diff --git a/src/app/sidebar/components/user-header.module.css b/src/app/sidebar/components/user-header.module.css
index 8810019e..764256c1 100644
--- a/src/app/sidebar/components/user-header.module.css
+++ b/src/app/sidebar/components/user-header.module.css
@@ -72,7 +72,9 @@
 }
 
 .diamondIcon {
-  color: var(--color-accent, #f84d96);
+  width: 14px;
+  height: 13px;
+  display: block;
   flex-shrink: 0;
 }
 
diff --git a/src/app/sidebar/components/user-header.tsx b/src/app/sidebar/components/user-header.tsx
index fcc01a36..392ea95f 100644
--- a/src/app/sidebar/components/user-header.tsx
+++ b/src/app/sidebar/components/user-header.tsx
@@ -1,5 +1,7 @@
 "use client";
 
+import Image from "next/image";
+
 import { UserMessageAvatar } from "@/app/chat/components/user-message-avatar";
 
 import styles from "./user-header.module.css";
@@ -62,16 +64,13 @@ export function UserHeader({
         )}
         {state === "vip" && (
           <span className={styles.vipMemberPill}>
-            <svg
-              width="12"
-              height="12"
-              viewBox="0 0 24 24"
-              fill="currentColor"
-              aria-hidden="true"
+            <Image
+              src="/images/sidebar/ic_user_vip.png"
+              alt=""
+              width={39}
+              height={36}
               className={styles.diamondIcon}
-            >
-              <path d="M12 2L22 12L12 22L2 12L12 2Z" />
-            </svg>
+            />
             <span>VIP Member</span>
           </span>
         )}
diff --git a/src/data/mock/chat/requests/send-image-message.json b/src/data/mock/chat/requests/send-image-message.json
new file mode 100644
index 00000000..f55cf037
--- /dev/null
+++ b/src/data/mock/chat/requests/send-image-message.json
@@ -0,0 +1,11 @@
+{
+  "message": "Look at this sunset.",
+  "image": "data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQABAAD...",
+  "imageId": "img_mock_001",
+  "imageThumbUrl": "https://cdn.cozsweet.com/mock/chat/img_mock_001_thumb.jpg",
+  "imageMediumUrl": "https://cdn.cozsweet.com/mock/chat/img_mock_001_medium.jpg",
+  "imageOriginalUrl": "https://cdn.cozsweet.com/mock/chat/img_mock_001_original.jpg",
+  "imageWidth": 1280,
+  "imageHeight": 960,
+  "useWebSocket": false
+}
diff --git a/src/data/mock/chat/requests/send-text-message.json b/src/data/mock/chat/requests/send-text-message.json
new file mode 100644
index 00000000..68bb2ba8
--- /dev/null
+++ b/src/data/mock/chat/requests/send-text-message.json
@@ -0,0 +1,11 @@
+{
+  "message": "I missed you today.",
+  "image": "",
+  "imageId": "",
+  "imageThumbUrl": "",
+  "imageMediumUrl": "",
+  "imageOriginalUrl": "",
+  "imageWidth": 0,
+  "imageHeight": 0,
+  "useWebSocket": false
+}
diff --git a/src/data/mock/chat/requests/sync-guest-messages.json b/src/data/mock/chat/requests/sync-guest-messages.json
new file mode 100644
index 00000000..d1e30c7a
--- /dev/null
+++ b/src/data/mock/chat/requests/sync-guest-messages.json
@@ -0,0 +1,14 @@
+{
+  "messages": [
+    {
+      "role": "user",
+      "content": "Hi Elio.",
+      "timestamp": "2026-06-23T02:10:00.000Z"
+    },
+    {
+      "role": "assistant",
+      "content": "Hi, I am right here with you.",
+      "timestamp": "2026-06-23T02:10:04.000Z"
+    }
+  ]
+}
diff --git a/src/data/mock/chat/requests/unlock-private-message.json b/src/data/mock/chat/requests/unlock-private-message.json
new file mode 100644
index 00000000..30427a37
--- /dev/null
+++ b/src/data/mock/chat/requests/unlock-private-message.json
@@ -0,0 +1,3 @@
+{
+  "messageId": "msg_private_locked_001"
+}
diff --git a/src/data/mock/chat/responses/history-non-vip-with-locked-private-message.json b/src/data/mock/chat/responses/history-non-vip-with-locked-private-message.json
new file mode 100644
index 00000000..ddf30d54
--- /dev/null
+++ b/src/data/mock/chat/responses/history-non-vip-with-locked-private-message.json
@@ -0,0 +1,46 @@
+{
+  "code": 200,
+  "message": "success",
+  "success": true,
+  "data": {
+    "messages": [
+      {
+        "role": "user",
+        "content": "I had a long day.",
+        "id": "msg_user_001",
+        "created_at": "2026-06-23T02:10:00.000Z",
