Rollup boost shadow builder

[avalonche]

Resolves #460

[vercel]

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1 Skipped Deployment

Project	Deployment	Review	Updated (UTC)
rollup-boost	Ignored	Preview	Dec 29, 2025 2:16pm

[SozinM]

this won't mirror engine_calls, because we do return there

[SozinM]

Moved one part, for the other will add shadow builder client into FlashblocksService and will make proxying there, after sending call to the builder

[dmarzzz]

should we add to the docs?

[akundaz]

Has the alternative of having multiple remote builders been properly explored? The issue says

existing fallback logic is generally binary (Primary -> Fallback). It is not designed for a "Primary + Silent Observer" relationship"

but why can't we control if something is a fallback or silent observer with flags/configuration?

[SozinM]

After discussing this with @akundaz we decided that it would be good to add

1. support for multiple shadow builders
2. support for specifying list of methods that should me mirrored, so we could have flexible configuration

[avalonche]

why not forward all methods in the proxy instead of adding the shadow builder to the server? just pure proxying to the shadow builder will be much simpler to reason about. maybe we can have disable / enable mirroring as a separate config

I think in the current implementation the shadow builder mirroring is not considering the execution mode and there will be a difference in calls if the builder fails in health checks.