refactor(auth): make keysigner internal

Drop the sks_signer build tag, mirroring the darwin keychain signer: the
TPM signer now compiles into every linux and windows/amd64 build via
constraint //go:build linux || (windows && amd64) — no -tags needed.
windows/arm64 is arch-excluded (go-ole has no arm64 VARIANT) and falls
back to client_secret only.

- goreleaser: drop -tags=sks_signer; merge windows-arm64 into the windows
  build (amd64+arm64) since no tag is needed and arm64 is arch-excluded.
- build-pkg-pr-new.sh: remove tag logic.
- doctor: update the no-signer hint (signer ships by default on macOS,
  Linux, Windows/amd64).
- Switching from a custom tag to GOOS/GOARCH constraints also lets
  go mod tidy track sks/go-tpm/go-ole correctly.

.github/workflows/release.yml

@@ -9,7 +9,11 @@ permissions:
   contents: read
 
 jobs:
+  # All platforms (incl. darwin keychain_signer) are CGO-free and cross-compiled
+  # on a single ubuntu runner in one goreleaser run (one checksums.txt). The
+  # darwin signer's runtime FFI is validated separately by the signer-test job.
   goreleaser:
+    needs: signer-test-macos
     runs-on: ubuntu-22.04
     permissions:
       contents: write
@@ -34,6 +38,21 @@ jobs:
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
+  # Validate the macOS keychain signer on real hardware. The release binaries are
+  # cross-compiled on ubuntu (CGO-free purego FFI), so this is the only step that
+  # needs a Mac — and it gates the release rather than producing it.
+  signer-test-macos:
+    runs-on: macos-latest
+    permissions:
+      contents: read
+    steps:
+      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
+      - uses: actions/setup-go@40f1582b2485089dde7abd97c1529aa768e1baff # v5
+        with:
+          go-version: '1.23'
+      - name: Keychain signer round-trip (CGO-free purego FFI)
+        run: LARK_KEYCHAIN_IT=1 CGO_ENABLED=0 go test -tags keychain_signer -run Keychain -v ./internal/keysigner/
+
   publish-npm:
     needs: goreleaser
     runs-on: ubuntu-22.04

.goreleaser.yml

@@ -5,15 +5,53 @@ before:
     - python3 scripts/fetch_meta.py
 
 builds:
-  - binary: lark-cli
+  # Linux & Windows: pure-Go TPM 2.0 signer is compiled in by default (no build
+  # tag), cross-compiled with CGO disabled — the binaries ship the platform key
+  # signer for private_key_jwt. windows/arm64 is the one exception: the sks
+  # Windows dependency stack (go-ole) has no arm64 support, so the signer file is
+  # arch-excluded there and that binary falls back to client_secret only.
+  - id: linux
+    binary: lark-cli
+    main: .
     env:
       - CGO_ENABLED=0
+    flags:
+      - -trimpath
+    ldflags:
+      - -s -w -X github.com/larksuite/cli/internal/build.Version={{ .Version }} -X github.com/larksuite/cli/internal/build.Date={{ .Date }}
+    goos:
+      - linux
+    goarch:
+      - amd64
+      - arm64
+  - id: windows
+    binary: lark-cli
+    main: .
+    env:
+      - CGO_ENABLED=0
+    flags:
+      - -trimpath
+    ldflags:
+      - -s -w -X github.com/larksuite/cli/internal/build.Version={{ .Version }} -X github.com/larksuite/cli/internal/build.Date={{ .Date }}
+    goos:
+      - windows
+    goarch:
+      - amd64
+      - arm64
+  # macOS: the keychain signer calls Security.framework via runtime FFI (purego),
+  # so it is CGO-free, compiled into every darwin build (no build tag), and
+  # cross-compiles from the same ubuntu runner as linux/windows.
+  - id: darwin
+    binary: lark-cli
+    main: .
+    env:
+      - CGO_ENABLED=0
+    flags:
+      - -trimpath
     ldflags:
       - -s -w -X github.com/larksuite/cli/internal/build.Version={{ .Version }} -X github.com/larksuite/cli/internal/build.Date={{ .Date }}
     goos:
       - darwin
-      - linux
-      - windows
     goarch:
       - amd64
       - arm64
@@ -23,7 +61,7 @@ archives:
   - name_template: "lark-cli-{{ .Version }}-{{ .Os }}-{{ .Arch }}"
     format_overrides:
       - goos: windows
-        format: zip
+        formats: [zip]
     files:
       - README.md
       - LICENSE

Makefile

@@ -33,7 +33,11 @@ build: fetch_meta
 	go build -trimpath -ldflags "$(LDFLAGS)" -o $(BINARY) .
 
 vet: fetch_meta
-	go vet ./...
+	# -unsafeptr=false: the macOS keychain signer dereferences dylib data-symbol
+	# addresses from purego.Dlsym (uintptr->unsafe.Pointer over stable C memory) —
+	# safe FFI, but go vet's unsafeptr can't prove it and has no inline suppress.
+	# golangci-lint still runs full govet (honoring the //nolint:govet) in CI.
+	go vet -unsafeptr=false ./...
 
 # fmt-check fails when any file would be reformatted by gofmt. Keep this
 # in sync with the fast-gate "Check formatting" step in CI.

cmd/auth/login.go

@@ -265,7 +265,7 @@ func authLoginRun(opts *LoginOptions) error {
 	if err != nil {
 		return err
 	}
-	authResp, err := larkauth.RequestDeviceAuthorization(httpClient, config.AppID, config.AppSecret, config.Brand, finalScope, f.IOStreams.ErrOut)
+	authResp, err := larkauth.RequestDeviceAuthorization(opts.Ctx, httpClient, larkauth.ClientAuthFromConfig(config), config.Brand, finalScope, f.IOStreams.ErrOut)
 	if err != nil {
 		return errs.NewAuthenticationError(errs.SubtypeUnknown, "device authorization failed: %v", err).WithCause(err)
 	}
@@ -325,7 +325,7 @@ func authLoginRun(opts *LoginOptions) error {
 
 	// Step 3: Poll for token
 	log(msg.WaitingAuth)
-	result := pollDeviceToken(opts.Ctx, httpClient, config.AppID, config.AppSecret, config.Brand,
+	result := pollDeviceToken(opts.Ctx, httpClient, larkauth.ClientAuthFromConfig(config), config.Brand,
 		authResp.DeviceCode, authResp.Interval, authResp.ExpiresIn, f.IOStreams.ErrOut)
 
 	if !result.OK {
@@ -415,7 +415,7 @@ func authLoginPollDeviceCode(opts *LoginOptions, config *core.CliConfig, msg *lo
 		fmt.Fprintln(f.IOStreams.ErrOut, msg.AgentTimeoutHint)
 	}
 	log(msg.WaitingAuth)
-	result := pollDeviceToken(opts.Ctx, httpClient, config.AppID, config.AppSecret, config.Brand,
+	result := pollDeviceToken(opts.Ctx, httpClient, larkauth.ClientAuthFromConfig(config), config.Brand,
 		opts.DeviceCode, 5, 600, f.IOStreams.ErrOut)
 
 	if !result.OK {

cmd/auth/login_test.go

@@ -847,7 +847,7 @@ func TestAuthLoginRun_DeviceCodeTokenNilCleansScopeCache(t *testing.T) {
 
 	original := pollDeviceToken
 	t.Cleanup(func() { pollDeviceToken = original })
-	pollDeviceToken = func(ctx context.Context, httpClient *http.Client, appId, appSecret string, brand core.LarkBrand, deviceCode string, interval, expiresIn int, errOut io.Writer) *larkauth.DeviceFlowResult {
+	pollDeviceToken = func(ctx context.Context, httpClient *http.Client, ca larkauth.ClientAuth, brand core.LarkBrand, deviceCode string, interval, expiresIn int, errOut io.Writer) *larkauth.DeviceFlowResult {
 		return &larkauth.DeviceFlowResult{OK: true, Token: nil}
 	}
 
@@ -886,7 +886,7 @@ func TestAuthLoginRun_JSONAbort_StdoutEventOnly_StderrEmpty(t *testing.T) {
 
 	original := pollDeviceToken
 	t.Cleanup(func() { pollDeviceToken = original })
-	pollDeviceToken = func(ctx context.Context, httpClient *http.Client, appId, appSecret string, brand core.LarkBrand, deviceCode string, interval, expiresIn int, errOut io.Writer) *larkauth.DeviceFlowResult {
+	pollDeviceToken = func(ctx context.Context, httpClient *http.Client, ca larkauth.ClientAuth, brand core.LarkBrand, deviceCode string, interval, expiresIn int, errOut io.Writer) *larkauth.DeviceFlowResult {
 		return &larkauth.DeviceFlowResult{OK: false, Message: "user denied"}
 	}
 

cmd/config/config_test.go

@@ -193,7 +193,7 @@ func TestSaveInitConfig_OmitLangPreservesPrior(t *testing.T) {
 		t.Fatalf("seed config: %v", err)
 	}
 
-	if err := saveInitConfig("", existing, f, "cli_x", core.PlainSecret("s2"), core.BrandFeishu, ""); err != nil {
+	if err := saveInitConfig("", existing, f, "cli_x", core.PlainSecret("s2"), core.BrandFeishu, "", "", nil); err != nil {
 		t.Fatalf("saveInitConfig (no --lang): %v", err)
 	}
 
@@ -206,6 +206,88 @@ func TestSaveInitConfig_OmitLangPreservesPrior(t *testing.T) {
 	}
 }
 
+func TestKeyRefFromResult_PrivateKeyJWT(t *testing.T) {
+	ref := keyRefFromResult(&configInitResult{
+		AuthMethod: core.AuthMethodPrivateKeyJWT,
+		KeyLabel:   "lark-cli-default",
+	})
+	if ref == nil {
+		t.Fatal("keyRefFromResult returned nil")
+	}
+	if ref.Source != "tee" || ref.ID != "lark-cli-default" {
+		t.Fatalf("key ref = %#v, want tee/lark-cli-default", ref)
+	}
+
+	if ref := keyRefFromResult(&configInitResult{AuthMethod: core.AuthMethodPrivateKeyJWT}); ref != nil {
+		t.Fatalf("missing key label should not persist key ref, got %#v", ref)
+	}
+	if ref := keyRefFromResult(&configInitResult{AuthMethod: core.AuthMethodClientSecret, KeyLabel: "ignored"}); ref != nil {
+		t.Fatalf("client_secret should not persist key ref, got %#v", ref)
+	}
+	if ref := keyRefFromResult(nil); ref != nil {
+		t.Fatalf("nil result should not persist key ref, got %#v", ref)
+	}
+}
+
+func TestSaveInitConfig_PrivateKeyJWTSingleAppPersistsSecretlessAuth(t *testing.T) {
+	t.Setenv("LARKSUITE_CLI_CONFIG_DIR", t.TempDir())
+	f, _, _, _ := cmdutil.TestFactory(t, nil)
+
+	keyRef := &core.SecretRef{Source: "tee", ID: "lark-cli-default"}
+	if err := saveInitConfig("", nil, f, "cli_pkjwt", core.SecretInput{}, core.BrandFeishu, "en_us", core.AuthMethodPrivateKeyJWT, keyRef); err != nil {
+		t.Fatalf("saveInitConfig private_key_jwt single app: %v", err)
+	}
+
+	got, err := core.LoadMultiAppConfig()
+	if err != nil {
+		t.Fatalf("LoadMultiAppConfig: %v", err)
+	}
+	if len(got.Apps) != 1 {
+		t.Fatalf("apps len = %d, want 1", len(got.Apps))
+	}
+	app := got.Apps[0]
+	if app.AppId != "cli_pkjwt" {
+		t.Fatalf("AppId = %q, want cli_pkjwt", app.AppId)
+	}
+	if app.AuthMethod != core.AuthMethodPrivateKeyJWT {
+		t.Fatalf("AuthMethod = %q, want private_key_jwt", app.AuthMethod)
+	}
+	if app.KeyRef == nil || app.KeyRef.Source != "tee" || app.KeyRef.ID != "lark-cli-default" {
+		t.Fatalf("KeyRef = %#v, want tee/lark-cli-default", app.KeyRef)
+	}
+	if app.AppSecret.Ref != nil || app.AppSecret.Plain != "" {
+		t.Fatalf("private_key_jwt config must stay secretless, AppSecret=%#v", app.AppSecret)
+	}
+}
+
+func TestSaveInitConfig_PrivateKeyJWTProfilePersistsSecretlessAuth(t *testing.T) {
+	t.Setenv("LARKSUITE_CLI_CONFIG_DIR", t.TempDir())
+	f, _, _, _ := cmdutil.TestFactory(t, nil)
+
+	keyRef := &core.SecretRef{Source: "tee", ID: "lark-cli-default"}
+	if err := saveInitConfig("prod", &core.MultiAppConfig{}, f, "cli_pkjwt", core.SecretInput{}, core.BrandLark, "en_us", core.AuthMethodPrivateKeyJWT, keyRef); err != nil {
+		t.Fatalf("saveInitConfig private_key_jwt profile: %v", err)
+	}
+
+	got, err := core.LoadMultiAppConfig()
+	if err != nil {
+		t.Fatalf("LoadMultiAppConfig: %v", err)
+	}
+	app := got.FindApp("prod")
+	if app == nil {
+		t.Fatalf("profile prod not saved: %#v", got.Apps)
+	}
+	if app.AuthMethod != core.AuthMethodPrivateKeyJWT {
+		t.Fatalf("AuthMethod = %q, want private_key_jwt", app.AuthMethod)
+	}
+	if app.KeyRef == nil || app.KeyRef.Source != "tee" || app.KeyRef.ID != "lark-cli-default" {
+		t.Fatalf("KeyRef = %#v, want tee/lark-cli-default", app.KeyRef)
+	}
+	if app.AppSecret.Ref != nil || app.AppSecret.Plain != "" {
+		t.Fatalf("private_key_jwt profile must stay secretless, AppSecret=%#v", app.AppSecret)
+	}
+}
+
 // TestConfigInitCmd_InvalidLang verifies a non-empty --lang on config init is
 // strictly validated the same way bind validates: wrong-case / typo / removed
 // codes / hyphen form all exit with ExitValidation. (Empty is a no-op.)
@@ -388,7 +470,7 @@ func TestSaveAsProfile_RejectsProfileNameCollisionWithExistingAppID(t *testing.T
 		},
 	}
 
-	err := saveAsProfile(existing, keychain.KeychainAccess(&noopConfigKeychain{}), "cli_prod", "app-new", core.PlainSecret("new-secret"), core.BrandLark, "en")
+	err := saveAsProfile(existing, keychain.KeychainAccess(&noopConfigKeychain{}), "cli_prod", "app-new", core.PlainSecret("new-secret"), core.BrandLark, "en", "", nil)
 	if err == nil {
 		t.Fatal("expected conflict error")
 	}
@@ -427,6 +509,46 @@ func TestWrapSaveConfigError_PassesTypedValidationThrough(t *testing.T) {
 	}
 }
 
+func TestSaveAsProfile_UpdatePersistsPrivateKeyJWT(t *testing.T) {
+	t.Setenv("LARKSUITE_CLI_CONFIG_DIR", t.TempDir())
+
+	existing := &core.MultiAppConfig{
+		Apps: []core.AppConfig{{
+			Name:      "prod",
+			AppId:     "cli_prod",
+			AppSecret: core.PlainSecret("old-secret"),
+			Brand:     core.BrandFeishu,
+			Users:     []core.AppUser{{UserOpenId: "ou_1", UserName: "User"}},
+		}},
+	}
+	keyRef := &core.SecretRef{Source: "tee", ID: "lark-cli-default"}
+
+	if err := saveAsProfile(existing, keychain.KeychainAccess(&noopConfigKeychain{}), "prod", "cli_prod", core.SecretInput{}, core.BrandLark, "en_us", core.AuthMethodPrivateKeyJWT, keyRef); err != nil {
+		t.Fatalf("saveAsProfile update private_key_jwt: %v", err)
+	}
+
+	got, err := core.LoadMultiAppConfig()
+	if err != nil {
+		t.Fatalf("LoadMultiAppConfig: %v", err)
+	}
+	app := got.FindApp("prod")
+	if app == nil {
+		t.Fatalf("profile prod not saved: %#v", got.Apps)
+	}
+	if app.AuthMethod != core.AuthMethodPrivateKeyJWT {
+		t.Fatalf("AuthMethod = %q, want private_key_jwt", app.AuthMethod)
+	}
+	if app.KeyRef == nil || app.KeyRef.Source != "tee" || app.KeyRef.ID != "lark-cli-default" {
+		t.Fatalf("KeyRef = %#v, want tee/lark-cli-default", app.KeyRef)
+	}
+	if app.AppSecret.Ref != nil || app.AppSecret.Plain != "" {
+		t.Fatalf("private_key_jwt update must stay secretless, AppSecret=%#v", app.AppSecret)
+	}
+	if len(app.Users) != 1 || app.Users[0].UserOpenId != "ou_1" {
+		t.Fatalf("same-app update should preserve users, Users=%#v", app.Users)
+	}
+}
+
 func TestUpdateExistingProfileWithoutSecret_RejectsAppIDChange(t *testing.T) {
 	multi := &core.MultiAppConfig{
 		CurrentApp: "prod",

cmd/config/init.go

@@ -19,6 +19,7 @@ import (
 	"github.com/larksuite/cli/internal/core"
 	"github.com/larksuite/cli/internal/i18n"
 	"github.com/larksuite/cli/internal/keychain"
+	"github.com/larksuite/cli/internal/keysigner"
 	"github.com/larksuite/cli/internal/output"
 )
 
@@ -31,6 +32,7 @@ type ConfigInitOptions struct {
 	AppSecretStdin bool   // read app-secret from stdin (avoids process list exposure)
 	Brand          string
 	New            bool
+	AuthMethod     string // --auth-method for --new: "" (default client_secret) | private_key_jwt
 
 	Lang         string // raw --lang (string for cobra); normalized to canonical/"" in validateInitLang
 	langExplicit bool   // true when --lang was explicitly passed
@@ -39,6 +41,8 @@ type ConfigInitOptions struct {
 
 	ProfileName string // when set, create/update a named profile instead of replacing Apps[0]
 
+	Restore bool // Restore re-registers the app already in config to recover a lost credential
+
 	// ForceInit overrides the agent-workspace guard. Without it, running
 	// init under OPENCLAW_HOME / HERMES_HOME refuses and points the caller
 	// at config bind — which is what AI agents almost always want. Manual
@@ -81,11 +85,13 @@ if the user explicitly wants a separate app inside the Agent workspace.`,
 	}
 
 	cmd.Flags().BoolVar(&opts.New, "new", false, "create a new app directly (skip mode selection)")
+	cmd.Flags().StringVar(&opts.AuthMethod, "auth-method", "", "auth method for --new: client_secret (default) or private_key_jwt (signed by a platform key, no app secret)")
 	cmd.Flags().StringVar(&opts.AppID, "app-id", "", "App ID (non-interactive)")
 	cmd.Flags().BoolVar(&opts.AppSecretStdin, "app-secret-stdin", false, "Read App Secret from stdin to avoid process list exposure")
 	cmd.Flags().StringVar(&opts.Brand, "brand", "feishu", "feishu or lark (non-interactive, default feishu)")
 	cmd.Flags().StringVar(&opts.Lang, "lang", "", "language preference (e.g. zh or zh_cn)")
 	cmd.Flags().StringVar(&opts.ProfileName, "name", "", "create or update a named profile (append instead of replace)")
+	cmd.Flags().BoolVar(&opts.Restore, "restore", false, "re-register the app already in config to recover a lost credential (keychain key / app secret); reuses the stored app ID and auth method")
 	cmd.Flags().BoolVar(&opts.ForceInit, "force-init", false, "allow init inside an Agent workspace (OPENCLAW_HOME / HERMES_HOME); use config bind instead unless you really want a separate app")
 	cmdutil.SetRisk(cmd, "write")
 
@@ -132,7 +138,7 @@ func guardAgentWorkspace(opts *ConfigInitOptions) error {
 
 // hasAnyNonInteractiveFlag returns true if any non-interactive flag is set.
 func (o *ConfigInitOptions) hasAnyNonInteractiveFlag() bool {
-	return o.New || o.AppID != "" || o.AppSecretStdin
+	return o.New || o.Restore || o.AppID != "" || o.AppSecretStdin
 }
 
 // cleanupOldConfig clears keychain entries (AppSecret + UAT) for all apps in existing config except the app whose AppId equals skipAppID.
@@ -151,11 +157,44 @@ func cleanupOldConfig(existing *core.MultiAppConfig, f *cmdutil.Factory, skipApp
 	}
 }
 
+// removeStaleSecretForPKJWT clears a secret left in the keychain when the SAME
+// appId is migrated from client_secret to private_key_jwt. cleanupOldConfig
+// explicitly skips a matching appId, and saveAsProfile only cleans up on an
+// appId change, so a same-appId migration would orphan the old secret. This
+// fills that gap. RemoveSecretStore only deletes Source=="keychain" entries, so
+// the new pkjwt tee key handle is never touched.
+func removeStaleSecretForPKJWT(existing *core.MultiAppConfig, profileName, appID string, kc keychain.KeychainAccess) {
+	if existing == nil {
+		return
+	}
+	var prior *core.AppConfig
+	if profileName != "" {
+		if idx := findProfileIndexByName(existing, profileName); idx >= 0 {
+			prior = &existing.Apps[idx]
+		}
+	} else {
+		prior = existing.CurrentAppConfig("")
+	}
+	if prior != nil && prior.AppId == appID && !prior.AppSecret.IsZero() {
+		core.RemoveSecretStore(prior.AppSecret, kc)
+	}
+}
+
+// keyRefFromResult builds the TEE key reference to persist for a private_key_jwt
+// registration result, or nil for client_secret.
+func keyRefFromResult(r *configInitResult) *core.SecretRef {
+	if r != nil && r.AuthMethod == core.AuthMethodPrivateKeyJWT && r.KeyLabel != "" {
+		return &core.SecretRef{Source: "tee", ID: r.KeyLabel}
+	}
+	return nil
+}
+
 // saveAsOnlyApp overwrites config.json with a single-app config.
-func saveAsOnlyApp(appId string, secret core.SecretInput, brand core.LarkBrand, lang string) error {
+func saveAsOnlyApp(appId string, secret core.SecretInput, brand core.LarkBrand, lang, authMethod string, keyRef *core.SecretRef) error {
 	config := &core.MultiAppConfig{
 		Apps: []core.AppConfig{{
 			AppId: appId, AppSecret: secret, Brand: brand, Lang: i18n.Lang(lang), Users: []core.AppUser{},
+			AuthMethod: authMethod, KeyRef: keyRef,
 		}},
 	}
 	return core.SaveMultiAppConfig(config)
@@ -164,9 +203,11 @@ func saveAsOnlyApp(appId string, secret core.SecretInput, brand core.LarkBrand,
 // saveInitConfig saves a new/updated app config, respecting --profile mode.
 // With profileName: appends or updates the named profile (preserves other profiles).
 // Without profileName: cleans up old config and saves as the only app.
-func saveInitConfig(profileName string, existing *core.MultiAppConfig, f *cmdutil.Factory, appId string, secret core.SecretInput, brand core.LarkBrand, lang string) error {
+// authMethod/keyRef carry the credential type: ("", nil) for client_secret,
+// (private_key_jwt, &{tee,label}) for the secretless TEE flow.
+func saveInitConfig(profileName string, existing *core.MultiAppConfig, f *cmdutil.Factory, appId string, secret core.SecretInput, brand core.LarkBrand, lang, authMethod string, keyRef *core.SecretRef) error {
 	if profileName != "" {
-		return saveAsProfile(existing, f.Keychain, profileName, appId, secret, brand, lang)
+		return saveAsProfile(existing, f.Keychain, profileName, appId, secret, brand, lang, authMethod, keyRef)
 	}
 	cleanupOldConfig(existing, f, appId)
 	var prior i18n.Lang
@@ -175,7 +216,7 @@ func saveInitConfig(profileName string, existing *core.MultiAppConfig, f *cmduti
 			prior = app.Lang
 		}
 	}
-	return saveAsOnlyApp(appId, secret, brand, string(preferredLang(i18n.Lang(lang), prior)))
+	return saveAsOnlyApp(appId, secret, brand, string(preferredLang(i18n.Lang(lang), prior)), authMethod, keyRef)
 }
 
 // wrapSaveConfigError passes an already-typed error (e.g. the --name conflict
@@ -195,7 +236,7 @@ func wrapSaveConfigError(err error) error {
 // saveAsProfile appends or updates a named profile in the config.
 // If a profile with the same name exists, it updates it; otherwise appends.
 // When updating, cleans up old keychain secrets if AppId changed.
-func saveAsProfile(existing *core.MultiAppConfig, kc keychain.KeychainAccess, profileName, appId string, secret core.SecretInput, brand core.LarkBrand, lang string) error {
+func saveAsProfile(existing *core.MultiAppConfig, kc keychain.KeychainAccess, profileName, appId string, secret core.SecretInput, brand core.LarkBrand, lang, authMethod string, keyRef *core.SecretRef) error {
 	multi := existing
 	if multi == nil {
 		multi = &core.MultiAppConfig{}
@@ -214,6 +255,8 @@ func saveAsProfile(existing *core.MultiAppConfig, kc keychain.KeychainAccess, pr
 		multi.Apps[idx].AppSecret = secret
 		multi.Apps[idx].Brand = brand
 		multi.Apps[idx].Lang = preferredLang(i18n.Lang(lang), multi.Apps[idx].Lang)
+		multi.Apps[idx].AuthMethod = authMethod
+		multi.Apps[idx].KeyRef = keyRef
 	} else {
 		if findAppIndexByAppID(multi, profileName) >= 0 {
 			return errs.NewValidationError(errs.SubtypeInvalidArgument,
@@ -222,12 +265,14 @@ func saveAsProfile(existing *core.MultiAppConfig, kc keychain.KeychainAccess, pr
 		}
 		// Append new profile
 		multi.Apps = append(multi.Apps, core.AppConfig{
-			Name:      profileName,
-			AppId:     appId,
-			AppSecret: secret,
-			Brand:     brand,
-			Lang:      i18n.Lang(lang),
-			Users:     []core.AppUser{},
+			Name:       profileName,
+			AppId:      appId,
+			AppSecret:  secret,
+			Brand:      brand,
+			Lang:       i18n.Lang(lang),
+			Users:      []core.AppUser{},
+			AuthMethod: authMethod,
+			KeyRef:     keyRef,
 		})
 	}
 	return core.SaveMultiAppConfig(multi)
@@ -305,6 +350,94 @@ func updateExistingProfileWithoutSecret(existing *core.MultiAppConfig, profileNa
 	return core.SaveMultiAppConfig(existing)
 }
 