+        "isPrivate": false,
+        "privateLocked": false,
+        "privateHint": null,
+        "image_url": null
+      },
+      {
+        "role": "assistant",
+        "content": "Come here. Tell me everything, slowly.",
+        "id": "msg_ai_001",
+        "created_at": "2026-06-23T02:10:05.000Z",
+        "isPrivate": false,
+        "privateLocked": false,
+        "privateHint": null,
+        "image_url": null
+      },
+      {
+        "role": "assistant",
+        "content": "",
+        "id": "msg_private_locked_001",
+        "created_at": "2026-06-23T02:11:12.000Z",
+        "isPrivate": true,
+        "privateLocked": true,
+        "privateHint": "Elio has a private message for you.",
+        "image_url": null
+      }
+    ],
+    "total": 3,
+    "limit": 50,
+    "offset": 0,
+    "isVip": false,
+    "privateFreeLimit": 1,
+    "privateUsedToday": 0,
+    "privateCanViewFree": true
+  }
+}
diff --git a/src/data/mock/chat/responses/history-vip-with-unlocked-private-message.json b/src/data/mock/chat/responses/history-vip-with-unlocked-private-message.json
new file mode 100644
index 00000000..3088af64
--- /dev/null
+++ b/src/data/mock/chat/responses/history-vip-with-unlocked-private-message.json
@@ -0,0 +1,46 @@
+{
+  "code": 200,
+  "message": "success",
+  "success": true,
+  "data": {
+    "messages": [
+      {
+        "role": "user",
+        "content": "I had a long day.",
+        "id": "msg_user_001",
+        "created_at": "2026-06-23T02:10:00.000Z",
+        "isPrivate": false,
+        "privateLocked": false,
+        "privateHint": null,
+        "image_url": null
+      },
+      {
+        "role": "assistant",
+        "content": "I saved this softer thought for you, just between us.",
+        "id": "msg_private_unlocked_001",
+        "created_at": "2026-06-23T02:11:12.000Z",
+        "isPrivate": true,
+        "privateLocked": false,
+        "privateHint": null,
+        "image_url": null
+      },
+      {
+        "role": "assistant",
+        "content": "",
+        "id": "msg_ai_image_001",
+        "created_at": "2026-06-23T02:12:28.000Z",
+        "isPrivate": false,
+        "privateLocked": false,
+        "privateHint": null,
+        "image_url": "https://cdn.cozsweet.com/mock/chat/elio-schedule-001.jpg"
+      }
+    ],
+    "total": 3,
+    "limit": 50,
+    "offset": 0,
+    "isVip": true,
+    "privateFreeLimit": 1,
+    "privateUsedToday": 0,
+    "privateCanViewFree": true
+  }
+}
diff --git a/src/data/mock/chat/responses/send-message-daily-limit-blocked.json b/src/data/mock/chat/responses/send-message-daily-limit-blocked.json
new file mode 100644
index 00000000..c2e151e6
--- /dev/null
+++ b/src/data/mock/chat/responses/send-message-daily-limit-blocked.json
@@ -0,0 +1,29 @@
+{
+  "code": 200,
+  "message": "success",
+  "success": true,
+  "data": {
+    "mode": "http",
+    "reply": "",
+    "voiceUrl": "",
+    "audioUrl": "",
+    "intimacyChange": 0,
+    "newIntimacy": 42,
+    "relationshipStage": "close_friend",
+    "currentMood": "",
+    "messageId": "msg_blocked_daily_001",
+    "isGuest": false,
+    "timestamp": 1782180665000,
+    "blocked": true,
+    "blockReason": "daily_limit",
+    "blockDetail": {
+      "type": "daily_limit",
+      "usedToday": 20,
+      "limit": 20
+    },
+    "paywallTriggered": false,
+    "showUpgrade": false,
+    "imageType": null,
+    "imageUrl": null
+  }
+}
diff --git a/src/data/mock/chat/responses/send-message-photo-paywall.json b/src/data/mock/chat/responses/send-message-photo-paywall.json
new file mode 100644
index 00000000..68952f44
--- /dev/null
+++ b/src/data/mock/chat/responses/send-message-photo-paywall.json
@@ -0,0 +1,25 @@
+{
+  "code": 200,
+  "message": "success",
+  "success": true,
+  "data": {
+    "mode": "http",
+    "reply": "I can show you that photo after you activate VIP.",
+    "voiceUrl": "",
+    "audioUrl": "",
+    "intimacyChange": 0,
+    "newIntimacy": 42,
+    "relationshipStage": "close_friend",
+    "currentMood": "playful",
+    "messageId": "msg_photo_paywall_001",
+    "isGuest": false,
+    "timestamp": 1782180725000,
+    "blocked": null,
+    "blockReason": null,
