From 7a8e287ce6afe0be523e096adc9e96a89e291211 Mon Sep 17 00:00:00 2001
From: DTTerastar <DT@Terastar.biz>
Date: Tue, 21 Apr 2026 20:43:20 -0400
Subject: [PATCH] fix: resolve dates and display timestamps in local time
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Two bug classes mirrored the fixes in crono-export-cli#5 and
liftoff-export-cli#14:

1. parseSince used bare time.Parse("2006-01-02", s), which defaults to
   UTC. When the parsed time flowed into a Unix-epoch API parameter
   (measurements startdate, intraday chunk bounds), the epoch was off
   by the user's UTC offset — so --since 2026-04-15 in EDT actually
   asked Withings for data starting 2026-04-14 20:00 EDT. Switched to
   time.ParseInLocation(..., time.Local).

2. Sleep, workout, measurement, and intraday Unix timestamps were
   converted with .UTC() before RFC3339 formatting, so CSV/JSON output
   rendered all times as UTC instead of the user's local zone. A
   10:30pm PST sleep session showed as 06:30Z the next day. Switched
   every display-side .UTC() → .Local(). Renamed the intraday CSV
   column datetime_utc → datetime to match.

JSON output is unaffected for struct fields that ride Go's default
time.Time marshaler (already RFC3339 with whatever zone the time.Time
carries); Unix-epoch fields (int64) were never timezone-dependent.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
---
 cmd/intraday.go     | 4 ++--
 cmd/measurements.go | 2 +-
 cmd/shared.go       | 2 +-
 cmd/sleep.go        | 4 ++--
 cmd/workouts.go     | 4 ++--
 5 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/cmd/intraday.go b/cmd/intraday.go
index 9f29411..fc8fd46 100644
--- a/cmd/intraday.go
+++ b/cmd/intraday.go
@@ -129,7 +129,7 @@ func writeIntradayCSV(samples []intradaySample) error {
 	w := csv.NewWriter(os.Stdout)
 	defer w.Flush()
 	header := []string{
-		"timestamp", "datetime_utc", "duration_sec",
+		"timestamp", "datetime", "duration_sec",
 		"steps", "distance_m", "elevation_m", "calories",
 		"heart_rate", "hrv_rmssd", "hrv_sdnn1", "hrv_quality", "spo2_auto",
 		"model", "model_id",
@@ -140,7 +140,7 @@ func writeIntradayCSV(samples []intradaySample) error {
 	for _, s := range samples {
 		row := []string{
 			strconv.FormatInt(s.Timestamp, 10),
-			time.Unix(s.Timestamp, 0).UTC().Format(time.RFC3339),
+			time.Unix(s.Timestamp, 0).Local().Format(time.RFC3339),
 			strconv.Itoa(s.Duration),
 			strconv.Itoa(s.Steps),
 			strconv.FormatFloat(s.Distance, 'f', -1, 64),
diff --git a/cmd/measurements.go b/cmd/measurements.go
index 9214aa1..2f8ced7 100644
--- a/cmd/measurements.go
+++ b/cmd/measurements.go
@@ -101,7 +101,7 @@ var measurementsCmd = &cobra.Command{
 				return err
 			}
 			for _, g := range resp.Measuregrps {
-				t := time.Unix(g.Date, 0).UTC()
+				t := time.Unix(g.Date, 0).Local()
 				for _, m := range g.Measures {
 					value := float64(m.Value) * math.Pow10(m.Unit)
 					name, ok := measureTypeNames[m.Type]
diff --git a/cmd/shared.go b/cmd/shared.go
index b1fa6a1..3b00a63 100644
--- a/cmd/shared.go
+++ b/cmd/shared.go
@@ -13,7 +13,7 @@ func parseSince(s string) (time.Time, error) {
 	if s == "" {
 		return time.Time{}, nil
 	}
-	if t, err := time.Parse("2006-01-02", s); err == nil {
+	if t, err := time.ParseInLocation("2006-01-02", s, time.Local); err == nil {
 		return t, nil
 	}
 	if len(s) < 2 {
diff --git a/cmd/sleep.go b/cmd/sleep.go
index bd737f9..66c6f17 100644
--- a/cmd/sleep.go
+++ b/cmd/sleep.go
@@ -302,8 +302,8 @@ func writeSleepCSV(series []sleepSeries) error {
 		}
 		_ = json.Unmarshal(s.Data, &d)
 
-		start := time.Unix(s.StartDate, 0).UTC()
-		end := time.Unix(s.EndDate, 0).UTC()
+		start := time.Unix(s.StartDate, 0).Local()
+		end := time.Unix(s.EndDate, 0).Local()
 		totalSleepMin := (d.Light + d.Deep + d.REM) / 60
 
 		row := []string{
diff --git a/cmd/workouts.go b/cmd/workouts.go
index 7cbaa51..d9bded3 100644
--- a/cmd/workouts.go
+++ b/cmd/workouts.go
@@ -163,8 +163,8 @@ func writeWorkoutsCSV(series []workoutSeries) error {
 		}
 		_ = json.Unmarshal(s.Data, &d)
 
-		start := time.Unix(s.StartDate, 0).UTC()
-		end := time.Unix(s.EndDate, 0).UTC()
+		start := time.Unix(s.StartDate, 0).Local()
+		end := time.Unix(s.EndDate, 0).Local()
 		category := workoutCategoryNames[s.Category]
 		if category == "" {
 			category = "unknown"