+// persistAndProbeResult saves a registration/restore result into profileName and
+// runs the post-registration probe. profileName == "" replaces the single app
+// (legacy); a named profile is updated in place. Shared by --new and --restore.
+func persistAndProbeResult(opts *ConfigInitOptions, f *cmdutil.Factory, profileName string, result *configInitResult) error {
+	existing, _ := core.LoadMultiAppConfig()
+
+	// private_key_jwt apps have no secret: persist auth method + TEE key ref.
+	// Registration success already validated the key (server bound the public
+	// key), so the app_secret probe is skipped.
+	if result.AuthMethod == core.AuthMethodPrivateKeyJWT {
+		if err := saveInitConfig(profileName, existing, f, result.AppID, core.SecretInput{}, result.Brand, opts.Lang, result.AuthMethod, keyRefFromResult(result)); err != nil {
+			return wrapSaveConfigError(err)
+		}
+		removeStaleSecretForPKJWT(existing, profileName, result.AppID, f.Keychain)
+		printLangPreferenceConfirmation(opts)
+		output.PrintJson(f.IOStreams.Out, map[string]interface{}{"appId": result.AppID, "authMethod": result.AuthMethod, "brand": result.Brand})
+		return runProbePKJWT(opts.Ctx, f, result.Brand, result.AppID, keysigner.Active(), result.KeyLabel)
+	}
+
+	secret, err := core.ForStorage(result.AppID, core.PlainSecret(result.AppSecret), f.Keychain)
+	if err != nil {
+		return errs.NewInternalError(errs.SubtypeSDKError, "%v", err).WithCause(err)
+	}
+	if err := saveInitConfig(profileName, existing, f, result.AppID, secret, result.Brand, opts.Lang, "", nil); err != nil {
+		return wrapSaveConfigError(err)
+	}
+	printLangPreferenceConfirmation(opts)
+	output.PrintJson(f.IOStreams.Out, map[string]interface{}{"appId": result.AppID, "appSecret": "****", "brand": result.Brand})
+	return runProbe(opts.Ctx, f, result.AppID, result.AppSecret, result.Brand)
+}
+
+// runRestoreFlow re-registers the app already in config to recover a lost
+// credential (deleted keychain key / lost app secret). It reads the existing
+// app id + auth method + brand from config (no secret needed — that's the lost
+// part) and re-runs the device-flow registration with the app id sent on begin,
+// so the server re-registers that app instead of creating a new one. The
+// re-issued credential is written back to the same profile.
+func runRestoreFlow(opts *ConfigInitOptions, existing *core.MultiAppConfig, f *cmdutil.Factory, msg *initMsg) error {
+	if existing == nil {
+		return errs.NewConfigError(errs.SubtypeNotConfigured, "nothing to restore: no config found").
+			WithHint("run: lark-cli config init")
+	}
+	app := existing.CurrentAppConfig(opts.ProfileName)
+	if app == nil || app.AppId == "" {
+		return errs.NewConfigError(errs.SubtypeNotConfigured, "nothing to restore: no app id in config%s", profileSuffix(opts.ProfileName)).
+			WithHint("run: lark-cli config init")
+	}
+
+	restoreAppID := app.AppId
+	// Reuse the stored auth method authoritatively — never prompt. Empty on disk
+	// means client_secret (omitempty back-compat); pass it explicitly so
+	// resolveRegisterAuthMethod doesn't fall through to the interactive picker.
+	authMethod := app.AuthMethod
+	if authMethod == "" {
+		authMethod = core.AuthMethodClientSecret
+	}
+	result, err := runCreateAppFlow(opts.Ctx, f, app.Brand, authMethod, msg, restoreAppID)
+	if err != nil {
+		return err
+	}
+	if result == nil {
+		return errs.NewInternalError(errs.SubtypeSDKError, "app restore returned no result")
+	}
+
+	// Safety: if the server did not honor app_id (e.g. not yet supported), it may
+	// have created a NEW app instead of restoring. Warn so the user is not silently
+	// switched to a different app id.
+	if result.AppID != restoreAppID {
+		fmt.Fprintf(f.IOStreams.ErrOut, "[lark-cli] [WARN] restore: server returned app %s, expected %s — it may have created a new app instead of restoring\n", result.AppID, restoreAppID)
+	}
+
+	// Write back to the profile we restored: an explicit --name, else the resolved
+	// app's own name. Empty name => legacy single-app replace.
+	saveProfile := opts.ProfileName
+	if saveProfile == "" {
+		saveProfile = app.Name
+	}
+	return persistAndProbeResult(opts, f, saveProfile, result)
+}
+
+// profileSuffix renders " (profile %q)" for error messages, or "" when unnamed.
+func profileSuffix(profileName string) string {
+	if profileName == "" {
+		return ""
+	}
+	return fmt.Sprintf(" (profile %q)", profileName)
+}
+
 func configInitRun(opts *ConfigInitOptions) error {
 	f := opts.Factory
 
@@ -335,6 +468,17 @@ func configInitRun(opts *ConfigInitOptions) error {
 		}
 	}
 
+	// --restore recovers an existing app; it is incompatible with creating a new
+	// app (--new) or importing one non-interactively (--app-id / stdin secret).
+	if opts.Restore {
+		if opts.New {
+			return errs.NewValidationError(errs.SubtypeInvalidArgument, "--restore cannot be combined with --new").WithParam("--restore")
+		}
+		if opts.AppID != "" || opts.AppSecretStdin {
+			return errs.NewValidationError(errs.SubtypeInvalidArgument, "--restore cannot be combined with --app-id / --app-secret-stdin").WithParam("--restore")
+		}
+	}
+
 	// Mode 1: Non-interactive
 	if opts.AppID != "" && opts.appSecret != "" {
 		brand := parseBrand(opts.Brand)
@@ -342,7 +486,7 @@ func configInitRun(opts *ConfigInitOptions) error {
 		if err != nil {
 			return errs.NewInternalError(errs.SubtypeSDKError, "%v", err).WithCause(err)
 		}
-		if err := saveInitConfig(opts.ProfileName, existing, f, opts.AppID, secret, brand, opts.Lang); err != nil {
+		if err := saveInitConfig(opts.ProfileName, existing, f, opts.AppID, secret, brand, opts.Lang, "", nil); err != nil {
 			return wrapSaveConfigError(err)
 		}
 		output.PrintSuccess(f.IOStreams.ErrOut, fmt.Sprintf("Configuration saved to %s", core.GetConfigPath()))
@@ -368,34 +512,26 @@ func configInitRun(opts *ConfigInitOptions) error {
 
 	msg := getInitMsg(opts.UILang)
 
+	// Mode: Restore (--restore) — re-register the app already in config.
+	if opts.Restore {
+		return runRestoreFlow(opts, existing, f, msg)
+	}
+
 	// Mode 3: Create new app directly (--new)
 	if opts.New {
-		result, err := runCreateAppFlow(opts.Ctx, f, parseBrand(opts.Brand), msg)
+		result, err := runCreateAppFlow(opts.Ctx, f, parseBrand(opts.Brand), opts.AuthMethod, msg, "")
 		if err != nil {
 			return err
 		}
 		if result == nil {
 			return errs.NewInternalError(errs.SubtypeSDKError, "app creation returned no result")
 		}
-		existing, _ := core.LoadMultiAppConfig()
-		secret, err := core.ForStorage(result.AppID, core.PlainSecret(result.AppSecret), f.Keychain)
-		if err != nil {
-			return errs.NewInternalError(errs.SubtypeSDKError, "%v", err).WithCause(err)
-		}
-		if err := saveInitConfig(opts.ProfileName, existing, f, result.AppID, secret, result.Brand, opts.Lang); err != nil {
-			return wrapSaveConfigError(err)
-		}
-		printLangPreferenceConfirmation(opts)
-		output.PrintJson(f.IOStreams.Out, map[string]interface{}{"appId": result.AppID, "appSecret": "****", "brand": result.Brand})
-		if err := runProbe(opts.Ctx, f, result.AppID, result.AppSecret, result.Brand); err != nil {
-			return err
-		}
-		return nil
+		return persistAndProbeResult(opts, f, opts.ProfileName, result)
 	}
 
 	// Mode 4: Interactive TUI (terminal)
 	if !opts.hasAnyNonInteractiveFlag() && f.IOStreams.IsTerminal {
-		result, err := runInteractiveConfigInit(opts.Ctx, f, msg)
+		result, err := runInteractiveConfigInit(opts.Ctx, f, opts.AuthMethod, msg)
 		if err != nil {
 			return err
 		}
@@ -406,13 +542,22 @@ func configInitRun(opts *ConfigInitOptions) error {
 
 		existing, _ := core.LoadMultiAppConfig()
 
-		if result.AppSecret != "" {
+		if result.AuthMethod == core.AuthMethodPrivateKeyJWT {
+			// Secretless create: persist auth method + TEE key ref, no secret.
+			if err := saveInitConfig(opts.ProfileName, existing, f, result.AppID, core.SecretInput{}, result.Brand, opts.Lang, result.AuthMethod, keyRefFromResult(result)); err != nil {
+				return wrapSaveConfigError(err)
+			}
+			removeStaleSecretForPKJWT(existing, opts.ProfileName, result.AppID, f.Keychain)
+			if err := runProbePKJWT(opts.Ctx, f, result.Brand, result.AppID, keysigner.Active(), result.KeyLabel); err != nil {
+				return err
+			}
+		} else if result.AppSecret != "" {
 			// New secret provided (either from "create" or "existing" with input)
 			secret, err := core.ForStorage(result.AppID, core.PlainSecret(result.AppSecret), f.Keychain)
 			if err != nil {
 				return errs.NewInternalError(errs.SubtypeSDKError, "%v", err).WithCause(err)
 			}
-			if err := saveInitConfig(opts.ProfileName, existing, f, result.AppID, secret, result.Brand, opts.Lang); err != nil {
+			if err := saveInitConfig(opts.ProfileName, existing, f, result.AppID, secret, result.Brand, opts.Lang, "", nil); err != nil {
 				return wrapSaveConfigError(err)
 			}
 		} else if result.Mode == "existing" && result.AppID != "" {
@@ -517,7 +662,7 @@ func configInitRun(opts *ConfigInitOptions) error {
 	if err != nil {
 		return errs.NewInternalError(errs.SubtypeSDKError, "%v", err).WithCause(err)
 	}
-	if err := saveInitConfig(opts.ProfileName, existing, f, resolvedAppId, storedSecret, parseBrand(resolvedBrand), opts.Lang); err != nil {
+	if err := saveInitConfig(opts.ProfileName, existing, f, resolvedAppId, storedSecret, parseBrand(resolvedBrand), opts.Lang, "", nil); err != nil {
 		return wrapSaveConfigError(err)
 	}
 	output.PrintSuccess(f.IOStreams.ErrOut, fmt.Sprintf("Configuration saved to %s", core.GetConfigPath()))

cmd/config/init_auth_method_test.go

@@ -0,0 +1,102 @@
+// Copyright (c) 2026 Lark Technologies Pte. Ltd.
+// SPDX-License-Identifier: MIT
+
+package config
+
+import (
+	"context"
+	"crypto"
+	"testing"
+
+	"github.com/larksuite/cli/internal/cmdutil"
+	"github.com/larksuite/cli/internal/core"
+	"github.com/larksuite/cli/internal/keysigner"
+)
+
+type authMethodTestSigner struct{}
+
+func (authMethodTestSigner) EnsureKey(context.Context, keysigner.KeyRef) (crypto.PublicKey, error) {
+	return nil, nil
+}
+
+func (authMethodTestSigner) PublicKey(context.Context, keysigner.KeyRef) (crypto.PublicKey, error) {
+	return nil, nil
+}
+
+func (authMethodTestSigner) Sign(context.Context, keysigner.KeyRef, []byte) ([]byte, string, error) {
+	return nil, "", nil
+}
+
+// TestResolveRegisterAuthMethod covers the non-interactive gating paths. The
+// darwin keychain signer is compiled into every build, so the test cannot rely
+// on the binary lacking a signer — it forces a known no-signer state for the
+// rejection cases, then registers a stub for the success case.
+func TestResolveRegisterAuthMethod(t *testing.T) {
+	f := &cmdutil.Factory{}
+
+	prevSigner := keysigner.Active()
+	t.Cleanup(func() { keysigner.Register(prevSigner) })
+	keysigner.Register(nil)
+
+	if m, err := resolveRegisterAuthMethod(f, core.AuthMethodClientSecret); err != nil || m != core.AuthMethodClientSecret {
+		t.Errorf("client_secret: got (%q, %v), want (client_secret, nil)", m, err)
+	}
+
+	if m, err := resolveRegisterAuthMethod(f, ""); err != nil || m != core.AuthMethodClientSecret {
+		t.Errorf("default: got (%q, %v), want (client_secret, nil)", m, err)
+	}
+
+	if _, err := resolveRegisterAuthMethod(f, "bogus"); err == nil {
+		t.Error("bogus auth-method: expected error")
+	}
+
+	if _, err := resolveRegisterAuthMethod(f, core.AuthMethodPrivateKeyJWT); err == nil {
+		t.Error("private_key_jwt without a signer: expected error")
+	}
+
+	keysigner.Register(authMethodTestSigner{})
+
+	if m, err := resolveRegisterAuthMethod(f, core.AuthMethodPrivateKeyJWT); err != nil || m != core.AuthMethodPrivateKeyJWT {
+		t.Errorf("private_key_jwt with signer: got (%q, %v), want (private_key_jwt, nil)", m, err)
+	}
+}
+
+// TestValidatePKJWTKeyBinding covers the guard that rejects a registration
+// resolving to private_key_jwt with no signing key bound (e.g. an existing
+// secret-based app was selected on the confirm page).
+func TestValidatePKJWTKeyBinding(t *testing.T) {
+	if err := validatePKJWTKeyBinding(core.AuthMethodPrivateKeyJWT, ""); err == nil {
+		t.Error("pkjwt with empty keyLabel: expected error")
+	}
+	if err := validatePKJWTKeyBinding(core.AuthMethodPrivateKeyJWT, "agent-key"); err != nil {
+		t.Errorf("pkjwt with keyLabel: expected nil, got %v", err)
+	}
+	if err := validatePKJWTKeyBinding(core.AuthMethodClientSecret, ""); err != nil {
+		t.Errorf("client_secret: expected nil, got %v", err)
+	}
+}
+
+// TestResolveFinalAuthMethod locks the authoritative-method logic. The 2nd case
+// is the real bug: we requested private_key_jwt but the server resolved to an
+// existing client_secret app — we must persist client_secret, not pkjwt.
+func TestResolveFinalAuthMethod(t *testing.T) {
+	if m := resolveFinalAuthMethod([]string{"client_secret", "private_key_jwt"}, core.AuthMethodClientSecret); m != core.AuthMethodPrivateKeyJWT {
+		t.Errorf("prefers private_key_jwt: got %q", m)
+	}
+	if m := resolveFinalAuthMethod([]string{"client_secret"}, core.AuthMethodPrivateKeyJWT); m != core.AuthMethodClientSecret {
+		t.Errorf("server client_secret must override requested pkjwt: got %q", m)
+	}
+	if m := resolveFinalAuthMethod(nil, core.AuthMethodPrivateKeyJWT); m != core.AuthMethodPrivateKeyJWT {
+		t.Errorf("fallback to requested when server is silent: got %q", m)
+	}
+	// Explicit empty slice (not just nil) also falls back to requested — the same
+	// len()==0 back-compat allowance the init guard relies on to let private_key_jwt
+	// proceed against an older server (see internal/auth
+	// TestRequestAppRegistrationInit_EmptySupportedAuthMethods).
+	if m := resolveFinalAuthMethod([]string{}, core.AuthMethodPrivateKeyJWT); m != core.AuthMethodPrivateKeyJWT {
+		t.Errorf("empty []string should fall back to requested private_key_jwt: got %q", m)
+	}
+	if m := resolveFinalAuthMethod(nil, ""); m != core.AuthMethodClientSecret {
+		t.Errorf("default to client_secret: got %q", m)
+	}
+}

cmd/config/init_interactive.go

@@ -5,7 +5,11 @@ package config
 
 import (
 	"context"
+	"errors"
 	"fmt"
+	"slices"
+	"strings"
+	"time"
 
 	"github.com/charmbracelet/huh"
 	"github.com/larksuite/cli/internal/build"
@@ -13,22 +17,26 @@ import (
 
 	"github.com/larksuite/cli/errs"
 	larkauth "github.com/larksuite/cli/internal/auth"
+	"github.com/larksuite/cli/internal/auth/jwt"
 	"github.com/larksuite/cli/internal/cmdutil"
 	"github.com/larksuite/cli/internal/core"
+	"github.com/larksuite/cli/internal/keysigner"
 	"github.com/larksuite/cli/internal/output"
 	"github.com/larksuite/cli/internal/transport"
 )
 
 // configInitResult holds the result of the interactive config init flow.
 type configInitResult struct {
-	Mode      string // "create" or "existing"
-	Brand     core.LarkBrand
-	AppID     string
-	AppSecret string
+	Mode       string // "create" or "existing"
+	Brand      core.LarkBrand
+	AppID      string
+	AppSecret  string
+	AuthMethod string // "" == client_secret; core.AuthMethodPrivateKeyJWT
+	KeyLabel   string // TEE key handle when AuthMethod == private_key_jwt
 }
 
 // runInteractiveConfigInit shows an interactive TUI for config init.
-func runInteractiveConfigInit(ctx context.Context, f *cmdutil.Factory, msg *initMsg) (*configInitResult, error) {
+func runInteractiveConfigInit(ctx context.Context, f *cmdutil.Factory, authMethodFlag string, msg *initMsg) (*configInitResult, error) {
 	// Phase 1: Choose mode
 	var mode string
 	form1 := huh.NewForm(
@@ -54,7 +62,7 @@ func runInteractiveConfigInit(ctx context.Context, f *cmdutil.Factory, msg *init
 		return runExistingAppForm(f, msg)
 	}
 
-	return runCreateAppFlow(ctx, f, "", msg)
+	return runCreateAppFlow(ctx, f, "", authMethodFlag, msg, "")
 }
 
 // runExistingAppForm shows a huh form for manually entering App ID / App Secret / Brand.
@@ -146,9 +154,59 @@ func runExistingAppForm(f *cmdutil.Factory, msg *initMsg) (*configInitResult, er
 	}, nil
 }
 
+// resolveRegisterAuthMethod decides the auth method for a new-app registration.
+// An explicit --auth-method flag wins; otherwise, on an interactive terminal with
+// a TEE signer available, the user is prompted; the default is client_secret.
+func resolveRegisterAuthMethod(f *cmdutil.Factory, flag string) (string, error) {
+	signerAvailable := keysigner.Active() != nil
+	switch flag {
+	case core.AuthMethodPrivateKeyJWT:
+		if !signerAvailable {
+			return "", errs.NewConfigError(errs.SubtypeInvalidClient,
+				"--auth-method private_key_jwt requires a platform key signer, which is unavailable on this device/build").
+				WithHint("omit --auth-method (or pass --auth-method client_secret) to register with an app secret")
+		}
+		return core.AuthMethodPrivateKeyJWT, nil
+	case core.AuthMethodClientSecret:
+		return core.AuthMethodClientSecret, nil
+	case "":
+		// fall through to interactive / default
+	default:
+		return "", errs.NewValidationError(errs.SubtypeInvalidArgument,
+			"unknown --auth-method %q (use client_secret or private_key_jwt)", flag)
+	}
+
+	if signerAvailable && f.IOStreams.IsTerminal {
+		var choice string
+		form := huh.NewForm(
+			huh.NewGroup(
+				huh.NewSelect[string]().
+					Title("Authentication method").
+					Options(
+						huh.NewOption("App Secret (client_secret)", core.AuthMethodClientSecret),
+						huh.NewOption("Secure key signer, no secret (private_key_jwt)", core.AuthMethodPrivateKeyJWT),
+					).
+					Value(&choice),
+			),
+		).WithTheme(cmdutil.ThemeFeishu())
+		if err := form.Run(); err != nil {
+			if errors.Is(err, huh.ErrUserAborted) {
+				return "", output.ErrBare(1)
+			}
+			return "", err
+		}
+		return choice, nil
+	}
+	return core.AuthMethodClientSecret, nil
+}
+
 // runCreateAppFlow runs the "create new app" flow via OpenClaw device flow.
 // If brandOverride is non-empty, skip the interactive brand selection.
-func runCreateAppFlow(ctx context.Context, f *cmdutil.Factory, brandOverride core.LarkBrand, msg *initMsg) (*configInitResult, error) {
+// authMethodFlag is the raw --auth-method value ("" when unset).
+// restoreAppID, when non-empty, is sent on the registration begin request so the
+// server re-registers that existing app (credential recovery) instead of creating
+// a new one. Empty preserves the normal new-app flow.
+func runCreateAppFlow(ctx context.Context, f *cmdutil.Factory, brandOverride core.LarkBrand, authMethodFlag string, msg *initMsg, restoreAppID string) (*configInitResult, error) {
 	var larkBrand core.LarkBrand
 	if brandOverride != "" {
 		larkBrand = brandOverride
@@ -176,11 +234,51 @@ func runCreateAppFlow(ctx context.Context, f *cmdutil.Factory, brandOverride cor
 		larkBrand = parseBrand(brand)
 	}
 
-	// Step 1: Request app registration (begin)
+	authMethod, err := resolveRegisterAuthMethod(f, authMethodFlag)
+	if err != nil {
+		return nil, err
+	}
+
+	// Step 1: Request app registration (begin).
 	// Use the shared proxy-plugin-aware transport so registration traffic is not
 	// a bypass of proxy plugin mode.
 	httpClient := transport.NewHTTPClient(0)
-	authResp, err := larkauth.RequestAppRegistration(httpClient, larkBrand, f.IOStreams.ErrOut)
+
+	// For private_key_jwt: init to obtain a nonce, then sign a TEE attestation
+	// (carrying the public key in its jwk header) to send with begin.
+	beginOpts := larkauth.AppRegistrationBeginOptions{}
+	keyLabel := ""
+	if authMethod == core.AuthMethodPrivateKeyJWT {
+		signer := keysigner.Active() // non-nil, guaranteed by resolveRegisterAuthMethod
+		initResp, initErr := larkauth.RequestAppRegistrationInit(httpClient)
+		if initErr != nil {
+			return nil, errs.NewConfigError(errs.SubtypeInvalidClient, "app registration init failed: %v", initErr).WithCause(initErr)
+		}
+		// An empty SupportedAuthMethods is intentionally treated as "older server /
+		// unknown": len()==0 makes this guard false, so the requested
+		// private_key_jwt proceeds. This mirrors resolveFinalAuthMethod's
+		// back-compat fallback to the requested method. Only an explicit list that
+		// omits private_key_jwt rejects here.
+		if len(initResp.SupportedAuthMethods) > 0 && !slices.Contains(initResp.SupportedAuthMethods, core.AuthMethodPrivateKeyJWT) {
+			return nil, errs.NewConfigError(errs.SubtypeInvalidClient,
+				"server does not support private_key_jwt for this app type (supported: %s)", strings.Join(initResp.SupportedAuthMethods, ", ")).
+				WithHint("register with --auth-method client_secret instead")
+		}
+		keyLabel = keysigner.DefaultKeyLabel
+		attestation, signErr := jwt.SignAttestation(ctx, signer, keysigner.KeyRef{Label: keyLabel}, initResp.Nonce, time.Now())
+		if signErr != nil {
+			return nil, errs.NewConfigError(errs.SubtypeInvalidClient, "failed to sign registration attestation: %v", signErr).WithCause(signErr)
+		}
+		beginOpts = larkauth.AppRegistrationBeginOptions{
+			AuthMethod:      core.AuthMethodPrivateKeyJWT,
+			AuthAttestation: attestation,
+		}
+	}
+
+	// Restore flow: re-register the existing app instead of creating a new one.
+	beginOpts.RestoreAppID = restoreAppID
+
+	authResp, err := larkauth.RequestAppRegistration(httpClient, larkBrand, beginOpts, f.IOStreams.ErrOut)
 	if err != nil {
 		return nil, errs.NewConfigError(errs.SubtypeInvalidClient, "app registration failed: %v", err).WithCause(err)
 	}
@@ -213,18 +311,28 @@ func runCreateAppFlow(ctx context.Context, f *cmdutil.Factory, brandOverride cor
 		return nil, errs.NewAuthenticationError(errs.SubtypeUnknown, "%v", err).WithCause(err)
 	}
 
-	// Step 4: Handle Lark brand special case
-	// If tenant_brand=lark and no client_secret, retry with lark brand endpoint
-	if result.ClientSecret == "" && result.UserInfo != nil && result.UserInfo.TenantBrand == "lark" {
-		// fmt.Fprintf(f.IOStreams.ErrOut, "%s\n", msg.DetectedLarkTenant)
+	// The final auth method is decided by the user/admin at confirmation and
+	// returned by poll — NOT necessarily what we requested. Selecting an existing
+	// client_secret app, for example, yields client_secret even though we sent
+	// private_key_jwt. Trust the result so we persist the truth.
+	finalMethod := resolveFinalAuthMethod(result.AuthMethods, authMethod)
+
+	// Lark brand special case (client_secret only): a lark-tenant app returns its
+	// secret only from the lark endpoint. private_key_jwt returns no secret, so
+	// this retry does not apply.
+	if finalMethod != core.AuthMethodPrivateKeyJWT && result.ClientSecret == "" && result.UserInfo != nil && result.UserInfo.TenantBrand == "lark" {
 		result, err = larkauth.PollAppRegistration(ctx, httpClient, core.BrandLark, authResp.DeviceCode, authResp.Interval, authResp.ExpiresIn, f.IOStreams.ErrOut)
 		if err != nil {
 			return nil, errs.NewNetworkError(errs.SubtypeNetworkTransport, "lark endpoint retry failed: %v", err).WithCause(err)
 		}
+		finalMethod = resolveFinalAuthMethod(result.AuthMethods, authMethod)
 	}
 
-	if result.ClientID == "" || result.ClientSecret == "" {
-		return nil, errs.NewConfigError(errs.SubtypeInvalidClient, "app registration succeeded but missing client_id or client_secret")
+	if result.ClientID == "" {
+		return nil, errs.NewConfigError(errs.SubtypeInvalidClient, "app registration succeeded but missing client_id")
+	}
+	if finalMethod != core.AuthMethodPrivateKeyJWT && result.ClientSecret == "" {
+		return nil, errs.NewConfigError(errs.SubtypeInvalidClient, "app registration succeeded but missing client_secret")
 	}
 
 	// Determine final brand from response
@@ -235,13 +343,67 @@ func runCreateAppFlow(ctx context.Context, f *cmdutil.Factory, brandOverride cor
 		finalBrand = core.BrandFeishu
 	}
 
+	// Surface a downgrade: requested private_key_jwt but the app resolved to a
+	// secret-based method (e.g. an existing app was selected). The key was NOT
+	// bound, so we must store the secret method, not private_key_jwt.
+	if authMethod == core.AuthMethodPrivateKeyJWT && finalMethod != core.AuthMethodPrivateKeyJWT {
+		fmt.Fprintf(f.IOStreams.ErrOut, "[lark-cli] note: requested private_key_jwt, but the app uses %q (e.g. an existing app was selected); storing %q.\n", finalMethod, finalMethod)
+	}
+
 	fmt.Fprintln(f.IOStreams.ErrOut)
 	output.PrintSuccess(f.IOStreams.ErrOut, fmt.Sprintf(msg.AppCreated, result.ClientID))
 
+	keyToStore := ""
+	if finalMethod == core.AuthMethodPrivateKeyJWT {
+		keyToStore = keyLabel
+	}
+	if err := validatePKJWTKeyBinding(finalMethod, keyToStore); err != nil {
+		return nil, err
+	}
 	return &configInitResult{
-		Mode:      "create",
-		Brand:     finalBrand,
-		AppID:     result.ClientID,
-		AppSecret: result.ClientSecret,
+		Mode:       "create",
+		Brand:      finalBrand,
+		AppID:      result.ClientID,
+		AppSecret:  result.ClientSecret, // empty for private_key_jwt; real secret otherwise
+		AuthMethod: finalMethod,
+		KeyLabel:   keyToStore,
 	}, nil
 }
+
+// validatePKJWTKeyBinding rejects a registration that resolved to
+// private_key_jwt without a signing key bound to it. keyLabel is non-empty only
+// when the local flow chose private_key_jwt and signed a TEE attestation; a
+// resolved method of private_key_jwt with no key handle would save an unusable
+// config (rejected later at config load, surfacing as "saved OK, fails on first
+// use"), so it is caught here at registration time instead.
+func validatePKJWTKeyBinding(finalMethod, keyLabel string) error {
+	if finalMethod == core.AuthMethodPrivateKeyJWT && keyLabel == "" {
+		return errs.NewConfigError(errs.SubtypeInvalidClient,
+			"registration resolved to private_key_jwt but no signing key was bound to this app (an existing secret-based app may have been selected)").
+			WithHint("re-register with: lark-cli config init --new --auth-method private_key_jwt")
+	}
+	return nil
+}
+
+// resolveFinalAuthMethod picks the authoritative method from the poll result,
+// preferring private_key_jwt, then client_secret. It falls back to the requested
+// method when the server returns nothing (older servers).
+func resolveFinalAuthMethod(serverMethods []string, requested string) string {
+	if len(serverMethods) == 0 {
+		if requested == "" {
+			return core.AuthMethodClientSecret
+		}
+		return requested
+	}
+	for _, m := range serverMethods {
+		if m == core.AuthMethodPrivateKeyJWT {
+			return core.AuthMethodPrivateKeyJWT
+		}
+	}
+	for _, m := range serverMethods {
+		if m == core.AuthMethodClientSecret {
+			return core.AuthMethodClientSecret
+		}
+	}
+	return serverMethods[0]
+}

cmd/config/init_probe.go

@@ -16,6 +16,7 @@ import (
 	"github.com/larksuite/cli/internal/cmdutil"
 	"github.com/larksuite/cli/internal/core"
 	"github.com/larksuite/cli/internal/credential"
+	"github.com/larksuite/cli/internal/keysigner"
 )
 
