fix(prompt): replay selected Cursor commands

Include client-resolved command content in model-visible user history so slash commands such as /init retain their actual instructions.

internal/backend/agent/prompt/replay_test.go

@@ -2,9 +2,67 @@ package promptengine
 
 import (
 	"reflect"
+	"strings"
 	"testing"
+
+	"cursor/gen/agentv1"
 )
 
+func TestBuildUserMessageReplayMessageIncludesSelectedCursorCommands(t *testing.T) {
+	message, ok := BuildUserMessageReplayMessage(&agentv1.UserMessage{
+		Text: "/init",
+		SelectedContext: &agentv1.SelectedContext{
+			CursorCommands: []*agentv1.SelectedCursorCommand{
+				{Name: "init", Content: "Analyze the repository and create AGENTS.md."},
+				{Name: `review"<&`, Content: "Review the implementation."},
+			},
+		},
+	})
+	if !ok {
+		t.Fatal("BuildUserMessageReplayMessage() returned ok=false")
+	}
+
+	want := strings.Join([]string{
+		"<user_query>\n/init\n</user_query>",
+		"<cursor_commands>\n" +
+			"<cursor_command name=\"init\">\nAnalyze the repository and create AGENTS.md.\n</cursor_command>\n\n" +
+			"<cursor_command name=\"review&quot;&lt;&amp;\">\nReview the implementation.\n</cursor_command>\n" +
+			"</cursor_commands>",
+	}, "\n\n")
+	if message.Role != "user" || message.Content != want {
+		t.Fatalf("message = %#v, want content %q", message, want)
+	}
+}
+
+func TestBuildUserMessageReplayMessageSkipsEmptyCursorCommandsAndKeepsOrder(t *testing.T) {
+	message, ok := BuildUserMessageReplayMessage(&agentv1.UserMessage{
+		Text: "run commands",
+		SelectedContext: &agentv1.SelectedContext{
+			CursorCommands: []*agentv1.SelectedCursorCommand{
+				nil,
+				{Name: "empty", Content: "  "},
+				{Content: "First command."},
+				{Name: "second", Content: "Second command."},
+			},
+		},
+	})
+	if !ok {
+		t.Fatal("BuildUserMessageReplayMessage() returned ok=false")
+	}
+
+	first := strings.Index(message.Content, "First command.")
+	second := strings.Index(message.Content, "Second command.")
+	if first < 0 || second < 0 || first >= second {
+		t.Fatalf("cursor command order was not preserved: %q", message.Content)
+	}
+	if strings.Contains(message.Content, "empty") {
+		t.Fatalf("empty cursor command was not skipped: %q", message.Content)
+	}
+	if !strings.Contains(message.Content, "<cursor_command>\nFirst command.\n</cursor_command>") {
+		t.Fatalf("unnamed cursor command was not rendered safely: %q", message.Content)
+	}
+}
+
 func TestBuildReplayMessagesFromPendingAssistantOutputsKeepsTextAndToolCallInOneAssistantTurn(t *testing.T) {
 	raw := `{
 		"id":"1",