# Re-test after every major model update

> Model updates can drastically reshuffle market shares, so a win measured last quarter can silently evaporate and the win-rate protocol should re-run within a set window on each major release.

<!-- Canonical: https://agentmint.net/signals/retest-on-model-updates/ · Signal in the AgentMint.net Signals Database · Evidence: reported (High confidence) · Last verified 2026-07-08 · Evidence types are load-bearing: spec-fact | reported | hypothesis (no measured). -->

- **Affects (funnel stage):** Choice
- **Evidence:** reported
- **Confidence:** High
- **Impact:** 3/3
- **Status:** active
- **Last verified:** 2026-07-08

## Per-platform status

Undocumented platforms show "unknown" - honest unknowns, never invented.

| Platform | Status | Notes | Source |
| --- | --- | --- | --- |
| ChatGPT | unknown | Not documented by this platform. | - |
| Gemini / Google AI Mode | unknown | Not documented by this platform. | - |
| Perplexity | unknown | Not documented by this platform. | - |
| Copilot | unknown | Not documented by this platform. | - |
| Claude | unknown | Not documented by this platform. | - |

## Evidence and sources

- [ACES (arXiv:2508.02630)](https://arxiv.org/abs/2508.02630) (2026-07-08)

## How to act on this

Track each engine's current model version and re-run the win-rate protocol within a fixed window whenever a major update lands, comparing against the last baseline.

### Related checklist items
- [Re-test after every major model update: behavior reshuffles.](https://agentmint.net/tools/agent-selection-checklist/#b-measurement-02) (Selection)

### Related signals
- [Defined agent win-rate measurement](https://agentmint.net/signals/agent-win-rate-measurement/)
- [Audit grid position bias per provider](https://agentmint.net/signals/position-bias-audit/)
- [Price sensitivity varies by model](https://agentmint.net/signals/model-specific-price-sensitivity/)

## Notes

Based on ACES (arXiv:2508.02630), a controlled agent-shopping simulation, not measured real-world sales.