diff --git a/internal/experiment/webconnectivity/cleartextflow.go b/internal/experiment/webconnectivity/cleartextflow.go
index a1712d8a61..bae9859c73 100644
--- a/internal/experiment/webconnectivity/cleartextflow.go
+++ b/internal/experiment/webconnectivity/cleartextflow.go
@@ -224,6 +224,9 @@ func (t *CleartextFlow) httpTransaction(ctx context.Context, network, address, a
 	txp model.HTTPTransport, req *http.Request, trace *measurexlite.Trace) (*http.Response, []byte, error) {
 	const maxbody = 1 << 19
 	started := trace.TimeSince(trace.ZeroTime)
+	t.TestKeys.AppendNetworkEvents(measurexlite.NewAnnotationArchivalNetworkEvent(
+		trace.Index, started, "http_transaction_start",
+	))
 	resp, err := txp.RoundTrip(req)
 	var body []byte
 	if err == nil {
@@ -235,6 +238,9 @@ func (t *CleartextFlow) httpTransaction(ctx context.Context, network, address, a
 		body, err = netxlite.ReadAllContext(ctx, reader)
 	}
 	finished := trace.TimeSince(trace.ZeroTime)
+	t.TestKeys.AppendNetworkEvents(measurexlite.NewAnnotationArchivalNetworkEvent(
+		trace.Index, finished, "http_transaction_done",
+	))
 	ev := measurexlite.NewArchivalHTTPRequestResult(
 		trace.Index,
 		started,
diff --git a/internal/experiment/webconnectivity/secureflow.go b/internal/experiment/webconnectivity/secureflow.go
index dd837d356e..ee19242e2a 100644
--- a/internal/experiment/webconnectivity/secureflow.go
+++ b/internal/experiment/webconnectivity/secureflow.go
@@ -276,6 +276,9 @@ func (t *SecureFlow) httpTransaction(ctx context.Context, network, address, alpn
 	txp model.HTTPTransport, req *http.Request, trace *measurexlite.Trace) (*http.Response, []byte, error) {
 	const maxbody = 1 << 19
 	started := trace.TimeSince(trace.ZeroTime)
+	t.TestKeys.AppendNetworkEvents(measurexlite.NewAnnotationArchivalNetworkEvent(
+		trace.Index, started, "http_transaction_start",
+	))
 	resp, err := txp.RoundTrip(req)
 	var body []byte
 	if err == nil {
@@ -287,6 +290,9 @@ func (t *SecureFlow) httpTransaction(ctx context.Context, network, address, alpn
 		body, err = netxlite.ReadAllContext(ctx, reader)
 	}
 	finished := trace.TimeSince(trace.ZeroTime)
+	t.TestKeys.AppendNetworkEvents(measurexlite.NewAnnotationArchivalNetworkEvent(
+		trace.Index, finished, "http_transaction_done",
+	))
 	ev := measurexlite.NewArchivalHTTPRequestResult(
 		trace.Index,
 		started,
diff --git a/internal/experiment/webconnectivity/testkeys.go b/internal/experiment/webconnectivity/testkeys.go
index 9518943efa..4db7f3e71f 100644
--- a/internal/experiment/webconnectivity/testkeys.go
+++ b/internal/experiment/webconnectivity/testkeys.go
@@ -8,6 +8,7 @@ package webconnectivity
 //
 
 import (
+	"sort"
 	"sync"
 
 	"github.com/ooni/probe-cli/v3/internal/engine/experiment/webconnectivity"
@@ -328,4 +329,9 @@ func NewTestKeys() *TestKeys {
 // must be called from the measurer after all the tasks have completed.
 func (tk *TestKeys) Finalize(logger model.Logger) {
 	tk.analysisToplevel(logger)
+	// Note: sort.SliceStable is WAI when the input slice is nil
+	// as demonstrated by https://go.dev/play/p/znA4MyGFVHC
+	sort.SliceStable(tk.NetworkEvents, func(i, j int) bool {
+		return tk.NetworkEvents[i].T < tk.NetworkEvents[j].T
+	})
 }