fix(chat): add package-level MCP call seam for toolbar remove-custom

- introduce removeChatToolbarCustomShortcutFn in toolbar_remove_custom.go
  as a package-level injection seam; default impl routes through
  callMCPToolOnServer against the im server so production behavior is
  unchanged
- update RunE to dispatch via the seam instead of calling
  callMCPToolOnServer inline
- add two TestCrossPlatformCoverage* tests that swap the seam via
  testseam.Swap and verify: (1) without --yes the seam is never called
  and a typed confirmation_required error is returned, (2) with --yes
  the seam is called exactly once with openCid and shortcutId. The
  stub forwards to deps.Caller.CallTool so the user_required contract
  gate (leaf.go) still sees the CallTool channel.

internal/helpers/toolbar_helpers_test.go

@@ -23,6 +23,7 @@ import (
 
 	"github.com/spf13/cobra"
 
+	"github.com/DingTalk-Real-AI/dingtalk-workspace-cli/internal/testseam"
 	"github.com/DingTalk-Real-AI/dingtalk-workspace-cli/pkg/edition"
 )
 
@@ -349,3 +350,63 @@ func TestCrossPlatformCoverageToolbarRemoveCustomCallsMCPWithExactArgsWhenYes(t
 		t.Fatalf("tool args = %#v, want %#v", call.args, wantArgs)
 	}
 }
+
+type removeCustomSeamCall struct {
+	openCid    string
+	shortcutId int64
+}
+
+type removeCustomSeamStub struct {
+	calls []removeCustomSeamCall
+	err   error
+}
+
+// invoke records the seam call and forwards to deps.Caller.CallTool so the
+// user_required contract gate (leaf.go) is satisfied. A pure short-circuit
+// would skip the CallTool channel and trigger
+// "user_required confirmation was never obtained via CallTool".
+func (s *removeCustomSeamStub) invoke(openCid string, shortcutId int64) error {
+	s.calls = append(s.calls, removeCustomSeamCall{openCid: openCid, shortcutId: shortcutId})
+	caller := GetCaller()
+	if caller == nil {
+		return s.err
+	}
+	_, err := caller.CallTool(context.Background(), "im", "remove_chat_toolbar_custom_shortcut", map[string]any{
+		"openCid":    openCid,
+		"shortcutId": shortcutId,
+	})
+	return err
+}
+
+func TestCrossPlatformCoverageToolbarRemoveCustomSeamRejectsWithoutYes(t *testing.T) {
+	stub := &removeCustomSeamStub{}
+	testseam.Swap(t, &removeChatToolbarCustomShortcutFn, stub.invoke)
+
+	err := executeToolbarCommand(t, newToolbarRemoveCustomCommand(), &toolbarTestCaller{},
+		"--conversation-id", "cidX", "--shortcut-id", "42")
+	requireTypedConfirmationError(t, err)
+	if len(stub.calls) != 0 {
+		t.Fatalf("expected 0 seam calls before --yes, got %d: %+v", len(stub.calls), stub.calls)
+	}
+}
+
+func TestCrossPlatformCoverageToolbarRemoveCustomSeamCallsWithExactArgsWhenYes(t *testing.T) {
+	stub := &removeCustomSeamStub{}
+	testseam.Swap(t, &removeChatToolbarCustomShortcutFn, stub.invoke)
+
+	err := executeToolbarCommand(t, newToolbarRemoveCustomCommand(), &toolbarTestCaller{},
+		"--conversation-id", "cidX", "--shortcut-id", "42", "--yes")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(stub.calls) != 1 {
+		t.Fatalf("expected exactly 1 seam call, got %d: %+v", len(stub.calls), stub.calls)
+	}
+	call := stub.calls[0]
+	if call.openCid != "cidX" {
+		t.Fatalf("seam openCid = %q, want cidX", call.openCid)
+	}
+	if call.shortcutId != int64(42) {
+		t.Fatalf("seam shortcutId = %d, want 42", call.shortcutId)
+	}
+}

internal/helpers/toolbar_remove_custom.go

@@ -20,6 +20,19 @@ import (
 	apperrors "github.com/DingTalk-Real-AI/dingtalk-workspace-cli/internal/errors"
 )
 
+// removeChatToolbarCustomShortcutFn is the package-level injection seam for
+// the remove-custom command's remote call. The default implementation routes
+// through callMCPToolOnServer against the im server, so production behavior is
+// unchanged. Tests swap it with testseam.Swap(t, &removeChatToolbarCustomShortcutFn, stub)
+// to capture the call without hitting a real remote. Like every package-var
+// seam in this repo it is not safe for t.Parallel tests.
+var removeChatToolbarCustomShortcutFn = func(openCid string, shortcutId int64) error {
+	return callMCPToolOnServer("im", "remove_chat_toolbar_custom_shortcut", map[string]any{
+		"openCid":    openCid,
+		"shortcutId": shortcutId,
+	})
+}
+
 func newToolbarRemoveCustomCommand() *cobra.Command {
 	cmd := &cobra.Command{
 		Use:     "remove-custom",
@@ -40,10 +53,7 @@ func newToolbarRemoveCustomCommand() *cobra.Command {
 					apperrors.WithActions("确认目标自定义入口", "获得用户确认后使用 --yes 执行"),
 				)
 			}
-			err = callMCPToolOnServer("im", "remove_chat_toolbar_custom_shortcut", map[string]any{
-				"openCid":    cid,
-				"shortcutId": shortcutId,
-			})
+			err = removeChatToolbarCustomShortcutFn(cid, shortcutId)
 			if isSystemBusy(err) {
 				return toolbarNewSystemBusyError()
 			}