feat(mail): append default signature when sending

shortcuts/mail/mail_lint_writepath_test.go

@@ -486,6 +486,7 @@ func TestMailSend_WritePathLintAutofixesFontInEML(t *testing.T) {
 		"--to", "alice@example.com",
 		"--subject", "Send",
 		"--body", `<font color="red">payload</font>`,
+		"--no-signature",
 		"--show-lint-details",
 	}, f, stdout)
 	if err != nil {

shortcuts/mail/mail_request_receipt_integration_test.go

@@ -127,6 +127,7 @@ func TestMailSend_RequestReceiptAddsHeader_Integration(t *testing.T) {
 		"--to", "bob@example.com",
 		"--subject", "hi",
 		"--body", "please confirm",
+		"--no-signature",
 		"--request-receipt",
 		"--confirm-send",
 	}, f, stdout); err != nil {
@@ -153,6 +154,7 @@ func TestMailSend_RequestReceiptNoSender_FailsValidation(t *testing.T) {
 		"--to", "bob@example.com",
 		"--subject", "hi",
 		"--body", "body",
+		"--no-signature",
 		"--request-receipt",
 		"--confirm-send",
 	}, f, stdout)

shortcuts/mail/mail_send.go

@@ -40,6 +40,7 @@
 		{Name: "request-receipt", Type: "bool", Desc: "Request a read receipt (Message Disposition Notification, RFC 3798) addressed to the sender. Recipient mail clients may prompt the user, send automatically, or silently ignore — delivery of a receipt is not guaranteed."},
 		{Name: "template-id", Desc: "Optional. Apply a saved template by ID (decimal integer string) before composing. The template's subject/body/to/cc/bcc/attachments are merged with user-supplied flags (user flags win). Requires --as user."},
 		signatureFlag,
+		noSignatureFlag,
 		priorityFlag,
 		eventSummaryFlag, eventStartFlag, eventEndFlag, eventLocationFlag,
 		showLintDetailsFlag},
@@ -57,8 +58,11 @@
 			api = api.GET(templateMailboxPath(mailboxID, tid)).
 				Desc("Fetch template to merge with compose flags (subject/body/to/cc/bcc/attachments).")
 		}
-		api = api.GET(mailboxPath(mailboxID, "profile")).
-			POST(mailboxPath(mailboxID, "drafts")).
+		api = api.GET(mailboxPath(mailboxID, "profile"))
+		if !runtime.Bool("no-signature") {
+			api = api.GET(mailboxPath(mailboxID, "settings", "signatures"))
+		}
+		api = api.POST(mailboxPath(mailboxID, "drafts")).
 			Body(map[string]interface{}{
 				"raw": "<base64url-EML>",
 				"_preview": map[string]interface{}{
@@ -98,7 +102,7 @@
 		if err := validateSendTime(runtime); err != nil {
 			return err
 		}
-		if err := validateSignatureWithPlainText(runtime.Bool("plain-text"), runtime.Str("signature-id")); err != nil {
+		if err := validateSignatureFlags(runtime.Bool("no-signature"), runtime.Str("signature-id")); err != nil {
 			return err
 		}
 		// Resolve the body content first (reading --body-file if set) so
@@ -195,7 +199,7 @@
 			}
 		}
 
-		sigResult, err := resolveSignature(ctx, runtime, mailboxID, signatureID, senderEmail)
+		sigResult, err := resolveComposeSignature(ctx, runtime, mailboxID, signatureID, senderEmail, runtime.Bool("no-signature"), !plainText)
 		if err != nil {
 			return err
 		}
@@ -230,7 +234,7 @@
 		// `lint_applied[]` / `original_blocked[]` even on the plain-text path.
 		lintApplied, lintBlocked := emptyLintEnvelopeFields()
 		if plainText {
-			composedTextBody = body
+			composedTextBody = appendPlainTextSignature(body, sigResult, resolveLang(runtime))
 			bld = bld.TextBody([]byte(composedTextBody))
 		} else if bodyIsHTML(body) || sigResult != nil {
 			// If signature is requested on plain-text body, auto-upgrade to HTML.

