fix: DM partners query uses SQL over all messages, not just inbox

The previous implementation only scanned inbox (pending messages),
so historical conversations with read/done messages were invisible.
New GetDMPartners() does a direct SQL query with window functions
to find all unique DM partners with most recent message preview
and unread count. Historical conversations now always show.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

internal/api/messages_handler.go

@@ -4,7 +4,6 @@ import (
 	"encoding/json"
 	"log/slog"
 	"net/http"
-	"sort"
 	"strconv"
 	"strings"
 	"time"
@@ -583,8 +582,8 @@ func (h *MessagesHandler) DMMessages(w http.ResponseWriter, r *http.Request) {
 }
 
 // DMPartners returns a list of agents the user has DM conversations with,
-// ordered by most recent message. Each entry includes the peer agent name,
-// last message preview, timestamp, and unread count.
+// ordered by most recent message. Queries ALL messages (not just inbox)
+// so historical conversations always appear.
 func (h *MessagesHandler) DMPartners(w http.ResponseWriter, r *http.Request) {
 	ownerID, ok := OwnerIDFromContext(r.Context())
 	if !ok {
@@ -603,86 +602,41 @@ func (h *MessagesHandler) DMPartners(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	ownedNames := make(map[string]bool, len(ownedAgents))
-	for _, a := range ownedAgents {
-		ownedNames[a.Name] = true
+	agentNames := make([]string, len(ownedAgents))
+	for i, a := range ownedAgents {
+		agentNames[i] = a.Name
 	}
 
-	// Get recent DMs for all owned agents
-	type partner struct {
+	partners, err := h.msgService.GetDMPartners(r.Context(), agentNames)
+	if err != nil {
+		h.logger.Error("get dm partners failed", "error", err)
+		writeJSON(w, http.StatusInternalServerError, errorBody("server_error", "Failed to get DM partners"))
+		return
+	}
+
+	// Resolve display names
+	type partnerWithDisplay struct {
 		Name        string `json:"name"`
 		DisplayName string `json:"display_name"`
 		LastMessage string `json:"last_message"`
 		LastTime    string `json:"last_time"`
 		Unread      int    `json:"unread"`
 	}
-	partnerMap := make(map[string]*partner)
-
-	for _, agent := range ownedAgents {
-		opts := messaging.ReadOptions{
-			Limit:       200,
-			IncludeRead: true,
+	result := make([]partnerWithDisplay, len(partners))
+	for i, p := range partners {
+		result[i] = partnerWithDisplay{
+			Name:        p.Name,
+			DisplayName: p.Name,
+			LastMessage: p.LastMessage,
+			LastTime:    p.LastTime,
+			Unread:      p.Unread,
 		}
-		result, err := h.msgService.ReadInbox(r.Context(), agent.Name, opts)
-		if err != nil {
-			continue
-		}
-		for _, msg := range result.Messages {
-			if msg.ChannelID != nil {
-				continue // skip channel messages
-			}
-			// Determine the peer (the other party in the DM)
-			peer := msg.FromAgent
-			if ownedNames[peer] {
-				peer = msg.ToAgent
-			}
-			if peer == "" || ownedNames[peer] {
-				continue // skip self-to-self
-			}
-
-			existing, exists := partnerMap[peer]
-			if !exists {
-				partnerMap[peer] = &partner{
-					Name:        peer,
-					DisplayName: peer,
-					LastMessage: truncateStr(msg.Body, 80),
-					LastTime:    msg.CreatedAt.Format(time.RFC3339),
-					Unread:      0,
-				}
-				existing = partnerMap[peer]
-			}
-
-			// Track newest message
-			lt, _ := time.Parse(time.RFC3339, existing.LastTime)
-			if msg.CreatedAt.After(lt) {
-				existing.LastMessage = truncateStr(msg.Body, 80)
-				existing.LastTime = msg.CreatedAt.Format(time.RFC3339)
-			}
-
-			// Count unread (pending messages TO owned agents)
-			if ownedNames[msg.ToAgent] && (msg.Status == "pending" || msg.Status == "processing") {
-				existing.Unread++
-			}
+		if a, err := h.agentService.GetAgent(r.Context(), p.Name); err == nil {
+			result[i].DisplayName = a.DisplayName
 		}
 	}
 
-	// Resolve display names
-	for peer, p := range partnerMap {
-		if a, err := h.agentService.GetAgent(r.Context(), peer); err == nil {
-			p.DisplayName = a.DisplayName
-		}
-	}
-
-	// Sort by last_time descending
-	partners := make([]*partner, 0, len(partnerMap))
-	for _, p := range partnerMap {
-		partners = append(partners, p)
-	}
-	sort.Slice(partners, func(i, j int) bool {
-		return partners[i].LastTime > partners[j].LastTime
-	})
-
-	writeJSON(w, http.StatusOK, map[string]any{"partners": partners})
+	writeJSON(w, http.StatusOK, map[string]any{"partners": result})
 }
 
 func (h *MessagesHandler) isAgentOwnedBy(r *http.Request, agentName string, ownerID int64) bool {

internal/messaging/service.go

@@ -531,6 +531,11 @@ func (s *MessagingService) GetDMMessages(ctx context.Context, ownedAgents []stri
 	return messages, nil
 }
 
