diff --git a/cmd/activity.go b/cmd/activity.go
index b2be778..a9b27d9 100644
--- a/cmd/activity.go
+++ b/cmd/activity.go
@@ -49,6 +49,12 @@ var activityCmd = &cobra.Command{
 	Use:   "activity",
 	Short: "Export daily activity (steps, distance, calories, HR zones)",
 	RunE: func(cmd *cobra.Command, args []string) error {
+		// Parse-level flag validation runs before any network call so an
+		// invalid --format exits non-zero hermetically (CONTRACT §4).
+		format, err := validateFormat(activityFormatFlag)
+		if err != nil {
+			return err
+		}
 		since, err := sinceOrDefault(activitySinceFlag, 30)
 		if err != nil {
 			return err
@@ -83,10 +89,6 @@ var activityCmd = &cobra.Command{
 
 		sort.Slice(all, func(i, j int) bool { return all[i].Date < all[j].Date })
 
-		format, err := validateFormat(activityFormatFlag)
-		if err != nil {
-			return err
-		}
 		switch format {
 		case "json":
 			return printJSON(all)
diff --git a/cmd/intraday.go b/cmd/intraday.go
index 3becff9..103a7f7 100644
--- a/cmd/intraday.go
+++ b/cmd/intraday.go
@@ -69,6 +69,12 @@ spo2_auto, steps and distance; native Withings trackers report steps and HR.
 
 Default window is the last 24h — intraday is dense; wider ranges are slow.`,
 	RunE: func(cmd *cobra.Command, args []string) error {
+		// Parse-level flag validation runs before any network call so an
+		// invalid --format exits non-zero hermetically (CONTRACT §4).
+		format, err := validateFormat(intradayFormatFlag)
+		if err != nil {
+			return err
+		}
 		since, err := sinceOrDefault(intradaySinceFlag, 1)
 		if err != nil {
 			return err
@@ -124,10 +130,6 @@ Default window is the last 24h — intraday is dense; wider ranges are slow.`,
 
 		sort.Slice(all, func(i, j int) bool { return all[i].Timestamp < all[j].Timestamp })
 
-		format, err := validateFormat(intradayFormatFlag)
-		if err != nil {
-			return err
-		}
 		switch format {
 		case "json":
 			return printJSON(all)
diff --git a/cmd/measurements.go b/cmd/measurements.go
index d75dda6..4faafe7 100644
--- a/cmd/measurements.go
+++ b/cmd/measurements.go
@@ -80,6 +80,12 @@ var measurementsCmd = &cobra.Command{
 	Use:   "measurements",
 	Short: "Export body measurements (weight, body fat, BP, etc.)",
 	RunE: func(cmd *cobra.Command, args []string) error {
+		// Parse-level flag validation runs before any network call so an
+		// invalid --format exits non-zero hermetically (CONTRACT §4).
+		format, err := validateFormat(measurementsFormatFlag)
+		if err != nil {
+			return err
+		}
 		since, err := sinceOrDefault(measurementsSinceFlag, 30)
 		if err != nil {
 			return err
@@ -131,10 +137,6 @@ var measurementsCmd = &cobra.Command{
 
 		sort.Slice(rows, func(i, j int) bool { return rows[i].Date.Before(rows[j].Date) })
 
-		format, err := validateFormat(measurementsFormatFlag)
-		if err != nil {
-			return err
-		}
 		switch format {
 		case "json":
 			return printJSON(rows)
diff --git a/cmd/sleep.go b/cmd/sleep.go
index b1a20f2..f23e91a 100644
--- a/cmd/sleep.go
+++ b/cmd/sleep.go
@@ -44,6 +44,12 @@ var sleepCmd = &cobra.Command{
 	Use:   "sleep",
 	Short: "Export nightly sleep summaries",
 	RunE: func(cmd *cobra.Command, args []string) error {
+		// Parse-level flag validation runs before any network call so an
+		// invalid --format exits non-zero hermetically (CONTRACT §4).
+		format, err := validateFormat(sleepFormatFlag)
+		if err != nil {
+			return err
+		}
 		since, err := sinceOrDefault(sleepSinceFlag, 30)
 		if err != nil {
 			return err
@@ -110,10 +116,6 @@ var sleepCmd = &cobra.Command{
 
 		sort.Slice(all, func(i, j int) bool { return all[i].StartDate < all[j].StartDate })
 
-		format, err := validateFormat(sleepFormatFlag)
-		if err != nil {
-			return err
-		}
 		switch format {
 		case "json":
 			return printJSON(all)
diff --git a/cmd/workouts.go b/cmd/workouts.go
index 0c65178..e465e1a 100644
--- a/cmd/workouts.go
+++ b/cmd/workouts.go
@@ -95,6 +95,12 @@ var workoutsCmd = &cobra.Command{
 	Use:   "workouts",
 	Short: "Export workouts (runs, walks, bikes, etc.)",
 	RunE: func(cmd *cobra.Command, args []string) error {
+		// Parse-level flag validation runs before any network call so an
+		// invalid --format exits non-zero hermetically (CONTRACT §4).
+		format, err := validateFormat(workoutsFormatFlag)
+		if err != nil {
+			return err
+		}
 		since, err := sinceOrDefault(workoutsSinceFlag, 90)
 		if err != nil {
 			return err
@@ -131,10 +137,6 @@ var workoutsCmd = &cobra.Command{
 
 		sort.Slice(all, func(i, j int) bool { return all[i].StartDate < all[j].StartDate })
 
-		format, err := validateFormat(workoutsFormatFlag)
-		if err != nil {
-			return err
-		}
 		switch format {
 		case "json":
 			return printJSON(all)