review: add optional applied_at to TelemetryState for observability

Author: archandatta

server/cmd/api/api/telemetry.go

@@ -98,10 +98,14 @@ func (s *ApiService) PatchTelemetry(_ context.Context, req oapi.PatchTelemetryRe
 
 // buildTelemetryResponse constructs a TelemetryState response from the current configuration.
 func (s *ApiService) buildTelemetryResponse() oapi.TelemetryState {
-	return oapi.TelemetryState{
+	resp := oapi.TelemetryState{
 		Config: telemetryConfigToOAPI(s.telemetrySession.Config()),
 		Seq:    int64(s.telemetrySession.Seq()),
 	}
+	if appliedAt := s.telemetrySession.AppliedAt(); !appliedAt.IsZero() {
+		resp.AppliedAt = &appliedAt
+	}
+	return resp
 }
 
 // telemetryConfigFromOAPI converts an *oapi.BrowserTelemetryConfig to a telemetry.TelemetryConfig.

server/cmd/api/api/telemetry_test.go

@@ -76,6 +76,8 @@ func TestPutTelemetry(t *testing.T) {
 		r201, ok := resp.(oapi.PutTelemetry201JSONResponse)
 		require.True(t, ok, "expected 201, got %T", resp)
 		require.NotNil(t, r201.Config.Browser)
+		require.NotNil(t, r201.AppliedAt)
+		assert.False(t, r201.AppliedAt.IsZero())
 	})
 
 	t.Run("creates session with config (201)", func(t *testing.T) {
@@ -136,6 +138,7 @@ func TestPutTelemetry(t *testing.T) {
 		assert.False(t, *r200.Config.Browser.Network.Enabled)
 		assert.False(t, *r200.Config.Browser.Page.Enabled)
 		assert.False(t, *r200.Config.Browser.Interaction.Enabled)
+		assert.Nil(t, r200.AppliedAt, "applied_at must be omitted when telemetry is unconfigured")
 	})
 }
 

server/e2e/e2e_s2_storage_test.go

@@ -80,7 +80,7 @@ func TestS2StorageWriter(t *testing.T) {
 	})
 	require.NoError(t, err)
 	require.Equal(t, http.StatusOK, stopResp.StatusCode(), "patch telemetry: %s", string(stopResp.Body))
-	t.Log("telemetry session stopped")
+	t.Log("telemetry configuration cleared")
 
 	// Give the storage writer time to flush to S2 (batcher linger + network).
 	time.Sleep(2 * time.Second)