diff --git a/op-service/eth/super_root.go b/op-service/eth/super_root.go
index 1b9601ccbd1f0..8334a37b310a6 100644
--- a/op-service/eth/super_root.go
+++ b/op-service/eth/super_root.go
@@ -78,6 +78,28 @@ func (o *SuperV1) Marshal() []byte {
 	return buf
 }
 
+func (o *SuperV1) MarshalJSON() ([]byte, error) {
+	return json.Marshal(&superV1JsonMarshalling{
+		Timestamp: hexutil.Uint64(o.Timestamp),
+		Chains:    o.Chains,
+	})
+}
+
+func (o *SuperV1) UnmarshalJSON(input []byte) error {
+	var dec superV1JsonMarshalling
+	if err := json.Unmarshal(input, &dec); err != nil {
+		return err
+	}
+	o.Timestamp = uint64(dec.Timestamp)
+	o.Chains = dec.Chains
+	return nil
+}
+
+type superV1JsonMarshalling struct {
+	Timestamp hexutil.Uint64     `json:"timestamp"`
+	Chains    []ChainIDAndOutput `json:"chains"`
+}
+
 func UnmarshalSuperRoot(data []byte) (Super, error) {
 	if len(data) < 1 {
 		return nil, ErrInvalidSuperRoot
diff --git a/op-service/eth/super_root_test.go b/op-service/eth/super_root_test.go
index 316b94e63e2f9..f7968dceeba16 100644
--- a/op-service/eth/super_root_test.go
+++ b/op-service/eth/super_root_test.go
@@ -2,6 +2,7 @@ package eth
 
 import (
 	"encoding/binary"
+	"encoding/json"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -77,6 +78,33 @@ func TestSuperRootV1Codec(t *testing.T) {
 	})
 }
 
+func TestSuperRootV1JSON(t *testing.T) {
+	t.Run("UseHexForTimestamp", func(t *testing.T) {
+		chainA := ChainIDAndOutput{ChainID: ChainIDFromUInt64(11), Output: Bytes32{0x01}}
+		superRoot := NewSuperV1(7000, chainA)
+		jsonData, err := json.Marshal(superRoot)
+		require.NoError(t, err)
+
+		values := make(map[string]any)
+		err = json.Unmarshal(jsonData, &values)
+		require.NoError(t, err)
+		require.Equal(t, "0x1b58", values["timestamp"])
+	})
+
+	t.Run("RoundTrip", func(t *testing.T) {
+		chainA := ChainIDAndOutput{ChainID: ChainIDFromUInt64(11), Output: Bytes32{0x01}}
+		chainB := ChainIDAndOutput{ChainID: ChainIDFromUInt64(12), Output: Bytes32{0x02}}
+		chainC := ChainIDAndOutput{ChainID: ChainIDFromUInt64(13), Output: Bytes32{0x03}}
+		superRoot := NewSuperV1(7000, chainA, chainB, chainC)
+		data, err := json.Marshal(superRoot)
+		require.NoError(t, err)
+		var actual SuperV1
+		err = json.Unmarshal(data, &actual)
+		require.NoError(t, err)
+		require.Equal(t, superRoot, &actual)
+	})
+}
+
 func TestResponseToSuper(t *testing.T) {
 	t.Run("SingleChain", func(t *testing.T) {
 		input := SuperRootResponse{
diff --git a/op-service/eth/superroot_at_timestamp.go b/op-service/eth/superroot_at_timestamp.go
new file mode 100644
index 0000000000000..c842233f4981f
--- /dev/null
+++ b/op-service/eth/superroot_at_timestamp.go
@@ -0,0 +1,35 @@
+package eth
+
+// OutputWithRequiredL1 is the full Output and its source L1 block
+type OutputWithRequiredL1 struct {
+	Output     *OutputResponse `json:"output"`
+	RequiredL1 BlockID         `json:"required_l1"`
+}
+
+type SuperRootResponseData struct {
+
+	// VerifiedRequiredL1 is the minimum L1 block including the required data to fully verify all blocks at this timestamp
+	VerifiedRequiredL1 BlockID `json:"verified_required_l1"`
+
+	// Super is the unhashed data for the superroot at the given timestamp after all verification is applied.
+	Super Super `json:"super"`
+
+	// SuperRoot is the superroot at the given timestamp after all verification is applied.
+	SuperRoot Bytes32 `json:"super_root"`
+}
+
+// AtTimestampResponse is the response superroot_atTimestamp
+type SuperRootAtTimestampResponse struct {
+	// CurrentL1 is the highest L1 block that has been fully derived and verified by all chains.
+	CurrentL1 BlockID `json:"current_l1"`
+
+	// OptimisticAtTimestamp is the L2 block that would be applied if verification were assumed to be successful,
+	// and the minimum L1 block required to derive them. If Data is nil, some chains may be absent from this map,
+	// indicating that there is no optimistic block for the chain at the requested timestamp that can be derived
+	// from the L1 data currently processed.
+	OptimisticAtTimestamp map[ChainID]OutputWithRequiredL1 `json:"optimistic_at_timestamp"`
+
+	// Data provides information about the super root at the requested timestamp if present. If block data at the
+	// requested timestamp is not present, the data will be nil.
+	Data *SuperRootResponseData `json:"data,omitempty"`
+}
diff --git a/op-supernode/supernode/activity/superroot/superroot.go b/op-supernode/supernode/activity/superroot/superroot.go
index 31d4a9c29fe0b..0224fd3c10cdd 100644
--- a/op-supernode/supernode/activity/superroot/superroot.go
+++ b/op-supernode/supernode/activity/superroot/superroot.go
@@ -2,6 +2,7 @@ package superroot
 
