fix(tz): server-side timezone conversion for all user-facing time displays

The audit showed only 5 of ~11 time-display surfaces converted to the
user's timezone; everything else rendered pgx-decoded UTC. The server
owns conversion — clients (web/app/KOReader) receive display-ready
strings or machine-readable instants and never convert.

- Progress page: LastUpdated formatted in the requesting user's tz
  (was raw UTC).
- Analytics: date-range defaults, day buckets, most-active-day, device
  last-sync, and popular-book last-read all computed in the user's tz —
  evening sessions no longer land on the next UTC day. Also fixed the
  end-date boundary: the query bounds with <= and the end bound was
  midnight, so the end date's own sessions (including 'today') never
  appeared.
- Queue page: new created_at_display field (admin tz) rendered by the
  template; created_at stays RFC3339 for API consumers.
- Admin hash-conflicts SSR bridge: detected date rendered in the
  admin's tz.
- OPDS: .UTC() before the Z-suffixed feed timestamps (honesty fix —
  correct today only because the session zone happens to be UTC).
- KOReader annotation datetimes deliberately untouched (device owns its
  display).

internal/handlers/analytics.go

@@ -2,6 +2,7 @@ package handlers
 
 import (
 	"bookhoard/internal/database"
+	"bookhoard/internal/utils"
 	"context"
 	"errors"
 	"fmt"
@@ -74,22 +75,32 @@ func (h *AnalyticsHandler) GetReadingStats(c *echo.Context) error {
 	startDate := c.QueryParam("start_date")
 	endDate := c.QueryParam("end_date")
 
+	// All range boundaries and day buckets are computed in the REQUESTING
+	// USER'S timezone: "today" and "which day did this session land on" are
+	// per-user calendar concepts, not UTC ones.
+	loc := utils.UserLocation(user.Timezone.String)
+	now := time.Now().In(loc)
+
 	if startDate == "" {
-		startDate = time.Now().AddDate(0, -1, 0).Format("01-02-2006")
+		startDate = now.AddDate(0, -1, 0).Format("01-02-2006")
 	}
 	if endDate == "" {
-		endDate = time.Now().Format("01-02-2006")
+		endDate = now.Format("01-02-2006")
 	}
 
-	startTime, err := time.Parse("01-02-2006", startDate)
+	startTime, err := time.ParseInLocation("01-02-2006", startDate, loc)
 	if err != nil {
 		return echo.NewHTTPError(http.StatusBadRequest, "invalid start_date format")
 	}
 
-	endTime, err := time.Parse("01-02-2006", endDate)
+	endTime, err := time.ParseInLocation("01-02-2006", endDate, loc)
 	if err != nil {
 		return echo.NewHTTPError(http.StatusBadRequest, "invalid end_date format")
 	}
+	// The query bounds with <=, so the end bound must be the last instant
+	// OF the end date — otherwise the end date's own sessions (including
+	// "today") never appear.
+	endTime = endTime.AddDate(0, 0, 1).Add(-time.Nanosecond)
 
 	ctx := context.Background()
 
@@ -103,12 +114,12 @@ func (h *AnalyticsHandler) GetReadingStats(c *echo.Context) error {
 		return echo.NewHTTPError(http.StatusInternalServerError, "failed to get reading history")
 	}
 
-	stats := h.calculateReadingStats(history)
+	stats := h.calculateReadingStats(history, loc)
 
 	return c.JSON(http.StatusOK, stats)
 }
 
-func (h *AnalyticsHandler) calculateReadingStats(history []database.GetUserReadingHistoryRow) ReadingStatsResponse {
+func (h *AnalyticsHandler) calculateReadingStats(history []database.GetUserReadingHistoryRow, loc *time.Location) ReadingStatsResponse {
 	stats := ReadingStatsResponse{
 		DailyReadingMinutes: make([]DailyReading, 0),
 	}
@@ -130,7 +141,7 @@ func (h *AnalyticsHandler) calculateReadingStats(history []database.GetUserReadi
 				longestSession = int(minutes)
 			}
 
-			dateKey := entry.CreatedAt.Time.Format("01-02-2006")
+			dateKey := entry.CreatedAt.Time.In(loc).Format("01-02-2006")
 			if dailyMap[dateKey] == nil {
 				dailyMap[dateKey] = &DailyReading{
 					Date: dateKey,
@@ -141,7 +152,7 @@ func (h *AnalyticsHandler) calculateReadingStats(history []database.GetUserReadi
 
 		if entry.PagesRead.Valid {
 			totalPages += int(entry.PagesRead.Int32)
-			dateKey := entry.CreatedAt.Time.Format("01-02-2006")
+			dateKey := entry.CreatedAt.Time.In(loc).Format("01-02-2006")
 			if dailyMap[dateKey] != nil {
 				dailyMap[dateKey].Pages += int(entry.PagesRead.Int32)
 			}
@@ -174,7 +185,7 @@ func (h *AnalyticsHandler) calculateReadingStats(history []database.GetUserReadi
 		stats.CompletionRate = float64(booksCompleted) / float64(totalBooks)
 	}
 
