chore: Strip unsupported signature formatting by channel (#13046)

# Pull Request Template

## Description

1. This PR is an enhancement to
https://github.com/chatwoot/chatwoot/pull/13045
It strips unsupported formatting from **message signatures** based on
each channel’s formatting capabilities defined in the `FORMATTING`
config

2. Remove usage of plain editor in Compose new conversation modal

Only the following signature elements are considered:
<strong>bold (<code inline="">strong</code>), italic (<code
inline="">em</code>), links (<code inline="">link</code>), images (<code
inline="">image</code>)</strong>.</p>

Any formatting not supported by the target channel is automatically
removed before the signature is appended.

<h3>Channel-wise Signature Formatting Support</h3>

Channel | Keeps in Signature | Strips from Signature
-- | -- | --
Email | bold, italic, links, images | —
WebWidget | bold, italic, links, images | —
API | bold, italic | links, images
WhatsApp | bold, italic | links, images
Telegram | bold, italic, links | images
Facebook | bold, italic | links, images
Instagram | bold, italic | links, images
Line | bold, italic | links, images
SMS | — | everything
Twilio SMS | — | everything
Twitter/X | — | everything


<hr>
<h3>📝 Note</h3>
<blockquote>
<p>Message signatures only support <strong>bold, italic, links, and
images</strong>.<br>
Other formatting options available in the editor (lists, code blocks,
strike-through, etc.) do <strong>not apply</strong> to signatures and
are ignored.</p>
</blockquote>

## Type of change

- [x] New feature (non-breaking change which adds functionality)

## How Has This Been Tested?

### Loom video
https://www.loom.com/share/d325ab86ca514c6d8f90dfe72a8928dd


## Checklist:

- [x] My code follows the style guidelines of this project
- [x] I have performed a self-review of my code
- [x] I have commented on my code, particularly in hard-to-understand
areas
- [ ] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged and published in downstream
modules

---------

Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>

app/javascript/dashboard/components-next/Editor/Editor.vue

@@ -24,6 +24,7 @@ const props = defineProps({
   allowSignature: { type: Boolean, default: false },
   sendWithSignature: { type: Boolean, default: false },
   channelType: { type: String, default: '' },
+  medium: { type: String, default: '' },
 });
 
 const emit = defineEmits(['update:modelValue']);
@@ -106,6 +107,7 @@ watch(
         :allow-signature="allowSignature"
         :send-with-signature="sendWithSignature"
         :channel-type="channelType"
+        :medium="medium"
         @input="handleInput"
         @focus="handleFocus"
         @blur="handleBlur"

app/javascript/dashboard/components-next/NewConversation/components/ComposeNewConversationForm.vue

@@ -6,6 +6,7 @@ import { INBOX_TYPES } from 'dashboard/helper/inbox';
 import {
   appendSignature,
   removeSignature,
+  getEffectiveChannelType,
 } from 'dashboard/helper/editorHelper';
 import {
   buildContactableInboxesList,
@@ -86,6 +87,12 @@ const whatsappMessageTemplates = computed(() =>
 
 const inboxChannelType = computed(() => props.targetInbox?.channelType || '');
 
+const inboxMedium = computed(() => props.targetInbox?.medium || '');
+
+const effectiveChannelType = computed(() =>
+  getEffectiveChannelType(inboxChannelType.value, inboxMedium.value)
+);
+
 const validationRules = computed(() => ({
   selectedContact: { required },
   targetInbox: { required },
@@ -202,7 +209,11 @@ const removeSignatureFromMessage = () => {
   // Always remove the signature from message content when inbox/contact is removed
   // to ensure no leftover signature content remains
   if (props.messageSignature) {
-    state.message = removeSignature(state.message, props.messageSignature);
+    state.message = removeSignature(
+      state.message,
+      props.messageSignature,
+      effectiveChannelType.value
+    );
   }
 };
 