 // probeTimeout is the total wall-clock budget for the credential probe step
@@ -90,3 +91,32 @@ func runProbe(parent context.Context, factory *cmdutil.Factory, appID, appSecret
 	_, _ = io.Copy(io.Discard, resp.Body)
 	return nil
 }
+
+// runProbePKJWT does a best-effort key-binding validation after a private_key_jwt
+// config is saved: it signs a client_assertion with the local platform key and
+// mints a token. A typed error (a deterministic server rejection — e.g. the key
+// is not bound to this app) is propagated so `config init` exits non-zero with
+// the canonical envelope; untyped errors (transport / HTTP / parse / timeout)
+// are swallowed (return nil). The mint itself is the probe — no second call.
+func runProbePKJWT(parent context.Context, factory *cmdutil.Factory, brand core.LarkBrand, clientID string, signer keysigner.Signer, keyLabel string) error {
+	if factory == nil || signer == nil {
+		return nil
+	}
+	httpClient, err := factory.HttpClient()
+	if err != nil {
+		return nil
+	}
+
+	ctx, cancel := context.WithTimeout(parent, probeTimeout)
+	defer cancel()
+
+	if _, err := credential.FetchTATWithAssertion(ctx, httpClient, brand, clientID, signer, keyLabel); err != nil {
+		// Typed = deterministic credential rejection → propagate. Untyped
+		// (transport / HTTP / parse / timeout) is ambiguous → stay silent.
+		if errs.IsTyped(err) {
+			return err
+		}
+		return nil
+	}
+	return nil
+}

cmd/config/init_probe_test.go

@@ -6,6 +6,11 @@ package config
 import (
 	"bytes"
 	"context"
+	"crypto"
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	crand "crypto/rand"
+	"crypto/sha256"
 	"errors"
 	"io"
 	"net/http"
@@ -17,14 +22,17 @@ import (
 	"github.com/larksuite/cli/internal/build"
 	"github.com/larksuite/cli/internal/cmdutil"
 	"github.com/larksuite/cli/internal/core"
+	"github.com/larksuite/cli/internal/keysigner"
 )
 
 // fakeRT routes requests to per-path handlers and records what it saw.
 type fakeRT struct {
 	tatHandler   func(req *http.Request) (*http.Response, error)
 	probeHandler func(req *http.Request) (*http.Response, error)
+	oauthHandler func(req *http.Request) (*http.Response, error)
 	tatCalls     int
 	probeCalls   int
+	oauthCalls   int
 	probeReq     *http.Request
 	probeBody    string
 }
@@ -48,10 +56,50 @@ func (f *fakeRT) RoundTrip(req *http.Request) (*http.Response, error) {
 			return jsonResp(200, `{"code":0,"data":{},"msg":"success"}`), nil
 		}
 		return f.probeHandler(req)
+	case strings.HasSuffix(req.URL.Path, "/authen/v2/oauth/token"):
+		f.oauthCalls++
+		if f.oauthHandler == nil {
+			return jsonResp(200, `{"access_token":"t-jwt"}`), nil
+		}
+		return f.oauthHandler(req)
 	}
 	return nil, errors.New("unexpected URL: " + req.URL.String())
 }
 
+// probeTestSigner is an in-memory real ECDSA P-256 signer used to sign the
+// client_assertion in runProbePKJWT tests (authMethodTestSigner returns a nil
+// key and cannot sign).
+type probeTestSigner struct{ key *ecdsa.PrivateKey }
+
+func newProbeTestSigner(t *testing.T) *probeTestSigner {
+	t.Helper()
+	k, err := ecdsa.GenerateKey(elliptic.P256(), crand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return &probeTestSigner{key: k}
+}
+
+func (p *probeTestSigner) EnsureKey(context.Context, keysigner.KeyRef) (crypto.PublicKey, error) {
+	return p.key.Public(), nil
+}
+
+func (p *probeTestSigner) PublicKey(context.Context, keysigner.KeyRef) (crypto.PublicKey, error) {
+	return p.key.Public(), nil
+}
+
+func (p *probeTestSigner) Sign(_ context.Context, _ keysigner.KeyRef, in []byte) ([]byte, string, error) {
+	h := sha256.Sum256(in)
+	r, s, err := ecdsa.Sign(crand.Reader, p.key, h[:])
+	if err != nil {
+		return nil, "", err
+	}
+	sig := make([]byte, 64)
+	r.FillBytes(sig[:32])
+	s.FillBytes(sig[32:])
+	return sig, keysigner.AlgES256, nil
+}
+
 func jsonResp(code int, body string) *http.Response {
 	return &http.Response{
 		StatusCode: code,
@@ -285,3 +333,42 @@ func TestRunProbe_TimeoutHonored(t *testing.T) {
 	// must stay silent and not block.
 	assertSilent(t, err, errBuf)
 }
+
+// runProbePKJWT: a deterministic server rejection (invalid_client) is propagated
+// as a typed ConfigError so config init exits non-zero.
+func TestRunProbePKJWT_DeterministicReject_Propagates(t *testing.T) {
+	rt := &fakeRT{oauthHandler: func(*http.Request) (*http.Response, error) {
+		return jsonResp(401, `{"error":"invalid_client","error_description":"unknown key"}`), nil
+	}}
+	f, errBuf := fakeFactory(t, rt)
+	err := runProbePKJWT(context.Background(), f, core.BrandFeishu, "cli_x", newProbeTestSigner(t), "agent-key")
+	if err == nil || !errs.IsTyped(err) {
+		t.Fatalf("expected propagated typed error, got %T %v", err, err)
+	}
+	if errBuf.Len() != 0 {
+		t.Errorf("runProbePKJWT must not write stderr, got %q", errBuf.String())
+	}
+}
+
+// runProbePKJWT: ambiguous upstream noise (HTTP 503) is swallowed — silent, exit 0.
+func TestRunProbePKJWT_Ambiguous_Silent(t *testing.T) {
+	rt := &fakeRT{oauthHandler: func(*http.Request) (*http.Response, error) {
+		return jsonResp(503, `unavailable`), nil
+	}}
+	f, errBuf := fakeFactory(t, rt)
+	assertSilent(t, runProbePKJWT(context.Background(), f, core.BrandFeishu, "cli_x", newProbeTestSigner(t), "agent-key"), errBuf)
+}
+
+// runProbePKJWT: a successful mint returns nil.
+func TestRunProbePKJWT_Success_Silent(t *testing.T) {
+	rt := &fakeRT{} // default oauth handler returns 200 + access_token
+	f, errBuf := fakeFactory(t, rt)
+	assertSilent(t, runProbePKJWT(context.Background(), f, core.BrandFeishu, "cli_x", newProbeTestSigner(t), "agent-key"), errBuf)
+}
+
+// runProbePKJWT: a nil signer is a defensive no-op (should not be reached, must
+// not panic).
+func TestRunProbePKJWT_NilSigner_Silent(t *testing.T) {
+	f, errBuf := fakeFactory(t, &fakeRT{})
+	assertSilent(t, runProbePKJWT(context.Background(), f, core.BrandFeishu, "cli_x", nil, "k"), errBuf)
+}

cmd/config/init_test.go

@@ -10,9 +10,25 @@ import (
 
 	"github.com/larksuite/cli/errs"
 	"github.com/larksuite/cli/internal/core"
+	"github.com/larksuite/cli/internal/keychain"
 	"github.com/larksuite/cli/internal/output"
 )
 
+// TestRunRestoreFlow_NothingToRestore covers the early guards that return before
+// any network/registration call: no config at all, and a config whose resolved
+// app has no app id (nothing to send on begin).
+func TestRunRestoreFlow_NothingToRestore(t *testing.T) {
+	// No config on disk.
+	if err := runRestoreFlow(&ConfigInitOptions{}, nil, nil, nil); err == nil {
+		t.Fatal("expected error when there is no config to restore")
+	}
+	// Config present but the resolved app has no app id.
+	existing := &core.MultiAppConfig{Apps: []core.AppConfig{{AppId: ""}}}
+	if err := runRestoreFlow(&ConfigInitOptions{}, existing, nil, nil); err == nil {
+		t.Fatal("expected error when the resolved app has no app id")
+	}
+}
+
 // updateExistingProfileWithoutSecret guards four blank-input scenarios. Each
 // must surface as *ValidationError(SubtypeInvalidArgument) per RFC 6749 §5.2:
 // SubtypeInvalidClient is reserved for IAM rejection of malformed credentials,
@@ -119,3 +135,62 @@ func assertValidationParam(t *testing.T, err error, wantParam string) {
 		t.Errorf("Param = %q, want %q", valErr.Param, wantParam)
 	}
 }
+
+// countingKeychain is an in-memory KeychainAccess that records whether Remove
+// was invoked, so the stale-secret cleanup can be asserted without a real OS
+// keychain.
+type countingKeychain struct {
+	store        map[string]string
+	removeCalled bool
+}
+
+func newCountingKeychain() *countingKeychain {
+	return &countingKeychain{store: map[string]string{}}
+}
+
+func (k *countingKeychain) Get(service, account string) (string, error) {
+	v, ok := k.store[service+"/"+account]
+	if !ok {
+		return "", keychain.ErrNotFound
+	}
+	return v, nil
+}
+
+func (k *countingKeychain) Set(service, account, value string) error {
+	k.store[service+"/"+account] = value
+	return nil
+}
+
+func (k *countingKeychain) Remove(service, account string) error {
+	k.removeCalled = true
+	delete(k.store, service+"/"+account)
+	return nil
+}
+
+func TestRemoveStaleSecretForPKJWT_SameAppID(t *testing.T) {
+	kc := newCountingKeychain()
+	ref, err := core.ForStorage("cli_same", core.PlainSecret("old-secret"), kc) // → Source:"keychain"
+	if err != nil {
+		t.Fatal(err)
+	}
+	existing := &core.MultiAppConfig{Apps: []core.AppConfig{{AppId: "cli_same", AppSecret: ref}}}
+	removeStaleSecretForPKJWT(existing, "", "cli_same", kc)
+	if !kc.removeCalled {
+		t.Error("same appId with keychain secret: expected kc.Remove to be invoked")
+	}
+}
+
+func TestRemoveStaleSecretForPKJWT_DifferentAppID(t *testing.T) {
+	kc := newCountingKeychain()
+	ref, _ := core.ForStorage("cli_old", core.PlainSecret("old-secret"), kc)
+	kc.removeCalled = false // ForStorage does not call Remove, but reset to be safe
+	existing := &core.MultiAppConfig{Apps: []core.AppConfig{{AppId: "cli_old", AppSecret: ref}}}
+	removeStaleSecretForPKJWT(existing, "", "cli_new", kc)
+	if kc.removeCalled {
+		t.Error("different appId: must NOT remove")
+	}
+}
+
+func TestRemoveStaleSecretForPKJWT_NilExisting(t *testing.T) {
+	removeStaleSecretForPKJWT(nil, "", "cli_x", newCountingKeychain()) // must not panic
+}

cmd/doctor/doctor.go

@@ -7,6 +7,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"io"
 	"net/http"
 	"os"
 	"sync"
@@ -19,6 +20,7 @@ import (
 	"github.com/larksuite/cli/internal/cmdutil"
 	"github.com/larksuite/cli/internal/core"
 	"github.com/larksuite/cli/internal/identitydiag"
+	"github.com/larksuite/cli/internal/keysigner"
 	"github.com/larksuite/cli/internal/output"
 	"github.com/larksuite/cli/internal/transport"
 	"github.com/larksuite/cli/internal/update"
@@ -132,6 +134,9 @@ func doctorRun(opts *DoctorOptions) error {
 		checks = append(checks, fail("identity_ready", "no usable bot or user identity is available", "run: lark-cli auth status --verify"))
 	}
 
+	// ── 3b. private_key_jwt / TEE signer (local; runs even with --offline) ──
+	checks = append(checks, teeSignerCheck(opts.Ctx, cfg))
+
 	// ── 4 & 5. Endpoint reachability ──
 	checks = append(checks, networkChecks(opts.Ctx, opts, ep)...)
 
@@ -145,6 +150,54 @@ func identityCheck(name string, id identitydiag.Identity) checkResult {
 	return warn(name, id.Message, id.Hint)
 }
 
+const teeUnavailableHint = "ensure the device secure hardware is accessible (Linux TPM: add your user to the 'tss' group or run with sufficient privileges)"
+
+// teeSignerCheck reports the private_key_jwt signing backend (TEE/TPM) status.
+// The probe is local hardware only (no network), so it runs even with --offline;
+// in a build without a TEE signer it short-circuits without touching any
+// hardware. It is a hard requirement for private_key_jwt apps and purely
+// informational for client_secret apps.
+func teeSignerCheck(ctx context.Context, cfg *core.CliConfig) checkResult {
+	usesPKJWT := cfg != nil && cfg.AuthMethod == core.AuthMethodPrivateKeyJWT
+	info, ok, err := keysigner.ProbeActiveHardware(ctx)
+	return teeCheckResult(info, ok, err, usesPKJWT)
+}
+
+// teeCheckResult maps a hardware probe to a doctor check. Split out from
+// teeSignerCheck so the full matrix is unit-testable without a TPM.
+func teeCheckResult(info keysigner.HardwareInfo, ok bool, probeErr error, usesPKJWT bool) checkResult {
+	const name = "tee_signer"
+
+	// No signer registered → private_key_jwt is unsupported on this build.
+	if !ok {
+		if usesPKJWT {
+			return fail(name,
+				"app uses private_key_jwt but this build has no TEE key signer",
+				"the platform key signer ships by default on macOS, Linux, and Windows/amd64; this platform (e.g. Windows/arm64) has none — use a supported platform or re-register with --auth-method client_secret")
+		}
+		return skip(name, "no TEE signer in this build (only private_key_jwt is affected; client_secret is unaffected)")
+	}
+
+	backend := info.Backend
+	if backend == "" {
+		backend = "tee"
+	}
+
+	switch {
+	case probeErr != nil:
+		return warn(name, fmt.Sprintf("%s signer present but probe errored: %s", backend, probeErr), "")
+	case info.Available:
+		if info.VendorName != "" {
+			return pass(name, fmt.Sprintf("%s TEE available (%s)", backend, info.VendorName))
+		}
+		return pass(name, fmt.Sprintf("%s TEE available", backend))
+	case usesPKJWT:
+		return fail(name, fmt.Sprintf("%s signer present but TEE unavailable: %s", backend, info.Reason), teeUnavailableHint)
+	default:
+		return warn(name, fmt.Sprintf("%s signer present but TEE unavailable: %s", backend, info.Reason), teeUnavailableHint)
+	}
+}
+
 // networkChecks probes Open API and MCP endpoints concurrently.
 func networkChecks(ctx context.Context, opts *DoctorOptions, ep core.Endpoints) []checkResult {
 	if opts.Offline {
@@ -234,14 +287,90 @@ func finishDoctor(f *cmdutil.Factory, checks []checkResult) error {
 		}
 	}
 
-	result := map[string]interface{}{
-		"ok":        allOK,
-		"workspace": core.CurrentWorkspace().Display(),
-		"checks":    checks,
+	workspace := core.CurrentWorkspace().Display()
+	// A terminal on STDOUT gets a readable report; pipes, redirects, scripts and
+	// tests keep the stable JSON contract (NO_COLOR disables ANSI styling).
+	// StdoutIsTerminal checks stdout specifically — IOStreams.IsTerminal reflects
+	// stdin, which would wrongly send the human report into `doctor | jq`.
+	if f.IOStreams.StdoutIsTerminal() {
+		renderDoctorHuman(f.IOStreams.Out, workspace, checks, allOK, os.Getenv("NO_COLOR") == "")
+	} else {
+		output.PrintJson(f.IOStreams.Out, map[string]interface{}{
+			"ok":        allOK,
+			"workspace": workspace,
+			"checks":    checks,
+		})
 	}
-	output.PrintJson(f.IOStreams.Out, result)
 	if !allOK {
 		return output.ErrBare(1)
 	}
 	return nil
 }
+
+// renderDoctorHuman writes a readable health report: one aligned line per check
+// with a colored status tag, an indented hint when present, and a summary line.
+func renderDoctorHuman(w io.Writer, workspace string, checks []checkResult, allOK, color bool) {
+	const (
+		green  = "\033[32m"
+		yellow = "\033[33m"
+		red    = "\033[31m"
+		gray   = "\033[90m"
+		bold   = "\033[1m"
+		reset  = "\033[0m"
+	)
+	colorOf := map[string]string{"pass": green, "warn": yellow, "fail": red, "skip": gray}
+	tagOf := map[string]string{"pass": "PASS", "warn": "WARN", "fail": "FAIL", "skip": "SKIP"}
+	paint := func(code, s string) string {
+		if !color || code == "" {
+			return s
+		}
+		return code + s + reset
+	}
+
+	nameW := 0
+	for _, c := range checks {
+		if len(c.Name) > nameW {
+			nameW = len(c.Name)
+		}
+	}
+
+	fmt.Fprintf(w, "\n%s  (workspace: %s)\n\n", paint(bold, "lark-cli doctor"), workspace)
+
+	var passN, warnN, failN, skipN int
+	for _, c := range checks {
+		tag := tagOf[c.Status]
+		if tag == "" {
+			tag = "????"
+		}
+		fmt.Fprintf(w, "  %s  %-*s  %s\n", paint(colorOf[c.Status], "["+tag+"]"), nameW, c.Name, c.Message)
+		if c.Hint != "" {
+			fmt.Fprintf(w, "         %-*s  %s\n", nameW, "", paint(gray, "↳ "+c.Hint))
+		}
+		switch c.Status {
+		case "pass":
+			passN++
+		case "warn":
+			warnN++
+		case "fail":
+			failN++
+		case "skip":
+			skipN++
+		}
+	}
+
+	headline := paint(green, "healthy")
+	if !allOK {
+		headline = paint(red, "problems found")
+	}
+	fmt.Fprintf(w, "\n  %s — %d passed", headline, passN)
+	if warnN > 0 {
+		fmt.Fprintf(w, ", %d warning(s)", warnN)
+	}
+	if failN > 0 {
+		fmt.Fprintf(w, ", %d failed", failN)
+	}
+	if skipN > 0 {
+		fmt.Fprintf(w, ", %d skipped", skipN)
+	}
+	fmt.Fprintln(w)
+}

cmd/doctor/doctor_test.go

@@ -4,14 +4,18 @@
 package doctor
 
 import (
+	"bytes"
 	"context"
 	"encoding/json"
+	"errors"
+	"strings"
 	"testing"
 
 	"github.com/spf13/cobra"
 
 	"github.com/larksuite/cli/internal/cmdutil"
 	"github.com/larksuite/cli/internal/core"
+	"github.com/larksuite/cli/internal/keysigner"
 )
 
 func TestNewCmdDoctor_FlagParsing(t *testing.T) {
@@ -139,6 +143,107 @@ func TestDoctorRun_SplitsBotAndMissingUserIdentity(t *testing.T) {
 	assertCheck(t, got.Checks, "identity_ready", "pass")
 }
 
+func TestTeeCheckResult(t *testing.T) {
+	avail := keysigner.HardwareInfo{Backend: "tpm2", Available: true, VendorName: "ACME"}
+	unavail := keysigner.HardwareInfo{Backend: "tpm2", Reason: "open /dev/tpmrm0: permission denied"}
+
+	cases := []struct {
+		name     string
+		info     keysigner.HardwareInfo
+		ok       bool
+		probeErr error
+		pkjwt    bool
+		want     string
+	}{
+		{"no signer + private_key_jwt → fail", keysigner.HardwareInfo{}, false, nil, true, "fail"},
+		{"no signer + client_secret → skip", keysigner.HardwareInfo{}, false, nil, false, "skip"},
+		{"available + private_key_jwt → pass", avail, true, nil, true, "pass"},
+		{"available + client_secret → pass", avail, true, nil, false, "pass"},
+		{"unavailable + private_key_jwt → fail", unavail, true, nil, true, "fail"},
+		{"unavailable + client_secret → warn", unavail, true, nil, false, "warn"},
+		{"probe error → warn", keysigner.HardwareInfo{Backend: "tpm2"}, true, errors.New("boom"), true, "warn"},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			got := teeCheckResult(tc.info, tc.ok, tc.probeErr, tc.pkjwt)
+			if got.Name != "tee_signer" {
+				t.Errorf("name = %q, want tee_signer", got.Name)
+			}
+			if got.Status != tc.want {
+				t.Errorf("status = %q, want %q (msg=%q)", got.Status, tc.want, got.Message)
+			}
+		})
+	}
+}
+
+// TestDoctorRun_TeeSignerWired proves the tee_signer check is part of doctorRun.
+// It asserts the build-independent invariant (a client_secret app must never
+// FAIL on TEE) so the test passes whether or not a signer is compiled in.
+func TestDoctorRun_TeeSignerWired(t *testing.T) {
+	t.Setenv("LARKSUITE_CLI_CONFIG_DIR", t.TempDir())
+	if err := core.SaveMultiAppConfig(&core.MultiAppConfig{
+		CurrentApp: "default",
+		Apps: []core.AppConfig{{
+			Name: "default", AppId: "test-app",
+			AppSecret: core.PlainSecret("secret"), Brand: core.BrandFeishu,
+		}},
+	}); err != nil {
+		t.Fatalf("SaveMultiAppConfig() error = %v", err)
+	}
+	f, stdout, _, _ := cmdutil.TestFactory(t, &core.CliConfig{
+		AppID: "test-app", AppSecret: "secret", Brand: core.BrandFeishu,
+	})
+	if err := doctorRun(&DoctorOptions{Factory: f, Ctx: context.Background(), Offline: true}); err != nil {
+		t.Fatalf("doctorRun() error = %v", err)
+	}
+	var got struct {
+		Checks []checkResult `json:"checks"`
+	}
+	if err := json.Unmarshal(stdout.Bytes(), &got); err != nil {
+		t.Fatalf("json.Unmarshal() error = %v", err)
+	}
+	var c *checkResult
+	for i := range got.Checks {
+		if got.Checks[i].Name == "tee_signer" {
+			c = &got.Checks[i]
+		}
+	}
+	if c == nil {
+		t.Fatalf("tee_signer check not present in doctor output: %#v", got.Checks)
+	}
+	if c.Status == "fail" {
+		t.Errorf("tee_signer = fail for a client_secret app; want skip/warn/pass (msg=%q)", c.Message)
+	}
+}
+
+func TestRenderDoctorHuman(t *testing.T) {
+	var buf bytes.Buffer
+	checks := []checkResult{
+		pass("cli_version", "1.0.50"),
+		warn("tee_signer", "tpm2 signer present but TEE unavailable", "add your user to the 'tss' group"),
+		fail("identity_ready", "no usable identity", "run: lark-cli auth status --verify"),
+		skip("endpoint_open", "skipped (--offline)"),
+	}
+	renderDoctorHuman(&buf, "local", checks, false, false)
+	out := buf.String()
+
+	for _, want := range []string{
+		"lark-cli doctor", "workspace: local",
+		"[PASS]", "cli_version", "1.0.50",
+		"[WARN]", "tee_signer", "↳ add your user to the 'tss' group",
+		"[FAIL]", "identity_ready", "↳ run: lark-cli auth status --verify",
+		"[SKIP]", "endpoint_open",
+		"problems found", "1 passed", "1 warning(s)", "1 failed", "1 skipped",
+	} {
+		if !strings.Contains(out, want) {
+			t.Errorf("output missing %q\n---\n%s", want, out)
+		}
+	}
+	if strings.Contains(out, "\033[") {
+		t.Errorf("color=false but ANSI escapes present:\n%s", out)
+	}
+}
+
 func assertCheck(t *testing.T, checks []checkResult, name, status string) {
 	t.Helper()
 	for _, check := range checks {

go.mod

@@ -7,6 +7,8 @@ require (
 	github.com/bmatcuk/doublestar/v4 v4.10.0
 	github.com/charmbracelet/huh v1.0.0
 	github.com/charmbracelet/lipgloss v1.1.0
+	github.com/facebookincubator/flog v0.0.0-20190930132826-d2511d0ce33c
+	github.com/facebookincubator/sks v0.0.0-20251112220143-6823f23937b4
 	github.com/gofrs/flock v0.8.1
 	github.com/google/uuid v1.6.0
 	github.com/itchyny/gojq v0.12.17
@@ -27,7 +29,10 @@ require (
 	gopkg.in/yaml.v3 v3.0.1
 )
 
+require github.com/ebitengine/purego v0.10.1
+
 require (
+	github.com/StackExchange/wmi v1.2.1 // indirect
 	github.com/atotto/clipboard v0.1.4 // indirect
 	github.com/aymanbagabas/go-osc52/v2 v2.0.1 // indirect
 	github.com/catppuccin/go v0.3.0 // indirect
@@ -42,12 +47,23 @@ require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/erikgeiser/coninput v0.0.0-20211004153227-1c3628e74d0f // indirect
+	github.com/go-ole/go-ole v1.2.5 // indirect
 	github.com/godbus/dbus/v5 v5.2.2 // indirect
 	github.com/gogo/protobuf v1.3.2 // indirect
+	github.com/google/btree v1.0.1 // indirect
+	github.com/google/certificate-transparency-go v1.1.2 // indirect
+	github.com/google/certtostore v1.0.3-0.20230404221207-8d01647071cc // indirect
+	github.com/google/deck v0.0.0-20230104221208-105ad94aa8ae // indirect
+	github.com/google/go-attestation v0.5.1 // indirect
+	github.com/google/go-tpm v0.9.0 // indirect
+	github.com/google/go-tspi v0.3.0 // indirect
 	github.com/gopherjs/gopherjs v1.17.2 // indirect
 	github.com/gorilla/websocket v1.5.0 // indirect
+	github.com/hashicorp/errwrap v1.0.0 // indirect
+	github.com/hashicorp/go-multierror v1.1.1 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/itchyny/timefmt-go v0.1.6 // indirect
+	github.com/jgoguen/go-utils v0.0.0-20200211015258-b42ad41486fd // indirect
 	github.com/jtolds/gls v4.20.0+incompatible // indirect
 	github.com/lucasb-eyer/go-colorful v1.2.0 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
@@ -57,10 +73,12 @@ require (
 	github.com/muesli/ansi v0.0.0-20230316100256-276c6243b2f6 // indirect
 	github.com/muesli/cancelreader v0.2.2 // indirect
 	github.com/muesli/termenv v0.16.0 // indirect
+	github.com/peterbourgon/diskv v2.0.1+incompatible // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/rivo/uniseg v0.4.7 // indirect
 	github.com/smarty/assertions v1.15.0 // indirect
 	github.com/tidwall/match v1.1.1 // indirect
 	github.com/tidwall/pretty v1.2.0 // indirect
 	github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e // indirect
+	golang.org/x/crypto v0.31.0 // indirect
 )

internal/auth/app_registration.go

@@ -31,6 +31,11 @@ type AppRegistrationResult struct {
 	ClientID     string
 	ClientSecret string
 	UserInfo     *AppRegUserInfo
+	// AuthMethods is the authoritative auth method(s) the app must use, as
+	// decided by the user/admin at confirmation (20260409 `auth_method` field).
+	// It may differ from what the client requested — e.g. selecting an existing
+	// client_secret app. Empty on older servers.
+	AuthMethods []string
 }
 
