fix(seahorse,session): preserve created_at across history bootstrap

pkg/agent/context_seahorse.go

@@ -6,6 +6,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"time"
 
 	"github.com/sipeed/picoclaw/pkg/logger"
 	"github.com/sipeed/picoclaw/pkg/providers"
@@ -200,6 +201,7 @@ func providerToSeahorseMessage(msg protocoltypes.Message) seahorse.Message {
 		ModelName:        msg.ModelName,
 		ReasoningContent: msg.ReasoningContent,
 		TokenCount:       tokenizer.EstimateMessageTokens(msg),
+		CreatedAt:        normalizeSeahorseMessageCreatedAt(msg.CreatedAt),
 	}
 
 	// Convert ToolCalls → MessageParts
@@ -235,6 +237,13 @@ func providerToSeahorseMessage(msg protocoltypes.Message) seahorse.Message {
 	return result
 }
 
+func normalizeSeahorseMessageCreatedAt(createdAt *time.Time) time.Time {
+	if createdAt == nil || createdAt.IsZero() {
+		return time.Time{}
+	}
+	return createdAt.UTC().Truncate(time.Second)
+}
+
 // seahorseToProviderMessages converts a seahorse.AssembleResult to []providers.Message.
 func seahorseToProviderMessages(result *seahorse.AssembleResult) []protocoltypes.Message {
 	messages := make([]protocoltypes.Message, 0, len(result.Messages))

pkg/agent/context_seahorse_test.go

@@ -171,11 +171,13 @@ func TestProviderToSeahorseMessageWithMedia(t *testing.T) {
 }
 
 func TestProviderToSeahorseMessageWithReasoning(t *testing.T) {
+	createdAt := time.Date(2026, 5, 6, 7, 8, 9, 123000000, time.UTC)
 	msg := protocoltypes.Message{
 		Role:             "assistant",
 		Content:          "response text",
 		ModelName:        "gpt-5.4-mini",
 		ReasoningContent: "I thought about this carefully",
+		CreatedAt:        &createdAt,
 	}
 
 	result := providerToSeahorseMessage(msg)
@@ -185,6 +187,9 @@ func TestProviderToSeahorseMessageWithReasoning(t *testing.T) {
 	if result.ModelName != "gpt-5.4-mini" {
 		t.Errorf("ModelName = %q, want %q", result.ModelName, "gpt-5.4-mini")
 	}
+	if !result.CreatedAt.Equal(time.Date(2026, 5, 6, 7, 8, 9, 0, time.UTC)) {
+		t.Errorf("CreatedAt = %v, want 2026-05-06 07:08:09 UTC", result.CreatedAt)
+	}
 }
 
 func TestSeahorseToProviderMessagesWithReasoning(t *testing.T) {

pkg/seahorse/short_engine.go

@@ -9,6 +9,7 @@ import (
 	"regexp"
 	"strings"
 	"sync"
+	"time"
 
 	_ "modernc.org/sqlite"
 
@@ -261,6 +262,7 @@ func (e *Engine) Ingest(ctx context.Context, sessionKey string, messages []Messa
 				msg.ModelName,
 				msg.ReasoningContent,
 				msg.TokenCount,
+				msg.CreatedAt,
 			)
 		} else {
 			added, err = e.store.AddMessageWithReasoning(
@@ -271,6 +273,7 @@ func (e *Engine) Ingest(ctx context.Context, sessionKey string, messages []Messa
 				msg.ModelName,
 				msg.ReasoningContent,
 				msg.TokenCount,
+				msg.CreatedAt,
 			)
 		}
 		if err != nil {
@@ -445,10 +448,14 @@ func (e *Engine) Bootstrap(ctx context.Context, sessionKey string, messages []Me
 	if err != nil {
 		return fmt.Errorf("bootstrap: repair model_name: %w", err)
 	}
-	if (repairedReasoning || repairedModelName) && len(dbMsgs) == len(messages) {
+	repairedCreatedAt, err := e.repairBootstrapCreatedAt(ctx, dbMsgs, messages)
+	if err != nil {
+		return fmt.Errorf("bootstrap: repair created_at: %w", err)
+	}
+	if (repairedReasoning || repairedModelName || repairedCreatedAt) && len(dbMsgs) == len(messages) {
 		matched := true
 		for i := range messages {
-			if !messageMatches(dbMsgs[i], messages[i]) {
+			if !messagesMatch(dbMsgs[i], messages[i], messageMatchOptions{}) {
 				matched = false
 				break
 			}
@@ -462,7 +469,7 @@ func (e *Engine) Bootstrap(ctx context.Context, sessionKey string, messages []Me
 	if len(dbMsgs) == len(messages) {
 		matched := true
 		for i := range messages {
-			if !messageMatches(dbMsgs[i], messages[i]) {
+			if !messagesMatch(dbMsgs[i], messages[i], messageMatchOptions{}) {
 				matched = false
 				break
 			}
@@ -477,7 +484,7 @@ func (e *Engine) Bootstrap(ctx context.Context, sessionKey string, messages []Me
 	compareLen := min(len(dbMsgs), len(messages))
 