shortcuts/mail/mail_send_confirm_output_test.go

@@ -149,6 +149,7 @@ func TestMailSendConfirmSendOutputsAutomationDisable(t *testing.T) {
 		"--to", "alice@example.com",
 		"--subject", "hello",
 		"--body", "world",
+		"--no-signature",
 		"--confirm-send",
 	}, f, stdout)
 	if err != nil {
@@ -203,6 +204,7 @@ func TestMailSendSaveDraftOutputsReference(t *testing.T) {
 		"--to", "alice@example.com",
 		"--subject", "hello",
 		"--body", "world",
+		"--no-signature",
 	}, f, stdout)
 	if err != nil {
 		t.Fatalf("save draft failed: %v", err)
@@ -243,6 +245,7 @@ func TestMailSend_WithCalendarEventEmbedded(t *testing.T) {
 		"--to", "alice@example.com",
 		"--subject", "Team Sync",
 		"--body", "<p>Please join us</p>",
+		"--no-signature",
 		"--event-summary", "Team Sync",
 		"--event-start", "2026-05-10T10:00+08:00",
 		"--event-end", "2026-05-10T11:00+08:00",

shortcuts/mail/mail_send_signature_test.go

@@ -0,0 +1,254 @@
+// Copyright (c) 2026 Lark Technologies Pte. Ltd.
+// SPDX-License-Identifier: MIT
+
+package mail
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+	"strings"
+	"testing"
+
+	"github.com/larksuite/cli/errs"
+	"github.com/larksuite/cli/internal/httpmock"
+)
+
+func TestMailSendDefaultSignatureHTML(t *testing.T) {
+	f, stdout, _, reg := mailShortcutTestFactory(t)
+	mailboxID := "sig-html@example.com"
+	draftStub := registerMailSendDraftStub(reg, mailboxID)
+	registerSignaturesStub(reg, mailboxID, []map[string]interface{}{
+		{"id": "sig_default", "name": "Default", "content": "<p>Default Signature</p>"},
+	}, []map[string]interface{}{
+		{"email_address": mailboxID, "send_mail_signature_id": "sig_default"},
+	})
+
+	err := runMountedMailShortcut(t, MailSend, []string{
+		"+send",
+		"--mailbox", mailboxID,
+		"--to", "alice@example.com",
+		"--subject", "hello",
+		"--body", "<p>Hello</p>",
+	}, f, stdout)
+	if err != nil {
+		t.Fatalf("send failed: %v", err)
+	}
+
+	eml := decodeDraftRawEML(t, draftStub)
+	if !strings.Contains(eml, "lark-mail-signature") {
+		t.Fatalf("expected signature wrapper in EML:\n%s", eml)
+	}
+	if !strings.Contains(eml, "Default Signature") {
+		t.Fatalf("expected default signature content in EML:\n%s", eml)
+	}
+}
+
+func TestMailSendDefaultSignaturePlainText(t *testing.T) {
+	f, stdout, _, reg := mailShortcutTestFactory(t)
+	mailboxID := "sig-plain@example.com"
+	draftStub := registerMailSendDraftStub(reg, mailboxID)
+	registerSignaturesStub(reg, mailboxID, []map[string]interface{}{
+		{"id": "sig_plain", "name": "Plain", "content": "<div>Best regards<br><strong>Alice</strong><img src=\"cid:logo\"></div>"},
+	}, []map[string]interface{}{
+		{"email_address": mailboxID, "send_mail_signature_id": "sig_plain"},
+	})
+
+	err := runMountedMailShortcut(t, MailSend, []string{
+		"+send",
+		"--mailbox", mailboxID,
+		"--to", "alice@example.com",
+		"--subject", "hello",
+		"--body", "Hi",
+		"--plain-text",
+	}, f, stdout)
+	if err != nil {
+		t.Fatalf("send failed: %v", err)
+	}
+
+	eml := decodeDraftRawEML(t, draftStub)
+	textBody := decodeSinglePartBase64Body(t, eml)
+	if !strings.Contains(textBody, "Hi\n\nBest regards") {
+		t.Fatalf("expected plain-text signature after blank line, body=%q EML:\n%s", textBody, eml)
+	}
