Implement inbox read cursors for unread threads

internal/cli/inbox/show.go

@@ -3,7 +3,6 @@ package inbox
 import (
 	"fmt"
 
-	"ai-workflow-skill/internal/db"
 	"ai-workflow-skill/internal/protocol"
 	"ai-workflow-skill/internal/store"
 
@@ -12,6 +11,7 @@ import (
 
 type showOptions struct {
 	threadID string
+	markRead bool
 }
 
 func newShowCmd(root *rootOptions) *cobra.Command {
@@ -23,14 +23,19 @@ func newShowCmd(root *rootOptions) *cobra.Command {
 		RunE: func(cmd *cobra.Command, args []string) error {
 			ctx := cmd.Context()
 
-			sqlDB, err := db.Open(ctx, root.dbPath)
+			sqlDB, err := openInboxDB(ctx, root.dbPath)
 			if err != nil {
 				return err
 			}
 			defer sqlDB.Close()
 
 			s := store.NewInboxStore(sqlDB)
-			detail, err := s.GetThread(ctx, opts.threadID)
+			agent := root.agent
+			if opts.markRead && agent == "" {
+				return protocol.InvalidInput("agent is required when using --mark-read", nil)
+			}
+
+			detail, err := s.GetThreadForAgent(ctx, opts.threadID, agent, opts.markRead)
 			if err != nil {
 				return err
 			}
@@ -66,6 +71,7 @@ func newShowCmd(root *rootOptions) *cobra.Command {
 	}
 
 	cmd.Flags().StringVar(&opts.threadID, "thread", "", "Thread ID")
+	cmd.Flags().BoolVar(&opts.markRead, "mark-read", false, "Advance the caller's read cursor to the latest message")
 	_ = cmd.MarkFlagRequired("thread")
 
 	return cmd