 	for i := range compareLen {
-		if messageMatches(dbMsgs[i], messages[i]) {
+		if messagesMatch(dbMsgs[i], messages[i], messageMatchOptions{}) {
 			anchor = i
 		} else {
 			// Mismatch detected - log details and rebuild
@@ -578,7 +585,11 @@ func (e *Engine) repairBootstrapReasoningContent(ctx context.Context, dbMsgs, me
 	}
 
 	for i := range overlap {
-		if !messageMatchesIgnoringReasoningAndModelName(dbMsgs[i], messages[i]) {
+		if !messagesMatch(dbMsgs[i], messages[i], messageMatchOptions{
+			IgnoreReasoningContent: true,
+			IgnoreModelName:        true,
+			IgnoreCreatedAt:        true,
+		}) {
 			return false, nil
 		}
 		if dbMsgs[i].ReasoningContent == messages[i].ReasoningContent {
@@ -629,7 +640,11 @@ func (e *Engine) repairBootstrapModelName(ctx context.Context, dbMsgs, messages
 	}
 
 	for i := range overlap {
-		if !messageMatchesIgnoringReasoningAndModelName(dbMsgs[i], messages[i]) {
+		if !messagesMatch(dbMsgs[i], messages[i], messageMatchOptions{
+			IgnoreReasoningContent: true,
+			IgnoreModelName:        true,
+			IgnoreCreatedAt:        true,
+		}) {
 			return false, nil
 		}
 		if dbMsgs[i].ModelName == messages[i].ModelName {
@@ -666,6 +681,64 @@ func (e *Engine) repairBootstrapModelName(ctx context.Context, dbMsgs, messages
 	return true, nil
 }
 
+func (e *Engine) repairBootstrapCreatedAt(ctx context.Context, dbMsgs, messages []Message) (bool, error) {
+	if len(dbMsgs) == 0 || len(messages) == 0 {
+		return false, nil
+	}
+
+	overlap := min(len(messages), len(dbMsgs))
+
+	var updates []struct {
+		index     int
+		messageID int64
+		createdAt time.Time
+	}
+
+	for i := range overlap {
+		if !messagesMatch(dbMsgs[i], messages[i], messageMatchOptions{
+			IgnoreReasoningContent: true,
+			IgnoreModelName:        true,
+			IgnoreCreatedAt:        true,
+		}) {
+			return false, nil
+		}
+
+		wantCreatedAt := normalizeMessageCreatedAt(messages[i].CreatedAt)
+		if wantCreatedAt.IsZero() {
+			return false, nil
+		}
+		if dbMsgs[i].CreatedAt.Equal(wantCreatedAt) {
+			continue
+		}
+
+		updates = append(updates, struct {
+			index     int
+			messageID int64
+			createdAt time.Time
+		}{
+			index:     i,
+			messageID: dbMsgs[i].ID,
+			createdAt: wantCreatedAt,
+		})
+	}
+
+	if len(updates) == 0 {
+		return false, nil
+	}
+
+	for _, update := range updates {
+		if err := e.store.UpdateMessageCreatedAt(ctx, update.messageID, update.createdAt); err != nil {
+			return false, err
+		}
+		dbMsgs[update.index].CreatedAt = update.createdAt
+	}
+
+	logger.InfoCF("seahorse", "bootstrap: repaired message created_at", map[string]any{
+		"messages": len(updates),
+	})
+	return true, nil
+}
+
 // truncate shortens a string for logging.
 func truncate(s string, maxLen int) string {
 	if len(s) <= maxLen {
@@ -674,29 +747,28 @@ func truncate(s string, maxLen int) string {
 	return s[:maxLen] + "..."
 }
 