@@ -214,9 +225,9 @@ const removeTargetInbox = value => {
 };
 
 const clearSelectedContact = () => {
+  removeSignatureFromMessage();
   emit('clearSelectedContact');
   state.attachedFiles = [];
-  removeSignatureFromMessage();
 };
 
 const onClickInsertEmoji = emoji => {
@@ -227,12 +238,16 @@ const handleAddSignature = signature => {
   state.message = appendSignature(
     state.message,
     signature,
-    inboxChannelType.value
+    effectiveChannelType.value
   );
 };
 
 const handleRemoveSignature = signature => {
-  state.message = removeSignature(state.message, signature);
+  state.message = removeSignature(
+    state.message,
+    signature,
+    effectiveChannelType.value
+  );
 };
 
 const handleAttachFile = files => {
@@ -356,10 +371,10 @@ const shouldShowMessageEditor = computed(() => {
       v-model="state.message"
       :message-signature="messageSignature"
       :send-with-signature="sendWithSignature"
-      :is-email-or-web-widget-inbox="inboxTypes.isEmailOrWebWidget"
       :has-errors="validationStates.isMessageInvalid"
       :has-attachments="state.attachedFiles.length > 0"
       :channel-type="inboxChannelType"
+      :medium="targetInbox?.medium || ''"
     />
 
     <AttachmentPreviews

app/javascript/dashboard/components-next/NewConversation/components/MessageEditor.vue

@@ -1,22 +1,15 @@
 <script setup>
-import { ref, watch, nextTick } from 'vue';
 import { useI18n } from 'vue-i18n';
-import {
-  appendSignature,
-  removeSignature,
-} from 'dashboard/helper/editorHelper';
 
 import Editor from 'dashboard/components-next/Editor/Editor.vue';
-import TextArea from 'dashboard/components-next/textarea/TextArea.vue';
-import CannedResponse from 'dashboard/components/widgets/conversation/CannedResponse.vue';
 
-const props = defineProps({
+defineProps({
-  isEmailOrWebWidgetInbox: { type: Boolean, required: true },
   hasErrors: { type: Boolean, default: false },
   hasAttachments: { type: Boolean, default: false },
   sendWithSignature: { type: Boolean, default: false },
   messageSignature: { type: String, default: '' },
   channelType: { type: String, default: '' },
+  medium: { type: String, default: '' },
 });
 
 const { t } = useI18n();
@@ -25,54 +18,10 @@ const modelValue = defineModel({
   type: String,
   default: '',
 });
-
-const state = ref({
-  hasSlashCommand: false,
-  showMentions: false,
-  mentionSearchKey: '',
-});
-
-watch(
-  modelValue,
-  newValue => {
-    if (props.isEmailOrWebWidgetInbox) return;
-
-    const bodyWithoutSignature = newValue
-      ? removeSignature(newValue, props.messageSignature)
-      : '';
-
-    // Check if message starts with slash
-    const startsWithSlash = bodyWithoutSignature.startsWith('/');
-
-    // Update slash command and mentions state
-    state.value = {
-      ...state.value,
-      hasSlashCommand: startsWithSlash,
-      showMentions: startsWithSlash,
-      mentionSearchKey: startsWithSlash ? bodyWithoutSignature.slice(1) : '',
-    };
-  },
-  { immediate: true }
-);
-
-const hideMention = () => {
-  state.value.showMentions = false;
-};
-
-const replaceText = async message => {
-  // Only append signature on replace if sendWithSignature is true
-  const finalMessage = props.sendWithSignature
-    ? appendSignature(message, props.messageSignature, props.channelType)
-    : message;
-
-  await nextTick();
-  modelValue.value = finalMessage;
-};
 </script>
 
 <template>
   <div class="flex-1 h-full" :class="[!hasAttachments && 'min-h-[200px]']">
-    <template v-if="isEmailOrWebWidgetInbox">
     <Editor
       v-model="modelValue"
       :placeholder="
@@ -90,33 +39,7 @@ const replaceText = async message => {
       allow-signature
       :send-with-signature="sendWithSignature"
       :channel-type="channelType"
+      :medium="medium"
     />
-    </template>
-    <template v-else>
-      <TextArea
-        v-model="modelValue"
-        :placeholder="
-          t('COMPOSE_NEW_CONVERSATION.FORM.MESSAGE_EDITOR.PLACEHOLDER')
-        "
-        class="!px-0 [&>div]:!px-4 [&>div]:!border-transparent [&>div]:!bg-transparent"
-        :custom-text-area-class="
-          hasErrors
-            ? 'placeholder:!text-n-ruby-9 dark:placeholder:!text-n-ruby-9'
-            : ''
-        "
-        auto-height
-        allow-signature
-        :signature="messageSignature"
-        :send-with-signature="sendWithSignature"
-      >
-        <CannedResponse
-          v-if="state.showMentions && state.hasSlashCommand"
-          v-on-clickaway="hideMention"
-          class="normal-editor__canned-box"
-          :search-key="state.mentionSearchKey"
-          @replace="replaceText"
-        />
-      </TextArea>
-    </template>
   </div>
 </template>