 import (
 	"context"
+	"errors"
 	"fmt"
 
 	"github.com/ethereum-optimism/optimism/op-service/eth"
@@ -32,77 +33,43 @@ func (s *Superroot) RPCService() interface{} { return &superrootAPI{s: s} }
 
 type superrootAPI struct{ s *Superroot }
 
-// OutputWithSource is the full Output and its source L1 block
-type OutputWithSource struct {
-	Output   *eth.OutputResponse
-	SourceL1 eth.BlockID
-}
-
-// L2WithRequiredL1 is a verified L2 block and the minimum L1 block at which the verification is possible
-type L2WithRequiredL1 struct {
-	L2            eth.BlockID
-	MinRequiredL1 eth.BlockID
-}
-
-// atTimestampResponse is the response superroot_atTimestamp
-// it contains:
-// - CurrentL1Derived: the current L1 block that each chain has derived up to (without any verification)
-// - CurrentL1Verified: the current L1 block that each verifier has processed up to
-// - VerifiedAtTimestamp: the L2 blocks which are fully verified at the given timestamp, and the minimum L1 block at which verification is possible
-// - OptimisticAtTimestamp: the L2 blocks which would be applied if verification were assumed to be successful, and their L1 sources
-// - SuperRoot: the superroot at the given timestamp using verified L2 blocks
-type atTimestampResponse struct {
-	CurrentL1Derived      map[eth.ChainID]eth.BlockID
-	CurrentL1Verified     map[string]eth.BlockID
-	VerifiedAtTimestamp   map[eth.ChainID]L2WithRequiredL1
-	OptimisticAtTimestamp map[eth.ChainID]OutputWithSource
-	MinCurrentL1          eth.BlockID
-	MinVerifiedRequiredL1 eth.BlockID
-	SuperRoot             eth.Bytes32
-}
-
 // AtTimestamp computes the super-root at the given timestamp, plus additional information about the current L1s, verified L2s, and optimistic L2s
-func (api *superrootAPI) AtTimestamp(ctx context.Context, timestamp uint64) (atTimestampResponse, error) {
+func (api *superrootAPI) AtTimestamp(ctx context.Context, timestamp uint64) (eth.SuperRootAtTimestampResponse, error) {
 	return api.s.atTimestamp(ctx, timestamp)
 }
 
