sPOL upgrade onboarding

Patterns for running cross-chain sPOL upgrades end-to-end — fork tests, runbooks, sanity scripts. The PolBridger-to-proxy upgrade (Apr 2026) was the first run that produced these notes; the patterns here are intentionally upgrade-shape-agnostic.

This is the home for patterns that vary per upgrade. Steady-state protocol documentation lives in CLAUDE.md.

When to use

Trigger this skill when the user is doing any of:

• Writing or revising fork tests that drive an upgrade end-to-end across one or both chains.
• Drafting / executing an upgrade runbook (deploy script, multisig calldata, sanity scripts, integrator notes).
• Onboarding a new contributor onto the upgrade workflow.