-// messageMatches compares two messages using role + reasoning_content and then
-// either content or parts. TokenCount is NOT compared because it may be
-// re-estimated differently during bootstrap (e.g., via tokenizer.EstimateMessageTokens).
-// For messages with Parts (tool_use, tool_result), compare Parts instead of Content
-// because structured messages are matched by their parts payload.
-func messageMatches(a, b Message) bool {
-	if a.Role != b.Role || a.ReasoningContent != b.ReasoningContent || a.ModelName != b.ModelName {
-		return false
-	}
-	return messageMatchesIgnoringReasoning(a, b)
+type messageMatchOptions struct {
+	IgnoreReasoningContent bool
+	IgnoreModelName        bool
+	IgnoreCreatedAt        bool
 }
 
-func messageMatchesIgnoringReasoning(a, b Message) bool {
-	if a.ModelName != b.ModelName {
-		return false
-	}
-	return messageMatchesIgnoringReasoningAndModelName(a, b)
-}
-
-func messageMatchesIgnoringReasoningAndModelName(a, b Message) bool {
+// messagesMatch compares two messages by role and payload, plus the optional
+// metadata fields used by bootstrap repair. TokenCount is intentionally ignored
+// because bootstrap may re-estimate it differently.
+func messagesMatch(a, b Message, opts messageMatchOptions) bool {
 	if a.Role != b.Role {
 		return false
 	}
+	if !opts.IgnoreReasoningContent && a.ReasoningContent != b.ReasoningContent {
+		return false
+	}
+	if !opts.IgnoreModelName && a.ModelName != b.ModelName {
+		return false
+	}
+	if !opts.IgnoreCreatedAt && !messageCreatedAtMatches(a.CreatedAt, b.CreatedAt) {
+		return false
+	}
 	// If either message has Parts, compare Parts
 	if len(a.Parts) > 0 || len(b.Parts) > 0 {
 		return partsMatch(a.Parts, b.Parts)
@@ -705,6 +777,18 @@ func messageMatchesIgnoringReasoningAndModelName(a, b Message) bool {
 	return a.Content == b.Content
 }
 
+// messageCreatedAtMatches treats missing timestamps as compatible so bootstrap
+// can preserve legacy histories while still enforcing exact equality once both
+// sides carry canonical created_at values.
+func messageCreatedAtMatches(a, b time.Time) bool {
+	na := normalizeMessageCreatedAt(a)
+	nb := normalizeMessageCreatedAt(b)
+	if na.IsZero() || nb.IsZero() {
+		return true
+	}
+	return na.Equal(nb)
+}
+
 // partsMatch compares two slices of MessagePart for equality.
 func partsMatch(a, b []MessagePart) bool {
 	if len(a) != len(b) {

pkg/seahorse/short_engine_test.go

@@ -57,8 +57,8 @@ func prepareBootstrapRepairConversation(
 	}
 
 	return conv, []Message{
-		{Role: "user", Content: "hello", TokenCount: 3},
-		{Role: "assistant", Content: "world", TokenCount: 3},
+		{Role: "user", Content: "hello", TokenCount: 3, CreatedAt: userMsg.CreatedAt},
+		{Role: "assistant", Content: "world", TokenCount: 3, CreatedAt: assistantMsg.CreatedAt},
 	}
 }
 
@@ -464,13 +464,19 @@ func TestBootstrapRepairsReasoningContentAndModelNameTogether(t *testing.T) {
 	}
 
 	err = eng.Bootstrap(ctx, sessionKey, []Message{
-		{Role: "user", Content: "hello", TokenCount: 3},
+		{
+			Role:       "user",
+			Content:    "hello",
+			TokenCount: 3,
+			CreatedAt:  time.Date(2026, 3, 4, 5, 6, 7, 0, time.UTC),
+		},
 		{
 			Role:             "assistant",
 			Content:          "world",
 			ModelName:        "gpt-5.4",
 			ReasoningContent: "let me think this through",
 			TokenCount:       3,
+			CreatedAt:        time.Date(2026, 3, 4, 5, 6, 8, 0, time.UTC),
 		},
 	})
 	if err != nil {
@@ -515,6 +521,7 @@ func TestBootstrapRepairsIncorrectNonEmptyModelName(t *testing.T) {
 		"wrong-model",
 		"",
 		3,
+		time.Time{},
 	)
 	if err != nil {
 		t.Fatalf("AddMessageWithReasoning assistant: %v", err)
@@ -545,6 +552,64 @@ func TestBootstrapRepairsIncorrectNonEmptyModelName(t *testing.T) {
 	}
 }
 