-func (s *Superroot) atTimestamp(ctx context.Context, timestamp uint64) (atTimestampResponse, error) {
-	currentL1Derived := map[eth.ChainID]eth.BlockID{}
-	// there are no Verification Activities yet, so there is no call to make to collect their CurrentL1
-	// this will be replaced with a call to the Verification Activities when they are implemented
-	currentL1Verified := map[string]eth.BlockID{}
-	verified := map[eth.ChainID]L2WithRequiredL1{}
-	optimistic := map[eth.ChainID]OutputWithSource{}
+func (s *Superroot) atTimestamp(ctx context.Context, timestamp uint64) (eth.SuperRootAtTimestampResponse, error) {
+	optimistic := map[eth.ChainID]eth.OutputWithRequiredL1{}
 	minCurrentL1 := eth.BlockID{}
 	minVerifiedRequiredL1 := eth.BlockID{}
 	chainOutputs := make([]eth.ChainIDAndOutput, 0, len(s.chains))
 
-	// get current l1s
+	// Get current l1s
 	// this informs callers that the chains local views have considered at least up to this L1 block
-	// but does not guarantee verifiers have processed this L1 block yet. This field is likely unhelpful, but I await feedback to confirm
+	// TODO(#18651): Currently there are no verifiers to consider, but once there are, this needs to be updated to consider if
+	// they have also processed the L1 data.
 	for chainID, chain := range s.chains {
 		currentL1, err := chain.CurrentL1(ctx)
 		if err != nil {
 			s.log.Warn("failed to get current L1", "chain_id", chainID.String(), "err", err)
-			return atTimestampResponse{}, err
+			return eth.SuperRootAtTimestampResponse{}, err
 		}
-		currentL1Derived[chainID] = currentL1.ID()
 		if currentL1.ID().Number < minCurrentL1.Number || minCurrentL1 == (eth.BlockID{}) {
 			minCurrentL1 = currentL1.ID()
 		}
 	}
 
+	notFound := false
 	// collect verified and optimistic L2 and L1 blocks at the given timestamp
 	for chainID, chain := range s.chains {
 		// verifiedAt returns the L2 block which is fully verified at the given timestamp, and the minimum L1 block at which verification is possible
 		verifiedL2, verifiedL1, err := chain.VerifiedAt(ctx, timestamp)
-		if err != nil {
-			s.log.Warn("failed to get verified L1", "chain_id", chainID.String(), "err", err)
-			return atTimestampResponse{}, fmt.Errorf("%w: %w", ethereum.NotFound, err)
-		}
-		verified[chainID] = L2WithRequiredL1{
-			L2:            verifiedL2,
-			MinRequiredL1: verifiedL1,
+		if errors.Is(err, ethereum.NotFound) {
+			notFound = true
+			continue // To allow other chains to populate unverified blocks
+		} else if err != nil {
+			s.log.Warn("failed to get verified block", "chain_id", chainID.String(), "err", err)
+			return eth.SuperRootAtTimestampResponse{}, fmt.Errorf("failed to get verified block: %w", err)
 		}
 		if verifiedL1.Number < minVerifiedRequiredL1.Number || minVerifiedRequiredL1 == (eth.BlockID{}) {
 			minVerifiedRequiredL1 = verifiedL1
@@ -111,38 +78,40 @@ func (s *Superroot) atTimestamp(ctx context.Context, timestamp uint64) (atTimest
 		outRoot, err := chain.OutputRootAtL2BlockNumber(ctx, verifiedL2.Number)
 		if err != nil {
 			s.log.Warn("failed to compute output root at L2 block", "chain_id", chainID.String(), "l2_number", verifiedL2.Number, "err", err)
-			return atTimestampResponse{}, fmt.Errorf("%w: %w", ethereum.NotFound, err)
+			return eth.SuperRootAtTimestampResponse{}, fmt.Errorf("failed to compute output root at L2 block %d for chain ID %v: %w", verifiedL2.Number, chainID, err)
 		}
 		chainOutputs = append(chainOutputs, eth.ChainIDAndOutput{ChainID: chainID, Output: outRoot})
 		// Optimistic output is the full output at the optimistic L2 block for the timestamp
 		optimisticOut, err := chain.OptimisticOutputAtTimestamp(ctx, timestamp)
 		if err != nil {
-			s.log.Warn("failed to get optimistic L1", "chain_id", chainID.String(), "err", err)
-			return atTimestampResponse{}, fmt.Errorf("%w: %w", ethereum.NotFound, err)
+			s.log.Warn("failed to get optimistic block", "chain_id", chainID.String(), "err", err)
+			return eth.SuperRootAtTimestampResponse{}, fmt.Errorf("failed to get optimistic block at timestamp %v for chain ID %v: %w", timestamp, chainID, err)
 		}
 		// Also include the source L1 for context
 		_, optimisticL1, err := chain.OptimisticAt(ctx, timestamp)
 		if err != nil {
 			s.log.Warn("failed to get optimistic source L1", "chain_id", chainID.String(), "err", err)
-			return atTimestampResponse{}, fmt.Errorf("%w: %w", ethereum.NotFound, err)
+			return eth.SuperRootAtTimestampResponse{}, fmt.Errorf("failed to get optimistic source L1 at timestamp %v for chain ID %v: %w", timestamp, chainID, err)
 		}
-		optimistic[chainID] = OutputWithSource{
-			Output:   optimisticOut,
-			SourceL1: optimisticL1,
+		optimistic[chainID] = eth.OutputWithRequiredL1{
+			Output:     optimisticOut,
+			RequiredL1: optimisticL1,
 		}
 	}
 
