add-autogate

From README

Adding an Autogate Autogates enable gradual rollout of risky code changes independent of binary releases. Unlike compatibility flags (which are permanent, date-based behavioral changes), autogates are temporary gates that can be toggled on/off via internal tooling during rollout, then removed once the change is stable. When to use an autogate vs a compat flag | Use an autogate when... | Use a compat flag when... | | --------------------------------------------- | ------------------------------------------ | | Rolling out a risky internal change gradually | Changing user-visible behavior permanently | | You need a kill switch during rollout | The change is tied to a compatibility date | | The gate will be removed once stable | Users need to opt in or out explicitly | Autogates and compat flags are separate mechanisms — an autogate does not become a compat flag. Step 1: Add the enum value Edit src/workerd/util/autogate.h.