diff --git a/devnet-sdk/descriptors/deployment.go b/devnet-sdk/descriptors/deployment.go
index 78fc0d7f9d48a..981569112a663 100644
--- a/devnet-sdk/descriptors/deployment.go
+++ b/devnet-sdk/descriptors/deployment.go
@@ -2,6 +2,7 @@ package descriptors
 
 import (
 	"encoding/json"
+	"fmt"
 	"net/http"
 
 	"github.com/ethereum-optimism/optimism/devnet-sdk/types"
@@ -10,6 +11,7 @@ import (
 
 type PortInfo struct {
 	Host        string `json:"host"`
+	Path        string `json:"path,omitempty"`
 	Scheme      string `json:"scheme,omitempty"`
 	Port        int    `json:"port,omitempty"`
 	PrivatePort int    `json:"private_port,omitempty"`
@@ -17,6 +19,14 @@ type PortInfo struct {
 	ReverseProxyHeader http.Header `json:"reverse_proxy_header,omitempty"`
 }
 
+func AppendPath(baseURL, path string) string {
+	url := baseURL
+	if path != "" {
+		url += fmt.Sprintf("/%s", path)
+	}
+	return url
+}
+
 // EndpointMap is a map of service names to their endpoints.
 type EndpointMap map[string]*PortInfo
 
diff --git a/op-acceptance-tests/tests/interop/message/init_test.go b/op-acceptance-tests/tests/interop/message/init_test.go
new file mode 100644
index 0000000000000..a1b67e9e6dbb0
--- /dev/null
+++ b/op-acceptance-tests/tests/interop/message/init_test.go
@@ -0,0 +1,14 @@
+package msg
+
+import (
+	"testing"
+
+	"github.com/ethereum-optimism/optimism/op-devstack/presets"
+)
+
+var SimpleInterop presets.TestSetup[*presets.SimpleInterop]
+
+func TestMain(m *testing.M) {
+	SimpleInterop = presets.NewSimpleInterop
+	presets.DoMain(m, presets.ConfigureSimpleInterop())
+}
diff --git a/op-acceptance-tests/tests/interop/message/interop_msg_test.go b/op-acceptance-tests/tests/interop/message/interop_msg_test.go
new file mode 100644
index 0000000000000..c0a67b2e60e78
--- /dev/null
+++ b/op-acceptance-tests/tests/interop/message/interop_msg_test.go
@@ -0,0 +1,27 @@
+package msg
+
+import (
+	"math/rand"
+	"testing"
+
+	"github.com/ethereum-optimism/optimism/op-acceptance-tests/tests/interop"
+	"github.com/ethereum-optimism/optimism/op-devstack/devtest"
+	"github.com/ethereum-optimism/optimism/op-service/eth"
+)
+
+// TestInitExecMsg tests basic interop messaging
+func TestInitExecMsg(gt *testing.T) {
+	t := devtest.SerialT(gt)
+	sys := SimpleInterop(t)
+	rng := rand.New(rand.NewSource(1234))
+	alice := sys.FunderA.NewFundedEOA(eth.ThousandEther)
+	bob := sys.FunderB.NewFundedEOA(eth.ThousandEther)
+
+	eventLoggerAddress := alice.DeployEventLogger()
+	// Trigger random init message at chain A
+	initIntent, _ := alice.SendInitMessage(interop.RandomInitTrigger(rng, eventLoggerAddress, rng.Intn(5), rng.Intn(30)))
+	// Make sure supervisor indexs block which includes init message
+	sys.Supervisor.AdvanceUnsafeHead(alice.ChainID(), 2)
+	// Single event in tx so index is 0
+	bob.SendExecMessage(initIntent, 0)
+}
diff --git a/op-devstack/dsl/eoa.go b/op-devstack/dsl/eoa.go
index ca4b33620b73b..3c0944c5efa29 100644
--- a/op-devstack/dsl/eoa.go
+++ b/op-devstack/dsl/eoa.go
@@ -5,10 +5,14 @@ import (
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/params"
 