app/javascript/dashboard/components/widgets/WootWriter/Editor.vue

@@ -54,6 +54,7 @@ import {
   getFormattingForEditor,
   getSelectionCoords,
   calculateMenuPosition,
+  getEffectiveChannelType,
 } from 'dashboard/helper/editorHelper';
 import {
   hasPressedEnterAndNotCmdOrShift,
@@ -81,6 +82,7 @@ const props = defineProps({
   // are triggered except when this flag is true
   allowSignature: { type: Boolean, default: false },
   channelType: { type: String, default: '' },
+  medium: { type: String, default: '' },
   showImageResizeToolbar: { type: Boolean, default: false }, // A kill switch to show or hide the image toolbar
   focusOnMount: { type: Boolean, default: true },
 });
@@ -105,10 +107,16 @@ const TYPING_INDICATOR_IDLE_TIME = 4000;
 const MAXIMUM_FILE_UPLOAD_SIZE = 4; // in MB
 const DEFAULT_FORMATTING = 'Context::Default';
 
+const effectiveChannelType = computed(() =>
+  getEffectiveChannelType(props.channelType, props.medium)
+);
+
 const editorSchema = computed(() => {
   if (!props.channelType) return messageSchema;
 
-  const formatType = props.isPrivate ? DEFAULT_FORMATTING : props.channelType;
+  const formatType = props.isPrivate
+    ? DEFAULT_FORMATTING
+    : effectiveChannelType.value;
   const formatting = getFormattingForEditor(formatType);
   return buildMessageSchema(formatting.marks, formatting.nodes);
 });
@@ -116,7 +124,7 @@ const editorSchema = computed(() => {
 const editorMenuOptions = computed(() => {
   const formatType = props.isPrivate
     ? DEFAULT_FORMATTING
-    : props.channelType || DEFAULT_FORMATTING;
+    : effectiveChannelType.value || DEFAULT_FORMATTING;
   const formatting = getFormattingForEditor(formatType);
   return formatting.menu;
 });
@@ -301,8 +309,13 @@ function isBodyEmpty(content) {
 
   // if the signature is present, we need to remove it before checking
   // note that we don't update the editorView, so this is safe
+  // Use effective channel type to match how signature was appended
   const bodyWithoutSignature = props.signature
-    ? removeSignatureHelper(content, props.signature)
+    ? removeSignatureHelper(
+        content,
+        props.signature,
+        effectiveChannelType.value
+      )
     : content;
 
   // trimming should remove all the whitespaces, so we can check the length
@@ -370,7 +383,11 @@ function addSignature() {
   // see if the content is empty, if it is before appending the signature
   // we need to add a paragraph node and move the cursor at the start of the editor
   const contentWasEmpty = isBodyEmpty(content);
-  content = appendSignature(content, props.signature, props.channelType);
+  content = appendSignature(
+    content,
+    props.signature,
+    effectiveChannelType.value
+  );
   // need to reload first, ensuring that the editorView is updated
   reloadState(content);
 
@@ -382,7 +399,11 @@ function addSignature() {
 function removeSignature() {
   if (!props.signature) return;
   let content = props.modelValue;
-  content = removeSignatureHelper(content, props.signature);
+  content = removeSignatureHelper(
+    content,
+    props.signature,
+    effectiveChannelType.value
+  );
   // reload the state, ensuring that the editorView is updated
   reloadState(content);
 }

app/javascript/dashboard/components/widgets/conversation/ReplyBox.vue

@@ -43,6 +43,7 @@ import fileUploadMixin from 'dashboard/mixins/fileUploadMixin';
 import {
   appendSignature,
   removeSignature,
+  getEffectiveChannelType,
 } from 'dashboard/helper/editorHelper';
 
 import { LOCAL_STORAGE_KEYS } from 'dashboard/constants/localStorage';
@@ -564,9 +565,13 @@ export default {
         return message;
       }
 