 // AppRegUserInfo contains user info returned from app registration.
@@ -39,8 +44,81 @@ type AppRegUserInfo struct {
 	TenantBrand string // "feishu" or "lark"
 }
 
-// RequestAppRegistration initiates the app registration device flow.
-func RequestAppRegistration(httpClient *http.Client, brand core.LarkBrand, errOut io.Writer) (*AppRegistrationResponse, error) {
+// AppRegistrationInit is the response from the app registration init endpoint.
+type AppRegistrationInit struct {
+	Nonce                string
+	SupportedAuthMethods []string // e.g. ["client_secret", "private_key_jwt"]
+}
+
+// AppRegistrationBeginOptions parametrizes the registration begin request.
+// A zero value selects the legacy client_secret flow, preserving prior behavior.
+type AppRegistrationBeginOptions struct {
+	AuthMethod      string // "" => client_secret; core.AuthMethodPrivateKeyJWT
+	AuthAttestation string // private_key_jwt: the TEE-signed attestation JWT
+	RestoreAppID    string // when set, asks the server to re-register this existing app
+}
+
+// RequestAppRegistrationInit performs the init step of the registration flow,
+// returning a server nonce (to be embedded in a TEE-signed attestation JWT) and
+// the auth methods the server supports for this archetype.
+func RequestAppRegistrationInit(httpClient *http.Client) (*AppRegistrationInit, error) {
+	// Registration always begins against the feishu accounts host (mirrors begin).
+	endpoint := core.ResolveEndpoints(core.BrandFeishu).Accounts + PathAppRegistration
+
+	form := url.Values{}
+	form.Set("action", "init")
+	form.Set("archetype", "PersonalAgent")
+
+	req, err := http.NewRequest("POST", endpoint, strings.NewReader(form.Encode()))
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+
+	resp, err := httpClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	logHTTPResponse(resp)
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("app registration init failed: read body: %w", err)
+	}
+
+	var data map[string]interface{}
+	if err := json.Unmarshal(body, &data); err != nil {
+		return nil, fmt.Errorf("app registration init failed: HTTP %d – response not JSON", resp.StatusCode)
+	}
+
+	if _, hasError := data["error"]; resp.StatusCode >= 400 || hasError {
+		msg := getStr(data, "error_description")
+		if msg == "" {
+			msg = getStr(data, "error")
+		}
+		if msg == "" {
+			msg = "Unknown error"
+		}
+		return nil, fmt.Errorf("app registration init failed: %s", msg)
+	}
+
+	out := &AppRegistrationInit{Nonce: getStr(data, "nonce")}
+	if methods, ok := data["supported_auth_methods"].([]interface{}); ok {
+		for _, m := range methods {
+			if s, ok := m.(string); ok {
+				out.SupportedAuthMethods = append(out.SupportedAuthMethods, s)
+			}
+		}
+	}
+	if out.Nonce == "" {
+		return nil, fmt.Errorf("app registration init failed: server returned no nonce")
+	}
+	return out, nil
+}
+
+// RequestAppRegistration initiates the app registration device flow (begin step).
+func RequestAppRegistration(httpClient *http.Client, brand core.LarkBrand, opts AppRegistrationBeginOptions, errOut io.Writer) (*AppRegistrationResponse, error) {
 	if errOut == nil {
 		errOut = io.Discard
 	}
@@ -49,11 +127,24 @@ func RequestAppRegistration(httpClient *http.Client, brand core.LarkBrand, errOu
 	regEp := core.ResolveEndpoints(core.BrandFeishu) // registration begin always uses feishu
 	endpoint := regEp.Accounts + PathAppRegistration
 
+	authMethod := opts.AuthMethod
+	if authMethod == "" {
+		authMethod = core.AuthMethodClientSecret
+	}
+
 	form := url.Values{}
 	form.Set("action", "begin")
 	form.Set("archetype", "PersonalAgent")
-	form.Set("auth_method", "client_secret")
+	form.Set("auth_method", authMethod)
 	form.Set("request_user_info", "open_id tenant_brand")
+	if opts.AuthAttestation != "" {
+		form.Set("auth_attestation", opts.AuthAttestation)
+	}
+	// Restore flow: carry the existing app id so the server re-registers it
+	// rather than creating a new app.
+	if opts.RestoreAppID != "" {
+		form.Set("app_id", opts.RestoreAppID)
+	}
 
 	req, err := http.NewRequest("POST", endpoint, strings.NewReader(form.Encode()))
 	if err != nil {
@@ -95,7 +186,24 @@ func RequestAppRegistration(httpClient *http.Client, brand core.LarkBrand, errOu
 
 	userCode := getStr(data, "user_code")
 	verificationUri := getStr(data, "verification_uri")
-	verificationUriComplete := fmt.Sprintf("%s/page/cli?user_code=%s", ep.Open, userCode)
+	// Prefer the server-provided complete URL (currently /page/launcher); fall
+	// back to building it from verification_uri, then to /page/launcher. The old
+	// hard-coded /page/cli is stale — the server now returns /page/launcher.
+	verificationUriComplete := getStr(data, "verification_uri_complete")
+	if verificationUriComplete == "" {
+		base := verificationUri
+		if base == "" {
+			base = ep.Open + "/page/launcher"
+		}
+		// The server may return verification_uri with its own query (e.g.
+		// client_id when registering against an existing app), so join with
+		// the same ?/& logic as BuildVerificationURL.
+		sep := "?"
+		if strings.Contains(base, "?") {
+			sep = "&"
+		}
+		verificationUriComplete = base + sep + "user_code=" + url.QueryEscape(userCode)
+	}
 
 	return &AppRegistrationResponse{
 		DeviceCode:              getStr(data, "device_code"),
@@ -107,6 +215,26 @@ func RequestAppRegistration(httpClient *http.Client, brand core.LarkBrand, errOu
 	}, nil
 }
 
+// parseAuthMethods normalizes the poll response `auth_method` field, which the
+// server returns as a JSON array of strings (e.g. ["private_key_jwt"]) — or, on
+// some variants, a single space-separated string.
+func parseAuthMethods(v interface{}) []string {
+	switch t := v.(type) {
+	case []interface{}:
+		out := make([]string, 0, len(t))
+		for _, m := range t {
+			if s, ok := m.(string); ok && s != "" {
+				out = append(out, s)
+			}
+		}
+		return out
+	case string:
+		return strings.Fields(t)
+	default:
+		return nil
+	}
+}
+
 // BuildVerificationURL appends CLI tracking parameters to the verification URL.
 func BuildVerificationURL(baseURL, cliVersion string) string {
 	sep := "&"
@@ -187,6 +315,7 @@ func PollAppRegistration(ctx context.Context, httpClient *http.Client, brand cor
 			result := &AppRegistrationResult{
 				ClientID:     getStr(data, "client_id"),
 				ClientSecret: getStr(data, "client_secret"),
+				AuthMethods:  parseAuthMethods(data["auth_method"]),
 			}
 			if userInfoRaw, ok := data["user_info"].(map[string]interface{}); ok {
 				result.UserInfo = &AppRegUserInfo{

internal/auth/app_registration_test.go

@@ -4,8 +4,14 @@
 package auth
 
 import (
+	"io"
+	"net/http"
+	"net/url"
+	"slices"
+	"strings"
 	"testing"
 
+	"github.com/larksuite/cli/internal/core"
 	"github.com/smartystreets/goconvey/convey"
 )
 
@@ -31,3 +37,184 @@ func Test_BuildVerificationURL(t *testing.T) {
 		})
 	})
 }
+
+// captureClient returns an http.Client that records the last request's form body
+// and replies with the given JSON payload.
+func captureClient(gotBody *url.Values, respJSON string) *http.Client {
+	return &http.Client{
+		Transport: roundTripFunc(func(req *http.Request) (*http.Response, error) {
+			if req.Body != nil {
+				b, _ := io.ReadAll(req.Body)
+				v, _ := url.ParseQuery(string(b))
+				*gotBody = v
+			}
+			return &http.Response{
+				StatusCode: http.StatusOK,
+				Header:     make(http.Header),
+				Body:       io.NopCloser(strings.NewReader(respJSON)),
+			}, nil
+		}),
+	}
+}
+
+func TestRequestAppRegistrationInit_ParsesNonceAndMethods(t *testing.T) {
+	var body url.Values
+	hc := captureClient(&body, `{"nonce":"n-123","supported_auth_methods":["client_secret","private_key_jwt"]}`)
+
+	out, err := RequestAppRegistrationInit(hc)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if out.Nonce != "n-123" {
+		t.Errorf("nonce = %q, want n-123", out.Nonce)
+	}
+	if len(out.SupportedAuthMethods) != 2 || out.SupportedAuthMethods[1] != "private_key_jwt" {
+		t.Errorf("methods = %v", out.SupportedAuthMethods)
+	}
+	if body.Get("action") != "init" {
+		t.Errorf("action = %q, want init", body.Get("action"))
+	}
+}
+
+func TestRequestAppRegistrationInit_ErrorOnMissingNonce(t *testing.T) {
+	var body url.Values
+	hc := captureClient(&body, `{"supported_auth_methods":["client_secret"]}`)
+	if _, err := RequestAppRegistrationInit(hc); err == nil {
+		t.Fatal("expected error when server returns no nonce")
+	}
+}
+
+// TestRequestAppRegistrationInit_EmptySupportedAuthMethods covers the older-server
+// back-compat path: an empty supported_auth_methods array parses to an empty
+// slice, so the init guard in cmd/config/init_interactive.go
+// (`len(SupportedAuthMethods) > 0 && !slices.Contains(...)`) stays false and does
+// NOT reject the requested private_key_jwt. This aligns with
+// resolveFinalAuthMethod(nil/[], private_key_jwt) == private_key_jwt
+// (see cmd/config TestResolveFinalAuthMethod).
+func TestRequestAppRegistrationInit_EmptySupportedAuthMethods(t *testing.T) {
+	var body url.Values
+	hc := captureClient(&body, `{"nonce":"n-1","supported_auth_methods":[]}`)
+
+	out, err := RequestAppRegistrationInit(hc)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if out.Nonce != "n-1" {
+		t.Errorf("nonce = %q, want n-1", out.Nonce)
+	}
+	if len(out.SupportedAuthMethods) != 0 {
+		t.Errorf("SupportedAuthMethods = %v, want empty", out.SupportedAuthMethods)
+	}
+	// Reproduce the init guard expression on the real parsed result: an empty
+	// slice must NOT reject private_key_jwt.
+	rejected := len(out.SupportedAuthMethods) > 0 &&
+		!slices.Contains(out.SupportedAuthMethods, core.AuthMethodPrivateKeyJWT)
+	if rejected {
+		t.Error("empty SupportedAuthMethods must allow private_key_jwt (older-server back-compat)")
+	}
+}
+
+const beginRespJSON = `{"device_code":"dc","user_code":"uc","verification_uri":"https://example/verify","expires_in":300,"interval":5}`
+
+func TestRequestAppRegistration_BeginDefaultsToClientSecret(t *testing.T) {
+	var body url.Values
+	hc := captureClient(&body, beginRespJSON)
+
+	if _, err := RequestAppRegistration(hc, core.BrandFeishu, AppRegistrationBeginOptions{}, nil); err != nil {
+		t.Fatal(err)
+	}
+	if body.Get("action") != "begin" {
+		t.Errorf("action = %q", body.Get("action"))
+	}
+	if body.Get("auth_method") != "client_secret" {
+		t.Errorf("auth_method = %q, want client_secret (default)", body.Get("auth_method"))
+	}
+	if body.Has("auth_attestation") {
+		t.Errorf("auth_attestation should be absent for client_secret, got %q", body.Get("auth_attestation"))
+	}
+	// Normal (non-restore) begin must NOT carry app_id.
+	if body.Has("app_id") {
+		t.Errorf("app_id should be absent when RestoreAppID is empty, got %q", body.Get("app_id"))
+	}
+}
+
+// TestRequestAppRegistration_BeginRestoreAppID verifies the restore flow sends the
+// existing app id on begin so the server re-registers that app.
+func TestRequestAppRegistration_BeginRestoreAppID(t *testing.T) {
+	var body url.Values
+	hc := captureClient(&body, beginRespJSON)
+
+	opts := AppRegistrationBeginOptions{RestoreAppID: "cli_restore_me"}
+	if _, err := RequestAppRegistration(hc, core.BrandFeishu, opts, nil); err != nil {
+		t.Fatal(err)
+	}
+	if body.Get("action") != "begin" {
+		t.Errorf("action = %q, want begin", body.Get("action"))
+	}
+	if body.Get("app_id") != "cli_restore_me" {
+		t.Errorf("app_id = %q, want cli_restore_me", body.Get("app_id"))
+	}
+}
+
+func TestRequestAppRegistration_VerificationURICompleteFallback(t *testing.T) {
+	cases := []struct {
+		name string
+		resp string
+		want string
+	}{
+		{
+			name: "bare verification_uri",
+			resp: `{"device_code":"dc","user_code":"uc","verification_uri":"https://example/verify","expires_in":300,"interval":5}`,
+			want: "https://example/verify?user_code=uc",
+		},
+		{
+			name: "verification_uri with existing query",
+			resp: `{"device_code":"dc","user_code":"uc","verification_uri":"https://example/verify?client_id=cli_x","expires_in":300,"interval":5}`,
+			want: "https://example/verify?client_id=cli_x&user_code=uc",
+		},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			var body url.Values
+			hc := captureClient(&body, tc.resp)
+			got, err := RequestAppRegistration(hc, core.BrandFeishu, AppRegistrationBeginOptions{}, nil)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if got.VerificationUriComplete != tc.want {
+				t.Errorf("VerificationUriComplete = %q, want %q", got.VerificationUriComplete, tc.want)
+			}
+		})
+	}
+}
+
+func TestParseAuthMethods(t *testing.T) {
+	if got := parseAuthMethods([]interface{}{"private_key_jwt", "client_secret"}); len(got) != 2 || got[0] != "private_key_jwt" {
+		t.Errorf("array form = %v", got)
+	}
+	if got := parseAuthMethods("client_secret private_key_jwt"); len(got) != 2 || got[1] != "private_key_jwt" {
+		t.Errorf("string form = %v", got)
+	}
+	if got := parseAuthMethods(nil); got != nil {
+		t.Errorf("nil form = %v, want nil", got)
+	}
+}
+
+func TestRequestAppRegistration_BeginPrivateKeyJWT(t *testing.T) {
+	var body url.Values
+	hc := captureClient(&body, beginRespJSON)
+
+	opts := AppRegistrationBeginOptions{
+		AuthMethod:      core.AuthMethodPrivateKeyJWT,
+		AuthAttestation: "header.claims.sig",
+	}
+	if _, err := RequestAppRegistration(hc, core.BrandFeishu, opts, nil); err != nil {
+		t.Fatal(err)
+	}
+	if body.Get("auth_method") != "private_key_jwt" {
+		t.Errorf("auth_method = %q, want private_key_jwt", body.Get("auth_method"))
+	}
+	if body.Get("auth_attestation") != "header.claims.sig" {
+		t.Errorf("auth_attestation = %q", body.Get("auth_attestation"))
+	}
+}

internal/auth/client_auth.go

@@ -0,0 +1,63 @@
+// Copyright (c) 2026 Lark Technologies Pte. Ltd.
+// SPDX-License-Identifier: MIT
+
+package auth
+
+import (
+	"context"
+	"fmt"
+	"net/url"
+	"time"
+
+	"github.com/larksuite/cli/internal/auth/jwt"
+	"github.com/larksuite/cli/internal/core"
+	"github.com/larksuite/cli/internal/keysigner"
+)
+
+// ClientAuth describes how to authenticate the OAuth client at the token
+// endpoint: with a client_secret (default) or a TEE-signed client_assertion
+// (private_key_jwt).
+type ClientAuth struct {
+	AppID      string
+	AppSecret  string
+	AuthMethod string // "" == client_secret; core.AuthMethodPrivateKeyJWT
+	Signer     keysigner.Signer
+	KeyLabel   string
+}
+
+// ClientAuthFromConfig builds a ClientAuth from resolved config, picking up the
+// active key signer for private_key_jwt apps.
+func ClientAuthFromConfig(cfg *core.CliConfig) ClientAuth {
+	if cfg == nil {
+		return ClientAuth{}
+	}
+	return ClientAuth{
+		AppID:      cfg.AppID,
+		AppSecret:  cfg.AppSecret,
+		AuthMethod: cfg.AuthMethod,
+		KeyLabel:   cfg.KeyLabel,
+		Signer:     keysigner.Active(),
+	}
+}
+
+func (c ClientAuth) isPrivateKeyJWT() bool { return c.AuthMethod == core.AuthMethodPrivateKeyJWT }
+
+// applyClientAssertion adds client_assertion(+type) to a token-endpoint form for
+// private_key_jwt and returns true. For client_secret it returns false, leaving
+// the caller to apply its own secret-based authentication. audience is the token
+// endpoint URL (the assertion's aud claim).
+func (c ClientAuth) applyClientAssertion(ctx context.Context, form url.Values, audience string) (bool, error) {
+	if !c.isPrivateKeyJWT() {
+		return false, nil
+	}
+	if c.Signer == nil {
+		return false, fmt.Errorf("private_key_jwt requires a key signer, but none is available on this build")
+	}
+	assertion, err := jwt.SignClientAssertion(ctx, c.Signer, keysigner.KeyRef{Label: c.KeyLabel}, c.AppID, audience, time.Now())
+	if err != nil {
+		return false, err
+	}
+	form.Set("client_assertion_type", jwt.ClientAssertionType)
+	form.Set("client_assertion", assertion)
+	return true, nil
+}

internal/auth/client_auth_test.go

@@ -0,0 +1,109 @@
+// Copyright (c) 2026 Lark Technologies Pte. Ltd.
+// SPDX-License-Identifier: MIT
+
+package auth
+
+import (
+	"context"
+	"crypto"
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	"crypto/sha256"
+	"net/url"
+	"testing"
+
+	"github.com/larksuite/cli/internal/auth/jwt"
+	"github.com/larksuite/cli/internal/core"
+	"github.com/larksuite/cli/internal/keysigner"
+)
+
+// fakeAuthSigner is a real in-memory ECDSA P-256 signer for client-auth tests.
+type fakeAuthSigner struct{ key *ecdsa.PrivateKey }
+
+func newFakeAuthSigner(t *testing.T) *fakeAuthSigner {
+	t.Helper()
+	k, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return &fakeAuthSigner{key: k}
+}
+
+func (f *fakeAuthSigner) EnsureKey(context.Context, keysigner.KeyRef) (crypto.PublicKey, error) {
+	return f.key.Public(), nil
+}
+func (f *fakeAuthSigner) PublicKey(context.Context, keysigner.KeyRef) (crypto.PublicKey, error) {
+	return f.key.Public(), nil
+}
+func (f *fakeAuthSigner) Sign(_ context.Context, _ keysigner.KeyRef, in []byte) ([]byte, string, error) {
+	h := sha256.Sum256(in)
+	r, s, err := ecdsa.Sign(rand.Reader, f.key, h[:])
+	if err != nil {
+		return nil, "", err
+	}
+	sig := make([]byte, 64)
+	r.FillBytes(sig[:32])
+	s.FillBytes(sig[32:])
+	return sig, keysigner.AlgES256, nil
+}
+
+func TestClientAuth_applyClientAssertion_ClientSecret(t *testing.T) {
+	ca := ClientAuth{AppID: "cli_a", AppSecret: "sec"} // AuthMethod "" => client_secret
+	form := url.Values{}
+	used, err := ca.applyClientAssertion(context.Background(), form, "https://aud/token")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if used {
+		t.Error("client_secret must not produce a client_assertion")
+	}
+	if form.Has("client_assertion") || form.Has("client_assertion_type") {
+		t.Errorf("form should be untouched, got %v", form)
+	}
+}
+
+func TestClientAuth_applyClientAssertion_PrivateKeyJWT(t *testing.T) {
+	ca := ClientAuth{
+		AppID:      "cli_a",
+		AuthMethod: core.AuthMethodPrivateKeyJWT,
+		Signer:     newFakeAuthSigner(t),
+		KeyLabel:   "k",
+	}
+	form := url.Values{}
+	used, err := ca.applyClientAssertion(context.Background(), form, "https://accounts.feishu.cn/open-apis/authen/v2/oauth/token")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !used {
+		t.Fatal("expected client_assertion to be applied")
+	}
+	if form.Get("client_assertion_type") != jwt.ClientAssertionType {
+		t.Errorf("client_assertion_type = %q", form.Get("client_assertion_type"))
+	}
+	if form.Get("client_assertion") == "" {
+		t.Error("client_assertion is empty")
+	}
+	if form.Has("client_secret") {
+		t.Error("client_secret must NOT be present for private_key_jwt")
+	}
+}
+
+func TestClientAuth_applyClientAssertion_NilSigner(t *testing.T) {
+	ca := ClientAuth{AppID: "cli_a", AuthMethod: core.AuthMethodPrivateKeyJWT} // Signer nil
+	if _, err := ca.applyClientAssertion(context.Background(), url.Values{}, "aud"); err == nil {
+		t.Fatal("expected error when private_key_jwt has no signer")
+	}
+}
+
+func TestClientAuthFromConfig(t *testing.T) {
+	ca := ClientAuthFromConfig(&core.CliConfig{
+		AppID:      "cli_x",
+		AppSecret:  "s",
+		AuthMethod: core.AuthMethodPrivateKeyJWT,
+		KeyLabel:   "label-1",
+	})
+	if ca.AppID != "cli_x" || ca.AppSecret != "s" || ca.AuthMethod != core.AuthMethodPrivateKeyJWT || ca.KeyLabel != "label-1" {
+		t.Errorf("ClientAuth = %+v", ca)
+	}
+}

internal/auth/device_flow.go

@@ -62,7 +62,7 @@ func ResolveOAuthEndpoints(brand core.LarkBrand) OAuthEndpoints {
 }
 
 // RequestDeviceAuthorization requests a device authorization code.
-func RequestDeviceAuthorization(httpClient *http.Client, appId, appSecret string, brand core.LarkBrand, scope string, errOut io.Writer) (*DeviceAuthResponse, error) {
+func RequestDeviceAuthorization(ctx context.Context, httpClient *http.Client, ca ClientAuth, brand core.LarkBrand, scope string, errOut io.Writer) (*DeviceAuthResponse, error) {
 	if errOut == nil {
 		errOut = io.Discard
 	}
@@ -77,18 +77,26 @@ func RequestDeviceAuthorization(httpClient *http.Client, appId, appSecret string
 		}
 	}
 
-	basicAuth := base64.StdEncoding.EncodeToString([]byte(appId + ":" + appSecret))
-
 	form := url.Values{}
-	form.Set("client_id", appId)
+	form.Set("client_id", ca.AppID)
 	form.Set("scope", scope)
 
-	req, err := http.NewRequest("POST", endpoints.DeviceAuthorization, strings.NewReader(form.Encode()))
+	// private_key_jwt authenticates the client with a signed assertion in the
+	// body; client_secret uses HTTP Basic.
+	usedAssertion, err := ca.applyClientAssertion(ctx, form, core.OpenAPIAudience(brand))
+	if err != nil {
+		return nil, err
+	}
+
+	req, err := http.NewRequestWithContext(ctx, "POST", endpoints.DeviceAuthorization, strings.NewReader(form.Encode()))
 	if err != nil {
 		return nil, err
 	}
 	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
-	req.Header.Set("Authorization", "Basic "+basicAuth)
+	if !usedAssertion {
+		basicAuth := base64.StdEncoding.EncodeToString([]byte(ca.AppID + ":" + ca.AppSecret))
+		req.Header.Set("Authorization", "Basic "+basicAuth)
+	}
 
 	resp, err := httpClient.Do(req)
 	if err != nil {
@@ -139,7 +147,7 @@ func RequestDeviceAuthorization(httpClient *http.Client, appId, appSecret string
 }
 
 // PollDeviceToken polls the token endpoint until authorization completes or times out.
-func PollDeviceToken(ctx context.Context, httpClient *http.Client, appId, appSecret string, brand core.LarkBrand, deviceCode string, interval, expiresIn int, errOut io.Writer) *DeviceFlowResult {
+func PollDeviceToken(ctx context.Context, httpClient *http.Client, ca ClientAuth, brand core.LarkBrand, deviceCode string, interval, expiresIn int, errOut io.Writer) *DeviceFlowResult {
 	if errOut == nil {
 		errOut = io.Discard
 	}
@@ -171,10 +179,16 @@ func PollDeviceToken(ctx context.Context, httpClient *http.Client, appId, appSec
 		form := url.Values{}
 		form.Set("grant_type", "urn:ietf:params:oauth:grant-type:device_code")
 		form.Set("device_code", deviceCode)
-		form.Set("client_id", appId)
-		form.Set("client_secret", appSecret)
+		form.Set("client_id", ca.AppID)
+		usedAssertion, caErr := ca.applyClientAssertion(ctx, form, core.OpenAPIAudience(brand))
+		if caErr != nil {
+			return &DeviceFlowResult{OK: false, Error: "invalid_client", Message: caErr.Error()}
+		}
+		if !usedAssertion {
+			form.Set("client_secret", ca.AppSecret)
+		}
 
-		req, err := http.NewRequest("POST", endpoints.Token, strings.NewReader(form.Encode()))
+		req, err := http.NewRequestWithContext(ctx, "POST", endpoints.Token, strings.NewReader(form.Encode()))
 		if err != nil {
 			continue
 		}

internal/auth/device_flow_test.go

@@ -7,8 +7,10 @@ import (
 	"bytes"
 	"context"
 	"fmt"
+	"io"
 	"log"
 	"net/http"
+	"net/url"
 	"strings"
 	"sync/atomic"
 	"testing"
@@ -83,7 +85,7 @@ func TestRequestDeviceAuthorization_LogsResponse(t *testing.T) {
 	})
 	t.Cleanup(restore)
 
-	_, err := RequestDeviceAuthorization(httpmock.NewClient(reg), "cli_a", "secret_b", core.BrandFeishu, "", nil)
+	_, err := RequestDeviceAuthorization(context.Background(), httpmock.NewClient(reg), ClientAuth{AppID: "cli_a", AppSecret: "secret_b"}, core.BrandFeishu, "", nil)
 	if err != nil {
 		t.Fatalf("RequestDeviceAuthorization() error: %v", err)
 	}
@@ -106,6 +108,66 @@ func TestRequestDeviceAuthorization_LogsResponse(t *testing.T) {
 	}
 }
 