-	stats.MostActiveDay = h.calculateMostActiveDay(history)
+	stats.MostActiveDay = h.calculateMostActiveDay(history, loc)
 
 	for _, data := range dailyMap {
 		stats.DailyReadingMinutes = append(stats.DailyReadingMinutes, *data)
@@ -183,13 +194,13 @@ func (h *AnalyticsHandler) calculateReadingStats(history []database.GetUserReadi
 	return stats
 }
 
-func (h *AnalyticsHandler) calculateMostActiveDay(history []database.GetUserReadingHistoryRow) string {
+func (h *AnalyticsHandler) calculateMostActiveDay(history []database.GetUserReadingHistoryRow, loc *time.Location) string {
 	dayCount := make(map[string]int)
 
 	days := []string{"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"}
 
 	for _, entry := range history {
-		day := days[entry.CreatedAt.Time.Weekday()]
+		day := days[entry.CreatedAt.Time.In(loc).Weekday()]
 		dayCount[day]++
 	}
 
@@ -222,7 +233,7 @@ func (h *AnalyticsHandler) GetDeviceUsage(c *echo.Context) error {
 		lastSync := ""
 		if u.LastSync != nil {
 			if t, ok := u.LastSync.(time.Time); ok {
-				lastSync = t.Format("01-02-2006 03:04:05 PM")
+				lastSync = utils.FormatTimeInTimezone(t, user.Timezone.String)
 			}
 		}
 
@@ -274,7 +285,7 @@ func (h *AnalyticsHandler) GetPopularBooks(c *echo.Context) error {
 		lastRead := ""
 		if book.LastRead != nil {
 			if t, ok := book.LastRead.(time.Time); ok {
-				lastRead = t.Format("01-02-2006 03:04:05 PM")
+				lastRead = utils.FormatTimeInTimezone(t, user.Timezone.String)
 			}
 		}
 

internal/handlers/opds.go

@@ -402,7 +402,7 @@ func (h *OPDSHandler) addAcquisitionEntries(ctx context.Context, feed *opds.Feed
 			author = item.Author.String
 		}
 
-		updated := item.UpdatedAt.Time.Format("2006-01-02T15:04:05Z")
+		updated := item.UpdatedAt.Time.UTC().Format("2006-01-02T15:04:05Z")
 
 		entry := opds.NewEntry(
 			fmt.Sprintf("urn:uuid:%s", bookUUID),
@@ -706,7 +706,7 @@ func (h *OPDSHandler) SearchDeviceCatalog(c *echo.Context) error {
 			author = item.Author.String
 		}
 
-		updated := item.UpdatedAt.Time.Format("2006-01-02T15:04:05Z")
+		updated := item.UpdatedAt.Time.UTC().Format("2006-01-02T15:04:05Z")
 
 		entry := opds.NewEntry(
 			fmt.Sprintf("urn:uuid:%s", bookUUID),

internal/handlers/progress.go

@@ -191,7 +191,7 @@ func (h *Handler) GetAllProgress(c *echo.Context) error {
 
 		lastUpdated := ""
 		if progress.LastReadAt.Valid {
-			lastUpdated = progress.LastReadAt.Time.Format("01-02-2006 03:04 PM")
+			lastUpdated = utils.FormatTimeInTimezone(progress.LastReadAt.Time, user.Timezone.String)
 		}
 
 		progressList = append(progressList, ProgressWithMedia{
@@ -261,7 +261,7 @@ func (h *Handler) GetAllProgressData(c *echo.Context) ([]ProgressWithMedia, erro
 
 		lastUpdated := ""
 		if progress.LastReadAt.Valid {
-			lastUpdated = progress.LastReadAt.Time.Format("01-02-2006 03:04 PM")
+			lastUpdated = utils.FormatTimeInTimezone(progress.LastReadAt.Time, user.Timezone.String)
 		}
 
 		progressList = append(progressList, ProgressWithMedia{

internal/handlers/queue.go

@@ -2,6 +2,7 @@ package handlers
 
 import (
 	"bookhoard/internal/database"
+	"bookhoard/internal/utils"
 	"context"
 	"net/http"
 	"strconv"
@@ -47,6 +48,10 @@ type QueueItemResponse struct {
 	Status       string  `json:"status"`
 	ErrorMessage *string `json:"error_message,omitempty"`
 	CreatedAt    string  `json:"created_at"`
+	// CreatedAtDisplay is the server-rendered wall-clock string in the
+	// requesting admin's timezone (templates render this; created_at stays
+	// machine-readable RFC3339 for API consumers).
+	CreatedAtDisplay string  `json:"created_at_display,omitempty"`
 	ProcessedAt      *string `json:"processed_at,omitempty"`
 }
 