+	if strings.Contains(textBody, "<div>") || strings.Contains(textBody, "<strong>") || strings.Contains(eml, "lark-mail-signature") {
+		t.Fatalf("plain-text signature should not include HTML tags or wrapper, body=%q EML:\n%s", textBody, eml)
+	}
+}
+
+func TestMailSendNoSignatureSkipsSignatureQuery(t *testing.T) {
+	f, stdout, _, reg := mailShortcutTestFactory(t)
+	mailboxID := "no-sig@example.com"
+	draftStub := registerMailSendDraftStub(reg, mailboxID)
+
+	err := runMountedMailShortcut(t, MailSend, []string{
+		"+send",
+		"--mailbox", mailboxID,
+		"--to", "alice@example.com",
+		"--subject", "hello",
+		"--body", "<p>Hello</p>",
+		"--no-signature",
+	}, f, stdout)
+	if err != nil {
+		t.Fatalf("send failed: %v", err)
+	}
+
+	eml := decodeDraftRawEML(t, draftStub)
+	if strings.Contains(eml, "lark-mail-signature") {
+		t.Fatalf("did not expect signature wrapper in EML:\n%s", eml)
+	}
+}
+
+func TestMailSendExplicitSignatureOverridesDefault(t *testing.T) {
+	f, stdout, _, reg := mailShortcutTestFactory(t)
+	mailboxID := "sig-explicit@example.com"
+	draftStub := registerMailSendDraftStub(reg, mailboxID)
+	registerSignaturesStub(reg, mailboxID, []map[string]interface{}{
+		{"id": "sig_default", "name": "Default", "content": "<p>Default Signature</p>"},
+		{"id": "sig_explicit", "name": "Explicit", "content": "<p>Explicit Signature</p>"},
+	}, []map[string]interface{}{
+		{"email_address": mailboxID, "send_mail_signature_id": "sig_default"},
+	})
+
+	err := runMountedMailShortcut(t, MailSend, []string{
+		"+send",
+		"--mailbox", mailboxID,
+		"--to", "alice@example.com",
+		"--subject", "hello",
+		"--body", "<p>Hello</p>",
+		"--signature-id", "sig_explicit",
+	}, f, stdout)
+	if err != nil {
+		t.Fatalf("send failed: %v", err)
+	}
+
+	eml := decodeDraftRawEML(t, draftStub)
+	if !strings.Contains(eml, "Explicit Signature") {
+		t.Fatalf("expected explicit signature in EML:\n%s", eml)
+	}
+	if strings.Contains(eml, "Default Signature") {
+		t.Fatalf("explicit signature should override default signature:\n%s", eml)
+	}
+}
+
+func TestMailSendNoSignatureAndSignatureIDMutuallyExclusive(t *testing.T) {
+	f, stdout, _, _ := mailShortcutTestFactory(t)
+	err := runMountedMailShortcut(t, MailSend, []string{
+		"+send",
+		"--to", "alice@example.com",
+		"--subject", "hello",
+		"--body", "Hello",
+		"--no-signature",
+		"--signature-id", "sig_123",
+	}, f, stdout)
+	var validationErr *errs.ValidationError
+	if !errors.As(err, &validationErr) {
+		t.Fatalf("expected validation error, got %T (%v)", err, err)
+	}
+	if !strings.Contains(err.Error(), "--no-signature and --signature-id are mutually exclusive") {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func TestMailSendDefaultSignatureMatchesFromUsage(t *testing.T) {
+	f, stdout, _, reg := mailShortcutTestFactory(t)
+	mailboxID := "owner@example.com"
+	draftStub := registerMailSendDraftStub(reg, mailboxID)
+	registerSignaturesStub(reg, mailboxID, []map[string]interface{}{
+		{"id": "sig_owner", "name": "Owner", "content": "<p>Owner Signature</p>"},
+		{"id": "sig_alias", "name": "Alias", "content": "<p>Alias Signature</p>"},
+	}, []map[string]interface{}{
+		{"email_address": mailboxID, "send_mail_signature_id": "sig_owner"},
+		{"email_address": "alias@example.com", "send_mail_signature_id": "sig_alias"},
+	})
+