+func TestBootstrapRepairsCreatedAt(t *testing.T) {
+	eng := newTestEngine(t)
+	ctx := context.Background()
+	sessionKey := "agent:repair-created-at"
+	conv, msgs := prepareBootstrapRepairConversation(t, eng, ctx, sessionKey)
+
+	wantCreatedAt := time.Date(2026, 3, 4, 5, 6, 7, 0, time.UTC)
+	msgs[1].CreatedAt = wantCreatedAt
+
+	err := eng.Bootstrap(ctx, sessionKey, msgs)
+	if err != nil {
+		t.Fatalf("Bootstrap: %v", err)
+	}
+
+	stored, err := eng.store.GetMessages(ctx, conv.ConversationID, 10, 0)
+	if err != nil {
+		t.Fatalf("GetMessages: %v", err)
+	}
+	if len(stored) != 2 {
+		t.Fatalf("stored messages = %d, want 2", len(stored))
+	}
+	if !stored[1].CreatedAt.Equal(wantCreatedAt) {
+		t.Fatalf("stored[1].CreatedAt = %v, want %v", stored[1].CreatedAt, wantCreatedAt)
+	}
+}
+
+func TestEngineIngestPreservesCreatedAt(t *testing.T) {
+	eng := newTestEngine(t)
+	ctx := context.Background()
+	wantCreatedAt := time.Date(2026, 4, 5, 6, 7, 8, 0, time.UTC)
+
+	msgs := []Message{
+		{
+			Role:       "assistant",
+			Content:    "world",
+			TokenCount: 4,
+			CreatedAt:  wantCreatedAt,
+		},
+	}
+
+	_, err := eng.Ingest(ctx, "agent:created-at", msgs)
+	if err != nil {
+		t.Fatalf("Ingest: %v", err)
+	}
+
+	conv, _ := eng.store.GetOrCreateConversation(ctx, "agent:created-at")
+	stored, err := eng.store.GetMessages(ctx, conv.ConversationID, 10, 0)
+	if err != nil {
+		t.Fatalf("GetMessages: %v", err)
+	}
+	if len(stored) != 1 {
+		t.Fatalf("stored messages = %d, want 1", len(stored))
+	}
+	if !stored[0].CreatedAt.Equal(wantCreatedAt) {
+		t.Fatalf("stored[0].CreatedAt = %v, want %v", stored[0].CreatedAt, wantCreatedAt)
+	}
+}
+
 func TestEngineIngestWithPartsPreservesReasoningContent(t *testing.T) {
 	eng := newTestEngine(t)
 	ctx := context.Background()
@@ -864,8 +929,19 @@ func TestBootstrapRepairsMissingReasoningContentWithoutDroppingSummaries(t *test
 	}
 
 	err = eng.Bootstrap(ctx, sessionKey, []Message{
-		{Role: "user", Content: "hello", TokenCount: 3},
-		{Role: "assistant", Content: "world", ReasoningContent: "let me think this through", TokenCount: 3},
+		{
+			Role:       "user",
+			Content:    "hello",
+			TokenCount: 3,
+			CreatedAt:  time.Date(2026, 3, 4, 5, 6, 7, 0, time.UTC),
+		},
+		{
+			Role:             "assistant",
+			Content:          "world",
+			ReasoningContent: "let me think this through",
+			TokenCount:       3,
+			CreatedAt:        time.Date(2026, 3, 4, 5, 6, 8, 0, time.UTC),
+		},
 	})
 	if err != nil {
 		t.Fatalf("Bootstrap: %v", err)

pkg/seahorse/store.go

@@ -8,6 +8,8 @@ import (
 	"time"
 )
 
+const sqliteTimeLayout = "2006-01-02 15:04:05"
+
 // Store provides SQLite storage for seahorse.
 type Store struct {
 	db *sql.DB
@@ -75,8 +77,8 @@ func (s *Store) GetConversationBySessionKey(ctx context.Context, sessionKey stri
 	if err != nil {
 		return nil, fmt.Errorf("get conversation by session key: %w", err)
 	}
-	conv.CreatedAt, _ = time.Parse("2006-01-02 15:04:05", createdAt)
-	conv.UpdatedAt, _ = time.Parse("2006-01-02 15:04:05", updatedAt)
+	conv.CreatedAt = parseSQLiteTime(createdAt)
+	conv.UpdatedAt = parseSQLiteTime(updatedAt)
 	return &conv, nil
 }
 
