graphvm + oraclevm + relayvm: complete FeePolicy coverage

graphvm: G-Chain is read-only (graphql.go explicitly rejects `mutation`
operations). Wires NoUserTxPolicy{} so any attempted user-tx is refused
at the boundary. Field + Initialize gate added; fee.Validate ensures
the policy choice is sound at boot.

oraclevm + relayvm: these chains are thin re-export shims of the
canonical impls in luxfi/oracle/vm and luxfi/relay/vm (which already
have feegate.go). Added in-file pointers documenting where the gate
lives, so future readers don't add a duplicate stub here.

Closes the FeePolicy migration: every VM in luxfi/chains/ either has
its own feegate.go (8 VMs), points to the canonical impl (oraclevm +
relayvm), or is exempt via native gas (evm). The matrix at
node/CLAUDE.md FeePolicy section is now complete.

graphvm/feegate.go

@@ -0,0 +1,24 @@
+// Copyright (C) 2019-2026, Lux Industries Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package graphvm
+
+import "github.com/luxfi/node/vms/types/fee"
+
+// newFeePolicy returns the canonical G-Chain FeePolicy.
+//
+// G-Chain is read-only — the GraphQL executor explicitly rejects
+// `mutation` operations (see graphql.go: "mutations not allowed:
+// G-chain is read-only"). There is no user-submitted-tx mempool, so
+// the only sound policy is NoUserTxPolicy{}: any path that ever tried
+// to admit a user-tx is a bug.
+//
+// Per node/CLAUDE.md FeePolicy section: service-only chains use
+// NoUserTxPolicy. Read-only chains are a subset of service-only.
+func newFeePolicy() fee.Policy {
+	return fee.NoUserTxPolicy{}
+}
+
+// FeePolicy exposes the chain's declared fee policy for diagnostics and
+// the boot-time Validate gate.
+func (vm *VM) FeePolicy() fee.Policy { return vm.feePolicy }

graphvm/vm.go

@@ -17,12 +17,13 @@ import (
 	"sync"
 	"time"
 
-	"github.com/luxfi/vm/chain"
 	"github.com/luxfi/database"
 	"github.com/luxfi/ids"
 	"github.com/luxfi/log"
+	"github.com/luxfi/node/vms/types/fee"
 	"github.com/luxfi/runtime"
 	vmcore "github.com/luxfi/vm"
+	"github.com/luxfi/vm/chain"
 	"github.com/luxfi/warp"
 
 	nodeversion "github.com/luxfi/node/version"
@@ -82,6 +83,10 @@ type VM struct {
 	// Synchronization
 	schemaMu sync.RWMutex
 	queryMu  sync.RWMutex
+
+	// G-Chain is read-only; the policy refuses all user-tx at the boundary.
+	// See feegate.go.
+	feePolicy fee.Policy
 }
 
 // GraphSchema represents a GraphQL schema definition
@@ -169,6 +174,12 @@ func (vm *VM) Initialize(
 	vm.dataIndexes = make(map[string]*DataIndex)
 	vm.chainSources = make(map[ids.ID]*ChainDataSource)
 
+	// Fee gate: read-only chain → NoUserTxPolicy (refuses all user-tx).
+	vm.feePolicy = newFeePolicy()
+	if err := fee.Validate(vm.feePolicy); err != nil {
+		return fmt.Errorf("feepolicy: %w", err)
+	}
+
 	// Parse genesis if needed
 	if len(vmInit.Genesis) > 0 {
 		if err := vm.parseGenesis(vmInit.Genesis); err != nil {

oraclevm/feegate.go

@@ -0,0 +1,15 @@
+// Copyright (C) 2019-2026, Lux Industries Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package oraclevm
+
+// FeePolicy lives at the canonical impl in luxfi/oracle/vm. This package
+// is a thin re-export shim (see oraclevm.go header); the gate is wired
+// there and re-exported via the type alias `VM = oraclevm.VM`, so any
+// caller that constructs a VM through this shim transitively gets the
+// NoUserTxPolicy{} declared in ~/work/lux/oracle/vm/feegate.go.
+//
+// See:
+//   - oraclevm.go: re-export shim
+//   - ~/work/lux/oracle/vm/feegate.go: canonical NoUserTxPolicy
+//   - ~/work/lux/node/CLAUDE.md FeePolicy section

relayvm/feegate.go

@@ -0,0 +1,15 @@
+// Copyright (C) 2019-2026, Lux Industries Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package relayvm
+
+// FeePolicy lives at the canonical impl in luxfi/relay/vm. This package
+// is a thin re-export shim (see relayvm.go header); the gate is wired
+// there and re-exported via the type alias `VM = relayvm.VM`, so any
+// caller that constructs a VM through this shim transitively gets the
+// NoUserTxPolicy{} declared in ~/work/lux/relay/vm/feegate.go.
+//
+// See:
+//   - relayvm.go: re-export shim
+//   - ~/work/lux/relay/vm/feegate.go: canonical NoUserTxPolicy
+//   - ~/work/lux/node/CLAUDE.md FeePolicy section