+// GetDMPartners returns all DM conversation partners for the owned agents.
+func (s *MessagingService) GetDMPartners(ctx context.Context, ownedAgents []string) ([]DMPartner, error) {
+	return s.store.GetDMPartners(ctx, ownedAgents)
+}
+
 // GetDMUnreadCounts returns unread DM counts grouped by peer agent.
 func (s *MessagingService) GetDMUnreadCounts(ctx context.Context, agentName string) ([]DMUnreadCount, error) {
 	return s.store.GetDMUnreadCounts(ctx, agentName)

internal/messaging/store.go

@@ -29,6 +29,7 @@ type MessageStore interface {
 	GetChannelMessages(ctx context.Context, channelID int64, limit, offset int) ([]*Message, error)
 	CountChannelMessages(ctx context.Context, channelID int64) (int, error)
 	GetDMMessages(ctx context.Context, agents []string, peerAgent string, limit int) ([]*Message, error)
+	GetDMPartners(ctx context.Context, agents []string) ([]DMPartner, error)
 	AgentExists(ctx context.Context, agentName string) (bool, error)
 	CountPendingDMs(ctx context.Context, agentName string) (int64, error)
 	GetPendingDMs(ctx context.Context, agentName string, limit int) ([]*Message, error)
@@ -687,6 +688,94 @@ func (s *SQLiteMessageStore) GetDMMessages(ctx context.Context, agents []string,
 	return scanMessages(rows)
 }
 
+// GetDMPartners returns all unique DM conversation partners for the owned agents,
+// with the most recent message preview and unread count. This queries ALL messages
+// (not just inbox) to show historical conversations.
+func (s *SQLiteMessageStore) GetDMPartners(ctx context.Context, agents []string) ([]DMPartner, error) {
+	if len(agents) == 0 {
+		return []DMPartner{}, nil
+	}
+
+	placeholders := make([]string, len(agents))
+	args := make([]any, 0, len(agents)*2)
+	for i, a := range agents {
+		placeholders[i] = "?"
+		args = append(args, a)
+	}
+	inClause := strings.Join(placeholders, ",")
+	// Duplicate args for the second IN clause
+	for _, a := range agents {
+		args = append(args, a)
+	}
+
+	// Find all DM partners with latest message and unread count
+	query := fmt.Sprintf(`
+		SELECT
+			peer,
+			last_body,
+			last_time,
+			COALESCE(SUM(is_unread), 0) as unread
+		FROM (
+			SELECT
+				CASE
+					WHEN from_agent IN (%s) THEN to_agent
+					ELSE from_agent
+				END as peer,
+				body as last_body,
+				created_at as last_time,
+				CASE
+					WHEN to_agent IN (%s) AND status IN ('pending', 'processing') THEN 1
+					ELSE 0
+				END as is_unread,
+				ROW_NUMBER() OVER (
+					PARTITION BY CASE WHEN from_agent IN (%s) THEN to_agent ELSE from_agent END
+					ORDER BY created_at DESC
+				) as rn
+			FROM messages
+			WHERE channel_id IS NULL
+			  AND (from_agent IN (%s) OR to_agent IN (%s))
+		) sub
+		WHERE rn = 1 AND peer != '' AND peer NOT IN (%s)
+		GROUP BY peer
+		ORDER BY last_time DESC
+		LIMIT 50`,
+		inClause, inClause, inClause, inClause, inClause, inClause,
+	)
+
+	// Need 6 copies of the args for the 6 IN clauses
+	fullArgs := make([]any, 0, len(agents)*6)
+	for i := 0; i < 6; i++ {
+		for _, a := range agents {
+			fullArgs = append(fullArgs, a)
+		}
+	}
+
+	rows, err := s.db.QueryContext(ctx, query, fullArgs...)
+	if err != nil {
+		return nil, fmt.Errorf("get dm partners: %w", err)
+	}
+	defer rows.Close()
+
+	var partners []DMPartner
+	for rows.Next() {
+		var p DMPartner
+		var body sql.NullString
+		if err := rows.Scan(&p.Name, &body, &p.LastTime, &p.Unread); err != nil {
+			return nil, err
+		}
+		if body.Valid && len(body.String) > 80 {
+			p.LastMessage = body.String[:80] + "..."
+		} else if body.Valid {
+			p.LastMessage = body.String
+		}
+		partners = append(partners, p)
+	}
+	if partners == nil {
+		partners = []DMPartner{}
+	}
+	return partners, rows.Err()
+}
+
 func (s *SQLiteMessageStore) CountPendingDMs(ctx context.Context, agentName string) (int64, error) {
 	var count int64
 	err := s.db.QueryRowContext(ctx,

internal/messaging/types.go

@@ -101,3 +101,11 @@ type DMUnreadCount struct {
 	UnreadCount   int    `json:"unread_count"`
 	LastMessageID int64  `json:"last_message_id"`
 }
+
+// DMPartner represents a DM conversation partner with summary info.
+type DMPartner struct {
+	Name        string `json:"name"`
+	LastMessage string `json:"last_message"`
+	LastTime    string `json:"last_time"`
+	Unread      int    `json:"unread"`
+}