@@ -153,8 +155,8 @@ func (s *Store) getMessageTimeRange(ctx context.Context, convID int64) (time.Tim
 	if err != nil || minTime == "" {
 		return time.Time{}, time.Time{}, err
 	}
-	oldest, _ := time.Parse("2006-01-02 15:04:05", minTime)
-	newest, _ := time.Parse("2006-01-02 15:04:05", maxTime)
+	oldest := parseSQLiteTime(minTime)
+	newest := parseSQLiteTime(maxTime)
 	return oldest, newest, nil
 }
 
@@ -162,7 +164,7 @@ func (s *Store) getMessageTimeRange(ctx context.Context, convID int64) (time.Tim
 
 // AddMessage appends a message to a conversation.
 func (s *Store) AddMessage(ctx context.Context, convID int64, role, content string, tokenCount int) (*Message, error) {
-	return s.AddMessageWithReasoning(ctx, convID, role, content, "", "", tokenCount)
+	return s.AddMessageWithReasoning(ctx, convID, role, content, "", "", tokenCount, time.Time{})
 }
 
 // AddMessageWithReasoning appends a message with reasoning content to a conversation.
@@ -171,16 +173,22 @@ func (s *Store) AddMessageWithReasoning(
 	convID int64,
 	role, content, modelName, reasoningContent string,
 	tokenCount int,
+	createdAt time.Time,
 ) (*Message, error) {
+	storedCreatedAt := normalizeMessageCreatedAt(createdAt)
+	if storedCreatedAt.IsZero() {
+		storedCreatedAt = normalizeMessageCreatedAt(time.Now())
+	}
 	result, err := s.db.ExecContext(
 		ctx,
-		"INSERT INTO messages (conversation_id, role, content, model_name, reasoning_content, token_count) VALUES (?, ?, ?, ?, ?, ?)",
+		"INSERT INTO messages (conversation_id, role, content, model_name, reasoning_content, token_count, created_at) VALUES (?, ?, ?, ?, ?, ?, ?)",
 		convID,
 		role,
 		content,
 		modelName,
 		reasoningContent,
 		tokenCount,
+		formatSQLiteTime(storedCreatedAt),
 	)
 	if err != nil {
 		return nil, fmt.Errorf("add message: %w", err)
@@ -194,6 +202,7 @@ func (s *Store) AddMessageWithReasoning(
 		ModelName:        modelName,
 		ReasoningContent: reasoningContent,
 		TokenCount:       tokenCount,
+		CreatedAt:        storedCreatedAt,
 	}, nil
 }
 
@@ -231,7 +240,7 @@ func (s *Store) AddMessageWithParts(
 	parts []MessagePart,
 	tokenCount int,
 ) (*Message, error) {
-	return s.AddMessageWithPartsAndReasoning(ctx, convID, role, parts, "", "", tokenCount)
+	return s.AddMessageWithPartsAndReasoning(ctx, convID, role, parts, "", "", tokenCount, time.Time{})
 }
 
 // AddMessageWithPartsAndReasoning adds a message with structured parts and reasoning content.
@@ -243,6 +252,7 @@ func (s *Store) AddMessageWithPartsAndReasoning(
 	modelName string,
 	reasoningContent string,
 	tokenCount int,
+	createdAt time.Time,
 ) (*Message, error) {
 	tx, err := s.db.BeginTx(ctx, nil)
 	if err != nil {
@@ -250,18 +260,24 @@ func (s *Store) AddMessageWithPartsAndReasoning(
 	}
 	defer tx.Rollback()
 
+	storedCreatedAt := normalizeMessageCreatedAt(createdAt)
+	if storedCreatedAt.IsZero() {
+		storedCreatedAt = normalizeMessageCreatedAt(time.Now())
+	}
+
 	// Derive readable content from Parts for FTS5 indexing and summary formatting
 	readableContent := partsToReadableContent(parts)
 
