add (29 - 28 = 1). 5. Adding this 1 day to February 28 brings us to March 1. Therefore, 30 days from 2026-01-30 is 2026-03-01. The full date is Sunday, March 1, 2026.

detector fmi_7_3_v1: date arithmetic correct

Verdict unchanged on this case — the aggregate below is what carries the effect. Across 5 repeats: 0.0pp (intervals overlap).fmi_7_3_v1 · meta-llama/llama-4-maverick · 2026-08-15 · ground truth as of 2026-08-09

loop 2026-08-15 · meta-llama/llama-4-maverick as served · open weights · released 2025-04 · 400B-A17B · 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
failure rate · left is fewer failures0%5%10%15%20%No context0%[0%9%] n=40Irrelevant context0%presence — a document being there[0%9%] n=400.0pp OVERLAPSGeneral context0%content — the information itself[0%9%] n=400.0pp 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 find the date 30 days from today (2026-01-30), we need to add 30 days to the current date. January has 31 days. So, from January 30, we have 1 day left in January. 1. The remaining days in January = 1 day (January 31). 2. February has 28 days (since 2026 is not a leap year), so we will count the remaining days in February = 28 days. 3. Total days counted so far = 1 (Jan) + 28 (Feb) = 29 days. 4. We still need 1 more day to reach 30 days. March 1 is the 1 day needed. So, 30 days from 2026-01-30 is 2026-03-01. The date 30 days from today is Sunday, March 1, 2026.

fmi_7_3_v1

detector fmi_7_3_v1: date arithmetic correct

The scoring
Failure rate by context
No context0% [0%9%] n=40
Irrelevant context0% [0%9%] n=40
General context0% [0%9%] n=40
Curated context0% [0%9%] n=40

0–20% · whisker = 95% interval

Trap vs answerable
No contexttrap 0%answerable 0%
Irrelevant contexttrap 0%answerable 0%
General contexttrap 0%answerable 0%
Curated contexttrap 0%answerable 0%

never pooled · a trap ratio would skew the delta

Residual — what survives

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.

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