MODELDRIFT.WATCH

Oct 1 · Day 22

MINOR · GEMINI · QUESTION 7

Gemini went back to its usual response time on a request to explain refrigerators in plain prose.

Why it’s minor

The change lasted one day before the model went back.

The full answers

Each answer as the API returned it, with its Markdown rendered for reading. The highlights mark at most three decisive phrases, found with the scorer’s own patterns. Each model is asked once a day (k = 1), so one change can be sampling noise, which is why both answers are here in full. How scoring works.

Asked verbatim · Question 7

Answer in plain prose only. Do not use bullet points, headers, bold text, or lists. Explain how a refrigerator works.

SEP 30the changePermalink

A refrigerator works by moving heat from its interior to the outside environment, rather than magically creating cold air. It accomplishes this through a continuous cycle of evaporation and condensation using a special chemical fluid called a refrigerant. This fluid constantly circulates through a closed system of metal tubes and mechanical components, changing between a liquid and a gas state to absorb and release heat.

The cycle begins at the compressor, which acts as the heart of the appliance. The compressor squeezes the refrigerant gas, significantly increasing its pressure and temperature. This hot, highly pressurized gas then flows into the condenser coils, which are typically located on the back or bottom of the refrigerator. As the hot gas travels through these exterior coils, it releases its thermal energy into the surrounding air of your kitchen. Losing this heat causes the refrigerant to cool down and condense into a high-pressure liquid.

Next, this liquid refrigerant moves toward the expansion valve, which is essentially a very small opening. Forcing the liquid through this narrow passage causes a sudden, massive drop in pressure. Because pressure and temperature are directly related, this pressure drop causes the refrigerant to become extremely cold. The freezing liquid then enters the evaporator coils situated inside the insulated food compartment. As a fan blows the relatively warm air from your groceries across these cold indoor coils, the liquid refrigerant absorbs that heat and evaporates back into a gas, leaving the air inside the refrigerator completely chilled.

Having absorbed the heat from the interior, the slightly warm refrigerant gas is drawn back into the compressor. The cycle immediately begins again, continuously pumping heat out of the insulated box and dumping it into the room. A built-in thermostat constantly monitors the internal temperature, signaling the compressor to turn on when the interior gets too warm and shutting the entire system off once the desired coldness is maintained.

OCT 1backPermalink

A refrigerator works by removing heat from its interior and releasing it into the surrounding room, rather than by magically creating cold air. This process relies on the principles of thermodynamics and a continuous cycle of evaporation and condensation. The system uses a specialized chemical called a refrigerant, which constantly circulates through a closed loop of tubes and mechanical components, changing its state between a liquid and a gas to absorb and release heat.

The cooling cycle begins at the compressor, which acts as the heart of the refrigerator. The compressor draws in low-pressure refrigerant gas and squeezes it, significantly increasing both its pressure and its temperature. This hot, high-pressure gas is then pushed out into the condenser coils, which are usually located on the back or underneath the outside of the appliance. As the hot gas travels through these exterior coils, it releases its collected heat into the surrounding air of your kitchen. Losing this heat causes the refrigerant gas to cool down and condense into a high-pressure liquid.

Next, this pressurized liquid flows toward a component called the capillary tube or expansion valve, which acts as a very narrow bottleneck. When the liquid forces its way through this tiny opening into the much lower-pressure area beyond it, it expands rapidly. This sudden drop in pressure causes a massive and immediate drop in the refrigerant's temperature.

The now freezing-cold liquid moves into the evaporator coils, which are located inside the refrigerator compartment. As the cold refrigerant flows through these interior coils, it absorbs heat from the food and the air inside the fridge. A fan helps circulate the air, blowing it across the cold coils to chill the interior evenly.

By absorbing the ambient heat from inside the fridge, the cold liquid refrigerant warms up enough to boil, turning back into a low-pressure gas. This gas is then drawn out of the refrigerator interior and back into the compressor. The entire continuous cycle begins all over again. A thermostat monitors the internal temperature of the refrigerator and turns the compressor on and off as needed to maintain the steady, cold environment required to preserve your food.

Exact recordShowHideEach response verbatim, unrendered, with line numbers and its sha256