+      const effectiveChannelType = getEffectiveChannelType(
+        this.channelType,
+        this.inbox?.medium || ''
+      );
       return this.sendWithSignature
-        ? appendSignature(message, this.messageSignature, this.channelType)
+        ? appendSignature(message, this.messageSignature, effectiveChannelType)
-        : removeSignature(message, this.messageSignature);
+        : removeSignature(message, this.messageSignature, effectiveChannelType);
     },
     removeFromDraft() {
       if (this.conversationIdByRoute) {
@@ -757,10 +762,14 @@ export default {
         // if signature is enabled, append it to the message
         // appendSignature ensures that the signature is not duplicated
         // so we don't need to check if the signature is already present
+        const effectiveChannelType = getEffectiveChannelType(
+          this.channelType,
+          this.inbox?.medium || ''
+        );
         message = appendSignature(
           message,
           this.messageSignature,
-          this.channelType
+          effectiveChannelType
         );
       }
 
@@ -800,10 +809,14 @@ export default {
       this.message = '';
       if (this.sendWithSignature && !this.isPrivate) {
         // if signature is enabled, append it to the message
+        const effectiveChannelType = getEffectiveChannelType(
+          this.channelType,
+          this.inbox?.medium || ''
+        );
         this.message = appendSignature(
           this.message,
           this.messageSignature,
-          this.channelType
+          effectiveChannelType
         );
       }
       this.attachedFiles = [];
@@ -1121,6 +1134,7 @@ export default {
         :signature="messageSignature"
         allow-signature
         :channel-type="channelType"
+        :medium="inbox.medium"
         @typing-off="onTypingOff"
         @typing-on="onTypingOn"
         @focus="onFocus"

app/javascript/dashboard/constants/editor.js

@@ -210,7 +210,12 @@ export const MARKDOWN_PATTERNS = [
     type: 'em', // PM: em, eg: *italic* or _italic_
     patterns: [
       { pattern: /(?<!\*)\*(?!\*)(.+?)(?<!\*)\*(?!\*)/g, replacement: '$1' },
-      { pattern: /(?<!_)_(?!_)(.+?)(?<!_)_(?!_)/g, replacement: '$1' },
+      // Match _text_ only at word boundaries (whitespace/string start/end)
+      // Preserves underscores in URLs (e.g., https://example.com/path_name) and variable names
+      {
+        pattern: /(?<=^|[\s])_([^_\s][^_]*[^_\s]|[^_\s])_(?=$|[\s])/g,
+        replacement: '$1',
+      },
     ],
   },
   {
@@ -227,11 +232,6 @@ export const MARKDOWN_PATTERNS = [
   },
 ];
 
-export const CHANNEL_WITH_RICH_SIGNATURE = [
-  'Channel::Email',
-  'Channel::WebWidget',
-];
-
 // Editor image resize options for Message Editor
 export const MESSAGE_EDITOR_IMAGE_RESIZES = [
   {

app/javascript/dashboard/helper/editorHelper.js

@@ -5,11 +5,8 @@ import {
 } from '@chatwoot/prosemirror-schema';
 import { replaceVariablesInMessage } from '@chatwoot/utils';
 import * as Sentry from '@sentry/vue';
-import {
+import { FORMATTING, MARKDOWN_PATTERNS } from 'dashboard/constants/editor';
-  FORMATTING,
+import { INBOX_TYPES, TWILIO_CHANNEL_MEDIUM } from 'dashboard/helper/inbox';
-  MARKDOWN_PATTERNS,
-  CHANNEL_WITH_RICH_SIGNATURE,
-} from 'dashboard/constants/editor';
 import camelcaseKeys from 'camelcase-keys';
 
 /**
@@ -35,6 +32,56 @@ export function extractTextFromMarkdown(markdown) {
     .trim(); // Trim any extra space
 }
 