+// captureRT records the last request + body and returns a canned device-auth response.
+func captureDeviceAuthClient(gotReq **http.Request, gotBody *string, respJSON string) *http.Client {
+	return &http.Client{Transport: roundTripFunc(func(req *http.Request) (*http.Response, error) {
+		*gotReq = req
+		if req.Body != nil {
+			b, _ := io.ReadAll(req.Body)
+			*gotBody = string(b)
+		}
+		return &http.Response{
+			StatusCode: http.StatusOK,
+			Header:     make(http.Header),
+			Body:       io.NopCloser(strings.NewReader(respJSON)),
+		}, nil
+	})}
+}
+
+const deviceAuthRespJSON = `{"device_code":"dc","user_code":"uc","verification_uri":"https://example/verify","expires_in":300,"interval":5}`
+
+func TestRequestDeviceAuthorization_PrivateKeyJWT_UsesAssertionNotBasic(t *testing.T) {
+	var req *http.Request
+	var body string
+	client := captureDeviceAuthClient(&req, &body, deviceAuthRespJSON)
+
+	ca := ClientAuth{AppID: "cli_a", AuthMethod: core.AuthMethodPrivateKeyJWT, Signer: newFakeAuthSigner(t), KeyLabel: "k"}
+	if _, err := RequestDeviceAuthorization(context.Background(), client, ca, core.BrandFeishu, "im:message:send", nil); err != nil {
+		t.Fatal(err)
+	}
+	if req.Header.Get("Authorization") != "" {
+		t.Errorf("private_key_jwt must NOT send Basic auth, got %q", req.Header.Get("Authorization"))
+	}
+	form, _ := url.ParseQuery(body)
+	if form.Get("client_assertion") == "" {
+		t.Error("missing client_assertion")
+	}
+	if form.Get("client_assertion_type") != "urn:ietf:params:oauth:client-assertion-type:jwt-bearer" {
+		t.Errorf("client_assertion_type = %q", form.Get("client_assertion_type"))
+	}
+	if form.Has("client_secret") {
+		t.Error("client_secret must not be present for private_key_jwt")
+	}
+}
+
+func TestRequestDeviceAuthorization_ClientSecret_UsesBasic(t *testing.T) {
+	var req *http.Request
+	var body string
+	client := captureDeviceAuthClient(&req, &body, deviceAuthRespJSON)
+
+	ca := ClientAuth{AppID: "cli_a", AppSecret: "sec"} // client_secret
+	if _, err := RequestDeviceAuthorization(context.Background(), client, ca, core.BrandFeishu, "", nil); err != nil {
+		t.Fatal(err)
+	}
+	if !strings.HasPrefix(req.Header.Get("Authorization"), "Basic ") {
+		t.Errorf("client_secret should use Basic auth, got %q", req.Header.Get("Authorization"))
+	}
+	form, _ := url.ParseQuery(body)
+	if form.Has("client_assertion") {
+		t.Error("client_secret must not send a client_assertion")
+	}
+}
+
 // TestFormatAuthCmdline_TruncatesExtraArgs verifies that long command lines are truncated.
 func TestFormatAuthCmdline_TruncatesExtraArgs(t *testing.T) {
 	got := keychain.FormatAuthCmdline([]string{
@@ -205,7 +267,7 @@ func TestPollDeviceToken_DefaultsZeroIntervalToFiveSeconds(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
 	t.Cleanup(cancel)
 
-	result := PollDeviceToken(ctx, client, "cli_a", "secret_b", core.BrandFeishu, "device-code", 0, 10, nil)
+	result := PollDeviceToken(ctx, client, ClientAuth{AppID: "cli_a", AppSecret: "secret_b"}, core.BrandFeishu, "device-code", 0, 10, nil)
 	if result == nil {
 		t.Fatal("PollDeviceToken() returned nil result")
 	}

internal/auth/jwt/jwt.go

@@ -0,0 +1,153 @@
+// Copyright (c) 2026 Lark Technologies Pte. Ltd.
+// SPDX-License-Identifier: MIT
+
+// Package jwt builds compact JWS tokens signed by a keysigner.Signer.
+//
+// It deliberately depends only on the standard library plus the existing
+// google/uuid dependency — no third-party JWT library is introduced, keeping
+// go.mod free of new dependencies. The actual signing (and, for ECDSA, the
+// ASN.1->r||s conversion) is delegated to the Signer implementation.
+package jwt
+
+import (
+	"context"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"time"
+
+	"github.com/google/uuid"
+	"github.com/larksuite/cli/internal/keysigner"
+)
+
+func b64(b []byte) string { return base64.RawURLEncoding.EncodeToString(b) }
+
+// buildSignedJWT builds a compact JWS:
+//
+//	base64url(header).base64url(claims).base64url(signature)
+//
+// alg is written into the header (it is part of the signed input) and verified
+// against the alg the signer reports, guarding against a header/key mismatch.
+// typ defaults to "JWT": the server's client_assertion generalizedValidation
+// REQUIRES `typ == "JWT"` (rejects otherwise with "malformed client assertion
+// jwt"), even though the spec examples (§8.1/§8.2) show only alg.
+func buildSignedJWT(ctx context.Context, signer keysigner.Signer, ref keysigner.KeyRef, alg string, header, claims map[string]any) (string, error) {
+	if signer == nil {
+		return "", fmt.Errorf("jwt: no signer available (private_key_jwt unsupported on this build)")
+	}
+	if header == nil {
+		header = map[string]any{}
+	}
+	header["alg"] = alg
+	if _, ok := header["typ"]; !ok {
+		header["typ"] = "JWT"
+	}
+
+	hb, err := json.Marshal(header)
+	if err != nil {
+		return "", fmt.Errorf("jwt: marshal header: %w", err)
+	}
+	cb, err := json.Marshal(claims)
+	if err != nil {
+		return "", fmt.Errorf("jwt: marshal claims: %w", err)
+	}
+
+	signingInput := b64(hb) + "." + b64(cb)
+	sig, gotAlg, err := signer.Sign(ctx, ref, []byte(signingInput))
+	if err != nil {
+		return "", fmt.Errorf("jwt: sign: %w", err)
+	}
+	if gotAlg != alg {
+		return "", fmt.Errorf("jwt: signer alg %q does not match header alg %q", gotAlg, alg)
+	}
+	return signingInput + "." + b64(sig), nil
+}
+
+// newJTI returns a random unique token identifier.
+func newJTI() string { return uuid.NewString() }
+
+// attestationTTL bounds the attestation JWT's lifetime. The init nonce (60s,
+// single-use) is the real anti-replay constraint; this is a modest margin for
+// clock skew on top of the immediate init→sign→begin round-trip.
+const attestationTTL = 2 * time.Minute
+
+// attestationClaims builds the registration attestation claim set per the App
+// Registration JWT spec: jti, iat, exp (all required) and the init-issued nonce.
+func attestationClaims(nonce string, now time.Time) map[string]any {
+	return map[string]any{
+		"jti":   newJTI(),
+		"iat":   now.Unix(),
+		"exp":   now.Add(attestationTTL).Unix(),
+		"nonce": nonce,
+	}
+}
+
+// clientAssertionClaims builds an RFC 7523 client_assertion claim set used to
+// mint tokens in place of client_secret. aud is the brand's token endpoint URL.
+func clientAssertionClaims(clientID, aud string, now time.Time, ttl time.Duration) map[string]any {
+	return map[string]any{
+		"iss": clientID,
+		"sub": clientID,
+		"aud": aud,
+		"iat": now.Unix(),
+		"exp": now.Add(ttl).Unix(),
+		"jti": newJTI(),
+	}
+}
+
+// ClientAssertionType is the RFC 7523 client_assertion_type value used for JWT
+// bearer client authentication at the token endpoint.
+const ClientAssertionType = "urn:ietf:params:oauth:client-assertion-type:jwt-bearer"
+
+// defaultAssertionTTL bounds a client_assertion's lifetime.
+const defaultAssertionTTL = 5 * time.Minute
+
+// SignAttestation signs the registration attestation JWT. The public key is
+// embedded in the JWS "jwk" header so the registration backend can bind it to
+// the app during action=begin; the claims carry the server nonce as a
+// proof-of-possession challenge.
+func SignAttestation(ctx context.Context, signer keysigner.Signer, ref keysigner.KeyRef, nonce string, now time.Time) (string, error) {
+	if signer == nil {
+		return "", fmt.Errorf("jwt: no signer available (private_key_jwt unsupported on this build)")
+	}
+	pub, err := signer.EnsureKey(ctx, ref)
+	if err != nil {
+		return "", fmt.Errorf("jwt: ensure key: %w", err)
+	}
+	alg, err := keysigner.AlgForKey(pub)
+	if err != nil {
+		return "", err
+	}
+	jwk, err := keysigner.PublicKeyJWK(pub)
+	if err != nil {
+		return "", err
+	}
+	return buildSignedJWT(ctx, signer, ref, alg, map[string]any{"jwk": jwk}, attestationClaims(nonce, now))
+}
+
+// SignClientAssertion mints a short-lived RFC 7523 client_assertion: it reads the
+// registered key (it must already exist — bound at registration; a missing key is
+// an error, not a reason to create a new unbound one), derives the JWS alg from
+// the public key, and signs an assertion whose audience is the brand's Open API
+// host. The server, holding the public key bound at registration, verifies it in
+// place of client_secret. The assertion header carries only alg (no jwk/kid);
+// the server locates the key via iss/sub = client_id.
+//
+// This is the model-independent glue: the assertion JWT is identical whether the
+// server augments an existing grant (device_code/refresh_token) with client
+// authentication or uses a dedicated jwt-bearer grant — only where the caller
+// attaches it differs.
+func SignClientAssertion(ctx context.Context, signer keysigner.Signer, ref keysigner.KeyRef, clientID, audience string, now time.Time) (string, error) {
+	if signer == nil {
+		return "", fmt.Errorf("jwt: no signer available (private_key_jwt unsupported on this build)")
+	}
+	pub, err := signer.PublicKey(ctx, ref)
+	if err != nil {
+		return "", fmt.Errorf("jwt: public key: %w", err)
+	}
+	alg, err := keysigner.AlgForKey(pub)
+	if err != nil {
+		return "", err
+	}
+	return buildSignedJWT(ctx, signer, ref, alg, map[string]any{}, clientAssertionClaims(clientID, audience, now, defaultAssertionTTL))
+}

internal/auth/jwt/jwt_test.go

@@ -0,0 +1,254 @@
+// Copyright (c) 2026 Lark Technologies Pte. Ltd.
+// SPDX-License-Identifier: MIT
+
+package jwt
+
+import (
+	"context"
+	"crypto"
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/json"
+	"math/big"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/larksuite/cli/internal/keysigner"
+)
+
+// fakeSigner is a real in-memory ECDSA P-256 signer, so tests exercise the full
+// JWS path and the produced token is actually cryptographically verifiable.
+type fakeSigner struct{ key *ecdsa.PrivateKey }
+
+func newFakeSigner(t *testing.T) *fakeSigner {
+	t.Helper()
+	k, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return &fakeSigner{key: k}
+}
+
+func (f *fakeSigner) EnsureKey(context.Context, keysigner.KeyRef) (crypto.PublicKey, error) {
+	return f.key.Public(), nil
+}
+func (f *fakeSigner) PublicKey(context.Context, keysigner.KeyRef) (crypto.PublicKey, error) {
+	return f.key.Public(), nil
+}
+func (f *fakeSigner) Sign(_ context.Context, _ keysigner.KeyRef, in []byte) ([]byte, string, error) {
+	h := sha256.Sum256(in)
+	r, s, err := ecdsa.Sign(rand.Reader, f.key, h[:])
+	if err != nil {
+		return nil, "", err
+	}
+	// JOSE ES256: fixed-width big-endian r||s (32 bytes each for P-256).
+	sig := make([]byte, 64)
+	r.FillBytes(sig[:32])
+	s.FillBytes(sig[32:])
+	return sig, keysigner.AlgES256, nil
+}
+
+func TestBuildSignedJWT_VerifiableES256(t *testing.T) {
+	f := newFakeSigner(t)
+	now := time.Unix(1700000000, 0)
+
+	tok, err := buildSignedJWT(context.Background(), f, keysigner.KeyRef{Label: "x"}, keysigner.AlgES256,
+		map[string]any{}, clientAssertionClaims("cli_app", "https://accounts.example/token", now, 5*time.Minute))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	parts := strings.Split(tok, ".")
+	if len(parts) != 3 {
+		t.Fatalf("want 3 JWS parts, got %d", len(parts))
+	}
+
+	hb, err := base64.RawURLEncoding.DecodeString(parts[0])
+	if err != nil {
+		t.Fatalf("header not base64url: %v", err)
+	}
+	var hdr map[string]any
+	if err := json.Unmarshal(hb, &hdr); err != nil {
+		t.Fatal(err)
+	}
+	if hdr["alg"] != "ES256" || hdr["typ"] != "JWT" {
+		t.Errorf("header = %v, want alg=ES256 typ=JWT (server generalizedValidation requires typ)", hdr)
+	}
+
+	cb, _ := base64.RawURLEncoding.DecodeString(parts[1])
+	var claims map[string]any
+	if err := json.Unmarshal(cb, &claims); err != nil {
+		t.Fatal(err)
+	}
+	if claims["iss"] != "cli_app" || claims["sub"] != "cli_app" || claims["aud"] != "https://accounts.example/token" {
+		t.Errorf("claims = %v", claims)
+	}
+
+	// Cryptographically verify the signature against the signing input.
+	sig, err := base64.RawURLEncoding.DecodeString(parts[2])
+	if err != nil {
+		t.Fatalf("sig not base64url: %v", err)
+	}
+	if len(sig) != 64 {
+		t.Fatalf("ES256 sig len = %d, want 64", len(sig))
+	}
+	r := new(big.Int).SetBytes(sig[:32])
+	s := new(big.Int).SetBytes(sig[32:])
+	h := sha256.Sum256([]byte(parts[0] + "." + parts[1]))
+	if !ecdsa.Verify(f.key.Public().(*ecdsa.PublicKey), h[:], r, s) {
+		t.Error("signature did not verify")
+	}
+}
+
+func TestBuildSignedJWT_NilSigner(t *testing.T) {
+	if _, err := buildSignedJWT(context.Background(), nil, keysigner.KeyRef{}, "ES256", nil, nil); err == nil {
+		t.Fatal("expected error for nil signer")
+	}
+}
+
+func TestBuildSignedJWT_AlgMismatch(t *testing.T) {
+	f := newFakeSigner(t) // always reports ES256
+	if _, err := buildSignedJWT(context.Background(), f, keysigner.KeyRef{}, keysigner.AlgRS256, nil, nil); err == nil {
+		t.Fatal("expected error when header alg != signer alg")
+	}
+}
+
+func TestBuildSignedJWT_MarshalErrors(t *testing.T) {
+	f := newFakeSigner(t)
+	ctx := context.Background()
+
+	_, err := buildSignedJWT(ctx, f, keysigner.KeyRef{}, keysigner.AlgES256,
+		map[string]any{"bad": func() {}}, nil)
+	if err == nil || !strings.Contains(err.Error(), "jwt: marshal header") {
+		t.Fatalf("header marshal error = %v, want prefix %q", err, "jwt: marshal header")
+	}
+
+	_, err = buildSignedJWT(ctx, f, keysigner.KeyRef{}, keysigner.AlgES256,
+		nil, map[string]any{"bad": make(chan int)})
+	if err == nil || !strings.Contains(err.Error(), "jwt: marshal claims") {
+		t.Fatalf("claims marshal error = %v, want prefix %q", err, "jwt: marshal claims")
+	}
+}
+
+func TestSignClientAssertion(t *testing.T) {
+	f := newFakeSigner(t)
+	now := time.Unix(1700000000, 0)
+	const aud = "https://accounts.feishu.cn/open-apis/authen/v2/oauth/token"
+
+	tok, err := SignClientAssertion(context.Background(), f, keysigner.KeyRef{Label: "k"}, "cli_app", aud, now)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	parts := strings.Split(tok, ".")
+	if len(parts) != 3 {
+		t.Fatalf("want 3 parts, got %d", len(parts))
+	}
+	cb, _ := base64.RawURLEncoding.DecodeString(parts[1])
+	var claims map[string]any
+	if err := json.Unmarshal(cb, &claims); err != nil {
+		t.Fatal(err)
+	}
+	if claims["iss"] != "cli_app" || claims["aud"] != aud {
+		t.Errorf("claims = %v", claims)
+	}
+
+	// Signature must verify against the key's public half.
+	sig, _ := base64.RawURLEncoding.DecodeString(parts[2])
+	r := new(big.Int).SetBytes(sig[:32])
+	s := new(big.Int).SetBytes(sig[32:])
+	h := sha256.Sum256([]byte(parts[0] + "." + parts[1]))
+	if !ecdsa.Verify(f.key.Public().(*ecdsa.PublicKey), h[:], r, s) {
+		t.Error("client_assertion signature did not verify")
+	}
+}
+
+func TestSignClientAssertion_NilSigner(t *testing.T) {
+	if _, err := SignClientAssertion(context.Background(), nil, keysigner.KeyRef{}, "cli_app", "aud", time.Unix(0, 0)); err == nil {
+		t.Fatal("expected error for nil signer")
+	}
+}
+
+func TestSignAttestation(t *testing.T) {
+	f := newFakeSigner(t)
+	now := time.Unix(1700000000, 0)
+
+	tok, err := SignAttestation(context.Background(), f, keysigner.KeyRef{Label: "k"}, "nonce-abc", now)
+	if err != nil {
+		t.Fatal(err)
+	}
+	parts := strings.Split(tok, ".")
+	if len(parts) != 3 {
+		t.Fatalf("want 3 parts, got %d", len(parts))
+	}
+
+	hb, _ := base64.RawURLEncoding.DecodeString(parts[0])
+	var hdr map[string]any
+	if err := json.Unmarshal(hb, &hdr); err != nil {
+		t.Fatal(err)
+	}
+	jwk, ok := hdr["jwk"].(map[string]any)
+	if !ok {
+		t.Fatalf("attestation header missing jwk: %v", hdr)
+	}
+	if jwk["kty"] != "EC" || jwk["crv"] != "P-256" || jwk["use"] != "sig" {
+		t.Errorf("jwk = %v", jwk)
+	}
+
+	cb, _ := base64.RawURLEncoding.DecodeString(parts[1])
+	var claims map[string]any
+	if err := json.Unmarshal(cb, &claims); err != nil {
+		t.Fatal(err)
+	}
+	if claims["nonce"] != "nonce-abc" {
+		t.Errorf("nonce = %v", claims["nonce"])
+	}
+	// jti, iat, exp are all required by the attestation spec.
+	iat, iatOK := claims["iat"].(float64)
+	exp, expOK := claims["exp"].(float64)
+	if !iatOK || !expOK || exp <= iat {
+		t.Errorf("claims iat/exp invalid: iat=%v exp=%v", claims["iat"], claims["exp"])
+	}
+	if jti, _ := claims["jti"].(string); jti == "" {
+		t.Error("claims jti empty")
+	}
+
+	// Signature verifies against the embedded key.
+	sig, _ := base64.RawURLEncoding.DecodeString(parts[2])
+	r := new(big.Int).SetBytes(sig[:32])
+	s := new(big.Int).SetBytes(sig[32:])
+	h := sha256.Sum256([]byte(parts[0] + "." + parts[1]))
+	if !ecdsa.Verify(f.key.Public().(*ecdsa.PublicKey), h[:], r, s) {
+		t.Error("attestation signature did not verify")
+	}
+}
+
+func TestSignAttestation_NilSigner(t *testing.T) {
+	if _, err := SignAttestation(context.Background(), nil, keysigner.KeyRef{}, "n", time.Unix(0, 0)); err == nil {
+		t.Fatal("expected error for nil signer")
+	}
+}
+
+func TestClaimFactories(t *testing.T) {
+	now := time.Unix(1700000000, 0)
+
+	a := attestationClaims("nonce-xyz", now)
+	if a["nonce"] != "nonce-xyz" || a["iat"] != now.Unix() {
+		t.Errorf("attestation claims = %v", a)
+	}
+	if a["exp"] != now.Add(attestationTTL).Unix() {
+		t.Errorf("attestation exp = %v, want %v", a["exp"], now.Add(attestationTTL).Unix())
+	}
+	if jti, _ := a["jti"].(string); jti == "" {
+		t.Error("attestation jti empty")
+	}
+
+	c := clientAssertionClaims("cli_app", "aud", now, time.Minute)
+	if c["exp"].(int64) != now.Add(time.Minute).Unix() {
+		t.Errorf("client_assertion exp = %v", c["exp"])
+	}
+}

internal/auth/uat_client.go

@@ -21,6 +21,7 @@ import (
 	"github.com/larksuite/cli/errs"
 	"github.com/larksuite/cli/internal/core"
 	"github.com/larksuite/cli/internal/errclass"
+	"github.com/larksuite/cli/internal/keysigner"
 	"github.com/larksuite/cli/internal/vfs"
 )
 
@@ -37,7 +38,10 @@ type UATCallOptions struct {
 	AppId      string
 	AppSecret  string
 	Domain     core.LarkBrand
-	ErrOut     io.Writer // diagnostic/status output (caller injects f.IOStreams.ErrOut)
+	AuthMethod string           // "" == client_secret; core.AuthMethodPrivateKeyJWT
+	KeyLabel   string           // TEE key handle for private_key_jwt
+	Signer     keysigner.Signer // active signer for private_key_jwt
+	ErrOut     io.Writer        // diagnostic/status output (caller injects f.IOStreams.ErrOut)
 }
 
 // UATStatus represents the status of a user access token.
@@ -61,6 +65,9 @@ func NewUATCallOptions(cfg *core.CliConfig, errOut io.Writer) UATCallOptions {
 		AppId:      cfg.AppID,
 		AppSecret:  cfg.AppSecret,
 		Domain:     cfg.Brand,
+		AuthMethod: cfg.AuthMethod,
+		KeyLabel:   cfg.KeyLabel,
+		Signer:     keysigner.Active(),
 		ErrOut:     errOut,
 	}
 }
@@ -193,7 +200,14 @@ func doRefreshToken(httpClient *http.Client, opts UATCallOptions, stored *Stored
 		form.Set("grant_type", "refresh_token")
 		form.Set("refresh_token", stored.RefreshToken)
 		form.Set("client_id", opts.AppId)
-		form.Set("client_secret", opts.AppSecret)
+		ca := ClientAuth{AppID: opts.AppId, AppSecret: opts.AppSecret, AuthMethod: opts.AuthMethod, Signer: opts.Signer, KeyLabel: opts.KeyLabel}
+		usedAssertion, caErr := ca.applyClientAssertion(context.Background(), form, core.OpenAPIAudience(opts.Domain))
+		if caErr != nil {
+			return nil, caErr
+		}
+		if !usedAssertion {
+			form.Set("client_secret", opts.AppSecret)
+		}
 
 		req, err := http.NewRequest("POST", endpoints.Token, strings.NewReader(form.Encode()))
 		if err != nil {

internal/auth/uat_client_options_test.go

@@ -38,3 +38,23 @@ func TestNewUATCallOptions(t *testing.T) {
 		t.Error("ErrOut not set correctly")
 	}
 }
+
+// TestNewUATCallOptions_PrivateKeyJWT verifies the auth-method fields propagate
+// so the refresh path can mint a client_assertion instead of sending a secret.
+func TestNewUATCallOptions_PrivateKeyJWT(t *testing.T) {
+	cfg := &core.CliConfig{
+		AppID:      "cli_pk",
+		Brand:      core.BrandFeishu,
+		UserOpenId: "ou_test",
+		AuthMethod: core.AuthMethodPrivateKeyJWT,
+		KeyLabel:   "agent-key",
+	}
+	opts := NewUATCallOptions(cfg, &bytes.Buffer{})
+
+	if opts.AuthMethod != core.AuthMethodPrivateKeyJWT {
+		t.Errorf("AuthMethod = %q, want private_key_jwt", opts.AuthMethod)
+	}
+	if opts.KeyLabel != "agent-key" {
+		t.Errorf("KeyLabel = %q, want agent-key", opts.KeyLabel)
+	}
+}

internal/cmdutil/iostreams.go

@@ -42,6 +42,16 @@ func NewIOStreams(in io.Reader, out, errOut io.Writer) *IOStreams {
 	return &IOStreams{In: in, Out: out, ErrOut: errOut, IsTerminal: isTerminal, StderrIsTerminal: stderrIsTerminal}
 }
 
+// StdoutIsTerminal reports whether Out is an interactive terminal. Unlike
+// IsTerminal — which reflects stdin and drives prompt decisions — this is the
+// correct check for OUTPUT formatting: `cmd | jq` must still emit machine output
+// from an interactive shell (stdin is a TTY there, but stdout is the pipe).
+// Buffers (tests) and redirects are not *os.File terminals, so they yield false.
+func (s *IOStreams) StdoutIsTerminal() bool {
+	f, ok := s.Out.(*os.File)
+	return ok && term.IsTerminal(int(f.Fd()))
+}
+
 // SystemIO creates an IOStreams wired to the process's standard file descriptors.
 //
 //nolint:forbidigo // entry point for real stdio

internal/cmdutil/iostreams_test.go

@@ -0,0 +1,28 @@
+// Copyright (c) 2026 Lark Technologies Pte. Ltd.
+// SPDX-License-Identifier: MIT
+
+package cmdutil
+
+import (
+	"bytes"
+	"os"
+	"testing"
+)
+
+func TestStdoutIsTerminal(t *testing.T) {
+	// Buffer-backed output (tests, captured output) is never a terminal.
+	if (&IOStreams{Out: &bytes.Buffer{}}).StdoutIsTerminal() {
+		t.Error("bytes.Buffer Out should not be a terminal")
+	}
+	// An os.Pipe write end is an *os.File but not a terminal — mirrors `cmd | jq`,
+	// the case the stdin-based IsTerminal would get wrong.
+	r, w, err := os.Pipe()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer r.Close()
+	defer w.Close()
+	if (&IOStreams{Out: w}).StdoutIsTerminal() {
+		t.Error("os.Pipe Out should not be a terminal")
+	}
+}

internal/core/config.go

@@ -36,6 +36,13 @@ type AppUser struct {
 	UserName   string `json:"userName"`
 }
 
+// Auth methods for app credentials. An empty AppConfig.AuthMethod means the
+// default, client_secret.
+const (
+	AuthMethodClientSecret  = "client_secret"   // app_id + app_secret
+	AuthMethodPrivateKeyJWT = "private_key_jwt" // TEE-signed client_assertion; no app secret
+)
+
 // AppConfig is a per-app configuration entry (stored format — secrets may be unresolved).
 type AppConfig struct {
 	Name       string      `json:"name,omitempty"`
@@ -46,6 +53,15 @@ type AppConfig struct {
 	DefaultAs  Identity    `json:"defaultAs,omitempty"` // AsUser | AsBot | AsAuto
 	StrictMode *StrictMode `json:"strictMode,omitempty"`
 	Users      []AppUser   `json:"users"`
+
+	// AuthMethod selects how tokens are minted. Empty == AuthMethodClientSecret
+	// (back-compat). AuthMethodPrivateKeyJWT uses a TEE-held key (see KeyRef) to
+	// sign client_assertion JWTs instead of sending an app secret.
+	AuthMethod string `json:"authMethod,omitempty"`
+	// KeyRef references the non-exportable signing key for private_key_jwt.
+	// Source is "tee" and ID is the backend key label; the actual key never
+	// leaves the secure backend, so this is a handle, not secret material.
+	KeyRef *SecretRef `json:"keyRef,omitempty"`
 }
 
 // ProfileName returns the display name for this app config.
@@ -161,7 +177,9 @@ type CliConfig struct {
 	UserOpenId          string
 	UserName            string
 	Lang                i18n.Lang
-	SupportedIdentities uint8 `json:"-"` // bitflag: 1=user, 2=bot; set by credential provider
+	SupportedIdentities uint8  `json:"-"` // bitflag: 1=user, 2=bot; set by credential provider
+	AuthMethod          string // "" == client_secret; AuthMethodPrivateKeyJWT
+	KeyLabel            string // resolved TEE key handle for private_key_jwt
 }
 
 // identityBotBit is the bit flag for bot identity in SupportedIdentities.
@@ -247,31 +265,58 @@ func ResolveConfigFromMulti(raw *MultiAppConfig, kc keychain.KeychainAccess, pro
 			WithHint("available profiles: %s", formatProfileNames(raw.ProfileNames()))
 	}
 
-	if err := ValidateSecretKeyMatch(app.AppId, app.AppSecret); err != nil {
-		return nil, errs.NewConfigError(errs.SubtypeNotConfigured, "appId and appSecret keychain key are out of sync").
-			WithHint("%s", err.Error()).
-			WithCause(err)
+	// Validate the auth method first so a malformed profile fails here rather
+	// than silently degrading to client_secret (unknown method) or failing later
+	// at token-signing. Empty stays empty — downstream treats it as client_secret
+	// (back-compat).
+	switch app.AuthMethod {
+	case "", AuthMethodClientSecret, AuthMethodPrivateKeyJWT:
+	default:
+		return nil, errs.NewConfigError(errs.SubtypeInvalidConfig, "unknown authMethod %q", app.AuthMethod).
+			WithHint("supported: %s, %s (empty defaults to %s)", AuthMethodClientSecret, AuthMethodPrivateKeyJWT, AuthMethodClientSecret)
 	}
 
