router: reserve the state-sync op-space (frontier round + App transport)

Appends seven ops above the existing op-space — GetStateSummaryFrontier,
StateSummaryFrontier, GetAcceptedStateSummary, AcceptedStateSummary, and the
AppRequest/AppResponse/AppError EVM fetch transport — so a node can route the
messages a pruned peer needs to re-fetch state instead of dropping them at the
chain router. Additive: every pre-existing wire value is unchanged. This is the
routing layer for state sync; the handler methods and sync-client driver that
consume these ops land on top.

Co-authored-by: Hanzo Dev <[email protected]>

core/router/router.go

@@ -51,6 +51,21 @@ const (
 	// Gossip method. Its wire value is fixed; append any new op ABOVE NumOps.
 	Gossip
 
+	// State-sync op-space. A node that pruned the ancestor state it needs re-fetches
+	// it from peers instead of stranding (the ErrPrunedAncestor / "side chain
+	// insertion" restart wedge). The four summary ops carry the frontier round — a
+	// behind node discovers a committed state summary and its α-weight; the three App
+	// ops are the EVM's own request/response transport for trie-leaf and code fetches,
+	// which the state-sync client rides to download the state under that summary.
+	// Appended ABOVE the pre-existing ops, so every wire value below is unchanged.
+	GetStateSummaryFrontier
+	StateSummaryFrontier
+	GetAcceptedStateSummary
+	AcceptedStateSummary
+	AppRequest
+	AppResponse
+	AppError
+
 	// NumOps is the count of router ops and the single source of truth for the
 	// op-space size. It is not a wire op — it is one past the last op. Node-side
 	// routing (node message.ToConsensusOp) is asserted to be a bijection onto

networking/handler/handler.go

@@ -47,4 +47,13 @@ const (
 	GetContext          = router.GetContext
 	Context             = router.Context
 	Gossip              = router.Gossip
+
+	// State-sync ops (frontier round + EVM App transport) — see core/router.
+	GetStateSummaryFrontier = router.GetStateSummaryFrontier
+	StateSummaryFrontier    = router.StateSummaryFrontier
+	GetAcceptedStateSummary = router.GetAcceptedStateSummary
+	AcceptedStateSummary    = router.AcceptedStateSummary
+	AppRequest              = router.AppRequest
+	AppResponse             = router.AppResponse
+	AppError                = router.AppError
 )