+/**
+ * Strip unsupported markdown formatting based on channel capabilities.
+ *
+ * @param {string} markdown - markdown text to process
+ * @param {string} channelType - The channel type to check supported formatting
+ * @returns {string} - The markdown with unsupported formatting removed
+ */
+export function stripUnsupportedSignatureMarkdown(markdown, channelType) {
+  if (!markdown) return '';
+
+  const { marks = [], nodes = [] } = FORMATTING[channelType] || {};
+  const has = (arr, key) => arr.includes(key);
+
+  // Define stripping rules: [condition, pattern, replacement]
+  const rules = [
+    [!has(nodes, 'image'), /!\[.*?\]\(.*?\)/g, ''],
+    [!has(marks, 'link'), /\[([^\]]+)\]\([^)]+\)/g, '$1'],
+    [!has(nodes, 'codeBlock'), /```[\s\S]*?```/g, ''],
+    [!has(marks, 'code'), /`([^`]+)`/g, '$1'],
+    [!has(marks, 'strong'), /\*\*([^*]+)\*\*/g, '$1'],
+    [!has(marks, 'strong'), /__([^_]+)__/g, '$1'],
+    [!has(marks, 'em'), /\*([^*]+)\*/g, '$1'],
+    // Match _text_ only at word boundaries (whitespace/string start/end)
+    // Preserves underscores in URLs (e.g., https://example.com/path_name) and variable names
+    [
+      !has(marks, 'em'),
+      /(?<=^|[\s])_([^_\s][^_]*[^_\s]|[^_\s])_(?=$|[\s])/g,
+      '$1',
+    ],
+    [!has(marks, 'strike'), /~~([^~]+)~~/g, '$1'],
+    [!has(nodes, 'blockquote'), /^>\s?/gm, ''],
+    [!has(nodes, 'bulletList'), /^[-*+]\s+/gm, ''],
+    [!has(nodes, 'orderedList'), /^\d+\.\s+/gm, ''],
+  ];
+
+  const result = rules.reduce(
+    (text, [shouldStrip, pattern, replacement]) =>
+      shouldStrip ? text.replace(pattern, replacement) : text,
+    markdown
+  );
+
+  return result
+    .split('\n')
+    .map(line => line.trim())
+    .filter(Boolean)
+    .join('\n')
+    .replace(/\n{2,}/g, '\n')
+    .trim();
+}
+
 /**
  * The delimiter used to separate the signature from the rest of the body.
  * @type {string}
@@ -97,29 +144,36 @@ export function findSignatureInBody(body, signature) {
 }
 
 /**
- * Checks if the channel supports image signatures.
+ * Gets the effective channel type for formatting purposes.
+ * For Twilio channels, returns WhatsApp or Twilio based on medium.
  *
- * @param {string} channelType - The channel type.
+ * @param {string} channelType - The channel type
- * @returns {boolean} - True if the channel supports image signatures.
+ * @param {string} medium - Optional. The medium for Twilio channels (sms/whatsapp)
+ * @returns {string} - The effective channel type for formatting
  */
-export function supportsImageSignature(channelType) {
+export function getEffectiveChannelType(channelType, medium) {
-  return CHANNEL_WITH_RICH_SIGNATURE.includes(channelType);
+  if (channelType === INBOX_TYPES.TWILIO) {
+    return medium === TWILIO_CHANNEL_MEDIUM.WHATSAPP
+      ? INBOX_TYPES.WHATSAPP
+      : INBOX_TYPES.TWILIO;
+  }
+  return channelType;
 }
 
 /**
  * Appends the signature to the body, separated by the signature delimiter.
- * Automatically strips images for channels that don't support image signatures.
+ * Automatically strips unsupported formatting based on channel capabilities.
  *
  * @param {string} body - The body to append the signature to.
  * @param {string} signature - The signature to append.
- * @param {string} channelType - Optional. The channel type to determine if images should be stripped.
+ * @param {string} channelType - Optional. The effective channel type to determine supported formatting.
+ *                               For Twilio channels, pass the result of getEffectiveChannelType().
  * @returns {string} - The body with the signature appended.
  */
 export function appendSignature(body, signature, channelType) {
-  // For channels that don't support images, strip markdown formatting
+  // Strip only unsupported formatting based on channel capabilities
-  const shouldStripImages = channelType && !supportsImageSignature(channelType);
+  const preparedSignature = channelType
-  const preparedSignature = shouldStripImages
+    ? stripUnsupportedSignatureMarkdown(signature, channelType)
-    ? extractTextFromMarkdown(signature)
     : signature;
   const cleanedSignature = cleanSignature(preparedSignature);
   // if signature is already present, return body
@@ -132,21 +186,28 @@ export function appendSignature(body, signature, channelType) {
 