-	secret, err := ResolveSecretInput(app.AppSecret, kc)
-	if err != nil {
-		if errs.IsTyped(err) {
-			return nil, err
+	// private_key_jwt carries no secret: validate the key handle and skip secret
+	// resolution entirely, so a stale/broken AppSecret ref never produces a
+	// confusing secret-resolution error for an otherwise-valid pkjwt profile.
+	var secret string
+	if app.AuthMethod == AuthMethodPrivateKeyJWT {
+		if app.KeyRef == nil || app.KeyRef.Source != "tee" || app.KeyRef.ID == "" {
+			return nil, errs.NewConfigError(errs.SubtypeInvalidConfig, "private_key_jwt requires a key handle (keyRef) but none is configured").
+				WithHint("re-run: lark-cli config init --new --auth-method private_key_jwt")
 		}
-		subtype := errs.SubtypeNotConfigured
-		if isMalformedConfigError(err) {
-			subtype = errs.SubtypeInvalidConfig
+	} else {
+		if err := ValidateSecretKeyMatch(app.AppId, app.AppSecret); err != nil {
+			return nil, errs.NewConfigError(errs.SubtypeNotConfigured, "appId and appSecret keychain key are out of sync").
+				WithHint("%s", err.Error()).
+				WithCause(err)
+		}
+		var resolveErr error
+		secret, resolveErr = ResolveSecretInput(app.AppSecret, kc)
+		if resolveErr != nil {
+			if errs.IsTyped(resolveErr) {
+				return nil, resolveErr
+			}
+			subtype := errs.SubtypeNotConfigured
+			if isMalformedConfigError(resolveErr) {
+				subtype = errs.SubtypeInvalidConfig
+			}
+			return nil, errs.NewConfigError(subtype, "%s", resolveErr.Error()).WithCause(resolveErr)
 		}
-		return nil, errs.NewConfigError(subtype, "%s", err.Error()).WithCause(err)
 	}
+
 	cfg := &CliConfig{
 		ProfileName: app.ProfileName(),
 		AppID:       app.AppId,
 		AppSecret:   secret,
 		Brand:       app.Brand,
 		Lang:        app.Lang,
+		AuthMethod:  app.AuthMethod,
 		DefaultAs:   app.DefaultAs,
 	}
+	if app.KeyRef != nil {
+		cfg.KeyLabel = app.KeyRef.ID
+	}
 	if len(app.Users) > 0 {
 		cfg.UserOpenId = app.Users[0].UserOpenId
 		cfg.UserName = app.Users[0].UserName

internal/core/config_test.go

@@ -133,6 +133,108 @@ func TestResolveConfigFromMulti_AcceptsPlainSecret(t *testing.T) {
 	}
 }
 
+// TestResolveConfigFromMulti_RejectsUnknownAuthMethod ensures an unsupported
+// authMethod fails at resolution rather than silently degrading to client_secret.
+func TestResolveConfigFromMulti_RejectsUnknownAuthMethod(t *testing.T) {
+	raw := &MultiAppConfig{
+		Apps: []AppConfig{
+			{
+				AppId:      "cli_abc",
+				AppSecret:  PlainSecret("my-secret"),
+				Brand:      BrandFeishu,
+				AuthMethod: "bogus_method",
+			},
+		},
+	}
+
+	_, err := ResolveConfigFromMulti(raw, nil, "")
+	if err == nil {
+		t.Fatal("expected error for unknown authMethod")
+	}
+	var cfgErr *errs.ConfigError
+	if !errors.As(err, &cfgErr) {
+		t.Fatalf("expected ConfigError, got %T: %v", err, err)
+	}
+}
+
+// TestResolveConfigFromMulti_PrivateKeyJWTRequiresKeyRef ensures private_key_jwt
+// without a key handle fails at resolution rather than later at token-signing.
+func TestResolveConfigFromMulti_PrivateKeyJWTRequiresKeyRef(t *testing.T) {
+	raw := &MultiAppConfig{
+		Apps: []AppConfig{
+			{
+				AppId:      "cli_abc",
+				AppSecret:  SecretInput{}, // private_key_jwt carries no app secret
+				Brand:      BrandFeishu,
+				AuthMethod: AuthMethodPrivateKeyJWT,
+				// KeyRef intentionally nil
+			},
+		},
+	}
+
+	_, err := ResolveConfigFromMulti(raw, nil, "")
+	if err == nil {
+		t.Fatal("expected error for private_key_jwt without keyRef")
+	}
+	var cfgErr *errs.ConfigError
+	if !errors.As(err, &cfgErr) {
+		t.Fatalf("expected ConfigError, got %T: %v", err, err)
+	}
+
+	// Control: same config WITH a keyRef resolves cleanly and sets KeyLabel.
+	raw.Apps[0].KeyRef = &SecretRef{Source: "tee", ID: "larksuite-cli-agent"}
+	cfg, err := ResolveConfigFromMulti(raw, nil, "")
+	if err != nil {
+		t.Fatalf("unexpected error with keyRef present: %v", err)
+	}
+	if cfg.KeyLabel != "larksuite-cli-agent" {
+		t.Errorf("KeyLabel = %q, want larksuite-cli-agent", cfg.KeyLabel)
+	}
+}
+
+// TestResolveConfigFromMulti_PKJWTSkipsSecretResolution ensures a private_key_jwt
+// profile that carries a stale/broken AppSecret ref still resolves cleanly: the
+// auth method is judged before any secret handling, so the stale ref is ignored
+// instead of producing a confusing secret-resolution failure.
+func TestResolveConfigFromMulti_PKJWTSkipsSecretResolution(t *testing.T) {
+	raw := &MultiAppConfig{
+		Apps: []AppConfig{{
+			AppId: "cli_pk",
+			// Stale keychain ref whose ID does not match appId — would trip
+			// ValidateSecretKeyMatch / ResolveSecretInput if it were reached.
+			AppSecret:  SecretInput{Ref: &SecretRef{Source: "keychain", ID: "appsecret:cli_OTHER"}},
+			Brand:      BrandFeishu,
+			AuthMethod: AuthMethodPrivateKeyJWT,
+			KeyRef:     &SecretRef{Source: "tee", ID: "agent-key"},
+			Users:      []AppUser{},
+		}},
+	}
+	cfg, err := ResolveConfigFromMulti(raw, stubKeychain{}, "")
+	if err != nil {
+		t.Fatalf("pkjwt with stale secret ref must skip secret resolution, got %v", err)
+	}
+	if cfg.AuthMethod != AuthMethodPrivateKeyJWT || cfg.KeyLabel != "agent-key" {
+		t.Errorf("got authMethod=%q keyLabel=%q", cfg.AuthMethod, cfg.KeyLabel)
+	}
+}
+
+// TestResolveConfigFromMulti_PKJWTRejectsBadKeyRef ensures the stricter keyRef
+// check (Source=="tee" && ID!="") rejects malformed handles.
+func TestResolveConfigFromMulti_PKJWTRejectsBadKeyRef(t *testing.T) {
+	for i, ref := range []*SecretRef{
+		{Source: "keychain", ID: "x"}, // wrong source
+		{Source: "tee", ID: ""},       // empty id
+	} {
+		raw := &MultiAppConfig{Apps: []AppConfig{{
+			AppId: "cli_pk", Brand: BrandFeishu,
+			AuthMethod: AuthMethodPrivateKeyJWT, KeyRef: ref, Users: []AppUser{},
+		}}}
+		if _, err := ResolveConfigFromMulti(raw, stubKeychain{}, ""); err == nil {
+			t.Errorf("case %d: expected ConfigError for bad keyRef", i)
+		}
+	}
+}
+
 func TestResolveConfigFromMulti_CarriesLang(t *testing.T) {
 	raw := &MultiAppConfig{
 		Apps: []AppConfig{

internal/core/types.go

@@ -3,6 +3,8 @@
 
 package core
 
+import "strings"
+
 // LarkBrand represents the Lark platform brand.
 // "feishu" targets China-mainland, "lark" targets international.
 // Any other string is treated as a custom base URL.
@@ -60,3 +62,10 @@ func ResolveEndpoints(brand LarkBrand) Endpoints {
 func ResolveOpenBaseURL(brand LarkBrand) string {
 	return ResolveEndpoints(brand).Open
 }
+
+// OpenAPIAudience returns the client_assertion `aud` value for the brand: the
+// bare Open API host per the App Authentication JWT spec — "open.feishu.cn" or
+// "open.larksuite.com" — not the full token endpoint URL.
+func OpenAPIAudience(brand LarkBrand) string {
+	return strings.TrimPrefix(ResolveOpenBaseURL(brand), "https://")
+}

internal/core/types_test.go

@@ -57,3 +57,12 @@ func TestResolveOpenBaseURL(t *testing.T) {
 		t.Errorf("ResolveOpenBaseURL(lark) = %q", got)
 	}
 }
+
+func TestOpenAPIAudience(t *testing.T) {
+	if got := OpenAPIAudience(BrandFeishu); got != "open.feishu.cn" {
+		t.Errorf("OpenAPIAudience(feishu) = %q, want open.feishu.cn", got)
+	}
+	if got := OpenAPIAudience(BrandLark); got != "open.larksuite.com" {
+		t.Errorf("OpenAPIAudience(lark) = %q, want open.larksuite.com", got)
+	}
+}

internal/credential/default_provider.go

@@ -17,6 +17,7 @@ import (
 	"github.com/larksuite/cli/internal/keychain"
 
 	extcred "github.com/larksuite/cli/extension/credential"
+	"github.com/larksuite/cli/internal/keysigner"
 )
 
 // classifyTATResponseCode wraps a deterministic (non-transient) failure from the
@@ -175,6 +176,23 @@ func (p *DefaultTokenProvider) doResolveTAT(ctx context.Context) (*TokenResult,
 	if err != nil {
 		return nil, err
 	}
+
+	// private_key_jwt apps have no app secret: mint via the jwt-bearer grant
+	// using a TEE-signed client_assertion instead.
+	if acct.AuthMethod == core.AuthMethodPrivateKeyJWT {
+		signer := keysigner.Active()
+		if signer == nil {
+			return nil, errs.NewConfigError(errs.SubtypeInvalidClient,
+				"profile uses private_key_jwt but no TEE key signer is available on this build").
+				WithHint("install a build with the platform key-signer extension, or reconfigure the app to use an app secret")
+		}
+		token, err := FetchTATWithAssertion(ctx, httpClient, acct.Brand, acct.AppID, signer, acct.KeyLabel)
+		if err != nil {
+			return nil, err
+		}
+		return &TokenResult{Token: token}, nil
+	}
+
 	token, err := FetchTAT(ctx, httpClient, acct.Brand, acct.AppID, acct.AppSecret)
 	if err != nil {
 		return nil, err

internal/credential/tat_fetch.go

@@ -11,8 +11,13 @@ import (
 	"net/http"
 	"net/url"
 	"strings"
+	"time"
 
+	"github.com/larksuite/cli/errs"
+	"github.com/larksuite/cli/internal/auth"
+	"github.com/larksuite/cli/internal/auth/jwt"
 	"github.com/larksuite/cli/internal/core"
+	"github.com/larksuite/cli/internal/keysigner"
 )
 
 // FetchTAT performs a single HTTP POST to mint a tenant access token via the
@@ -100,3 +105,96 @@ func FetchTAT(ctx context.Context, httpClient *http.Client, brand core.LarkBrand
 	}
 	return "", classifyTATResponseCode(result.Code, result.Error, desc, string(brand), appID)
 }
+
+// FetchTATWithAssertion mints a tenant access token for a private_key_jwt app via
+// the RFC 7523 jwt-bearer grant: it signs a short-lived client_assertion with the
+// TEE-held key and posts it to the unified OAuth token endpoint, replacing the
+// app_secret entirely.
+//
+// The unified v2 token endpoint returns the minted token as access_token
+// (tenant_access_token is accepted as a fallback).
+func FetchTATWithAssertion(ctx context.Context, httpClient *http.Client, brand core.LarkBrand, clientID string, signer keysigner.Signer, keyLabel string) (string, error) {
+	if signer == nil {
+		return "", fmt.Errorf("private_key_jwt requires a key signer, but none is available on this build")
+	}
+	ep := core.ResolveEndpoints(brand)
+	endpoint := ep.Open + auth.PathOAuthTokenV2
+
+	assertion, err := jwt.SignClientAssertion(ctx, signer, keysigner.KeyRef{Label: keyLabel}, clientID, core.OpenAPIAudience(brand), time.Now())
+	if err != nil {
+		return "", err
+	}
+
+	form := url.Values{}
+	form.Set("grant_type", "urn:ietf:params:oauth:grant-type:jwt-bearer")
+	form.Set("client_id", clientID)
+	form.Set("client_assertion_type", jwt.ClientAssertionType)
+	form.Set("client_assertion", assertion)
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, endpoint, strings.NewReader(form.Encode()))
+	if err != nil {
+		return "", err
+	}
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+
+	resp, err := httpClient.Do(req)
+	if err != nil {
+		return "", err
+	}
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return "", fmt.Errorf("read token response: %w", err)
+	}
+
+	var result struct {
+		Code              int    `json:"code"`
+		Msg               string `json:"msg"`
+		Error             string `json:"error"`
+		ErrorDescription  string `json:"error_description"`
+		AccessToken       string `json:"access_token"`
+		TenantAccessToken string `json:"tenant_access_token"`
+	}
+	_ = json.Unmarshal(body, &result) // best-effort; error body may not be JSON
+
+	token := result.AccessToken
+	if token == "" {
+		token = result.TenantAccessToken
+	}
+	if resp.StatusCode == http.StatusOK && token != "" && result.Error == "" && result.Code == 0 {
+		return token, nil
+	}
+
+	// Surface the server's reason, preferring the OAuth `error` code (e.g.
+	// unauthorized_client) which is more diagnostic than the description alone.
+	detail := result.ErrorDescription
+	if detail == "" {
+		detail = result.Msg
+	}
+	if detail == "" {
+		detail = strings.TrimSpace(string(body))
+	}
+	if result.Error != "" {
+		return "", classifyAssertionError(result.Error, resp.StatusCode, detail)
+	}
+	return "", fmt.Errorf("token endpoint HTTP %d (code=%d): %s", resp.StatusCode, result.Code, detail)
+}
+
+// classifyAssertionError maps the OAuth token endpoint's `error` field to a
+// typed or untyped error. Only deterministic client-credential rejections get a
+// typed errs.ConfigError (so runProbePKJWT can tell "this key is not bound to
+// this app" apart from upstream noise); every other error (e.g.
+// temporarily_unavailable) stays untyped and is swallowed by the probe. detail
+// carries only the server's error_description / msg / body text — it never
+// echoes the client_assertion or private key (the assertion lives only in the
+// request form).
+func classifyAssertionError(oauthError string, httpStatus int, detail string) error {
+	switch oauthError {
+	case "invalid_client", "unauthorized_client", "invalid_grant":
+		return errs.NewConfigError(errs.SubtypeInvalidClient,
+			"token endpoint rejected the key (%s): %s", oauthError, detail)
+	default:
+		return fmt.Errorf("token endpoint HTTP %d (%s): %s", httpStatus, oauthError, detail)
+	}
+}

internal/credential/tat_fetch_test.go

@@ -5,15 +5,24 @@ package credential
 
 import (
 	"context"
+	"crypto"
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/json"
 	"errors"
 	"io"
 	"net/http"
 	"net/http/httptest"
+	"net/url"
 	"strings"
 	"testing"
 
 	"github.com/larksuite/cli/errs"
 	"github.com/larksuite/cli/internal/core"
+	"github.com/larksuite/cli/internal/keysigner"
 )
 
 // stubRoundTripper lets us assert request shape and return canned responses.
@@ -307,3 +316,147 @@ func (r *urlRewriteRT) RoundTrip(req *http.Request) (*http.Response, error) {
 	req2.Header = req.Header
 	return http.DefaultTransport.RoundTrip(req2)
 }
+
+// fakeTATSigner is a real in-memory ECDSA P-256 signer for assertion tests.
+type fakeTATSigner struct{ key *ecdsa.PrivateKey }
+
+func newFakeTATSigner(t *testing.T) *fakeTATSigner {
+	t.Helper()
+	k, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return &fakeTATSigner{key: k}
+}
+
+func (f *fakeTATSigner) EnsureKey(context.Context, keysigner.KeyRef) (crypto.PublicKey, error) {
+	return f.key.Public(), nil
+}
+func (f *fakeTATSigner) PublicKey(context.Context, keysigner.KeyRef) (crypto.PublicKey, error) {
+	return f.key.Public(), nil
+}
+func (f *fakeTATSigner) Sign(_ context.Context, _ keysigner.KeyRef, in []byte) ([]byte, string, error) {
+	h := sha256.Sum256(in)
+	r, s, err := ecdsa.Sign(rand.Reader, f.key, h[:])
+	if err != nil {
+		return nil, "", err
+	}
+	sig := make([]byte, 64)
+	r.FillBytes(sig[:32])
+	s.FillBytes(sig[32:])
+	return sig, keysigner.AlgES256, nil
+}
+
+func TestFetchTATWithAssertion_Success(t *testing.T) {
+	rt := &stubRoundTripper{respCode: 200, respBody: `{"access_token":"t-jwt","token_type":"Bearer","expires_in":7200}`}
+	hc := &http.Client{Transport: rt}
+
+	token, err := FetchTATWithAssertion(context.Background(), hc, core.BrandFeishu, "cli_app", newFakeTATSigner(t), "agent-key")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if token != "t-jwt" {
+		t.Errorf("token = %q, want t-jwt", token)
+	}
+	if rt.gotReq.URL.String() != "https://open.feishu.cn/open-apis/authen/v2/oauth/token" {
+		t.Errorf("url = %s", rt.gotReq.URL.String())
+	}
+
+	form, err := url.ParseQuery(rt.gotBody)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if form.Get("grant_type") != "urn:ietf:params:oauth:grant-type:jwt-bearer" {
+		t.Errorf("grant_type = %q", form.Get("grant_type"))
+	}
+	if form.Get("client_assertion_type") != "urn:ietf:params:oauth:client-assertion-type:jwt-bearer" {
+		t.Errorf("client_assertion_type = %q", form.Get("client_assertion_type"))
+	}
+	if form.Get("client_assertion") == "" {
+		t.Error("client_assertion is empty")
+	}
+	if form.Has("client_secret") {
+		t.Error("client_secret must NOT be sent for private_key_jwt")
+	}
+
+	// The assertion's aud must be the bare Open host per the App Authentication
+	// JWT spec — not the full token endpoint URL.
+	jwtParts := strings.Split(form.Get("client_assertion"), ".")
+	if len(jwtParts) != 3 {
+		t.Fatalf("malformed client_assertion: %q", form.Get("client_assertion"))
+	}
+	payload, err := base64.RawURLEncoding.DecodeString(jwtParts[1])
+	if err != nil {
+		t.Fatalf("assertion payload not base64url: %v", err)
+	}
+	var claims map[string]any
+	if err := json.Unmarshal(payload, &claims); err != nil {
+		t.Fatal(err)
+	}
+	if claims["aud"] != "open.feishu.cn" {
+		t.Errorf("client_assertion aud = %v, want open.feishu.cn", claims["aud"])
+	}
+	if claims["iss"] != "cli_app" || claims["sub"] != "cli_app" {
+		t.Errorf("client_assertion iss/sub = %v/%v, want cli_app", claims["iss"], claims["sub"])
+	}
+	if form.Get("client_id") != "cli_app" {
+		t.Errorf("client_id = %q", form.Get("client_id"))
+	}
+}
+
+func TestFetchTATWithAssertion_NilSigner(t *testing.T) {
+	hc := &http.Client{Transport: &stubRoundTripper{respCode: 200, respBody: `{}`}}
+	if _, err := FetchTATWithAssertion(context.Background(), hc, core.BrandFeishu, "cli_app", nil, "k"); err == nil {
+		t.Fatal("expected error when signer is nil")
+	}
+}
+
+func TestFetchTATWithAssertion_ServerError(t *testing.T) {
+	rt := &stubRoundTripper{respCode: 200, respBody: `{"error":"invalid_client","error_description":"unknown key"}`}
+	hc := &http.Client{Transport: rt}
+	if _, err := FetchTATWithAssertion(context.Background(), hc, core.BrandFeishu, "cli_app", newFakeTATSigner(t), "k"); err == nil {
+		t.Fatal("expected error for invalid_client response")
+	}
+}
+
+// Deterministic OAuth client rejections must be typed (ConfigError /
+// SubtypeInvalidClient) so runProbePKJWT can tell "the key is not bound to this
+// app" apart from transport noise.
+func TestFetchTATWithAssertion_DeterministicReject_Typed(t *testing.T) {
+	for _, oauthErr := range []string{"invalid_client", "unauthorized_client", "invalid_grant"} {
+		rt := &stubRoundTripper{respCode: 401, respBody: `{"error":"` + oauthErr + `","error_description":"bad key"}`}
+		hc := &http.Client{Transport: rt}
+		_, err := FetchTATWithAssertion(context.Background(), hc, core.BrandFeishu, "cli_app", newFakeTATSigner(t), "k")
+		if err == nil {
+			t.Fatalf("%s: expected error", oauthErr)
+		}
+		if !errs.IsTyped(err) {
+			t.Errorf("%s: must be typed, got %T", oauthErr, err)
+		}
+		var cfgErr *errs.ConfigError
+		if !errors.As(err, &cfgErr) || cfgErr.Subtype != errs.SubtypeInvalidClient {
+			t.Errorf("%s: want ConfigError/InvalidClient, got %T %v", oauthErr, err, err)
+		}
+	}
+}
+
+// Unrecognized OAuth errors and non-payload noise stay UNTYPED so the probe
+// treats them as upstream noise and stays silent.
+func TestFetchTATWithAssertion_AmbiguousError_Untyped(t *testing.T) {
+	cases := []string{
+		`{"error":"temporarily_unavailable","error_description":"retry"}`,
+		`{"code":99999,"msg":"weird"}`,
+		`not json`,
+	}
+	for _, body := range cases {
+		rt := &stubRoundTripper{respCode: 503, respBody: body}
+		hc := &http.Client{Transport: rt}
+		_, err := FetchTATWithAssertion(context.Background(), hc, core.BrandFeishu, "cli_app", newFakeTATSigner(t), "k")
+		if err == nil {
+			t.Fatalf("body %q: expected error", body)
+		}
+		if errs.IsTyped(err) {
+			t.Errorf("body %q: must be UNTYPED, got typed %T", body, err)
+		}
+	}
+}

internal/credential/types.go

@@ -26,6 +26,8 @@ type Account struct {
 	UserName            string
 	Lang                i18n.Lang
 	SupportedIdentities uint8
+	AuthMethod          string // "" == client_secret; core.AuthMethodPrivateKeyJWT
+	KeyLabel            string // resolved TEE key handle for private_key_jwt
 }
 
 const runtimePlaceholderAppSecret = "__LARKSUITE_CLI_TOKEN_ONLY__"
@@ -69,6 +71,8 @@ func AccountFromCliConfig(cfg *core.CliConfig) *Account {
 		UserName:            cfg.UserName,
 		Lang:                cfg.Lang,
 		SupportedIdentities: cfg.SupportedIdentities,
+		AuthMethod:          cfg.AuthMethod,
+		KeyLabel:            cfg.KeyLabel,
 	}
 }
 
@@ -87,6 +91,8 @@ func (a *Account) ToCliConfig() *core.CliConfig {
 		UserName:            a.UserName,
 		Lang:                a.Lang,
 		SupportedIdentities: a.SupportedIdentities,
+		AuthMethod:          a.AuthMethod,
+		KeyLabel:            a.KeyLabel,
 	}
 }
 

internal/identitydiag/diagnostics.go

@@ -82,7 +82,9 @@ func diagnoseBot(ctx context.Context, f *cmdutil.Factory, cfg *core.CliConfig, v
 			Hint:    "check strict mode or the active credential provider",
 		}
 	}
-	if cfg.SupportedIdentities == 0 && !credential.HasRealAppSecret(cfg.AppSecret) {
+	// private_key_jwt apps have no app secret — the bot/tenant token is minted via
+	// a TEE-signed client_assertion — so absence of a secret is NOT "unconfigured".
+	if cfg.SupportedIdentities == 0 && !credential.HasRealAppSecret(cfg.AppSecret) && cfg.AuthMethod != core.AuthMethodPrivateKeyJWT {
 		return Identity{
 			Status:  StatusNotConfigured,
 			Message: "Bot identity: not configured (missing app secret or bot token)",

