diff --git a/sender/dispatcher.go b/sender/dispatcher.go
index 3e0c5c7..b3614c9 100644
--- a/sender/dispatcher.go
+++ b/sender/dispatcher.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"log"
 	"sync"
+	"time"
 
 	"github.com/sei-protocol/sei-load/generator"
 	"github.com/sei-protocol/sei-load/stats"
@@ -95,6 +96,10 @@ func (d *Dispatcher) Run(ctx context.Context) error {
 			return nil
 		}
 
+		// Stamp before hand-off: the dispatcher is sole owner here (tx just
+		// returned by the generator, not yet enqueued), so this write is race-free.
+		tx.IntendedSendTime = time.Now()
+
 		// Send the transaction
 		if err := d.sender.Send(ctx, tx); err != nil {
 			return err
@@ -117,6 +122,9 @@ func (d *Dispatcher) RunBatch(ctx context.Context, count int) error {
 		if !ok {
 			return fmt.Errorf("dispatcher: generator returned nil transaction (batch %d/%d)", i+1, count)
 		}
+		// Stamp before hand-off (see Run).
+		tx.IntendedSendTime = time.Now()
+
 		// Send the transaction
 		if err := d.sender.Send(ctx, tx); err != nil {
 			log.Printf("Dispatcher: Failed to send transaction %d/%d: %v", i+1, count, err)
diff --git a/sender/worker.go b/sender/worker.go
index 3c15862..9b48a8a 100644
--- a/sender/worker.go
+++ b/sender/worker.go
@@ -239,6 +239,9 @@ func (w *Worker) processTransactions(ctx context.Context, client *http.Client) e
 		}
 
 		startTime := time.Now()
+		// This goroutine solely owns tx between dequeue and the sentTxs hand-off,
+		// so stamping the actual send-attempt time here is race-free (see LoadTx).
+		tx.AttemptedSendTime = startTime
 		err = w.sendTransaction(ctx, client, tx)
 		// Record statistics if collector is available
 		if w.collector != nil {
diff --git a/types/scenario.go b/types/scenario.go
index 754e8cf..db5e6a7 100644
--- a/types/scenario.go
+++ b/types/scenario.go
@@ -4,17 +4,38 @@ import (
 	"encoding/json"
 	"fmt"
 	"math/big"
+	"time"
 
 	"github.com/ethereum/go-ethereum/common"
 	ethtypes "github.com/ethereum/go-ethereum/core/types"
 )
 
 // LoadTx is a wrapper that has pre-encoded json rpc payload and eth transaction.
+//
+// Lifecycle timestamp concurrency contract: a *LoadTx is passed by pointer
+// through buffered channels (txChan, sentTxs). Each lifecycle timestamp is
+// written at most once, by whichever goroutine owns the tx at that stage, and
+// is immutable thereafter; ownership transfers with the pointer across the
+// channels, so the writes need no locking. A zero timestamp means "not
+// recorded" (e.g. prewarm txs, or a stage not yet reached) — consumers must
+// treat it as untracked, never as the zero epoch.
 type LoadTx struct {
 	EthTx          *ethtypes.Transaction
 	JSONRPCPayload []byte
 	Payload        []byte
 	Scenario       *TxScenario
+
+	// IntendedSendTime is when the tx was scheduled to be sent, written by the
+	// dispatcher before the tx is enqueued. It currently holds the enqueue time,
+	// which is back-pressured under load; until an open-loop scheduler sets it to
+	// the intended schedule instant, it must not be used to derive latency.
+	IntendedSendTime time.Time
+	// AttemptedSendTime is when the send was actually attempted, written by the
+	// worker goroutine that owns the tx between dequeue and the sentTxs hand-off.
+	AttemptedSendTime time.Time
+	// InclusionTime is when the tx was observed included on-chain, written only
+	// by the inclusion tracker.
+	InclusionTime time.Time
 }
 
 // JSONRPCRequest represents json rpc request.