+	err := runMountedMailShortcut(t, MailSend, []string{
+		"+send",
+		"--mailbox", mailboxID,
+		"--from", "alias@example.com",
+		"--to", "alice@example.com",
+		"--subject", "hello",
+		"--body", "<p>Hello</p>",
+	}, f, stdout)
+	if err != nil {
+		t.Fatalf("send failed: %v", err)
+	}
+
+	eml := decodeDraftRawEML(t, draftStub)
+	if !strings.Contains(eml, "Alias Signature") {
+		t.Fatalf("expected alias signature in EML:\n%s", eml)
+	}
+	if strings.Contains(eml, "Owner Signature") {
+		t.Fatalf("expected --from usage to win over fallback default:\n%s", eml)
+	}
+}
+
+func TestAppendPlainTextSignatureDoesNotTruncate(t *testing.T) {
+	longText := strings.Repeat("x", 240)
+	got := appendPlainTextSignature("Hi", &signatureResult{RenderedContent: "<p>" + longText + "</p>"}, "en_us")
+	if !strings.Contains(got, longText) {
+		t.Fatalf("plain-text signature was truncated: %q", got)
+	}
+}
+
+func registerSignaturesStub(reg *httpmock.Registry, mailboxID string, signatures []map[string]interface{}, usages []map[string]interface{}) *httpmock.Stub {
+	stub := &httpmock.Stub{
+		Method: "GET",
+		URL:    "/user_mailboxes/" + mailboxID + "/settings/signatures",
+		Body: map[string]interface{}{
+			"code": 0,
+			"data": map[string]interface{}{
+				"signatures": signatures,
+				"usages":     usages,
+			},
+		},
+	}
+	reg.Register(stub)
+	return stub
+}
+
+func registerMailSendDraftStub(reg *httpmock.Registry, mailboxID string) *httpmock.Stub {
+	stub := &httpmock.Stub{
+		Method: "POST",
+		URL:    "/user_mailboxes/" + mailboxID + "/drafts",
+		Body: map[string]interface{}{
+			"code": 0,
+			"data": map[string]interface{}{
+				"draft_id": "draft_001",
+			},
+		},
+	}
+	reg.Register(stub)
+	return stub
+}
+
+func decodeDraftRawEML(t *testing.T, stub *httpmock.Stub) string {
+	t.Helper()
+	var reqBody map[string]interface{}
+	if err := json.Unmarshal(stub.CapturedBody, &reqBody); err != nil {
+		t.Fatalf("unmarshal captured draft body: %v", err)
+	}
+	raw, _ := reqBody["raw"].(string)
+	decoded, err := base64.URLEncoding.DecodeString(raw)
+	if err != nil {
+		t.Fatalf("base64url decode raw EML: %v", err)
+	}
+	return string(decoded)
+}
+
+func decodeSinglePartBase64Body(t *testing.T, eml string) string {
+	t.Helper()
+	parts := strings.SplitN(eml, "\r\n\r\n", 2)
+	if len(parts) != 2 {
+		parts = strings.SplitN(eml, "\n\n", 2)
+	}
+	if len(parts) != 2 {
+		t.Fatalf("EML missing body separator:\n%s", eml)
+	}
+	encoded := strings.TrimSpace(parts[1])
+	decoded, err := base64.StdEncoding.DecodeString(encoded)
+	if err != nil {
+		t.Fatalf("decode base64 body: %v; body=%q", err, encoded)
+	}
+	return strings.ReplaceAll(string(decoded), "\r\n", "\n")
+}

shortcuts/mail/mail_template_shortcut_test.go

@@ -1041,6 +1041,7 @@ func TestFetchTemplateAttachmentURLs_FailedReasons(t *testing.T) {
 		"--to", "alice@example.com",
 		"--subject", "s",
 		"--body", "<p>b</p>",
+		"--no-signature",
 		"--template-id", "33",
 	}, f, stdout)
 	if err == nil || !strings.Contains(err.Error(), "download URL not returned") {
@@ -1140,6 +1141,7 @@ func TestMailSend_TemplateIDAppliesInlineAndSmall(t *testing.T) {
 		"--to", "alice@example.com",
 		"--subject", "override-subj",
 		"--body", "<p>user body</p>",
+		"--no-signature",
 		"--template-id", "42",
 	}, f, stdout)
 	if err != nil {