@@ -136,6 +141,8 @@ func (h *QueueHandler) ListDeviceQueueItems(c *echo.Context) error {
 			Status:       item.Status.String,
 			ErrorMessage: textPtrToString(item.ErrorMessage),
 			CreatedAt:    item.CreatedAt.Time.Format("2006-01-02T15:04:05Z07:00"),
+			CreatedAtDisplay: utils.FormatTimeInTimezone(
+				item.CreatedAt.Time, user.Timezone.String),
 			ProcessedAt: timestamptzPtrToString(item.ProcessedAt),
 		})
 	}
@@ -189,6 +196,8 @@ func (h *QueueHandler) GetQueueData(c *echo.Context) ([]QueueItemResponse, error
 			Status:       item.Status.String,
 			ErrorMessage: textPtrToString(item.ErrorMessage),
 			CreatedAt:    item.CreatedAt.Time.Format("2006-01-02T15:04:05Z07:00"),
+			CreatedAtDisplay: utils.FormatTimeInTimezone(
+				item.CreatedAt.Time, user.Timezone.String),
 			ProcessedAt: timestamptzPtrToString(item.ProcessedAt),
 		})
 	}

internal/router/frontend.go

@@ -1071,7 +1071,7 @@ func registerFrontendRoutes(cfg *Config) {
 				LibraryName: p.LibraryName,
 				SHA256:      p.FileSha256,
 				SHAShort:    p.FileSha256[:16] + "…",
-				CreatedAt:   p.CreatedAt.Time.Format("Jan 2, 2006"),
+				CreatedAt: p.CreatedAt.Time.In(utils.UserLocation(user.Timezone)).Format("Jan 2, 2006"),
 				Items:       []templates.HashConflictItemData{},
 			}
 

internal/utils/timeformat.go

@@ -0,0 +1,31 @@
+package utils
+
+import (
+	"time"
+)
+
+// UserLocation resolves an IANA timezone name to a *time.Location, falling
+// back to UTC for empty or invalid values. The single resolution point for
+// server-side display conversion: the server owns timezone rendering, so
+// clients receive display-ready strings (or tz-aware instants) and never
+// convert themselves.
+func UserLocation(timezone string) *time.Location {
+	if timezone == "" {
+		return time.UTC
+	}
+	loc, err := time.LoadLocation(timezone)
+	if err != nil || loc == nil {
+		return time.UTC
+	}
+	return loc
+}
+
+// FormatTimeInTimezone renders t in the given IANA timezone as
+// MM-DD-YYYY HH:MM AM/PM (the established display format across the
+// templates). Zero times render empty.
+func FormatTimeInTimezone(t time.Time, timezone string) string {
+	if t.IsZero() {
+		return ""
+	}
+	return t.In(UserLocation(timezone)).Format("01-02-2006 03:04 PM")
+}

templates/queue.templ

@@ -140,7 +140,7 @@ templ Queue(user User, queueItems []handlers.QueueItemResponse, stats handlers.Q
 							</div>
 							<div class="flex justify-between items-center text-sm" style="color: var(--text-secondary)">
 								<span>Attempts: { item.Attempts }/{ item.MaxAttempts }</span>
-								<span>{ item.CreatedAt }</span>
+								<span>{ item.CreatedAtDisplay }</span>
 							</div>
 							if item.ErrorMessage != nil {
 								<div class="mt-2 text-sm flex items-start gap-2" style="color: var(--status-danger);">

templates/queue_templ.go

@@ -244,9 +244,9 @@ func Queue(user User, queueItems []handlers.QueueItemResponse, stats handlers.Qu
 				return templ_7745c5c3_Err
 			}
 			var templ_7745c5c3_Var13 string
-			templ_7745c5c3_Var13, templ_7745c5c3_Err = templ.JoinStringErrs(item.CreatedAt)
+			templ_7745c5c3_Var13, templ_7745c5c3_Err = templ.JoinStringErrs(item.CreatedAtDisplay)
 			if templ_7745c5c3_Err != nil {
-				return templ.Error{Err: templ_7745c5c3_Err, FileName: `queue.templ`, Line: 143, Col: 30}
+				return templ.Error{Err: templ_7745c5c3_Err, FileName: `queue.templ`, Line: 143, Col: 37}
 			}
 			_, templ_7745c5c3_Err = templ_7745c5c3_Buffer.WriteString(templ.EscapeString(templ_7745c5c3_Var13))
 			if templ_7745c5c3_Err != nil {