Spanner migrations: Automating dual-write with Antigravity CLI for minimal disruption

When Google’s Finance Engineering team needed to modernize their legacy data layer, they chose Spanner , a globally distributed, strongly consistent, multi-model database with high availability capabilities. But migrating to Spanner without taking production services offline was a daunting engineering challenge: As the internal team responsible for the application, we needed to manually rewrite dual-write logic across dozens of Data Access Objects (DAOs), a process that is slow and prone to human error. Further, doing so without disruption would have required implementing multi-phase dual-writ