Reject an empty pr edit title Gitea would ignore

cmd/agentpr/main.go

@@ -163,6 +163,11 @@ func newPREditCmd() *cobra.Command {
 			// leave the title as it is, not blank it.
 			var opts agent.EditPROptions
 			if cmd.Flags().Changed("title") {
+				// Gitea ignores an empty title, so sending one would report
+				// success while changing nothing.
+				if title == "" {
+					return fmt.Errorf("--title cannot be empty: a title can be set but not cleared")
+				}
 				opts.Title = &title
 			}
 			if cmd.Flags().Changed("body") {

cmd/agentpr/main_test.go

@@ -33,3 +33,19 @@ func TestPREditRequiresTitleOrBody(t *testing.T) {
 		t.Errorf("error = %q, want it to name the missing flags", err)
 	}
 }
+
+// Gitea silently ignores an empty title, so `pr edit --title ""` would report
+// success while changing nothing; it must fail before any Vault/Gitea call.
+func TestPREditRejectsEmptyTitle(t *testing.T) {
+	cmd := newRootCmd()
+	cmd.SetArgs([]string{"pr", "edit", "--repo", "unkin/repo", "--pr", "7", "--title", ""})
+	cmd.SetOut(io.Discard)
+	cmd.SetErr(io.Discard)
+	err := cmd.Execute()
+	if err == nil {
+		t.Fatal("Execute() = nil, want an error for an empty --title")
+	}
+	if !strings.Contains(err.Error(), "--title cannot be empty") {
+		t.Errorf("error = %q, want it to reject the empty title", err)
+	}
+}