-	// Build super root from collected outputs
-	superV1 := eth.NewSuperV1(timestamp, chainOutputs...)
-	superRoot := eth.SuperRoot(superV1)
-
-	return atTimestampResponse{
-		CurrentL1Derived:      currentL1Derived,
-		CurrentL1Verified:     currentL1Verified,
-		VerifiedAtTimestamp:   verified,
+	response := eth.SuperRootAtTimestampResponse{
+		CurrentL1:             minCurrentL1,
 		OptimisticAtTimestamp: optimistic,
-		MinCurrentL1:          minCurrentL1,
-		MinVerifiedRequiredL1: minVerifiedRequiredL1,
-		SuperRoot:             superRoot,
-	}, nil
+	}
+	if !notFound {
+		// Build super root from collected outputs
+		superV1 := eth.NewSuperV1(timestamp, chainOutputs...)
+		superRoot := eth.SuperRoot(superV1)
+		response.Data = &eth.SuperRootResponseData{
+			VerifiedRequiredL1: minVerifiedRequiredL1,
+			Super:              superV1,
+			SuperRoot:          superRoot,
+		}
+	}
+	return response, nil
 }
diff --git a/op-supernode/supernode/activity/superroot/superroot_test.go b/op-supernode/supernode/activity/superroot/superroot_test.go
index f85acd8572ee2..c5d4d50003efd 100644
--- a/op-supernode/supernode/activity/superroot/superroot_test.go
+++ b/op-supernode/supernode/activity/superroot/superroot_test.go
@@ -7,6 +7,7 @@ import (
 
 	"github.com/ethereum-optimism/optimism/op-service/eth"
 	cc "github.com/ethereum-optimism/optimism/op-supernode/supernode/chain_container"
+	"github.com/ethereum/go-ethereum"
 	gethlog "github.com/ethereum/go-ethereum/log"
 	"github.com/stretchr/testify/require"
 )
@@ -97,14 +98,12 @@ func TestSuperroot_AtTimestamp_Succeeds(t *testing.T) {
 	api := &superrootAPI{s: s}
 	out, err := api.AtTimestamp(context.Background(), 123)
 	require.NoError(t, err)
-	require.Len(t, out.CurrentL1Derived, 2)
-	require.Len(t, out.VerifiedAtTimestamp, 2)
 	require.Len(t, out.OptimisticAtTimestamp, 2)
 	// min values
-	require.Equal(t, uint64(2000), out.MinCurrentL1.Number)
-	require.Equal(t, uint64(1000), out.MinVerifiedRequiredL1.Number)
+	require.Equal(t, uint64(2000), out.CurrentL1.Number)
+	require.Equal(t, uint64(1000), out.Data.VerifiedRequiredL1.Number)
 	// With zero outputs, the superroot will be deterministic, just ensure it's set
-	_ = out.SuperRoot
+	_ = out.Data.SuperRoot
 }
 
