fix(acp): drop cursor placeholder slash-command descriptions (#2781)

apps/backend/internal/agentctl/acpcompat/cursor.go

@@ -116,3 +116,29 @@ func MigrateCursorModel(
 	}
 	return bareModelID, merged, true
 }
+
+// NormalizeCommandDescription drops cursor-agent's placeholder slash-command
+// description. cursor-agent emits a bare dash run ("---") as the description
+// for project/user slash commands that have no real description; passing it
+// through renders a meaningless "---" in the command palette, so treat it as
+// absent. The rewrite is Cursor-scoped: another agent may legitimately
+// advertise a dashes-only description, so descriptions from non-Cursor agents
+// are returned unchanged.
+//
+// This lives here, rather than next to either caller, because both the live
+// session adapter and the host-utility capability probe surface the same
+// commands and must agree; a cleanup applied to only one path leaves the other
+// rendering the placeholder.
+func NormalizeCommandDescription(agentID, description string) string {
+	if agentID != CursorAgentID {
+		return description
+	}
+	trimmed := strings.TrimSpace(description)
+	if trimmed == "" {
+		return description
+	}
+	if strings.Trim(trimmed, "-") == "" {
+		return ""
+	}
+	return description
+}

apps/backend/internal/agentctl/acpcompat/cursor_test.go

@@ -107,3 +107,36 @@ func TestMigrateCursorModel_PreservesExplicitOptions(t *testing.T) {
 		t.Error("MigrateCursorModel mutated the input options")
 	}
 }
+
+func TestNormalizeCommandDescription_CursorClearsDashPlaceholder(t *testing.T) {
+	cases := []struct {
+		name string
+		in   string
+		want string
+	}{
+		{name: "single dash", in: "---", want: ""},
+		{name: "padded dash run", in: "  ---  ", want: ""},
+		{name: "one dash", in: "-", want: ""},
+		{name: "real description", in: "Commit changes", want: "Commit changes"},
+		{name: "already empty", in: "", want: ""},
+		{name: "dash in text kept", in: "foo - bar", want: "foo - bar"},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			if got := NormalizeCommandDescription(CursorAgentID, tc.in); got != tc.want {
+				t.Errorf("NormalizeCommandDescription(cursor, %q) = %q, want %q", tc.in, got, tc.want)
+			}
+		})
+	}
+}
+
+// A dashes-only description from a non-Cursor agent is legitimate and must be
+// returned unchanged; the placeholder cleanup is Cursor-scoped.
+func TestNormalizeCommandDescription_OtherAgentsUnchanged(t *testing.T) {
+	for _, agentID := range []string{"claude-acp", "codex-acp", GrokAgentID, ""} {
+		if got := NormalizeCommandDescription(agentID, "---"); got != "---" {
+			t.Errorf("NormalizeCommandDescription(%q, %q) = %q, want %q (non-Cursor untouched)",
+				agentID, "---", got, "---")
+		}
+	}
+}

apps/backend/internal/agentctl/server/adapter/transport/acp/adapter_updates.go

@@ -5,6 +5,7 @@ import (
 	"strings"
 
 	"github.com/coder/acp-go-sdk"
+	"github.com/kandev/kandev/internal/agentctl/acpcompat"
 	"github.com/kandev/kandev/internal/agentctl/server/adapter/transport/shared"
 	"github.com/kandev/kandev/internal/agentctl/types/streams"
 	"go.uber.org/zap"
@@ -654,7 +655,7 @@ func (a *Adapter) convertAvailableCommands(sessionID string, update *acp.Session
 		seen[cmd.Name] = struct{}{}
 		ac := streams.AvailableCommand{
 			Name:        cmd.Name,
-			Description: cmd.Description,
+			Description: acpcompat.NormalizeCommandDescription(a.agentID, cmd.Description),
 		}
 		if cmd.Input != nil && cmd.Input.Unstructured != nil {
 			ac.InputHint = cmd.Input.Unstructured.Hint

apps/backend/internal/agentctl/server/adapter/transport/acp/conversion_test.go

@@ -7,6 +7,7 @@ import (
 	"time"
 
 	"github.com/coder/acp-go-sdk"
+	"github.com/kandev/kandev/internal/agentctl/acpcompat"
 	"github.com/kandev/kandev/internal/agentctl/server/adapter/transport/shared"
 	"github.com/kandev/kandev/internal/agentctl/types/streams"
 	"github.com/kandev/kandev/internal/common/logger"
@@ -1079,6 +1080,62 @@ func TestConvertAvailableCommands_NoDuplicates(t *testing.T) {
 	}
 }
 
