fix: skip flag-completion registration outside completion path

cmd/api/api.go

@@ -100,7 +100,7 @@ func NewCmdApiWithContext(ctx context.Context, f *cmdutil.Factory, runF func(*AP
 		}
 		return nil, cobra.ShellCompDirectiveNoFileComp
 	}
-	_ = cmd.RegisterFlagCompletionFunc("format", func(_ *cobra.Command, _ []string, _ string) ([]string, cobra.ShellCompDirective) {
+	cmdutil.RegisterFlagCompletion(cmd, "format", func(_ *cobra.Command, _ []string, _ string) ([]string, cobra.ShellCompDirective) {
 		return []string{"json", "ndjson", "table", "csv"}, cobra.ShellCompDirectiveNoFileComp
 	})
 

cmd/auth/login.go

@@ -72,7 +72,7 @@ browser. Run it in the background and retrieve the verification URL from its out
 	cmd.Flags().BoolVar(&opts.NoWait, "no-wait", false, "initiate device authorization and return immediately; use --device-code to complete")
 	cmd.Flags().StringVar(&opts.DeviceCode, "device-code", "", "poll and complete authorization with a device code from a previous --no-wait call")
 
-	_ = cmd.RegisterFlagCompletionFunc("domain", func(_ *cobra.Command, _ []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+	cmdutil.RegisterFlagCompletion(cmd, "domain", func(_ *cobra.Command, _ []string, toComplete string) ([]string, cobra.ShellCompDirective) {
 		return completeDomain(toComplete), cobra.ShellCompDirectiveNoFileComp
 	})
 

cmd/root.go

@@ -85,6 +85,8 @@
 		fmt.Fprintln(os.Stderr, "Error:", err)
 		return 1
 	}
+	configureFlagCompletions(os.Args)
+
 	f, rootCmd := buildInternal(
 		context.Background(), inv,
 		WithIO(os.Stdin, os.Stdout, os.Stderr),
@@ -153,6 +155,12 @@
 	return false
 }
 
+// configureFlagCompletions enables cmdutil.RegisterFlagCompletion only when
+// the invocation will actually serve a __complete request.
+func configureFlagCompletions(args []string) {
+	cmdutil.SetFlagCompletionsDisabled(!isCompletionCommand(args))
+}
+
 // handleRootError dispatches a command error to the appropriate handler
 // and returns the process exit code.
 func handleRootError(f *cmdutil.Factory, err error) int {

cmd/root_test.go

@@ -196,3 +196,28 @@ func TestRootLong_AgentSkillsLinkTargetsReadmeSection(t *testing.T) {
 		t.Fatalf("root help should not reference the removed install-ai-agent-skills anchor, got:\n%s", rootLong)
 	}
 }
+
+func TestConfigureFlagCompletions(t *testing.T) {
+	t.Cleanup(func() { cmdutil.SetFlagCompletionsDisabled(false) })
+
+	tests := []struct {
+		name         string
+		args         []string
+		wantDisabled bool
+	}{
+		{"plain command", []string{"im", "+send"}, true},
+		{"help flag", []string{"im", "--help"}, true},
+		{"no args", []string{}, true},
+		{"__complete request", []string{"__complete", "im", "+send", ""}, false},
+		{"completion subcommand", []string{"completion", "bash"}, false},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			cmdutil.SetFlagCompletionsDisabled(!tc.wantDisabled)
+			configureFlagCompletions(tc.args)
+			if got := cmdutil.FlagCompletionsDisabled(); got != tc.wantDisabled {
+				t.Fatalf("FlagCompletionsDisabled() = %v, want %v", got, tc.wantDisabled)
+			}
+		})
+	}
+}

cmd/schema/schema.go

@@ -377,7 +377,7 @@ func NewCmdSchema(f *cmdutil.Factory, runF func(*SchemaOptions) error) *cobra.Co
 