 func TestSuperroot_AtTimestamp_ComputesSuperRoot(t *testing.T) {
@@ -141,7 +140,7 @@ func TestSuperroot_AtTimestamp_ComputesSuperRoot(t *testing.T) {
 		{ChainID: eth.ChainIDFromUInt64(420), Output: out2},
 	}
 	expected := eth.SuperRoot(eth.NewSuperV1(ts, chainOutputs...))
-	require.Equal(t, expected, resp.SuperRoot)
+	require.Equal(t, expected, resp.Data.SuperRoot)
 }
 
 func TestSuperroot_AtTimestamp_ErrorOnCurrentL1(t *testing.T) {
@@ -170,6 +169,30 @@ func TestSuperroot_AtTimestamp_ErrorOnVerifiedAt(t *testing.T) {
 	require.Error(t, err)
 }
 
+func TestSuperroot_AtTimestamp_NotFoundOnVerifiedAt(t *testing.T) {
+	t.Parallel()
+	chains := map[eth.ChainID]cc.ChainContainer{
+		eth.ChainIDFromUInt64(10): &mockCC{
+			verifiedErr: fmt.Errorf("nope: %w", ethereum.NotFound),
+		},
+		eth.ChainIDFromUInt64(11): &mockCC{
+			verL2:     eth.BlockID{Number: 200},
+			verL1:     eth.BlockID{Number: 1100},
+			optL2:     eth.BlockID{Number: 200},
+			optL1:     eth.BlockID{Number: 1100},
+			output:    eth.Bytes32{0x12},
+			currentL1: eth.BlockRef{Number: 2100},
+		},
+	}
+	s := New(gethlog.New(), chains)
+	api := &superrootAPI{s: s}
+	actual, err := api.AtTimestamp(context.Background(), 123)
+	require.NoError(t, err)
+	require.Nil(t, actual.Data)
+	require.NotContains(t, actual.OptimisticAtTimestamp, eth.ChainIDFromUInt64(10))
+	require.Contains(t, actual.OptimisticAtTimestamp, eth.ChainIDFromUInt64(11))
+}
+
 func TestSuperroot_AtTimestamp_ErrorOnOutputRoot(t *testing.T) {
 	t.Parallel()
 	chains := map[eth.ChainID]cc.ChainContainer{
@@ -206,8 +229,6 @@ func TestSuperroot_AtTimestamp_EmptyChains(t *testing.T) {
 	api := &superrootAPI{s: s}
 	out, err := api.AtTimestamp(context.Background(), 123)
 	require.NoError(t, err)
-	require.Len(t, out.CurrentL1Derived, 0)
-	require.Len(t, out.VerifiedAtTimestamp, 0)
 	require.Len(t, out.OptimisticAtTimestamp, 0)
 }
 
diff --git a/op-supernode/supernode/chain_container/chain_container.go b/op-supernode/supernode/chain_container/chain_container.go
index 0e262ee94db1c..f3122b0be240f 100644
--- a/op-supernode/supernode/chain_container/chain_container.go
+++ b/op-supernode/supernode/chain_container/chain_container.go
@@ -276,6 +276,7 @@ func (c *simpleChainContainer) CurrentL1(ctx context.Context) (eth.BlockRef, err
 }
 
