chore: insert resolved variable value in reply editor (#14921)

# Pull Request Template

## Description

This PR makes reply editor variables insert their resolved value (for
example, the contact's name) instead of the raw `{{contact.name}}`
placeholder, matching canned response behavior. This works both when
picking a variable from the `{{` menu and when an agent manually types
out `{{contact.name}}` — it resolves the moment the closing `}}` is
typed.

If a variable has no value, the `{{placeholder}}` is kept so the backend
can still resolve it when the message is sent. Private notes are left
untouched.

For safety, a resolved value that itself contains Liquid syntax `({{ }}`
or `{% %})` also keeps its placeholder, so customer-controlled fields
can never inject Liquid into the outgoing message.

Fixes
https://linear.app/chatwoot/issue/CW-7528/reply-editor-inserts-variable-placeholder-instead-of-the-value

## Type of change

- [x] Bug fix (non-breaking change which fixes an issue)

## How Has This Been Tested?

1. Open a conversation and add a reply.
2. Type `{{` and pick a variable that has a value (e.g. Contact name) →
it inserts the actual value.
3. Manually type `{{contact.name}}` and close the braces → it
auto-resolves to the value.
4. Insert/type a variable with no value → the `{{placeholder}}` stays;
confirm it resolves correctly on send.
5. Repeat in a private note → placeholders are left as-is.


## 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

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

@@ -62,6 +62,7 @@ import {
   calculateMenuPosition,
   getEffectiveChannelType,
   stripUnsupportedFormatting,
+  createVariableInputRule,
 } from 'dashboard/helper/editorHelper';
 import {
   hasPressedEnterAndNotCmdOrShift,
@@ -306,6 +307,10 @@ const plugins = computed(() => {
       searchTerm: variableSearchTerm,
       isAllowed: () => !props.isPrivate,
     }),
+    createVariableInputRule({
+      isPrivate: () => props.isPrivate,
+      getVariables: () => props.variables,
+    }),
     createSuggestionPlugin({
       trigger: ':',
       minChars: 2,

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

@@ -48,6 +48,8 @@ import {
   appendSignature,
   removeSignature,
   getEffectiveChannelType,
+  getAgentVariables,
+  getContactVariables,
 } from 'dashboard/helper/editorHelper';
 import { useCopilotReply } from 'dashboard/composables/useCopilotReply';
 import { useKbd } from 'dashboard/composables/utils/useKbd';
@@ -393,7 +395,13 @@ export default {
         contact: this.currentContact,
         inbox: this.inbox,
       });
-      return variables;
+      // Match the backend drops: names are Ruby-capitalized and
+      // {{agent.*}} is the message sender, not the assignee.
+      return {
+        ...variables,
+        ...getContactVariables(this.currentContact),
+        ...getAgentVariables(this.currentUser),
+      };
     },
     connectedPortalSlug() {
       const { help_center: portal = {} } = this.inbox;