 /**
  * Removes the signature from the body, along with the signature delimiter.
- * Tries to find both the original signature and the stripped version (for non-image channels).
+ * Tries to find both the original signature and the stripped version.
  *
  * @param {string} body - The body to remove the signature from.
  * @param {string} signature - The signature to remove.
+ * @param {string} channelType - Optional. The effective channel type for channel-specific stripping.
+ *                               For Twilio channels, pass the result of getEffectiveChannelType().
  * @returns {string} - The body with the signature removed.
  */
-export function removeSignature(body, signature) {
+export function removeSignature(body, signature, channelType) {
-  // Build list of signatures to try: original first, then stripped version
+  // Build list of signatures to try: original, channel-stripped, and fully stripped
-  // Always try both to handle cases where channelType is unknown or inbox is being removed
   const cleanedSignature = cleanSignature(signature);
-  const strippedSignature = cleanSignature(extractTextFromMarkdown(signature));
+  const channelStripped = channelType
-  const signaturesToTry =
+    ? cleanSignature(stripUnsupportedSignatureMarkdown(signature, channelType))
-    cleanedSignature === strippedSignature
+    : null;
-      ? [cleanedSignature]
+  const fullyStripped = cleanSignature(extractTextFromMarkdown(signature));
-      : [cleanedSignature, strippedSignature];
+
+  // Try signatures in order: original → channel-specific → fully stripped
+  const signaturesToTry = [
+    cleanedSignature,
+    channelStripped,
+    fullyStripped,
+  ].filter((sig, i, arr) => sig && arr.indexOf(sig) === i); // Remove nulls and duplicates
 
   // Find the first matching signature
   const signatureIndex = signaturesToTry.reduce(

app/javascript/dashboard/helper/inbox.js

@@ -13,6 +13,11 @@ export const INBOX_TYPES = {
   VOICE: 'Channel::Voice',
 };
 
+export const TWILIO_CHANNEL_MEDIUM = {
+  WHATSAPP: 'whatsapp',
+  SMS: 'sms',
+};
+
 const INBOX_ICON_MAP_FILL = {
   [INBOX_TYPES.WEB]: 'i-ri-global-fill',
   [INBOX_TYPES.FB]: 'i-ri-messenger-fill',

app/javascript/dashboard/helper/specs/editorHelper.spec.js

@@ -5,7 +5,7 @@ import {
   replaceSignature,
   cleanSignature,
   extractTextFromMarkdown,
-  supportsImageSignature,
+  stripUnsupportedSignatureMarkdown,
   insertAtCursor,
   findNodeToInsertImage,
   setURLWithQueryAndSize,
@@ -145,10 +145,63 @@ describe('appendSignature', () => {
   });
 });
 
+describe('stripUnsupportedSignatureMarkdown', () => {
+  const richSignature =
+    '**Bold** _italic_ [link](http://example.com) ![](http://localhost:3000/image.png)';
+
+  it('keeps all formatting for Email channel (supports image, link, strong, em)', () => {
+    const result = stripUnsupportedSignatureMarkdown(
+      richSignature,
+      'Channel::Email'
+    );
+    expect(result).toContain('**Bold**');
+    expect(result).toContain('_italic_');
+    expect(result).toContain('[link](http://example.com)');
+    expect(result).toContain('![](http://localhost:3000/image.png)');
+  });
+  it('strips images but keeps bold/italic for Api channel', () => {
+    const result = stripUnsupportedSignatureMarkdown(
+      richSignature,
+      'Channel::Api'
+    );
+    expect(result).toContain('**Bold**');
+    expect(result).toContain('_italic_');
+    expect(result).toContain('link'); // link text kept
+    expect(result).not.toContain('[link]('); // link syntax removed
+    expect(result).not.toContain('![]('); // image removed
+  });
+  it('strips images but keeps bold/italic/link for Telegram channel', () => {
+    const result = stripUnsupportedSignatureMarkdown(
+      richSignature,
+      'Channel::Telegram'
+    );
+    expect(result).toContain('**Bold**');
+    expect(result).toContain('_italic_');
+    expect(result).toContain('[link](http://example.com)');
+    expect(result).not.toContain('![](');
+  });
+  it('strips all formatting for SMS channel', () => {
+    const result = stripUnsupportedSignatureMarkdown(
+      richSignature,
+      'Channel::Sms'
+    );
+    expect(result).toContain('Bold');
+    expect(result).toContain('italic');
+    expect(result).toContain('link');
+    expect(result).not.toContain('**');
+    expect(result).not.toContain('_');
+    expect(result).not.toContain('[');
+    expect(result).not.toContain('![](');
+  });
+  it('returns empty string for empty input', () => {
+    expect(stripUnsupportedSignatureMarkdown('', 'Channel::Api')).toBe('');
+    expect(stripUnsupportedSignatureMarkdown(null, 'Channel::Api')).toBe('');
+  });
+});
+
 describe('appendSignature with channelType', () => {
   const signatureWithImage =
     'Thanks\n![](http://localhost:3000/image.png?cw_image_height=24px)';
-  const strippedSignature = 'Thanks';
 