 	result, err := tx.ExecContext(
 		ctx,
-		"INSERT INTO messages (conversation_id, role, content, model_name, reasoning_content, token_count) VALUES (?, ?, ?, ?, ?, ?)",
+		"INSERT INTO messages (conversation_id, role, content, model_name, reasoning_content, token_count, created_at) VALUES (?, ?, ?, ?, ?, ?, ?)",
 		convID,
 		role,
 		readableContent,
 		modelName,
 		reasoningContent,
 		tokenCount,
+		formatSQLiteTime(storedCreatedAt),
 	)
 	if err != nil {
 		return nil, fmt.Errorf("add message: %w", err)
@@ -299,6 +315,7 @@ func (s *Store) AddMessageWithPartsAndReasoning(
 		ModelName:        modelName,
 		ReasoningContent: reasoningContent,
 		TokenCount:       tokenCount,
+		CreatedAt:        storedCreatedAt,
 		Parts:            make([]MessagePart, len(parts)),
 	}
 	for i, p := range parts {
@@ -344,7 +361,7 @@ func (s *Store) GetMessages(ctx context.Context, convID int64, limit int, before
 		); err != nil {
 			return nil, err
 		}
-		msg.CreatedAt, _ = time.Parse("2006-01-02 15:04:05", createdAt)
+		msg.CreatedAt = parseSQLiteTime(createdAt)
 		msgs = append(msgs, msg)
 	}
 	if err := rows.Err(); err != nil {
@@ -387,7 +404,7 @@ func (s *Store) GetMessageByID(ctx context.Context, messageID int64) (*Message,
 	if err != nil {
 		return nil, err
 	}
-	msg.CreatedAt, _ = time.Parse("2006-01-02 15:04:05", createdAt)
+	msg.CreatedAt = parseSQLiteTime(createdAt)
 	msg.Parts, _ = s.loadMessageParts(ctx, msg.ID)
 	return &msg, nil
 }
@@ -435,6 +452,32 @@ func (s *Store) UpdateMessageModelName(ctx context.Context, messageID int64, mod
 	return nil
 }
 
+func (s *Store) UpdateMessageCreatedAt(ctx context.Context, messageID int64, createdAt time.Time) error {
+	storedCreatedAt := normalizeMessageCreatedAt(createdAt)
+	if storedCreatedAt.IsZero() {
+		return fmt.Errorf("message %d created_at cannot be zero", messageID)
+	}
+
+	result, err := s.db.ExecContext(
+		ctx,
+		"UPDATE messages SET created_at = ? WHERE message_id = ?",
+		formatSQLiteTime(storedCreatedAt),
+		messageID,
+	)
+	if err != nil {
+		return fmt.Errorf("update message created_at: %w", err)
+	}
+
+	rowsAffected, err := result.RowsAffected()
+	if err != nil {
+		return fmt.Errorf("update message created_at rows affected: %w", err)
+	}
+	if rowsAffected == 0 {
+		return fmt.Errorf("message %d not found", messageID)
+	}
+	return nil
+}
+
 func (s *Store) loadMessageParts(ctx context.Context, msgID int64) ([]MessagePart, error) {
 	rows, err := s.db.QueryContext(ctx,
 		`SELECT part_id, message_id, type, text, name, arguments, tool_call_id, media_uri, mime_type
@@ -648,7 +691,7 @@ func (s *Store) GetSummarySourceMessages(ctx context.Context, summaryID string)
 		); err != nil {
 			return nil, err
 		}
-		msg.CreatedAt, _ = time.Parse("2006-01-02 15:04:05", createdAt)
+		msg.CreatedAt = parseSQLiteTime(createdAt)
 		msgs = append(msgs, msg)
 	}
 	if err := rows.Err(); err != nil {
@@ -714,8 +757,7 @@ func (s *Store) GetContextItems(ctx context.Context, convID int64) ([]ContextIte
 			item.MessageID = messageID.Int64
 		}
 		if createdAt.Valid {
-			t, _ := time.Parse("2006-01-02 15:04:05", createdAt.String)
-			item.CreatedAt = t
+			item.CreatedAt = parseSQLiteTime(createdAt.String)
 		}
 		items = append(items, item)
 	}
@@ -1449,7 +1491,7 @@ func (s *Store) scanSearchResults(rows *sql.Rows, withRank bool) ([]SearchResult
 			}
 		}
 		r.Kind = SummaryKind(kind)
-		r.CreatedAt, _ = time.Parse("2006-01-02 15:04:05", createdAt)
+		r.CreatedAt = parseSQLiteTime(createdAt)
 		results = append(results, r)
 	}
 	return results, nil
@@ -1573,7 +1615,7 @@ func (s *Store) scanMessageSearchResults(rows *sql.Rows, withRank bool) ([]Searc
 			}
 		}
 		r.Snippet = content
-		r.CreatedAt, _ = time.Parse("2006-01-02 15:04:05", createdAt)
+		r.CreatedAt = parseSQLiteTime(createdAt)
 		results = append(results, r)
 	}
 	if err := rows.Err(); err != nil {
@@ -1606,7 +1648,7 @@ func (s *Store) scanSummary(ctx context.Context, where string, args ...any) (*Su
 		return nil, err
 	}
 	sum.Kind = SummaryKind(kind)
-	sum.CreatedAt, _ = time.Parse("2006-01-02 15:04:05", createdAt)
+	sum.CreatedAt = parseSQLiteTime(createdAt)
 	if earliestAt.Valid {
 		t, _ := time.Parse(time.RFC3339, earliestAt.String)
 		sum.EarliestAt = &t
@@ -1633,7 +1675,7 @@ func (s *Store) scanSummaries(rows *sql.Rows) ([]Summary, error) {
 			return nil, err
 		}
 		sum.Kind = SummaryKind(kind)
-		sum.CreatedAt, _ = time.Parse("2006-01-02 15:04:05", createdAt)
+		sum.CreatedAt = parseSQLiteTime(createdAt)
 		if earliestAt.Valid {
 			t, _ := time.Parse(time.RFC3339, earliestAt.String)
 			sum.EarliestAt = &t
@@ -1659,6 +1701,22 @@ func isUniqueViolation(err error) bool {
 		contains(err.Error(), "constraint failed"))
 }
 