 	cmd.ValidArgsFunction = completeSchemaPath(f)
 	cmd.Flags().StringVar(&opts.Format, "format", "json", "output format: json (default) | pretty")
-	_ = cmd.RegisterFlagCompletionFunc("format", func(_ *cobra.Command, _ []string, _ string) ([]string, cobra.ShellCompDirective) {
+	cmdutil.RegisterFlagCompletion(cmd, "format", func(_ *cobra.Command, _ []string, _ string) ([]string, cobra.ShellCompDirective) {
 		return []string{"json", "pretty"}, cobra.ShellCompDirectiveNoFileComp
 	})
 

cmd/service/service.go

@@ -189,7 +189,7 @@ func NewCmdServiceMethodWithContext(ctx context.Context, f *cmdutil.Factory, spe
 			cmd.Flags().StringVar(&opts.File, "file", "", "file to upload ([field=]path, supports - for stdin)")
 		}
 	}
-	_ = cmd.RegisterFlagCompletionFunc("format", func(_ *cobra.Command, _ []string, _ string) ([]string, cobra.ShellCompDirective) {
+	cmdutil.RegisterFlagCompletion(cmd, "format", func(_ *cobra.Command, _ []string, _ string) ([]string, cobra.ShellCompDirective) {
 		return []string{"json", "ndjson", "table", "csv"}, cobra.ShellCompDirectiveNoFileComp
 	})
 

internal/cmdutil/completion.go

@@ -0,0 +1,37 @@
+// Copyright (c) 2026 Lark Technologies Pte. Ltd.
+// SPDX-License-Identifier: MIT
+
+package cmdutil
+
+import (
+	"sync/atomic"
+
+	"github.com/spf13/cobra"
+)
+
+// Cobra keeps completion callbacks in a package-global map keyed by
+// *pflag.Flag with no removal path, so registrations made for a *cobra.Command
+// outlive the command itself. Skip registration when the current invocation
+// will not serve a completion request.
+var flagCompletionsDisabled atomic.Bool
+
+// SetFlagCompletionsDisabled switches RegisterFlagCompletion between
+// registering and no-op. Typically set once at process start.
+func SetFlagCompletionsDisabled(disabled bool) {
+	flagCompletionsDisabled.Store(disabled)
+}
+
+// FlagCompletionsDisabled reports the current switch state.
+func FlagCompletionsDisabled() bool {
+	return flagCompletionsDisabled.Load()
+}
+
+// RegisterFlagCompletion wraps (*cobra.Command).RegisterFlagCompletionFunc
+// and honors the package switch. The underlying error is swallowed to match
+// the `_ = cmd.RegisterFlagCompletionFunc(...)` style already used here.
+func RegisterFlagCompletion(cmd *cobra.Command, flagName string, fn cobra.CompletionFunc) {
+	if flagCompletionsDisabled.Load() {
+		return
+	}
+	_ = cmd.RegisterFlagCompletionFunc(flagName, fn)
+}