+	"github.com/ethereum-optimism/optimism/devnet-sdk/contracts/bindings"
+	"github.com/ethereum-optimism/optimism/devnet-sdk/contracts/constants"
 	"github.com/ethereum-optimism/optimism/op-service/eth"
 	"github.com/ethereum-optimism/optimism/op-service/retry"
+	"github.com/ethereum-optimism/optimism/op-service/txintent"
 	"github.com/ethereum-optimism/optimism/op-service/txplan"
 )
 
@@ -115,3 +119,33 @@ func (u *EOA) VerifyBalanceExact(v eth.ETH) {
 	actual := u.balance()
 	u.t.Require().Equal(v, actual, "must have expected balance")
 }
+
+func (u *EOA) DeployEventLogger() common.Address {
+	tx := txplan.NewPlannedTx(u.Plan(), txplan.WithData(common.FromHex(bindings.EventloggerBin)))
+	res, err := tx.Included.Eval(u.ctx)
+	u.t.Require().NoError(err, "failed to deploy EventLogger")
+	eventLoggerAddress := res.ContractAddress
+	u.log.Info("deployed EventLogger", "chainID", tx.ChainID.Value(), "address", eventLoggerAddress)
+	return eventLoggerAddress
+}
+
+func (u *EOA) SendInitMessage(trigger *txintent.InitTrigger) (*txintent.IntentTx[*txintent.InitTrigger, *txintent.InteropOutput], *types.Receipt) {
+	tx := txintent.NewIntent[*txintent.InitTrigger, *txintent.InteropOutput](u.Plan())
+	tx.Content.Set(trigger)
+	receipt, err := tx.PlannedTx.Included.Eval(u.ctx)
+	u.t.Require().NoError(err, "init msg receipt not found")
+	u.log.Info("init message included", "chain", u.ChainID(), "block", receipt.BlockNumber)
+	return tx, receipt
+}
+
+func (u *EOA) SendExecMessage(initIntent *txintent.IntentTx[*txintent.InitTrigger, *txintent.InteropOutput], eventIdx int) (*txintent.IntentTx[*txintent.ExecTrigger, *txintent.InteropOutput], *types.Receipt) {
+	tx := txintent.NewIntent[*txintent.ExecTrigger, *txintent.InteropOutput](u.Plan())
+	tx.Content.DependOn(&initIntent.Result)
+	tx.Content.Fn(txintent.ExecuteIndexed(constants.CrossL2Inbox, &initIntent.Result, eventIdx))
+	receipt, err := tx.PlannedTx.Included.Eval(u.ctx)
+	u.t.Require().NoError(err, "exec msg receipt not found")
+	u.log.Info("exec message included", "chain", u.ChainID(), "block", receipt.BlockNumber)
+	// Check single ExecutingMessage triggered
+	u.t.Require().Equal(1, len(receipt.Logs))
+	return tx, receipt
+}
diff --git a/op-devstack/dsl/supervisor.go b/op-devstack/dsl/supervisor.go
index f0ae67dee1f6e..710bdcd2fce34 100644
--- a/op-devstack/dsl/supervisor.go
+++ b/op-devstack/dsl/supervisor.go
@@ -3,6 +3,7 @@ package dsl
 import (
 	"context"
 	"errors"
+	"fmt"
 	"time"
 
 	"github.com/ethereum-optimism/optimism/op-devstack/stack"
@@ -100,3 +101,23 @@ func (s *Supervisor) SafeBlockID(chainID eth.ChainID) eth.BlockID {
 