+func normalizeMessageCreatedAt(createdAt time.Time) time.Time {
+	if createdAt.IsZero() {
+		return time.Time{}
+	}
+	return createdAt.UTC().Truncate(time.Second)
+}
+
+func formatSQLiteTime(t time.Time) string {
+	return normalizeMessageCreatedAt(t).Format(sqliteTimeLayout)
+}
+
+func parseSQLiteTime(raw string) time.Time {
+	parsed, _ := time.Parse(sqliteTimeLayout, raw)
+	return parsed
+}
+
 func contains(s, sub string) bool {
 	return len(s) >= len(sub) && searchSubstring(s, sub)
 }

pkg/seahorse/store_test.go

@@ -213,6 +213,7 @@ func TestStoreAddAndGetMessagesWithReasoningContent(t *testing.T) {
 		"gpt-5.4-mini",
 		"let me think",
 		5,
+		time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC),
 	)
 	if err != nil {
 		t.Fatalf("AddMessageWithReasoning: %v", err)
@@ -223,6 +224,9 @@ func TestStoreAddAndGetMessagesWithReasoningContent(t *testing.T) {
 	if msg.ModelName != "gpt-5.4-mini" {
 		t.Fatalf("ModelName = %q, want %q", msg.ModelName, "gpt-5.4-mini")
 	}
+	if !msg.CreatedAt.Equal(time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)) {
+		t.Fatalf("CreatedAt = %v, want 2026-01-02 03:04:05 UTC", msg.CreatedAt)
+	}
 
 	msgs, err := s.GetMessages(ctx, conv.ConversationID, 10, 0)
 	if err != nil {
@@ -237,6 +241,9 @@ func TestStoreAddAndGetMessagesWithReasoningContent(t *testing.T) {
 	if msgs[0].ModelName != "gpt-5.4-mini" {
 		t.Errorf("ModelName = %q, want %q", msgs[0].ModelName, "gpt-5.4-mini")
 	}
+	if !msgs[0].CreatedAt.Equal(time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)) {
+		t.Errorf("CreatedAt = %v, want 2026-01-02 03:04:05 UTC", msgs[0].CreatedAt)
+	}
 
 	found, err := s.GetMessageByID(ctx, msg.ID)
 	if err != nil {
@@ -248,6 +255,9 @@ func TestStoreAddAndGetMessagesWithReasoningContent(t *testing.T) {
 	if found.ModelName != "gpt-5.4-mini" {
 		t.Errorf("GetMessageByID ModelName = %q, want %q", found.ModelName, "gpt-5.4-mini")
 	}
+	if !found.CreatedAt.Equal(time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)) {
+		t.Errorf("GetMessageByID CreatedAt = %v, want 2026-01-02 03:04:05 UTC", found.CreatedAt)
+	}
 }
 