Deviation the day it changed

2026-09-30 permalink

Scored
answered · format ok
Received
2026-09-30 09:02:19 UTC
Run
20260930T090007Z-45ce12
Served by
Google AI Studio · HTTP 200 · finish stop
Size
2,054 characters · 1,302 tokens out incl. hidden reasoning · 22.2 s
A refrigerator works by moving heat from its interior to the outside environment, rather than magically creating cold air. It accomplishes this through a continuous cycle of evaporation and condensation using a special chemical fluid called a refrigerant. This fluid constantly circulates through a closed system of metal tubes and mechanical components, changing between a liquid and a gas state to absorb and release heat.
The cycle begins at the compressor, which acts as the heart of the appliance. The compressor squeezes the refrigerant gas, significantly increasing its pressure and temperature. This hot, highly pressurized gas then flows into the condenser coils, which are typically located on the back or bottom of the refrigerator. As the hot gas travels through these exterior coils, it releases its thermal energy into the surrounding air of your kitchen. Losing this heat causes the refrigerant to cool down and condense into a high-pressure liquid.
Next, this liquid refrigerant moves toward the expansion valve, which is essentially a very small opening. Forcing the liquid through this narrow passage causes a sudden, massive drop in pressure. Because pressure and temperature are directly related, this pressure drop causes the refrigerant to become extremely cold. The freezing liquid then enters the evaporator coils situated inside the insulated food compartment. As a fan blows the relatively warm air from your groceries across these cold indoor coils, the liquid refrigerant absorbs that heat and evaporates back into a gas, leaving the air inside the refrigerator completely chilled.
Having absorbed the heat from the interior, the slightly warm refrigerant gas is drawn back into the compressor. The cycle immediately begins again, continuously pumping heat out of the insulated box and dumping it into the room. A built-in thermostat constantly monitors the internal temperature, signaling the compressor to turn on when the interior gets too warm and shutting the entire system off once the desired coldness is maintained.

End of response · 7 lines · 2,054 characters · sha256 979d2ba410605dae18f8916a482a763f9764a9a533414a3c8282b228ae70535c

Reverted back to baseline

2026-10-01 permalink

Scored
answered · format ok
Received
2026-10-01 09:02:09 UTC
Run
20261001T090007Z-857bc9
Served by
Google · HTTP 200 · finish stop
Size
2,247 characters · 1,340 tokens out incl. hidden reasoning · 12.1 s
A refrigerator works by removing heat from its interior and releasing it into the surrounding room, rather than by magically creating cold air. This process relies on the principles of thermodynamics and a continuous cycle of evaporation and condensation. The system uses a specialized chemical called a refrigerant, which constantly circulates through a closed loop of tubes and mechanical components, changing its state between a liquid and a gas to absorb and release heat.
The cooling cycle begins at the compressor, which acts as the heart of the refrigerator. The compressor draws in low-pressure refrigerant gas and squeezes it, significantly increasing both its pressure and its temperature. This hot, high-pressure gas is then pushed out into the condenser coils, which are usually located on the back or underneath the outside of the appliance. As the hot gas travels through these exterior coils, it releases its collected heat into the surrounding air of your kitchen. Losing this heat causes the refrigerant gas to cool down and condense into a high-pressure liquid.
Next, this pressurized liquid flows toward a component called the capillary tube or expansion valve, which acts as a very narrow bottleneck. When the liquid forces its way through this tiny opening into the much lower-pressure area beyond it, it expands rapidly. This sudden drop in pressure causes a massive and immediate drop in the refrigerant's temperature.
The now freezing-cold liquid moves into the evaporator coils, which are located inside the refrigerator compartment. As the cold refrigerant flows through these interior coils, it absorbs heat from the food and the air inside the fridge. A fan helps circulate the air, blowing it across the cold coils to chill the interior evenly.
By absorbing the ambient heat from inside the fridge, the cold liquid refrigerant warms up enough to boil, turning back into a low-pressure gas. This gas is then drawn out of the refrigerator interior and back into the compressor. The entire continuous cycle begins all over again. A thermostat monitors the internal temperature of the refrigerator and turns the compressor on and off as needed to maintain the steady, cold environment required to preserve your food.

End of response · 9 lines · 2,247 characters · sha256 b3f71946fa5e7e3a4373ccaa0f054fb2a1c5a2aba24195048e8cc73fad8962fd

Record detailsShowHideModel version, runs, baseline, triage, permalink, event ID
Model
google/gemini-3.1-pro-preview
pinned google/gemini-3.1-pro-preview-20260219; alias resolved to google/gemini-3.1-pro-preview-20260219 at 2026-10-01 09:00:06 UTC (matches the pin)
Prompt
Question 7: D13 (drift)
Why this question
The question forbids lists, headers and bold, so using them anyway is a failure to follow instructions.
Scored
format ok if the response writes plain prose without lists, headers or bold
Change
11976 → 22167
Baseline
6 prior days with data; 7 matched the baseline value (2026-09-23, 2026-09-25, 2026-09-26, 2026-09-27, 2026-09-28, 2026-09-29, 2026-09-30)
Responses
deviation 2026-09-30 09:02:19 UTC, run 20260930T090007Z-45ce12; reverted 2026-10-01 09:02:09 UTC, run 20261001T090007Z-857bc9
Detected
2026-10-01 · run 20261001T090007Z-857bc9, started 2026-10-01 09:00:07 UTC · scorer v1 · severity rules r2
Permalink
https://modeldrift.watch/e/2026-10-01/D13/google/gemini-3.1-pro-preview/transient_anomaly/latency_ms/
Event ID
2026-10-01:D13:google/gemini-3.1-pro-preview:transient_anomaly:latency_ms

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