 // VerifiedAt returns the verified L2 and L1 blocks for the given L2 timestamp.
+// Must return ethereum.NotFound if there is no safe block at the specified timestamp.
 func (c *simpleChainContainer) VerifiedAt(ctx context.Context, ts uint64) (l2, l1 eth.BlockID, err error) {
 	l2Block, err := c.SafeBlockAtTimestamp(ctx, ts)
 	if err != nil {
diff --git a/op-supernode/supernode/chain_container/engine_controller/engine_controller.go b/op-supernode/supernode/chain_container/engine_controller/engine_controller.go
index 1fbe41706b2d8..1da93c3a93d83 100644
--- a/op-supernode/supernode/chain_container/engine_controller/engine_controller.go
+++ b/op-supernode/supernode/chain_container/engine_controller/engine_controller.go
@@ -9,6 +9,7 @@ import (
 	"github.com/ethereum-optimism/optimism/op-service/eth"
 	opmetrics "github.com/ethereum-optimism/optimism/op-service/metrics"
 	"github.com/ethereum-optimism/optimism/op-service/sources"
+	"github.com/ethereum/go-ethereum"
 	gethlog "github.com/ethereum/go-ethereum/log"
 )
 
@@ -16,6 +17,7 @@ import (
 type EngineController interface {
 	// SafeBlockAtTimestamp returns the L2 block ref for the block at or before the given timestamp,
 	// clamped to the current SAFE head.
+	// Must return ethereum.NotFound if there is no safe block at the specified timestamp.
 	SafeBlockAtTimestamp(ctx context.Context, ts uint64) (eth.L2BlockRef, error)
 	// OutputV0AtBlockNumber returns the output preimage for the given L2 block number.
 	OutputV0AtBlockNumber(ctx context.Context, num uint64) (*eth.OutputV0, error)
@@ -60,9 +62,10 @@ func NewEngineControllerFromConfig(ctx context.Context, log gethlog.Logger, vncf
 var (
 	ErrNoEngineClient = errors.New("engine client not initialized")
 	ErrNoRollupConfig = errors.New("rollup config not available")
-	ErrNotFound       = errors.New("not found")
 )
 
+// SafeBlockAtTimestamp returns the L2 block ref for the block at or before the given timestamp,
+// clamped to the current SAFE head. Must return ethereum.NotFound if no safe block is available at the timestamp.
 func (e *simpleEngineController) SafeBlockAtTimestamp(ctx context.Context, ts uint64) (eth.L2BlockRef, error) {
 	if e.l2 == nil {
 		return eth.L2BlockRef{}, ErrNoEngineClient
@@ -81,7 +84,7 @@ func (e *simpleEngineController) SafeBlockAtTimestamp(ctx context.Context, ts ui
 	}
 	if num > safeHead.Number {
 		e.log.Warn("engine_controller: target block number exceeds safe head", "targetBlockNumber", num, "safeHead", safeHead.Number)
-		return eth.L2BlockRef{}, ErrNotFound
+		return eth.L2BlockRef{}, ethereum.NotFound
 	}
 	e.log.Debug("engine_controller: computed safe block number from timestamp",
 		"timestamp", ts, "targetBlockNumber", num, "safeHead", safeHead.Number, "safeHeadErr", err)
diff --git a/op-supernode/supernode/chain_container/engine_controller/engine_controller_test.go b/op-supernode/supernode/chain_container/engine_controller/engine_controller_test.go
index 6545b15f7ef20..013544f985d49 100644
--- a/op-supernode/supernode/chain_container/engine_controller/engine_controller_test.go
+++ b/op-supernode/supernode/chain_container/engine_controller/engine_controller_test.go
@@ -7,6 +7,7 @@ import (
 
 	"github.com/ethereum-optimism/optimism/op-node/rollup"
 	"github.com/ethereum-optimism/optimism/op-service/eth"
+	"github.com/ethereum/go-ethereum"
 	"github.com/ethereum/go-ethereum/common"
 	gethlog "github.com/ethereum/go-ethereum/log"
 	"github.com/stretchr/testify/require"
@@ -94,7 +95,7 @@ func TestEngineController_TargetBlockNumber(t *testing.T) {
 	require.Equal(t, m.ref, numRef)
 	// ts = genesis + 2*1000 => block #1000, with safe head now below target
 	_, err = ec.SafeBlockAtTimestamp(context.Background(), 1_000+2*1000)
-	require.ErrorIs(t, err, ErrNotFound)
+	require.ErrorIs(t, err, ethereum.NotFound)
 }
 
 func TestEngineController_SentinelErrors(t *testing.T) {