internal/keysigner/keysigner.go

@@ -0,0 +1,212 @@
+// Copyright (c) 2026 Lark Technologies Pte. Ltd.
+// SPDX-License-Identifier: MIT
+
+// Package keysigner defines the pluggable signing abstraction used by the
+// private_key_jwt registration and authentication flow.
+//
+// The open-source core only declares the Signer interface and pure-stdlib key
+// helpers. The platform implementations that hold a non-exportable private key
+// (TPM 2.0 via facebookincubator/sks on Linux/Windows, a non-extractable
+// Keychain key on macOS) live OUTSIDE this core — in a build-tagged module or
+// extension — and register themselves via Register from init(). This keeps
+// CGO-heavy and license-sensitive dependencies out of the open-source build.
+package keysigner
+
+import (
+	"context"
+	"crypto"
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rsa"
+	"crypto/x509"
+	"encoding/asn1"
+	"encoding/base64"
+	"errors"
+	"fmt"
+	"math/big"
+	"strings"
+)
+
+// KeyRef identifies a non-exportable signing key held by a backend
+// (TEE/TPM/Keychain). It is a stable handle (label), never the key material.
+type KeyRef struct {
+	// Label is the backend key label/tag (e.g. "larksuite-cli-agent").
+	Label string
+}
+
+// Signer signs JWS signing inputs with a non-exportable key.
+type Signer interface {
+	// EnsureKey returns the public key for ref, creating the key if absent.
+	EnsureKey(ctx context.Context, ref KeyRef) (crypto.PublicKey, error)
+	// PublicKey returns the public key for ref without creating it.
+	PublicKey(ctx context.Context, ref KeyRef) (crypto.PublicKey, error)
+	// Sign signs signingInput and returns a JOSE-format signature plus the JWS
+	// alg ("ES256"/"RS256"). Implementations apply the alg's hash and, for
+	// ECDSA, MUST return the fixed-width r||s form required by RFC 7518 §3.4
+	// (not ASN.1 DER), because the backend (TPM/Keychain) typically yields DER.
+	Sign(ctx context.Context, ref KeyRef, signingInput []byte) (sig []byte, alg string, err error)
+}
+
+// Supported JWS algorithms.
+const (
+	AlgES256 = "ES256"
+	AlgRS256 = "RS256"
+)
+
+// DefaultKeyLabel is the backend key label lark-cli uses for its device signing
+// key. One non-exportable key is created on first private_key_jwt registration
+// and reused across subsequent app registrations on the same device.
+const DefaultKeyLabel = "larksuite-cli-agent"
+
+// HardwareInfo describes the secure hardware backing a Signer, as reported by a
+// HardwareProber. It is advisory/diagnostic: it tells a user whether
+// private_key_jwt can use a real TEE on this device.
+type HardwareInfo struct {
+	Backend    string // backing technology, e.g. "tpm2" or "keychain"
+	Available  bool   // the hardware is present and usable for signing
+	VendorName string // hardware vendor/manufacturer, when known
+	VendorInfo string // additional vendor detail, when known
+	Reason     string // when Available is false, a human-readable cause
+}
+
+// HardwareProber is an optional capability a Signer may implement to report on
+// the secure hardware backing it (TPM/TEE vendor and availability) WITHOUT
+// creating or using a key. Probing never mutates key state.
+type HardwareProber interface {
+	ProbeHardware(ctx context.Context) (HardwareInfo, error)
+}
+
+// ProbeActiveHardware probes the active signer's secure hardware. ok is false
+// when there is no active signer or it does not implement HardwareProber — in
+// which case private_key_jwt is unsupported on this build. When ok is true, info
+// reports availability and, if unavailable, info.Reason explains why.
+func ProbeActiveHardware(ctx context.Context) (info HardwareInfo, ok bool, err error) {
+	return probeHardware(ctx, Active())
+}
+
+// probeHardware is the registry-independent core of ProbeActiveHardware, so it
+// can be unit-tested without touching the global signer.
+func probeHardware(ctx context.Context, s Signer) (HardwareInfo, bool, error) {
+	p, ok := s.(HardwareProber)
+	if !ok {
+		return HardwareInfo{}, false, nil
+	}
+	info, err := p.ProbeHardware(ctx)
+	return info, true, err
+}
+
+// cleanProbeError renders err's message with redundant re-wraps collapsed. Some
+// backends (e.g. facebookincubator/sks) wrap an error twice with the SAME "%w"
+// prefix, yielding "P: P: cause"; this peels each outer layer whose only
+// contribution is to repeat the prefix already present in the wrapped error,
+// leaving a single "P: cause". A layer that adds genuinely new context is kept.
+func cleanProbeError(err error) string {
+	if err == nil {
+		return ""
+	}
+	msg := err.Error()
+	for {
+		inner := errors.Unwrap(err)
+		if inner == nil {
+			break
+		}
+		innerMsg := inner.Error()
+		prefix, ok := strings.CutSuffix(msg, innerMsg)
+		if !ok || prefix == "" || !strings.HasPrefix(innerMsg, prefix) {
+			break
+		}
+		msg, err = innerMsg, inner
+	}
+	return msg
+}
+
+// AlgForKey returns the JWS alg for a public key: EC P-256 -> ES256, RSA -> RS256.
+// The signer backend chooses the key type (the macOS keychain signer uses an
+// RSA-2048 key, hence RS256).
+func AlgForKey(pub crypto.PublicKey) (string, error) {
+	switch k := pub.(type) {
+	case *ecdsa.PublicKey:
+		if k.Curve == elliptic.P256() {
+			return AlgES256, nil
+		}
+		return "", fmt.Errorf("keysigner: unsupported EC curve %q (only P-256/ES256)", k.Curve.Params().Name)
+	case *rsa.PublicKey:
+		return AlgRS256, nil
+	default:
+		return "", fmt.Errorf("keysigner: unsupported public key type %T", pub)
+	}
+}
+
+// ecdsaDERToJOSE converts an ASN.1 DER-encoded ECDSA signature — the form most
+// TEE/TPM backends emit (e.g. facebookincubator/sks marshals the TPM's r,s with
+// asn1.Marshal) — into the fixed-width r||s form JWS requires for ES256
+// (RFC 7518 §3.4). byteLen is the curve coordinate size (32 for P-256), so the
+// result is exactly 2*byteLen bytes with r and s each left-zero-padded.
+//
+// This is intentionally part of the pure-stdlib core (not a platform signer) so
+// it can be unit-tested with a software key on any machine, including TPM-less CI.
+func ecdsaDERToJOSE(der []byte, byteLen int) ([]byte, error) {
+	var sig struct{ R, S *big.Int }
+	rest, err := asn1.Unmarshal(der, &sig)
+	if err != nil {
+		return nil, fmt.Errorf("keysigner: parse ECDSA DER signature: %w", err)
+	}
+	if len(rest) != 0 {
+		return nil, fmt.Errorf("keysigner: %d trailing byte(s) after ECDSA DER signature", len(rest))
+	}
+	if sig.R == nil || sig.S == nil || sig.R.Sign() <= 0 || sig.S.Sign() <= 0 {
+		return nil, fmt.Errorf("keysigner: ECDSA signature has non-positive r/s")
+	}
+	// Guard before FillBytes, which panics if the scalar does not fit in byteLen.
+	if sig.R.BitLen() > byteLen*8 || sig.S.BitLen() > byteLen*8 {
+		return nil, fmt.Errorf("keysigner: ECDSA r/s exceeds %d-byte coordinate", byteLen)
+	}
+	out := make([]byte, 2*byteLen)
+	sig.R.FillBytes(out[:byteLen])
+	sig.S.FillBytes(out[byteLen:])
+	return out, nil
+}
+
+// EncodePublicKey marshals pub to PKIX DER and base64-encodes it (std encoding),
+// matching the public-key form the registration backend binds to the app.
+func EncodePublicKey(pub crypto.PublicKey) (string, error) {
+	der, err := x509.MarshalPKIXPublicKey(pub)
+	if err != nil {
+		return "", fmt.Errorf("keysigner: encode public key: %w", err)
+	}
+	return base64.StdEncoding.EncodeToString(der), nil
+}
+
+// PublicKeyJWK returns the RFC 7517 JSON Web Key for pub, used to embed the
+// public key in the attestation JWT's "jwk" header so the registration backend
+// can bind it to the app. EC keys use base64url fixed-width coordinates
+// (RFC 7518 §6.2.1); RSA keys use base64url-encoded modulus and exponent.
+func PublicKeyJWK(pub crypto.PublicKey) (map[string]any, error) {
+	switch k := pub.(type) {
+	case *ecdsa.PublicKey:
+		if k.Curve != elliptic.P256() {
+			return nil, fmt.Errorf("keysigner: JWK supports EC P-256 only, got %q", k.Curve.Params().Name)
+		}
+		const coordLen = 32 // P-256 field element size
+		x := make([]byte, coordLen)
+		y := make([]byte, coordLen)
+		k.X.FillBytes(x)
+		k.Y.FillBytes(y)
+		return map[string]any{
+			"use": "sig",
+			"kty": "EC",
+			"crv": "P-256",
+			"x":   base64.RawURLEncoding.EncodeToString(x),
+			"y":   base64.RawURLEncoding.EncodeToString(y),
+		}, nil
+	case *rsa.PublicKey:
+		return map[string]any{
+			"use": "sig",
+			"kty": "RSA",
+			"n":   base64.RawURLEncoding.EncodeToString(k.N.Bytes()),
+			"e":   base64.RawURLEncoding.EncodeToString(big.NewInt(int64(k.E)).Bytes()),
+		}, nil
+	default:
+		return nil, fmt.Errorf("keysigner: unsupported public key type %T for JWK", pub)
+	}
+}

internal/keysigner/keysigner_test.go

@@ -0,0 +1,240 @@
+// Copyright (c) 2026 Lark Technologies Pte. Ltd.
+// SPDX-License-Identifier: MIT
+
+package keysigner
+
+import (
+	"context"
+	"crypto"
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/sha256"
+	"crypto/x509"
+	"encoding/base64"
+	"errors"
+	"fmt"
+	"math/big"
+	"reflect"
+	"testing"
+)
+
+func TestAlgForKey(t *testing.T) {
+	ec, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if alg, err := AlgForKey(ec.Public()); err != nil || alg != AlgES256 {
+		t.Errorf("P-256: alg=%q err=%v, want ES256/nil", alg, err)
+	}
+
+	rsaKey, err := rsa.GenerateKey(rand.Reader, 2048)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if alg, err := AlgForKey(rsaKey.Public()); err != nil || alg != AlgRS256 {
+		t.Errorf("RSA: alg=%q err=%v, want RS256/nil", alg, err)
+	}
+
+	ec384, err := ecdsa.GenerateKey(elliptic.P384(), rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := AlgForKey(ec384.Public()); err == nil {
+		t.Error("P-384: expected unsupported-curve error")
+	}
+
+	if _, err := AlgForKey("not a key"); err == nil {
+		t.Error("string: expected unsupported-type error")
+	}
+}
+
+func TestEncodePublicKeyRoundTrip(t *testing.T) {
+	ec, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+	enc, err := EncodePublicKey(ec.Public())
+	if err != nil {
+		t.Fatal(err)
+	}
+	der, err := base64.StdEncoding.DecodeString(enc)
+	if err != nil {
+		t.Fatalf("not valid base64: %v", err)
+	}
+	pub, err := x509.ParsePKIXPublicKey(der)
+	if err != nil {
+		t.Fatalf("not valid PKIX: %v", err)
+	}
+	if !reflect.DeepEqual(pub, ec.Public()) {
+		t.Error("public key did not round-trip")
+	}
+}
+
+func TestPublicKeyJWK_EC(t *testing.T) {
+	ec, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+	jwk, err := PublicKeyJWK(ec.Public())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if jwk["kty"] != "EC" || jwk["crv"] != "P-256" {
+		t.Errorf("jwk = %v, want kty=EC crv=P-256", jwk)
+	}
+	if jwk["use"] != "sig" {
+		t.Errorf("jwk use = %v, want sig", jwk["use"])
+	}
+	x, _ := jwk["x"].(string)
+	xb, err := base64.RawURLEncoding.DecodeString(x)
+	if err != nil || len(xb) != 32 {
+		t.Errorf("x = %q (decoded %d bytes), want 32-byte base64url", x, len(xb))
+	}
+	if _, ok := jwk["y"].(string); !ok {
+		t.Error("jwk missing y")
+	}
+}
+
+func TestPublicKeyJWK_RSA(t *testing.T) {
+	rsaKey, err := rsa.GenerateKey(rand.Reader, 2048)
+	if err != nil {
+		t.Fatal(err)
+	}
+	jwk, err := PublicKeyJWK(rsaKey.Public())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if jwk["kty"] != "RSA" || jwk["n"] == "" || jwk["e"] == "" {
+		t.Errorf("jwk = %v, want kty=RSA with n,e", jwk)
+	}
+	if jwk["use"] != "sig" {
+		t.Errorf("jwk use = %v, want sig", jwk["use"])
+	}
+}
+
+func TestPublicKeyJWK_UnsupportedCurve(t *testing.T) {
+	ec384, err := ecdsa.GenerateKey(elliptic.P384(), rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := PublicKeyJWK(ec384.Public()); err == nil {
+		t.Error("P-384: expected error")
+	}
+}
+
+func TestECDSADERToJOSE(t *testing.T) {
+	key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Iterate so we hit signatures whose r or s has its high bit set (ASN.1 pads
+	// those with a leading 0x00) and whose scalars are short (need left-zero
+	// padding) — verifying fixed-width conversion in both directions.
+	for i := 0; i < 64; i++ {
+		digest := sha256.Sum256([]byte{byte(i), byte(i >> 8), 'j', 'w', 't'})
+		der, err := ecdsa.SignASN1(rand.Reader, key, digest[:])
+		if err != nil {
+			t.Fatal(err)
+		}
+		jose, err := ecdsaDERToJOSE(der, 32)
+		if err != nil {
+			t.Fatalf("iter %d: %v", i, err)
+		}
+		if len(jose) != 64 {
+			t.Fatalf("iter %d: len(jose)=%d, want 64 (fixed-width r||s)", i, len(jose))
+		}
+		r := new(big.Int).SetBytes(jose[:32])
+		s := new(big.Int).SetBytes(jose[32:])
+		if !ecdsa.Verify(&key.PublicKey, digest[:], r, s) {
+			t.Fatalf("iter %d: converted r||s did not verify against the public key", i)
+		}
+	}
+}
+
+func TestECDSADERToJOSE_Errors(t *testing.T) {
+	if _, err := ecdsaDERToJOSE([]byte{0x01, 0x02, 0x03}, 32); err == nil {
+		t.Error("garbage DER: expected error")
+	}
+	key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+	digest := sha256.Sum256([]byte("trailing"))
+	der, err := ecdsa.SignASN1(rand.Reader, key, digest[:])
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := ecdsaDERToJOSE(append(der, 0x00), 32); err == nil {
+		t.Error("DER with trailing byte: expected error")
+	}
+}
+
+type stubSigner struct{}
+
+func (stubSigner) EnsureKey(context.Context, KeyRef) (crypto.PublicKey, error)  { return nil, nil }
+func (stubSigner) PublicKey(context.Context, KeyRef) (crypto.PublicKey, error)  { return nil, nil }
+func (stubSigner) Sign(context.Context, KeyRef, []byte) ([]byte, string, error) { return nil, "", nil }
+
+func TestCleanProbeError(t *testing.T) {
+	cause := errors.New("open /dev/tpmrm0: permission denied")
+	const p = "sks: error fetching Secure Hardware Vendor Data: "
+
+	// sks double-wraps with the same %w prefix → collapse to a single prefix.
+	doubled := fmt.Errorf(p+"%w", fmt.Errorf(p+"%w", cause))
+	if got, want := cleanProbeError(doubled), p+cause.Error(); got != want {
+		t.Errorf("doubled: got %q, want %q", got, want)
+	}
+	// Triple wrap collapses too.
+	if got, want := cleanProbeError(fmt.Errorf(p+"%w", doubled)), p+cause.Error(); got != want {
+		t.Errorf("tripled: got %q, want %q", got, want)
+	}
+	// A layer adding genuinely new context is preserved.
+	if got, want := cleanProbeError(fmt.Errorf("load: %w", cause)), "load: "+cause.Error(); got != want {
+		t.Errorf("distinct prefix: got %q, want %q", got, want)
+	}
+	// nil and unwrapped-leaf cases.
+	if got := cleanProbeError(nil); got != "" {
+		t.Errorf("nil: got %q, want empty", got)
+	}
+	if got := cleanProbeError(cause); got != cause.Error() {
+		t.Errorf("leaf: got %q, want %q", got, cause.Error())
+	}
+}
+
+type proberSigner struct {
+	stubSigner
+	info HardwareInfo
+}
+
+func (p proberSigner) ProbeHardware(context.Context) (HardwareInfo, error) { return p.info, nil }
+
+func TestProbeHardware(t *testing.T) {
+	// nil signer and a signer that does not implement HardwareProber both yield ok=false.
+	if _, ok, _ := probeHardware(context.Background(), nil); ok {
+		t.Error("nil signer: ok should be false")
+	}
+	if _, ok, _ := probeHardware(context.Background(), stubSigner{}); ok {
+		t.Error("non-prober signer: ok should be false")
+	}
+
+	want := HardwareInfo{Backend: "tpm2", Available: true, VendorName: "ACME"}
+	info, ok, err := probeHardware(context.Background(), proberSigner{info: want})
+	if err != nil || !ok {
+		t.Fatalf("prober: ok=%v err=%v, want true/nil", ok, err)
+	}
+	if info != want {
+		t.Errorf("info = %+v, want %+v", info, want)
+	}
+}
+
+func TestRegistry(t *testing.T) {
+	if Active() != nil {
+		t.Skip("a signer is already registered in this build")
+	}
+	Register(stubSigner{})
+	if _, ok := Active().(stubSigner); !ok {
+		t.Error("Active did not return the registered signer")
+	}
+}

internal/keysigner/registry.go

@@ -0,0 +1,29 @@
+// Copyright (c) 2026 Lark Technologies Pte. Ltd.
+// SPDX-License-Identifier: MIT
+
+package keysigner
+
+import "sync"
+
+var (
+	mu     sync.RWMutex
+	active Signer
+)
+
+// Register sets the active Signer. It is typically called from the init() of a
+// build-tagged or extension package that provides the platform TEE/Keychain
+// implementation. The last registration wins (one backend per platform).
+func Register(s Signer) {
+	mu.Lock()
+	defer mu.Unlock()
+	active = s
+}
+
+// Active returns the registered Signer, or nil if none is available — in which
+// case private_key_jwt is unsupported on this build and only client_secret auth
+// can be used.
+func Active() Signer {
+	mu.RLock()
+	defer mu.RUnlock()
+	return active
+}

internal/keysigner/signer_keychain_darwin.go

@@ -0,0 +1,613 @@
+//go:build darwin
+
+// Copyright (c) 2026 Lark Technologies Pte. Ltd.
+// SPDX-License-Identifier: MIT
+
+// macOS non-exportable Keychain signer (compiled into every darwin build).
+//
+// It does NOT use the Secure Enclave / hardware TEE (which would require
+// code-signing entitlements that are unfriendly to open source). Instead it
+// generates an RSA-2048 key in software, imports it into a dedicated app
+// keychain as NON-EXTRACTABLE (`security import -x`), then deletes the software
+// copy — so the private key can sign but can never be exported. Signing is
+// RSASSA-PKCS1v15-SHA256 (RS256).
+//
+// Unlike the original revision, this implementation calls the Security and
+// CoreFoundation frameworks via RUNTIME FFI (github.com/ebitengine/purego)
+// instead of cgo. The security model is identical (the private key is still a
+// non-extractable keychain key and every signature is produced by the OS via
+// SecKeyCreateSignature), but the binary builds with CGO_ENABLED=0 and can be
+// cross-compiled for darwin from any host — so release binaries no longer
+// require a native macOS build runner.
+//
+// Build with:  go build   (cgo-free; compiled into every darwin build, no tag)
+package keysigner
+
+import (
+	"context"
+	"crypto"
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/sha1"
+	"crypto/sha256"
+	"crypto/x509"
+	"encoding/base64"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"sync"
+	"unsafe"
+
+	"github.com/ebitengine/purego"
+	"github.com/larksuite/cli/internal/vfs"
+)
+
+// ---- Security / CoreFoundation runtime bindings (purego, no cgo) ----
+
+const (
+	cfFrameworkPath  = "/System/Library/Frameworks/CoreFoundation.framework/CoreFoundation"
+	secFrameworkPath = "/System/Library/Frameworks/Security.framework/Security"
+
+	// kCFStringEncodingUTF8 (CFStringBuiltInEncodings).
+	cfStringEncodingUTF8 = 0x08000100
+
+	// OSStatus values.
+	errSecSuccess = 0
+)
+
+var (
+	ffiOnce sync.Once
+	ffiErr  error
+
+	cfDataCreate          func(alloc uintptr, bytes *byte, length int) uintptr
+	cfDataGetLength       func(d uintptr) int
+	cfDataGetBytePtr      func(d uintptr) unsafe.Pointer
+	cfStringCreate        func(alloc uintptr, cstr *byte, encoding uint32) uintptr
+	cfArrayCreate         func(alloc uintptr, values *uintptr, numValues int, cb uintptr) uintptr
+	cfDictCreateMutable   func(alloc uintptr, capacity int, keyCB, valCB uintptr) uintptr
+	cfDictSetValue        func(dict, key, val uintptr)
+	cfRelease             func(ref uintptr)
+	cfErrorGetCode        func(e uintptr) int
+	secKeychainOpen       func(path *byte, out *uintptr) int32
+	secItemCopyMatching   func(query uintptr, result *uintptr) int32
+	secItemUpdate         func(query, attrs uintptr) int32
+	secKeyCreateSignature func(key, algo, data uintptr, errOut *uintptr) uintptr
+
+	// CFTypeRef data-symbol constants (deref to obtain the held ref value).
+	kSecClass                uintptr
+	kSecClassKey             uintptr
+	kSecAttrKeyClass         uintptr
+	kSecAttrKeyClassPrivate  uintptr
+	kSecAttrKeyType          uintptr
+	kSecAttrKeyTypeRSA       uintptr
+	kSecAttrApplicationLabel uintptr
+	kSecReturnRef            uintptr
+	kSecMatchSearchList      uintptr
+	kSecAttrLabel            uintptr
+	kCFBooleanTrue           uintptr
+	algRSAPKCS1SHA256        uintptr
+
+	// Struct-symbol constants (passed BY ADDRESS, not dereferenced).
+	cbTypeArray uintptr
+	cbDictKey   uintptr
+	cbDictValue uintptr
+)
+
+// loadFFI resolves the framework functions and constants once. Any failure
+// (framework missing, symbol absent) is returned to every caller so signing
+// fails cleanly rather than crashing.
+func loadFFI() error {
+	ffiOnce.Do(func() {
+		cf, err := purego.Dlopen(cfFrameworkPath, purego.RTLD_NOW|purego.RTLD_GLOBAL)
+		if err != nil {
+			ffiErr = fmt.Errorf("keysigner: dlopen CoreFoundation: %w", err)
+			return
+		}
+		sec, err := purego.Dlopen(secFrameworkPath, purego.RTLD_NOW|purego.RTLD_GLOBAL)
+		if err != nil {
+			ffiErr = fmt.Errorf("keysigner: dlopen Security: %w", err)
+			return
+		}
+
+		purego.RegisterLibFunc(&cfDataCreate, cf, "CFDataCreate")
+		purego.RegisterLibFunc(&cfDataGetLength, cf, "CFDataGetLength")
+		purego.RegisterLibFunc(&cfDataGetBytePtr, cf, "CFDataGetBytePtr")
+		purego.RegisterLibFunc(&cfStringCreate, cf, "CFStringCreateWithCString")
+		purego.RegisterLibFunc(&cfArrayCreate, cf, "CFArrayCreate")
+		purego.RegisterLibFunc(&cfDictCreateMutable, cf, "CFDictionaryCreateMutable")
+		purego.RegisterLibFunc(&cfDictSetValue, cf, "CFDictionarySetValue")
+		purego.RegisterLibFunc(&cfRelease, cf, "CFRelease")
+		purego.RegisterLibFunc(&cfErrorGetCode, cf, "CFErrorGetCode")
+		purego.RegisterLibFunc(&secKeychainOpen, sec, "SecKeychainOpen")
+		purego.RegisterLibFunc(&secItemCopyMatching, sec, "SecItemCopyMatching")
+		purego.RegisterLibFunc(&secItemUpdate, sec, "SecItemUpdate")
+		purego.RegisterLibFunc(&secKeyCreateSignature, sec, "SecKeyCreateSignature")
+
+		// CFStringRef/CFBooleanRef constants: Dlsym gives the address of the
+		// exported variable; deref once to read the ref it holds.
+		derefs := []struct {
+			dst    *uintptr
+			handle uintptr
+			name   string
+		}{
+			{&kSecClass, sec, "kSecClass"},
+			{&kSecClassKey, sec, "kSecClassKey"},
+			{&kSecAttrKeyClass, sec, "kSecAttrKeyClass"},
+			{&kSecAttrKeyClassPrivate, sec, "kSecAttrKeyClassPrivate"},
+			{&kSecAttrKeyType, sec, "kSecAttrKeyType"},
+			{&kSecAttrKeyTypeRSA, sec, "kSecAttrKeyTypeRSA"},
+			{&kSecAttrApplicationLabel, sec, "kSecAttrApplicationLabel"},
+			{&kSecReturnRef, sec, "kSecReturnRef"},
+			{&kSecMatchSearchList, sec, "kSecMatchSearchList"},
+			{&kSecAttrLabel, sec, "kSecAttrLabel"},
+			{&kCFBooleanTrue, cf, "kCFBooleanTrue"},
+			{&algRSAPKCS1SHA256, sec, "kSecKeyAlgorithmRSASignatureDigestPKCS1v15SHA256"},
+		}
+		for _, d := range derefs {
+			sym, e := purego.Dlsym(d.handle, d.name)
+			if e != nil || sym == 0 {
+				ffiErr = fmt.Errorf("keysigner: dlsym %s: %v", d.name, e)
+				return
+			}
+			// deref of a stable dylib data-symbol address (not Go-managed memory), so safe.
+			*d.dst = *(*uintptr)(unsafe.Pointer(sym)) //nolint:govet // unsafeptr: see comment above
+		}
+
+		// Callback structs are passed by address (no deref).
+		addrs := []struct {
+			dst    *uintptr
+			handle uintptr
+			name   string
+		}{
+			{&cbTypeArray, cf, "kCFTypeArrayCallBacks"},
+			{&cbDictKey, cf, "kCFTypeDictionaryKeyCallBacks"},
+			{&cbDictValue, cf, "kCFTypeDictionaryValueCallBacks"},
+		}
+		for _, a := range addrs {
+			sym, e := purego.Dlsym(a.handle, a.name)
+			if e != nil || sym == 0 {
+				ffiErr = fmt.Errorf("keysigner: dlsym %s: %v", a.name, e)
+				return
+			}
+			*a.dst = sym
+		}
+	})
+	return ffiErr
+}
+
+// cstr returns a pointer to a NUL-terminated copy of s. The backing array stays
+// alive while the returned pointer is reachable.
+func cstr(s string) *byte {
+	b := append([]byte(s), 0)
+	return &b[0]
+}
+
+// cfBytes wraps Go bytes in a CFData (CFDataCreate copies the bytes). Caller
+// releases the returned CFDataRef.
+func cfBytes(b []byte) uintptr {
+	var p *byte
+	if len(b) > 0 {
+		p = &b[0]
+	}
+	d := cfDataCreate(0, p, len(b))
+	runtime.KeepAlive(b)
+	return d
+}
+
+// keychainSearchArray opens the dedicated keychain file and wraps it in a
+// CFArray for kSecMatchSearchList. Caller releases the returned array.
+//
+// NOTE: SecKeychainOpen / the file-based keychain are deprecated by Apple in
+// favor of the data-protection keychain. They still function on current macOS;
+// migrating off them is tracked separately and is independent of the cgo→purego
+// change (the original cgo version used the same APIs).
+func keychainSearchArray(keychainPath string) (uintptr, error) {
+	var kc uintptr
+	if st := secKeychainOpen(cstr(keychainPath), &kc); st != errSecSuccess {
+		return 0, keychainError("open keychain", int(st))
+	}
+	vals := [1]uintptr{kc}
+	arr := cfArrayCreate(0, &vals[0], 1, cbTypeArray)
+	cfRelease(kc) // the array retains it
+	if arr == 0 {
+		return 0, fmt.Errorf("keysigner: CFArrayCreate(search list) failed")
+	}
+	return arr, nil
+}
+
+// findPrivateKey locates the non-extractable private key by its application
+// label within the dedicated keychain. Caller releases the returned SecKeyRef.
+func findPrivateKey(appLabel []byte, keychainPath string) (uintptr, error) {
+	search, err := keychainSearchArray(keychainPath)
+	if err != nil {
+		return 0, err
+	}
+	defer cfRelease(search)
+
+	labelData := cfBytes(appLabel)
+	defer cfRelease(labelData)
+
+	q := cfDictCreateMutable(0, 0, cbDictKey, cbDictValue)
+	if q == 0 {
+		return 0, fmt.Errorf("keysigner: CFDictionaryCreateMutable(query) failed")
+	}
+	defer cfRelease(q)
+	cfDictSetValue(q, kSecClass, kSecClassKey)
+	cfDictSetValue(q, kSecAttrKeyClass, kSecAttrKeyClassPrivate)
+	cfDictSetValue(q, kSecAttrKeyType, kSecAttrKeyTypeRSA)
+	cfDictSetValue(q, kSecAttrApplicationLabel, labelData)
+	cfDictSetValue(q, kSecReturnRef, kCFBooleanTrue)
+	cfDictSetValue(q, kSecMatchSearchList, search)
+
+	var keyRef uintptr
+	if st := secItemCopyMatching(q, &keyRef); st != errSecSuccess {
+		return 0, keychainError("find private key", int(st))
+	}
+	return keyRef, nil
+}
+
+// securityBin is invoked by absolute path so a poisoned PATH cannot hijack it.
+const securityBin = "/usr/bin/security"
+
+// keychainSigner implements Signer using a macOS non-exportable Keychain key.
+type keychainSigner struct{}
+
+func init() { Register(keychainSigner{}) }
+
+// ProbeHardware reports the macOS Keychain backend backing this signer. The
+// keychain signer is compiled into every darwin build and needs no special
+// hardware, so it reports available whenever the Security tooling is present.
+// It performs no key access, so it never prompts. Implementing HardwareProber
+// is what lets `doctor` report the signer as present rather than treating the
+// (prober-less) signer as "no TEE signer in this build".
+func (keychainSigner) ProbeHardware(_ context.Context) (HardwareInfo, error) {
+	info := HardwareInfo{Backend: "keychain", VendorName: "macOS Keychain"}
+	// A missing security tool is a status (Available=false via Reason), not a
+	// probe error — so we deliberately return a nil error here.
+	if _, err := vfs.Stat(securityBin); err != nil {
+		info.Reason = securityBin + " not found"
+		return info, nil //nolint:nilerr // absence is reported via Reason, not as an error
+	}
+	info.Available = true
+	return info, nil
+}
+
+func (keychainSigner) EnsureKey(_ context.Context, ref KeyRef) (crypto.PublicKey, error) {
+	if md, err := readKeyMetadata(ref.Label); err == nil {
+		return decodePublicKey(md.PublicKey)
+	} else if !os.IsNotExist(err) {
+		return nil, err
+	}
+	return createKeychainKey(ref.Label)
+}
+
+func (keychainSigner) PublicKey(_ context.Context, ref KeyRef) (crypto.PublicKey, error) {
+	md, err := readKeyMetadata(ref.Label)
+	if err != nil {
+		return nil, err
+	}
+	return decodePublicKey(md.PublicKey)
+}
+
+func (keychainSigner) Sign(_ context.Context, ref KeyRef, signingInput []byte) ([]byte, string, error) {
+	if err := loadFFI(); err != nil {
+		return nil, "", err
+	}
+	md, err := readKeyMetadata(ref.Label)
+	if err != nil {
+		return nil, "", err
+	}
+	appLabel, err := hex.DecodeString(md.AppLabel)
+	if err != nil {
+		return nil, "", fmt.Errorf("keysigner: decode app label: %w", err)
+	}
+	if len(appLabel) == 0 {
+		// Guard the &appLabel[0] pointer below against corrupted metadata.
+		return nil, "", fmt.Errorf("keysigner: key metadata for %q has empty app label", ref.Label)
+	}
+	keychain, err := ensureKeychain()
+	if err != nil {
+		return nil, "", err
+	}
+
+	keyRef, err := findPrivateKey(appLabel, keychain)
+	if err != nil {
+		return nil, "", err
+	}
+	defer cfRelease(keyRef)
+
+	digest := sha256.Sum256(signingInput)
+	digestData := cfBytes(digest[:])
+	defer cfRelease(digestData)
+
+	var errRef uintptr
+	sigRef := secKeyCreateSignature(keyRef, algRSAPKCS1SHA256, digestData, &errRef)
+	if sigRef == 0 {
+		code := 0
+		if errRef != 0 {
+			code = cfErrorGetCode(errRef)
+			cfRelease(errRef)
+		}
+		return nil, "", fmt.Errorf("keysigner: SecKeyCreateSignature failed (CFError %d)", code)
+	}
+	defer cfRelease(sigRef)
+
+	n := cfDataGetLength(sigRef)
+	bp := cfDataGetBytePtr(sigRef)
+	out := make([]byte, n)
+	copy(out, unsafe.Slice((*byte)(bp), n))
+	// RS256: the SecKey PKCS1v15-SHA256 signature is the JOSE signature as-is.
+	return out, AlgRS256, nil
+}
+
+// keyMetadata records the public key + the keychain application-label used to
+// locate the non-extractable private key.
+type keyMetadata struct {
+	PublicKey string `json:"public_key"` // PKIX DER, std base64 (see EncodePublicKey)
+	AppLabel  string `json:"app_label"`  // hex(sha1(PKCS1 public key))
+}
+
+func createKeychainKey(label string) (crypto.PublicKey, error) {
+	metadataPath, err := keyMetadataPath(label)
+	if err != nil {
+		return nil, err
+	}
+
+	privateKey, err := rsa.GenerateKey(rand.Reader, 2048)
+	if err != nil {
+		return nil, fmt.Errorf("keysigner: generate RSA key: %w", err)
+	}
+	appLabel := sha1.Sum(x509.MarshalPKCS1PublicKey(&privateKey.PublicKey))
+
+	pemFile, err := vfs.CreateTemp("", "lark-keysigner-*.pem")
+	if err != nil {
+		return nil, fmt.Errorf("keysigner: temp key file: %w", err)
+	}
+	pemPath := pemFile.Name()
+	defer vfs.Remove(pemPath)
+	if err := pemFile.Chmod(0600); err != nil {
+		pemFile.Close()
+		return nil, err
+	}
+	der := x509.MarshalPKCS1PrivateKey(privateKey)
+	if _, err := pemFile.WriteString("-----BEGIN RSA PRIVATE KEY-----\n" +
+		base64Wrap(der) + "-----END RSA PRIVATE KEY-----\n"); err != nil {
+		pemFile.Close()
+		return nil, err
+	}
+	if err := pemFile.Close(); err != nil {
+		return nil, err
+	}
+
+	executable, err := vfs.Executable()
+	if err != nil {
+		return nil, fmt.Errorf("keysigner: resolve executable: %w", err)
+	}
+	keychain, err := ensureKeychain()
+	if err != nil {
+		return nil, err
+	}
+	// -x: import as NON-EXTRACTABLE; the software copy (pemPath) is then removed.
+	importCmd := exec.Command(securityBin, "import", pemPath, "-k", keychain, "-t", "priv", "-f", "openssl", "-x", "-A", "-T", executable)
+	if out, err := importCmd.CombinedOutput(); err != nil {
+		return nil, fmt.Errorf("keysigner: import non-extractable key: %w: %s", err, summarizeCmdOutput(out))
+	}
+	if err := setKeychainKeyLabel(appLabel[:], keychain, label); err != nil {
+		return nil, err
+	}
+
+	encodedPub, err := EncodePublicKey(&privateKey.PublicKey)
+	if err != nil {
+		return nil, err
+	}
+	if err := writeKeyMetadata(metadataPath, keyMetadata{PublicKey: encodedPub, AppLabel: hex.EncodeToString(appLabel[:])}); err != nil {
+		return nil, err
+	}
+	return &privateKey.PublicKey, nil
+}
+
+func setKeychainKeyLabel(appLabel []byte, keychain, label string) error {
+	if err := loadFFI(); err != nil {
+		return err
+	}
+	search, err := keychainSearchArray(keychain)
+	if err != nil {
+		return err
+	}
+	defer cfRelease(search)
+
+	labelData := cfBytes(appLabel)
+	defer cfRelease(labelData)
+
+	q := cfDictCreateMutable(0, 0, cbDictKey, cbDictValue)
+	if q == 0 {
+		return fmt.Errorf("keysigner: CFDictionaryCreateMutable(query) failed")
+	}
+	defer cfRelease(q)
+	cfDictSetValue(q, kSecClass, kSecClassKey)
+	cfDictSetValue(q, kSecAttrKeyClass, kSecAttrKeyClassPrivate)
+	cfDictSetValue(q, kSecAttrKeyType, kSecAttrKeyTypeRSA)
+	cfDictSetValue(q, kSecAttrApplicationLabel, labelData)
+	cfDictSetValue(q, kSecMatchSearchList, search)
+
+	cfLabel := cfStringCreate(0, cstr(label), cfStringEncodingUTF8)
+	if cfLabel == 0 {
+		return fmt.Errorf("keysigner: CFStringCreateWithCString failed")
+	}
+	defer cfRelease(cfLabel)
+	attrs := cfDictCreateMutable(0, 0, cbDictKey, cbDictValue)
+	if attrs == 0 {
+		return fmt.Errorf("keysigner: CFDictionaryCreateMutable(attrs) failed")
+	}
+	defer cfRelease(attrs)
+	cfDictSetValue(attrs, kSecAttrLabel, cfLabel)
+
+	if st := secItemUpdate(q, attrs); st != errSecSuccess {
+		return keychainError("set keychain key label", int(st))
+	}
+	return nil
+}
+
+func decodePublicKey(encoded string) (crypto.PublicKey, error) {
+	der, err := base64.StdEncoding.DecodeString(encoded)
+	if err != nil {
+		return nil, fmt.Errorf("keysigner: decode public key: %w", err)
+	}
+	return x509.ParsePKIXPublicKey(der)
+}
+
+// base64Wrap PEM-wraps DER bytes at 64 columns.
+func base64Wrap(der []byte) string {
+	enc := base64.StdEncoding.EncodeToString(der)
+	var b strings.Builder
+	for i := 0; i < len(enc); i += 64 {
+		end := i + 64
+		if end > len(enc) {
+			end = len(enc)
+		}
+		b.WriteString(enc[i:end])
+		b.WriteByte('\n')
+	}
+	return b.String()
+}
+
+func readKeyMetadata(label string) (*keyMetadata, error) {
+	path, err := keyMetadataPath(label)
+	if err != nil {
+		return nil, err
+	}
+	data, err := vfs.ReadFile(path)
+	if err != nil {
+		return nil, err // preserves os.ErrNotExist for EnsureKey
+	}
+	var md keyMetadata
+	if err := json.Unmarshal(data, &md); err != nil {
+		return nil, fmt.Errorf("keysigner: parse key metadata: %w", err)
+	}
+	return &md, nil
+}
+
+func writeKeyMetadata(path string, md keyMetadata) error {
+	if err := vfs.MkdirAll(filepath.Dir(path), 0700); err != nil {
+		return err
+	}
+	data, err := json.MarshalIndent(md, "", "  ")
+	if err != nil {
+		return err
+	}
+	return vfs.WriteFile(path, data, 0600)
+}
+
+func ensureKeychain() (string, error) {
+	keychainPath, err := keychainFilePath()
+	if err != nil {
+		return "", err
+	}
+	password, err := keychainPassword()
+	if err != nil {
+		return "", err
+	}
+	if _, err := vfs.Stat(keychainPath); err != nil {
+		if !os.IsNotExist(err) {
+			return "", fmt.Errorf("keysigner: stat keychain: %w", err)
+		}
+		if err := vfs.MkdirAll(filepath.Dir(keychainPath), 0700); err != nil {
+			return "", err
+		}
+		for _, args := range [][]string{
+			{"create-keychain", "-p", password, keychainPath},
+			{"set-keychain-settings", keychainPath},
+			{"unlock-keychain", "-p", password, keychainPath},
+		} {
+			if out, err := exec.Command(securityBin, args...).CombinedOutput(); err != nil {
+				return "", fmt.Errorf("keysigner: security %s: %w: %s", args[0], err, summarizeCmdOutput(out))
+			}
+		}
+	}
+	return keychainPath, nil
+}
+
+func keysignerDir() (string, error) {
+	configDir, err := os.UserConfigDir()
+	if err != nil {
+		return "", fmt.Errorf("keysigner: resolve config dir: %w", err)
+	}
+	return filepath.Join(configDir, "lark-cli", "keysigner"), nil
+}
+
+func keychainFilePath() (string, error) {
+	dir, err := keysignerDir()
+	if err != nil {
+		return "", err
+	}
+	return filepath.Join(dir, "lark-cli.keychain"), nil
+}
+
+func keychainPassword() (string, error) {
+	dir, err := keysignerDir()
+	if err != nil {
+		return "", err
+	}
+	path := filepath.Join(dir, "keychain.pass")
+	if data, err := vfs.ReadFile(path); err == nil {
+		if pw := strings.TrimSpace(string(data)); pw != "" {
+			return pw, nil
+		}
+		return "", fmt.Errorf("keysigner: empty keychain password")
+	} else if !os.IsNotExist(err) {
+		return "", err
+	}
+	buf := make([]byte, 32)
+	if _, err := rand.Read(buf); err != nil {
+		return "", err
+	}
+	pw := hex.EncodeToString(buf)
+	if err := vfs.MkdirAll(filepath.Dir(path), 0700); err != nil {
+		return "", err
+	}
+	if err := vfs.WriteFile(path, []byte(pw+"\n"), 0600); err != nil {
+		return "", err
+	}
+	return pw, nil
+}
+
+func keyMetadataPath(label string) (string, error) {
+	dir, err := keysignerDir()
+	if err != nil {
+		return "", err
+	}
+	id := sha256.Sum256([]byte(label))
+	return filepath.Join(dir, "keys", hex.EncodeToString(id[:])+".json"), nil
+}
+
+// summarizeCmdOutput bounds external command output before it is embedded in
+// an error: first line only, capped at 200 chars.
+func summarizeCmdOutput(out []byte) string {
+	s := strings.TrimSpace(string(out))
+	if i := strings.IndexByte(s, '\n'); i >= 0 {
+		s = strings.TrimSpace(s[:i])
+	}
+	const maxLen = 200
+	if len(s) > maxLen {
+		s = s[:maxLen] + "..."
+	}
+	return s
+}
+
+func keychainError(operation string, status int) error {
+	switch status {
+	case -25299:
+		return fmt.Errorf("keysigner: %s: key already exists", operation)
+	case -25300:
+		return fmt.Errorf("keysigner: %s: key not found", operation)
+	case -2:
+		return fmt.Errorf("keysigner: %s: allocation failed", operation)
+	default:
+		return fmt.Errorf("keysigner: %s: Security framework status %d", operation, status)
+	}
+}

