# No change detected in anthropic/claude-sonnet-4-5

From 2026-10-31 to 2026-10-31, we didn't see a single day on which its answers changed.
**If your system is misbehaving, a change in this model isn't the explanation.**

> **We stopped observing this model after 2026-10-31.** The record up to that day is kept as is, and we know nothing about what happened after it.

| Observed via | **The provider's official API, called directly** (so a change here means the model changed) |
|---|---|
| First observed | 2026-10-31 (nothing before this date is known) |
| Last observed | 2026-10-31 |
| Days observed | 1 |
| Days with a change | 0 |
| Same answer on both calls (latest day) | 79% |

---

## If something is still wrong, check these

- Changes to your own prompts or downstream code (check your deploy history)
- Changes in the product layer (coding assistants, SDKs and so on). **Products can change even when the API doesn't**
- The endpoint you're calling may not be the one we observe here

---

## About this record

- Every day, we ask the same fixed set of 100 questions (probe set `en-v2`) at temperature 0, **twice each**
- The probe set is frozen (SHA-256 `d967055a5389e58a8767faf6be90996f…`) and **has never been changed**
- **What counts as a change**: we look at four things
    1. Content: a question whose answer was stable gets a different answer (the threshold is recalculated daily from how much this model wobbles)
    2. Length: answer lengths shift well beyond the usual same-day wobble
    3. Refusals: the way it handles judgment calls changes
    4. Wobble: the share of questions that get the same answer twice changes
- When comparing two days, **we only compare questions observed on both days** (so a network failure isn't mistaken for a change)
- **We don't use response time (latency)**, since it also reflects conditions on our end
- The entire record is free to read. Access to the most recent few days may become paid in the future.
- The data is licensed under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/). Please credit https://aimodelrecord.com when you use it.

## Badge

Add this to your README to show whether this model has changed. It links back to this page.

```
[![anthropic/claude-sonnet-4-5](https://aimodelrecord.com/badge/anthropic/claude-sonnet-4-5.svg)](https://aimodelrecord.com/m/anthropic/claude-sonnet-4-5.html)
```