---
title: "Stability Index Changelog"
canonical: "https://pharos.watch/methodology/stability-index-changelog/archive/v2/"
description: "Stability Index Changelog - Pharos methodology version history."
---

# Stability Index Changelog

[All versions](https://pharos.watch/methodology/stability-index-changelog/)

<a id="changelog-v-2-1"></a>

## v2.1 - Trend hardening and retention safety

**Effective:** 2026-02-27

Hardened trend input handling and operationalized rolling retention for PSI samples.

- NaN/Infinity trend values now treated as 0 before clamp
- No formula change, but edge-case score corruption prevented
- Sample retention/pruning standardized to 90 days

Origin: Reconstructed from git commit history

Commits: `76aa8c6`, `74aa1cd`

<a id="changelog-v-2-0"></a>

## v2.0 - Removed freezes, rebalanced caps

**Effective:** 2026-02-26

Major methodology revision removing freezes and reallocating penalty capacity.

- Removed freezes component from formula
- Severity cap increased 60 -> 68
- Breadth cap increased 15 -> 17
- Formula became: 100 - severity - breadth + trend

Origin: Reconstructed from git commit history

Commits: `bc2cfcf`