internal/cmdutil/completion_test.go

@@ -0,0 +1,78 @@
+// Copyright (c) 2026 Lark Technologies Pte. Ltd.
+// SPDX-License-Identifier: MIT
+
+package cmdutil
+
+import (
+	"runtime"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/spf13/cobra"
+)
+
+func TestSetFlagCompletionsDisabled_RoundTrip(t *testing.T) {
+	t.Cleanup(func() { SetFlagCompletionsDisabled(false) })
+
+	if FlagCompletionsDisabled() {
+		t.Fatal("expected default false")
+	}
+	SetFlagCompletionsDisabled(true)
+	if !FlagCompletionsDisabled() {
+		t.Fatal("expected true after Set(true)")
+	}
+	SetFlagCompletionsDisabled(false)
+	if FlagCompletionsDisabled() {
+		t.Fatal("expected false after Set(false)")
+	}
+}
+
+// When disabled, a *cobra.Command must be collectable after the caller drops
+// its reference — i.e. the wrapper did not touch cobra's global map.
+func TestRegisterFlagCompletion_Disabled_DoesNotRetainCommand(t *testing.T) {
+	SetFlagCompletionsDisabled(true)
+	t.Cleanup(func() { SetFlagCompletionsDisabled(false) })
+
+	const N = 5
+	var collected atomic.Int32
+	func() {
+		for range N {
+			cmd := &cobra.Command{Use: "x"}
+			cmd.Flags().String("foo", "", "")
+			RegisterFlagCompletion(cmd, "foo", func(_ *cobra.Command, _ []string, _ string) ([]cobra.Completion, cobra.ShellCompDirective) {
+				return nil, cobra.ShellCompDirectiveNoFileComp
+			})
+			runtime.SetFinalizer(cmd, func(_ *cobra.Command) { collected.Add(1) })
+		}
+	}()
+	// Finalizers run on a dedicated goroutine after GC; loop to give it time.
+	for range 30 {
+		runtime.GC()
+		time.Sleep(20 * time.Millisecond)
+	}
+	if got := collected.Load(); int(got) != N {
+		t.Fatalf("expected %d *cobra.Command finalizers to fire when completions disabled, got %d", N, got)
+	}
+}
+
+// When enabled, the registered completion must be reachable via cobra.
+func TestRegisterFlagCompletion_Enabled_DoesRegister(t *testing.T) {
+	SetFlagCompletionsDisabled(false)
+
+	cmd := &cobra.Command{Use: "x"}
+	cmd.Flags().String("foo", "", "")
+	want := []cobra.Completion{"a", "b"}
+	RegisterFlagCompletion(cmd, "foo", func(_ *cobra.Command, _ []string, _ string) ([]cobra.Completion, cobra.ShellCompDirective) {
+		return want, cobra.ShellCompDirectiveNoFileComp
+	})
+
+	fn, ok := cmd.GetFlagCompletionFunc("foo")
+	if !ok {
+		t.Fatal("expected completion func to be registered")
+	}
+	got, _ := fn(cmd, nil, "")
+	if len(got) != 2 || got[0] != "a" || got[1] != "b" {
+		t.Fatalf("unexpected completion result: %v", got)
+	}
+}

internal/cmdutil/identity_flag.go

@@ -54,7 +54,7 @@ func addIdentityFlag(ctx context.Context, cmd *cobra.Command, f *Factory, target
 	}
 
 	registerIdentityFlag(cmd, target, cfg.defaultValue, cfg.usage)
-	_ = cmd.RegisterFlagCompletionFunc("as", func(_ *cobra.Command, _ []string, _ string) ([]string, cobra.ShellCompDirective) {
+	RegisterFlagCompletion(cmd, "as", func(_ *cobra.Command, _ []string, _ string) ([]string, cobra.ShellCompDirective) {
 		return cfg.completionValues, cobra.ShellCompDirectiveNoFileComp
 	})
 }

shortcuts/common/runner.go

@@ -876,7 +876,7 @@ func registerShortcutFlagsWithContext(ctx context.Context, cmd *cobra.Command, f
 		}
 		if len(fl.Enum) > 0 {
 			vals := fl.Enum
-			_ = cmd.RegisterFlagCompletionFunc(fl.Name, func(_ *cobra.Command, _ []string, _ string) ([]string, cobra.ShellCompDirective) {
+			cmdutil.RegisterFlagCompletion(cmd, fl.Name, func(_ *cobra.Command, _ []string, _ string) ([]string, cobra.ShellCompDirective) {
 				return vals, cobra.ShellCompDirectiveNoFileComp
 			})
 		}
@@ -892,7 +892,7 @@ func registerShortcutFlagsWithContext(ctx context.Context, cmd *cobra.Command, f
 	cmd.Flags().StringP("jq", "q", "", "jq expression to filter JSON output")
 	cmdutil.AddShortcutIdentityFlag(ctx, cmd, f, s.AuthTypes)
 	if s.HasFormat {
-		_ = cmd.RegisterFlagCompletionFunc("format", func(_ *cobra.Command, _ []string, _ string) ([]string, cobra.ShellCompDirective) {
+		cmdutil.RegisterFlagCompletion(cmd, "format", func(_ *cobra.Command, _ []string, _ string) ([]string, cobra.ShellCompDirective) {
 			return []string{"json", "pretty", "table", "ndjson", "csv"}, cobra.ShellCompDirectiveNoFileComp
 		})
 	}