internal/keysigner/signer_keychain_darwin_test.go

@@ -0,0 +1,62 @@
+//go:build darwin
+
+// Copyright (c) 2026 Lark Technologies Pte. Ltd.
+// SPDX-License-Identifier: MIT
+
+package keysigner
+
+import (
+	"context"
+	"crypto"
+	"crypto/rsa"
+	"crypto/sha256"
+	"os"
+	"testing"
+)
+
+// TestKeychainSignerRegistered confirms the keychain_signer build self-registers
+// (init → Register), so keysigner.Active() is non-nil. No keychain access.
+func TestKeychainSignerRegistered(t *testing.T) {
+	if _, ok := Active().(keychainSigner); !ok {
+		t.Fatalf("Active() = %T, want keychainSigner (keychain_signer build must self-register)", Active())
+	}
+}
+
+// TestKeychainSignerRoundTrip creates a real non-extractable RSA key, signs, and
+// verifies RS256 against the returned public key. Gated by LARK_KEYCHAIN_IT
+// because it mutates the dedicated lark-cli keychain store. The signer is now
+// cgo-free (purego runtime FFI), so it runs with CGO_ENABLED=0. Run with:
+//
+//	LARK_KEYCHAIN_IT=1 go test -run RoundTrip ./internal/keysigner/
+func TestKeychainSignerRoundTrip(t *testing.T) {
+	if os.Getenv("LARK_KEYCHAIN_IT") == "" {
+		t.Skip("set LARK_KEYCHAIN_IT=1 to run (mutates the macOS keychain)")
+	}
+	s := keychainSigner{}
+	ref := KeyRef{Label: "lark-cli-keychain-it"}
+
+	pub, err := s.EnsureKey(context.Background(), ref)
+	if err != nil {
+		t.Fatalf("EnsureKey: %v", err)
+	}
+	rsaPub, ok := pub.(*rsa.PublicKey)
+	if !ok {
+		t.Fatalf("public key = %T, want *rsa.PublicKey", pub)
+	}
+	if alg, err := AlgForKey(pub); err != nil || alg != AlgRS256 {
+		t.Fatalf("AlgForKey = %q, %v; want RS256", alg, err)
+	}
+
+	input := []byte("header.payload")
+	sig, alg, err := s.Sign(context.Background(), ref, input)
+	if err != nil {
+		t.Fatalf("Sign: %v", err)
+	}
+	if alg != AlgRS256 {
+		t.Errorf("Sign alg = %q, want RS256", alg)
+	}
+	h := sha256.Sum256(input)
+	if err := rsa.VerifyPKCS1v15(rsaPub, crypto.SHA256, h[:], sig); err != nil {
+		t.Errorf("RS256 signature did not verify: %v", err)
+	}
+}

internal/keysigner/signer_sks.go

@@ -0,0 +1,135 @@
+//go:build linux || (windows && amd64)
+
+// Copyright (c) 2026 Lark Technologies Pte. Ltd.
+// SPDX-License-Identifier: MIT
+
+// TPM 2.0 signer (compiled into every linux and windows/amd64 build, no build
+// tag required), backed by github.com/facebookincubator/sks.
+//
+// sks holds a non-exportable ECDSA P-256 key in the platform TPM and signs
+// SHA-256 digests. On Linux it talks to /dev/tpmrm0; on Windows it uses the
+// Microsoft Platform Crypto Provider (CNG). Both backends return an ASN.1 DER
+// ECDSA signature, which we convert to the fixed-width r||s form JWS requires for
+// ES256 (see ecdsaDERToJOSE). One key is created on the first private_key_jwt
+// registration (DefaultKeyLabel) and reused for subsequent app registrations and
+// every client_assertion on the same device.
+//
+// Excluded from windows/arm64: the sks Windows dependency stack (go-ole) has no
+// arm64 VARIANT and fails to compile, so windows/arm64 falls back to
+// client_secret only (keysigner.Active() is nil). On darwin the keychain signer
+// is used instead. CGO is never required.
+package keysigner
+
+import (
+	"context"
+	"crypto"
+	"crypto/ecdsa"
+	"crypto/sha256"
+	"fmt"
+	"io"
+
+	"github.com/facebookincubator/flog"
+	"github.com/facebookincubator/sks"
+)
+
+// p256ByteLen is the P-256 coordinate width. sks regular keys are always ECDSA
+// P-256, so ES256 signatures are 2*p256ByteLen bytes of r||s.
+const p256ByteLen = 32
+
+// keyTag is the sks key tag. Both the Linux and Windows sks backends address
+// keys by label and ignore the tag, but the macOS backend uses it, so we set a
+// stable namespaced value for forward compatibility.
+const keyTag = "com.larksuite.cli"
+
+// sksSigner implements Signer (and HardwareProber) using a non-exportable
+// TPM 2.0 ECDSA key via sks.
+type sksSigner struct{}
+
+func init() {
+	Register(sksSigner{})
+	// This sks version logs verbose TPM-operation chatter to stderr via flog (a
+	// glog fork it owns exclusively) — e.g. "Loaded TPM device", "Found handle
+	// for key" on every sign. The CLI does not use flog, so silence it
+	// process-wide here; real failures are returned as errors, never relied upon
+	// from these logs. (Newer sks switched to slog, but that lands only on its
+	// go-1.24 line, which we avoid to keep the module on go 1.23.)
+	flog.SetOutput(io.Discard)
+}
+
+// EnsureKey returns the public key for ref, creating the TPM key if absent.
+// sks.NewKey is find-or-create: it returns the existing key when one is present.
+func (sksSigner) EnsureKey(_ context.Context, ref KeyRef) (crypto.PublicKey, error) {
+	key, err := sks.NewKey(ref.Label, keyTag, false, true, nil)
+	if err != nil {
+		return nil, fmt.Errorf("keysigner: ensure TPM key %q: %w", ref.Label, err)
+	}
+	defer key.Close()
+	return ecdsaPublic(ref.Label, key.Public())
+}
+
+// PublicKey returns the public key for ref without creating it. FromLabelTag does
+// not touch the TPM until Public() loads the sealed key; a missing key yields a
+// nil public key, which we surface as an error — at runtime the key MUST already
+// exist (it was bound to the app at registration), so we never silently mint a
+// new, unbound one here.
+func (sksSigner) PublicKey(_ context.Context, ref KeyRef) (crypto.PublicKey, error) {
+	pub := sks.FromLabelTag(ref.Label).Public()
+	if pub == nil {
+		return nil, fmt.Errorf("keysigner: TPM key %q not found", ref.Label)
+	}
+	return ecdsaPublic(ref.Label, pub)
+}
+
+// Sign signs signingInput with the TPM key and returns a JOSE-format ES256
+// signature (fixed-width r||s) plus its alg.
+func (sksSigner) Sign(_ context.Context, ref KeyRef, signingInput []byte) ([]byte, string, error) {
+	key, err := sks.NewKey(ref.Label, keyTag, false, true, nil)
+	if err != nil {
+		return nil, "", fmt.Errorf("keysigner: load TPM key %q: %w", ref.Label, err)
+	}
+	defer key.Close()
+
+	// ES256 signs the SHA-256 digest of the JWS signing input.
+	digest := sha256.Sum256(signingInput)
+	der, err := key.Sign(nil, digest[:], crypto.SHA256)
+	if err != nil {
+		return nil, "", fmt.Errorf("keysigner: TPM sign with key %q: %w", ref.Label, err)
+	}
+	// Both sks backends emit ASN.1 DER; JWS ES256 requires fixed-width r||s
+	// (RFC 7518 §3.4).
+	rs, err := ecdsaDERToJOSE(der, p256ByteLen)
+	if err != nil {
+		return nil, "", err
+	}
+	return rs, AlgES256, nil
+}
+
+// ProbeHardware reports on the TPM backing this signer without touching any key.
+// A failure to reach the TPM (no device, permission denied, not TPM 2.0) is
+// reported as Available=false with Reason set, NOT as a Go error — the probe
+// still succeeded in determining that the TEE is currently unusable.
+func (sksSigner) ProbeHardware(_ context.Context) (HardwareInfo, error) {
+	info := HardwareInfo{Backend: "tpm2"}
+	data, err := sks.GetSecureHardwareVendorData()
+	if err != nil {
+		info.Reason = cleanProbeError(err)
+		return info, nil
+	}
+	info.VendorName = data.VendorName
+	info.VendorInfo = data.VendorInfo
+	info.Available = data.IsTPM20CompliantDevice
+	if !info.Available {
+		info.Reason = "secure hardware is not a TPM 2.0 compliant device"
+	}
+	return info, nil
+}
+
+// ecdsaPublic asserts that an sks public key is an ECDSA key (it always is for
+// regular sks keys) so the caller gets the concrete type AlgForKey/PublicKeyJWK expect.
+func ecdsaPublic(label string, pub crypto.PublicKey) (*ecdsa.PublicKey, error) {
+	ecPub, ok := pub.(*ecdsa.PublicKey)
+	if !ok {
+		return nil, fmt.Errorf("keysigner: TPM key %q public is %T, want *ecdsa.PublicKey", label, pub)
+	}
+	return ecPub, nil
+}

internal/keysigner/signer_sks_test.go

@@ -0,0 +1,122 @@
+//go:build linux || (windows && amd64)
+
+// Copyright (c) 2026 Lark Technologies Pte. Ltd.
+// SPDX-License-Identifier: MIT
+
+package keysigner
+
+import (
+	"bytes"
+	"context"
+	"crypto/ecdsa"
+	"crypto/sha256"
+	"io"
+	"math/big"
+	"strings"
+	"testing"
+
+	"github.com/facebookincubator/flog"
+	"github.com/facebookincubator/sks"
+)
+
+// TestFlogSilenced verifies the mechanism init() relies on to keep sks's flog
+// TPM chatter off the CLI's stderr: SetOutput redirects flog, and io.Discard
+// drops it. Cleanup restores io.Discard so init()'s silencing holds for the
+// rest of the package's tests.
+func TestFlogSilenced(t *testing.T) {
+	var buf bytes.Buffer
+	flog.SetOutput(&buf)
+	t.Cleanup(func() { flog.SetOutput(io.Discard) })
+
+	flog.Info("captured-line")
+	if !strings.Contains(buf.String(), "captured-line") {
+		t.Fatalf("flog.SetOutput(buffer) did not capture output: %q", buf.String())
+	}
+
+	flog.SetOutput(io.Discard)
+	buf.Reset()
+	flog.Info("should-be-discarded")
+	if buf.Len() != 0 {
+		t.Errorf("flog output not discarded: %q", buf.String())
+	}
+}
+
+// requireTEE skips the test unless the TPM is present and usable. On a Linux
+// machine with a TPM but a restrictive device owner (`/dev/tpmrm0` is `tss:tss`
+// by default), grant access with `sudo usermod -aG tss $USER` then re-login, or
+// run the test under sudo.
+func requireTEE(t *testing.T) {
+	t.Helper()
+	info, err := sksSigner{}.ProbeHardware(context.Background())
+	if err != nil || !info.Available {
+		reason := info.Reason
+		if err != nil {
+			reason = err.Error()
+		}
+		t.Skipf("TEE not available (%s)", reason)
+	}
+}
+
+// TestSKSSignerRoundTrip exercises the full registration→assertion contract
+// against the real TPM: create the key, read it back without creating, derive
+// the JWS alg + JWK, sign, and verify the fixed-width r||s output.
+func TestSKSSignerRoundTrip(t *testing.T) {
+	requireTEE(t)
+
+	var s sksSigner
+	ctx := context.Background()
+	ref := KeyRef{Label: "larksuite-cli-test"}
+
+	// Best-effort cleanup so the test key does not linger in the TPM-sealed store.
+	t.Cleanup(func() {
+		if k, err := sks.NewKey(ref.Label, keyTag, false, true, nil); err == nil {
+			_ = k.Remove()
+			_ = k.Close()
+		}
+	})
+
+	pub, err := s.EnsureKey(ctx, ref)
+	if err != nil {
+		t.Fatalf("EnsureKey: %v", err)
+	}
+	ecPub, ok := pub.(*ecdsa.PublicKey)
+	if !ok {
+		t.Fatalf("EnsureKey returned %T, want *ecdsa.PublicKey", pub)
+	}
+
+	// PublicKey (no-create) must return the same key bound at EnsureKey.
+	pub2, err := s.PublicKey(ctx, ref)
+	if err != nil {
+		t.Fatalf("PublicKey: %v", err)
+	}
+	if !ecPub.Equal(pub2) {
+		t.Fatal("PublicKey returned a different key than EnsureKey")
+	}
+
+	// The JWT layer derives alg + JWK from the public key; both must work.
+	if alg, err := AlgForKey(pub); err != nil || alg != AlgES256 {
+		t.Fatalf("AlgForKey = %q, %v; want ES256", alg, err)
+	}
+	if _, err := PublicKeyJWK(pub); err != nil {
+		t.Fatalf("PublicKeyJWK: %v", err)
+	}
+
+	// Sign a representative JWS signing input and verify the converted r||s.
+	input := []byte("eyJhbGciOiJFUzI1NiJ9.eyJzdWIiOiJjbGkifQ")
+	sig, alg, err := s.Sign(ctx, ref, input)
+	if err != nil {
+		t.Fatalf("Sign: %v", err)
+	}
+	if alg != AlgES256 {
+		t.Fatalf("Sign alg = %q, want ES256", alg)
+	}
+	if len(sig) != 2*p256ByteLen {
+		t.Fatalf("len(sig) = %d, want %d (fixed-width r||s)", len(sig), 2*p256ByteLen)
+	}
+	digest := sha256.Sum256(input)
+	r := new(big.Int).SetBytes(sig[:p256ByteLen])
+	ss := new(big.Int).SetBytes(sig[p256ByteLen:])
+	if !ecdsa.Verify(ecPub, digest[:], r, ss) {
+		t.Fatal("TPM signature did not verify against the public key")
+	}
+}

scripts/build-pkg-pr-new.sh

@@ -24,6 +24,10 @@ build_target() {
     ext=".exe"
   fi
 
+  # The platform key signers are compiled in by build constraint, no tags:
+  # darwin keychain (//go:build darwin) and linux/windows-amd64 TPM
+  # (//go:build linux || (windows && amd64)). windows/arm64 arch-excludes the TPM
+  # signer (go-ole has no arm64) and falls back to client_secret only.
   local output="$OUT_DIR/bin/lark-cli-${goos}-${goarch}${ext}"
   echo "Building ${goos}/${goarch} -> ${output}"
   CGO_ENABLED=0 GOOS="$goos" GOARCH="$goarch" go build -trimpath -ldflags "$LDFLAGS" -o "$output" ./main.go

sidecar/server-multi-tenant-demo/auth_bridge.go

@@ -204,7 +204,7 @@ func (ab *authBridge) handleLogin(w http.ResponseWriter, _ *http.Request, body [
 		len(strings.Fields(scope)), req.Domains, clientID)
 
 	authResp, err := larkauth.RequestDeviceAuthorization(
-		ab.httpCl, ab.appID, ab.appSecret, ab.brand, scope, io.Discard,
+		context.Background(), ab.httpCl, larkauth.ClientAuth{AppID: ab.appID, AppSecret: ab.appSecret}, ab.brand, scope, io.Discard,
 	)
 	if err != nil {
 		jsonError(w, http.StatusBadGateway, "device authorization failed: "+err.Error())
@@ -255,7 +255,7 @@ func (ab *authBridge) handlePoll(w http.ResponseWriter, r *http.Request, body []
 	}()
 
 	result := larkauth.PollDeviceToken(
-		ctx, ab.httpCl, ab.appID, ab.appSecret, ab.brand,
+		ctx, ab.httpCl, larkauth.ClientAuth{AppID: ab.appID, AppSecret: ab.appSecret}, ab.brand,
 		req.DeviceCode, 5, 600, io.Discard,
 	)