Local History vs Automated Refactoring for Zero‑Downtime PHP Application Migration

The goal is to migrate a small PHP application without any downtime while preserving existing behavior.

The constraint requires the migration to occur on a live system where traffic cannot be paused, forcing a decision between using Local History snapshots to isolate changes or relying on PhpStorm's automated refactoring tools to rewrite code paths in place.

Uncertainty remains about whether Local History can guarantee consistent state during partial updates, and whether refactoring will miss dynamic references in older PHP code, potentially causing runtime errors.

Can Local History safely isolate incremental updates without downtime? Does automated refactoring reliably rewrite all references for zero‑downtime migration?