Add LastMessageAt field to conversation

Replaced `LatestConversationMessages` with `LoadConversationList`, which
utilizes `LastMessageAt` for much faster conversation loading in the
conversation listing TUI and `lmcli list` command.

pkg/cmd/list.go

@@ -20,9 +20,9 @@ func ListCmd(ctx *lmcli.Context) *cobra.Command {
 		Short:   "List conversations",
 		Long:    `List conversations in order of recent activity`,
 		RunE: func(cmd *cobra.Command, args []string) error {
-			messages, err := ctx.Conversations.LatestConversationMessages()
+			list, err := ctx.Conversations.LoadConversationList()
 			if err != nil {
-				return fmt.Errorf("Could not fetch conversations: %v", err)
+				return fmt.Errorf("Could not load conversations: %v", err)
 			}
 
 			type Category struct {
@@ -57,12 +57,12 @@ func ListCmd(ctx *lmcli.Context) *cobra.Command {
 
 			all, _ := cmd.Flags().GetBool("all")
 
-			for _, message := range messages {
-				messageAge := now.Sub(message.CreatedAt)
+			for _, item := range list.Items {
+				age := now.Sub(item.LastMessageAt)
 
 				var category string
 				for _, c := range categories {
-					if messageAge < c.cutoff {
+					if age < c.cutoff {
 						category = c.name
 						break
 					}
@@ -70,14 +70,14 @@ func ListCmd(ctx *lmcli.Context) *cobra.Command {
 
 				formatted := fmt.Sprintf(
 					"%s - %s - %s",
-					message.Conversation.ShortName.String,
-					util.HumanTimeElapsedSince(messageAge),
-					message.Conversation.Title,
+					item.ShortName,
+					util.HumanTimeElapsedSince(age),
+					item.Title,
 				)
 
 				categorized[category] = append(
 					categorized[category],
-					ConversationLine{messageAge, formatted},
+					ConversationLine{age, formatted},
 				)
 			}
 
@@ -93,7 +93,7 @@ func ListCmd(ctx *lmcli.Context) *cobra.Command {
 				fmt.Printf("%s:\n", category.name)
 				for _, conv := range conversationLines {
 					if conversationsPrinted >= count && !all {
-						fmt.Printf("%d remaining conversation(s), use --all to view.\n", len(messages)-conversationsPrinted)
+						fmt.Printf("%d remaining conversation(s), use --all to view.\n", list.Total-conversationsPrinted)
 						break outer
 					}