 func TestStoreAddMessageWithParts(t *testing.T) {
@@ -301,6 +311,7 @@ func TestStoreAddMessageWithPartsAndReasoningContent(t *testing.T) {
 		"gpt-5.4",
 		"need to inspect the file first",
 		10,
+		time.Date(2026, 2, 3, 4, 5, 6, 0, time.UTC),
 	)
 	if err != nil {
 		t.Fatalf("AddMessageWithPartsAndReasoning: %v", err)
@@ -323,6 +334,9 @@ func TestStoreAddMessageWithPartsAndReasoningContent(t *testing.T) {
 	if msgs[0].ModelName != "gpt-5.4" {
 		t.Errorf("ModelName = %q, want %q", msgs[0].ModelName, "gpt-5.4")
 	}
+	if !msgs[0].CreatedAt.Equal(time.Date(2026, 2, 3, 4, 5, 6, 0, time.UTC)) {
+		t.Errorf("CreatedAt = %v, want 2026-02-03 04:05:06 UTC", msgs[0].CreatedAt)
+	}
 }
 
 func TestStoreGetMessageCount(t *testing.T) {

pkg/session/manager.go

@@ -60,6 +60,21 @@ func (sm *SessionManager) GetOrCreate(key string) *Session {
 	return session
 }
 
+func ensureMessageCreatedAt(msg *providers.Message, fallback time.Time) {
+	if msg.CreatedAt != nil && !msg.CreatedAt.IsZero() {
+		return
+	}
+	ts := fallback
+	msg.CreatedAt = &ts
+}
+
+func normalizeHistoryCreatedAt(history []providers.Message) {
+	now := time.Now()
+	for i := range history {
+		ensureMessageCreatedAt(&history[i], now)
+	}
+}
+
 func (sm *SessionManager) AddMessage(sessionKey, role, content string) {
 	sm.AddFullMessage(sessionKey, providers.Message{
 		Role:    role,
@@ -88,9 +103,7 @@ func (sm *SessionManager) AddFullMessage(sessionKey string, msg providers.Messag
 	}
 
 	now := time.Now()
-	if msg.CreatedAt == nil {
-		msg.CreatedAt = &now
-	}
+	ensureMessageCreatedAt(&msg, now)
 
 	session.Messages = append(session.Messages, msg)
 	session.Updated = now
@@ -280,6 +293,7 @@ func (sm *SessionManager) loadSessions() error {
 			continue
 		}
 		session.Messages = messageutil.FilterInvalidHistoryMessages(session.Messages)
+		normalizeHistoryCreatedAt(session.Messages)
 
 		sm.sessions[session.Key] = &session
 	}
@@ -305,13 +319,8 @@ func (sm *SessionManager) SetHistory(key string, history []providers.Message) {
 		// from the caller's slice.
 		msgs := make([]providers.Message, len(history))
 		copy(msgs, history)
-		now := time.Now()
-		for i := range msgs {
-			if msgs[i].CreatedAt == nil {
-				msgs[i].CreatedAt = &now
-			}
-		}
+		normalizeHistoryCreatedAt(msgs)
 		session.Messages = msgs
-		session.Updated = now
+		session.Updated = time.Now()
 	}
 }

pkg/session/manager_test.go

@@ -83,3 +83,32 @@ func TestSave_RejectsPathTraversal(t *testing.T) {
 		t.Errorf("expected foo_bar.json in storage (sanitized from foo/bar)")
 	}
 }
+
+func TestLoadSessions_NormalizesMissingCreatedAt(t *testing.T) {
+	tmpDir := t.TempDir()
+	sessionPath := filepath.Join(tmpDir, "telegram_legacy.json")
+	legacy := `{
+  "key": "telegram:legacy",
+  "messages": [
+    {
+      "role": "user",
+      "content": "hello"
+    }
+  ],
+  "created": "2026-01-01T00:00:00Z",
+  "updated": "2026-01-01T00:00:00Z"
+}`
+
+	if err := os.WriteFile(sessionPath, []byte(legacy), 0o644); err != nil {
+		t.Fatalf("WriteFile: %v", err)
+	}
+
+	sm := NewSessionManager(tmpDir)
+	history := sm.GetHistory("telegram:legacy")
+	if len(history) != 1 {
+		t.Fatalf("history = %d, want 1", len(history))
+	}
+	if history[0].CreatedAt == nil || history[0].CreatedAt.IsZero() {
+		t.Fatalf("history[0].CreatedAt = %v, want non-zero timestamp", history[0].CreatedAt)
+	}
+}