shortcuts/common/runner_flag_completion_test.go

@@ -0,0 +1,98 @@
+// Copyright (c) 2026 Lark Technologies Pte. Ltd.
+// SPDX-License-Identifier: MIT
+
+package common
+
+import (
+	"context"
+	"testing"
+
+	"github.com/larksuite/cli/internal/cmdutil"
+	"github.com/spf13/cobra"
+)
+
+// TestShortcutMount_FlagCompletionsRegistered exercises the two
+// cmdutil.RegisterFlagCompletion call sites in registerShortcutFlagsWithContext:
+// the per-flag enum completion (runner.go:879) and the auto-injected --format
+// completion (runner.go:895).
+func TestShortcutMount_FlagCompletionsRegistered(t *testing.T) {
+	t.Cleanup(func() { cmdutil.SetFlagCompletionsDisabled(false) })
+	cmdutil.SetFlagCompletionsDisabled(false)
+
+	f, _, _, _ := cmdutil.TestFactory(t, nil)
+	parent := &cobra.Command{Use: "root"}
+	shortcut := Shortcut{
+		Service:     "docs",
+		Command:     "+fetch",
+		Description: "fetch doc",
+		HasFormat:   true,
+		Flags: []Flag{
+			{Name: "sort-by", Desc: "sort", Enum: []string{"asc", "desc"}},
+		},
+		Execute: func(context.Context, *RuntimeContext) error { return nil },
+	}
+	shortcut.Mount(parent, f)
+
+	cmd, _, err := parent.Find([]string{"+fetch"})
+	if err != nil {
+		t.Fatalf("Find() error = %v", err)
+	}
+
+	// Enum flag completion.
+	fn, ok := cmd.GetFlagCompletionFunc("sort-by")
+	if !ok {
+		t.Fatal("expected completion func for --sort-by")
+	}
+	got, _ := fn(cmd, nil, "")
+	if len(got) != 2 || got[0] != "asc" || got[1] != "desc" {
+		t.Fatalf("sort-by completion = %v, want [asc desc]", got)
+	}
+
+	// HasFormat-injected --format completion.
+	fn, ok = cmd.GetFlagCompletionFunc("format")
+	if !ok {
+		t.Fatal("expected completion func for --format")
+	}
+	got, _ = fn(cmd, nil, "")
+	want := []string{"json", "pretty", "table", "ndjson", "csv"}
+	if len(got) != len(want) {
+		t.Fatalf("format completion = %v, want %v", got, want)
+	}
+	for i, v := range want {
+		if got[i] != v {
+			t.Fatalf("format completion[%d] = %q, want %q", i, got[i], v)
+		}
+	}
+}
+
+// TestShortcutMount_FlagCompletionsDisabled verifies the switch actually
+// prevents the two registrations from landing in cobra's global map.
+func TestShortcutMount_FlagCompletionsDisabled(t *testing.T) {
+	t.Cleanup(func() { cmdutil.SetFlagCompletionsDisabled(false) })
+	cmdutil.SetFlagCompletionsDisabled(true)
+
+	f, _, _, _ := cmdutil.TestFactory(t, nil)
+	parent := &cobra.Command{Use: "root"}
+	shortcut := Shortcut{
+		Service:     "docs",
+		Command:     "+fetch",
+		Description: "fetch doc",
+		HasFormat:   true,
+		Flags: []Flag{
+			{Name: "sort-by", Desc: "sort", Enum: []string{"asc", "desc"}},
+		},
+		Execute: func(context.Context, *RuntimeContext) error { return nil },
+	}
+	shortcut.Mount(parent, f)
+
+	cmd, _, err := parent.Find([]string{"+fetch"})
+	if err != nil {
+		t.Fatalf("Find() error = %v", err)
+	}
+	if _, ok := cmd.GetFlagCompletionFunc("sort-by"); ok {
+		t.Fatal("did not expect completion func for --sort-by when disabled")
+	}
+	if _, ok := cmd.GetFlagCompletionFunc("format"); ok {
+		t.Fatal("did not expect completion func for --format when disabled")
+	}
+}