   it('keeps images for Email channel', () => {
     const result = appendSignature(
@@ -166,24 +219,31 @@ describe('appendSignature with channelType', () => {
     );
     expect(result).toContain('![](http://localhost:3000/image.png');
   });
-  it('strips images for Api channel', () => {
+  it('strips images but keeps text for Api channel', () => {
     const result = appendSignature('Hello', signatureWithImage, 'Channel::Api');
     expect(result).not.toContain('![](');
-    expect(result).toContain(strippedSignature);
+    expect(result).toContain('Thanks');
   });
-  it('strips images for WhatsApp channel', () => {
+  it('strips images but keeps text for WhatsApp channel', () => {
     const result = appendSignature(
       'Hello',
       signatureWithImage,
       'Channel::Whatsapp'
     );
     expect(result).not.toContain('![](');
-    expect(result).toContain(strippedSignature);
+    expect(result).toContain('Thanks');
   });
   it('keeps images when channelType is not provided', () => {
     const result = appendSignature('Hello', signatureWithImage);
     expect(result).toContain('![](http://localhost:3000/image.png');
   });
+  it('keeps bold/italic for channels that support them', () => {
+    const boldSignature = '**Bold** *italic* Thanks';
+    const result = appendSignature('Hello', boldSignature, 'Channel::Api');
+    // Api supports strong and em
+    expect(result).toContain('**Bold**');
+    expect(result).toContain('*italic*');
+  });
 });
 
 describe('cleanSignature', () => {
@@ -331,24 +391,6 @@ describe('extractTextFromMarkdown', () => {
   });
 });
 
-describe('supportsImageSignature', () => {
-  it('returns true for Email channel', () => {
-    expect(supportsImageSignature('Channel::Email')).toBe(true);
-  });
-  it('returns true for WebWidget channel', () => {
-    expect(supportsImageSignature('Channel::WebWidget')).toBe(true);
-  });
-  it('returns false for Api channel', () => {
-    expect(supportsImageSignature('Channel::Api')).toBe(false);
-  });
-  it('returns false for WhatsApp channel', () => {
-    expect(supportsImageSignature('Channel::Whatsapp')).toBe(false);
-  });
-  it('returns false for Telegram channel', () => {
-    expect(supportsImageSignature('Channel::Telegram')).toBe(false);
-  });
-});
-
 describe('insertAtCursor', () => {
   it('should return undefined if editorView is not provided', () => {
     const result = insertAtCursor(undefined, schema.text('Hello'), 0);
@@ -884,6 +926,26 @@ describe('stripUnsupportedFormatting', () => {
       );
     });
 
+    it('preserves underscores in URLs and mid-word positions', () => {
+      // Underscores in URLs should not be stripped as italic formatting
+      expect(
+        stripUnsupportedFormatting(
+          'https://www.chatwoot.com/new_first_second-third/ssd',
+          emptySchema
+        )
+      ).toBe('https://www.chatwoot.com/new_first_second-third/ssd');
+
+      // Underscores in variable names should not be stripped
+      expect(
+        stripUnsupportedFormatting('some_variable_name', emptySchema)
+      ).toBe('some_variable_name');
+
+      // But actual italic formatting with spaces should still be stripped
+      expect(
+        stripUnsupportedFormatting('hello _world_ there', emptySchema)
+      ).toBe('hello world there');
+    });
+
     it('strips inline code formatting', () => {
       expect(stripUnsupportedFormatting('`inline code`', emptySchema)).toBe(
         'inline code'