 	return syncStatus.Chains[chainID].CrossSafe
 }
+
+func (s *Supervisor) AdvanceUnsafeHead(chainID eth.ChainID, block uint64) {
+	initial := s.FetchSyncStatus()
+	chInitial, ok := initial.Chains[chainID]
+	s.require.True(ok, fmt.Sprintf("chain sync status not found: chain id: %d", chainID))
+	required := chInitial.LocalUnsafe.Number + block
+	attempts := int(block + 3) // intentionally allow few more attempts for avoid flaking
+	err := retry.Do0(s.ctx, attempts, &retry.FixedStrategy{Dur: 2 * time.Second},
+		func() error {
+			chStatus := s.FetchSyncStatus().Chains[chainID]
+			s.log.Info("Supervisor view of unsafe head", "chain", chainID, "unsafe", chStatus.LocalUnsafe)
+			if chStatus.LocalUnsafe.Number < required {
+				s.log.Info("Unsafe head sync status not ready",
+					"chain", chainID, "initialUnsafe", chInitial.LocalUnsafe, "currentUnsafe", chStatus.LocalUnsafe, "minRequired", required)
+				return fmt.Errorf("expected head to advance")
+			}
+			return nil
+		})
+	s.require.NoError(err)
+}
diff --git a/op-devstack/sysext/helpers.go b/op-devstack/sysext/helpers.go
index 56e150c6c4f5e..a152cb4a38f96 100644
--- a/op-devstack/sysext/helpers.go
+++ b/op-devstack/sysext/helpers.go
@@ -75,14 +75,15 @@ func (orch *Orchestrator) findProtocolService(service *descriptors.Service, prot
 	for proto, endpoint := range service.Endpoints {
 		if proto == protocol {
 			if orch.env.Env.ReverseProxyURL != "" && !orch.useDirectCnx {
-				return orch.env.Env.ReverseProxyURL, endpoint.ReverseProxyHeader, nil
+				return descriptors.AppendPath(orch.env.Env.ReverseProxyURL, endpoint.Path), endpoint.ReverseProxyHeader, nil
 			}
 
 			port := endpoint.Port
 			if orch.usePrivatePorts {
 				port = endpoint.PrivatePort
 			}
-			return fmt.Sprintf("http://%s:%d", endpoint.Host, port), nil, nil
+			url := descriptors.AppendPath(fmt.Sprintf("http://%s:%d", endpoint.Host, port), endpoint.Path)
+			return url, nil, nil
 		}
 	}
 	return "", nil, fmt.Errorf("protocol %s not found", protocol)
diff --git a/op-devstack/sysext/l1.go b/op-devstack/sysext/l1.go
index d6819bd7a885b..e6ed47bdf1f4a 100644
--- a/op-devstack/sysext/l1.go
+++ b/op-devstack/sysext/l1.go
@@ -1,6 +1,8 @@
 package sysext
 
 import (
+	"fmt"
+
 	"github.com/ethereum-optimism/optimism/op-devstack/shim"
 	"github.com/ethereum-optimism/optimism/op-devstack/stack"
 	"github.com/ethereum-optimism/optimism/op-service/eth"
@@ -52,6 +54,9 @@ func (o *Orchestrator) hydrateL1(system stack.ExtensibleSystem) {
 	}
 
 	if faucet, ok := env.Env.L1.Services["faucet"]; ok {
+		for _, endpoint := range faucet.Endpoints {
+			endpoint.Path = fmt.Sprintf("chain/%s", l1.ChainID().String())
+		}
 		l1.AddFaucet(shim.NewFaucet(shim.FaucetConfig{
 			CommonConfig: commonConfig,
 			Client:       o.rpcClient(t, faucet, RPCProtocol),
diff --git a/op-devstack/sysext/l2.go b/op-devstack/sysext/l2.go
index aa00cb56c7fc1..3609ab2ce6a81 100644
--- a/op-devstack/sysext/l2.go
+++ b/op-devstack/sysext/l2.go
@@ -1,6 +1,7 @@
 package sysext
 
 import (
+	"fmt"
 	"strings"
 
 	"github.com/ethereum-optimism/optimism/devnet-sdk/descriptors"
@@ -57,6 +58,9 @@ func (o *Orchestrator) hydrateL2(net *descriptors.L2Chain, system stack.Extensib
 	o.hydrateL2ProxydMaybe(net, l2)
 
 	if faucet, ok := net.Services["faucet"]; ok {
+		for _, endpoint := range faucet.Endpoints {
+			endpoint.Path = fmt.Sprintf("chain/%s", l2.ChainID().String())
+		}
 		l2.AddFaucet(shim.NewFaucet(shim.FaucetConfig{
 			CommonConfig: commonConfig,
 			Client:       o.rpcClient(t, faucet, RPCProtocol),