+func TestConvertAvailableCommands_CursorPlaceholderDescriptionCleared(t *testing.T) {
+	a := newTestAdapterForAgent(acpcompat.CursorAgentID)
+	// cursor-agent sends a bare dash run for commands with no real description.
+	update := &acp.SessionAvailableCommandsUpdate{
+		AvailableCommands: []acp.AvailableCommand{
+			{Name: "bootstrap-go-service", Description: "---"},
+			{Name: "preferences", Description: "  ---  "},
+			{Name: "commit", Description: "Commit changes"},
+			{Name: "worktree", Description: ""},
+		},
+	}
+
+	result := a.convertAvailableCommands("session-placeholder", update)
+
+	if len(result.AvailableCommands) != 4 {
+		t.Fatalf("expected 4 commands, got %d", len(result.AvailableCommands))
+	}
+	if result.AvailableCommands[0].Description != "" {
+		t.Errorf("command[0].Description = %q, want empty (dash placeholder cleared)",
+			result.AvailableCommands[0].Description)
+	}
+	if result.AvailableCommands[1].Description != "" {
+		t.Errorf("command[1].Description = %q, want empty (padded dash placeholder cleared)",
+			result.AvailableCommands[1].Description)
+	}
+	if result.AvailableCommands[2].Description != "Commit changes" {
+		t.Errorf("command[2].Description = %q, want %q (real description preserved)",
+			result.AvailableCommands[2].Description, "Commit changes")
+	}
+	if result.AvailableCommands[3].Description != "" {
+		t.Errorf("command[3].Description = %q, want empty (already empty preserved)",
+			result.AvailableCommands[3].Description)
+	}
+}
+
+// A non-Cursor agent that legitimately advertises a dashes-only description
+// keeps it: the placeholder cleanup is Cursor-scoped.
+func TestConvertAvailableCommands_NonCursorDescriptionPreserved(t *testing.T) {
+	a := newTestAdapterForAgent("claude-acp")
+	update := &acp.SessionAvailableCommandsUpdate{
+		AvailableCommands: []acp.AvailableCommand{
+			{Name: "rule", Description: "---"},
+		},
+	}
+
+	result := a.convertAvailableCommands("session-noncursor", update)
+
+	if len(result.AvailableCommands) != 1 {
+		t.Fatalf("expected 1 command, got %d", len(result.AvailableCommands))
+	}
+	if result.AvailableCommands[0].Description != "---" {
+		t.Errorf("command[0].Description = %q, want %q (non-Cursor description untouched)",
+			result.AvailableCommands[0].Description, "---")
+	}
+}
+
 // --- generated usage/session-info updates ---
 
 func TestConvertNotification_UsageUpdateFixture(t *testing.T) {

apps/backend/internal/agentctl/server/utility/acp_executor.go

@@ -653,6 +653,7 @@ func isOpenCodeModelID(id string) bool {
 }
 
 type acpProbeNotificationState struct {
+	agentID             string
 	mu                  sync.Mutex
 	commands            []ProbeCommand
 	configOptions       []acp.SessionConfigOption
@@ -661,8 +662,9 @@ type acpProbeNotificationState struct {
 	gotConfigOptions    chan struct{}
 }
 
-func newACPProbeNotificationState() *acpProbeNotificationState {
+func newACPProbeNotificationState(agentID string) *acpProbeNotificationState {
 	return &acpProbeNotificationState{
+		agentID:          agentID,
 		gotCommands:      make(chan struct{}, 1),
 		gotConfigOptions: make(chan struct{}, 1),
 	}
@@ -685,7 +687,7 @@ func (s *acpProbeNotificationState) handle(n acp.SessionNotification) {
 		for _, command := range update.AvailableCommands {
 			s.commands = append(s.commands, ProbeCommand{
 				Name:        command.Name,
-				Description: command.Description,
+				Description: acpcompat.NormalizeCommandDescription(s.agentID, command.Description),
 			})
 		}
 		s.mu.Unlock()
@@ -843,7 +845,7 @@ func (e *ACPInferenceExecutor) probeACPSessionWithContext(
 	mode string,
 	requestedConfigOptions map[string]string,
 ) (*ProbeResponse, error) {
-	updates := newACPProbeNotificationState()
+	updates := newACPProbeNotificationState(agentID)
 
 	client := acpclient.NewClient(
 		acpclient.WithLogger(e.logger),