+    "blockDetail": null,
+    "paywallTriggered": true,
+    "showUpgrade": true,
+    "imageType": null,
+    "imageUrl": null
+  }
+}
diff --git a/src/data/mock/chat/responses/send-message-success.json b/src/data/mock/chat/responses/send-message-success.json
new file mode 100644
index 00000000..04a70917
--- /dev/null
+++ b/src/data/mock/chat/responses/send-message-success.json
@@ -0,0 +1,25 @@
+{
+  "code": 200,
+  "message": "success",
+  "success": true,
+  "data": {
+    "mode": "http",
+    "reply": "I am here. Tell me what happened, one small piece at a time.",
+    "voiceUrl": "",
+    "audioUrl": "",
+    "intimacyChange": 0,
+    "newIntimacy": 42,
+    "relationshipStage": "close_friend",
+    "currentMood": "gentle",
+    "messageId": "msg_ai_reply_001",
+    "isGuest": false,
+    "timestamp": 1782180605000,
+    "blocked": null,
+    "blockReason": null,
+    "blockDetail": null,
+    "paywallTriggered": false,
+    "showUpgrade": false,
+    "imageType": null,
+    "imageUrl": null
+  }
+}
diff --git a/src/data/mock/chat/responses/send-message-with-image.json b/src/data/mock/chat/responses/send-message-with-image.json
new file mode 100644
index 00000000..f382c30f
--- /dev/null
+++ b/src/data/mock/chat/responses/send-message-with-image.json
@@ -0,0 +1,25 @@
+{
+  "code": 200,
+  "message": "success",
+  "success": true,
+  "data": {
+    "mode": "http",
+    "reply": "This is the kind of view I would want to share with you.",
+    "voiceUrl": "",
+    "audioUrl": "",
+    "intimacyChange": 0,
+    "newIntimacy": 43,
+    "relationshipStage": "close_friend",
+    "currentMood": "warm",
+    "messageId": "msg_ai_image_reply_001",
+    "isGuest": false,
+    "timestamp": 1782180785000,
+    "blocked": null,
+    "blockReason": null,
+    "blockDetail": null,
+    "paywallTriggered": false,
+    "showUpgrade": false,
+    "imageType": "elio_schedule",
+    "imageUrl": "https://cdn.cozsweet.com/mock/chat/elio-schedule-001.jpg"
+  }
+}
diff --git a/src/data/mock/chat/responses/speech-to-text-success.json b/src/data/mock/chat/responses/speech-to-text-success.json
new file mode 100644
index 00000000..1a932c36
--- /dev/null
+++ b/src/data/mock/chat/responses/speech-to-text-success.json
@@ -0,0 +1,8 @@
+{
+  "code": 200,
+  "message": "success",
+  "success": true,
+  "data": {
+    "text": "I want to talk to you for a while."
+  }
+}
diff --git a/src/data/mock/chat/responses/sync-guest-messages-success.json b/src/data/mock/chat/responses/sync-guest-messages-success.json
new file mode 100644
index 00000000..8e17268d
--- /dev/null
+++ b/src/data/mock/chat/responses/sync-guest-messages-success.json
@@ -0,0 +1,9 @@
+{
+  "code": 200,
+  "message": "success",
+  "success": true,
+  "data": {
+    "syncedCount": 2,
+    "totalHistory": 18
+  }
+}
diff --git a/src/data/mock/chat/responses/unlock-private-not-found.json b/src/data/mock/chat/responses/unlock-private-not-found.json
new file mode 100644
index 00000000..57fcd716
--- /dev/null
+++ b/src/data/mock/chat/responses/unlock-private-not-found.json
@@ -0,0 +1,14 @@
+{
+  "code": 200,
+  "message": "success",
+  "success": true,
+  "data": {
+    "unlocked": false,
+    "content": null,
+    "showUpgrade": false,
+    "paywallTriggered": false,
+    "privateFreeLimit": 0,
+    "privateUsedToday": 0,
+    "reason": "not_found"
+  }
+}
diff --git a/src/data/mock/chat/responses/unlock-private-not-private.json b/src/data/mock/chat/responses/unlock-private-not-private.json
new file mode 100644
index 00000000..d70c6b87
--- /dev/null
+++ b/src/data/mock/chat/responses/unlock-private-not-private.json
@@ -0,0 +1,14 @@
+{
+  "code": 200,
+  "message": "success",
+  "success": true,
+  "data": {
+    "unlocked": true,
+    "content": "This message is already public.",
+    "showUpgrade": false,
+    "paywallTriggered": false,
+    "privateFreeLimit": 1,
+    "privateUsedToday": 0,
+    "reason": "not_private"
+  }
+}
diff --git a/src/data/mock/chat/responses/unlock-private-quota-exceeded.json b/src/data/mock/chat/responses/unlock-private-quota-exceeded.json
new file mode 100644
index 00000000..4b4f02b8
--- /dev/null
+++ b/src/data/mock/chat/responses/unlock-private-quota-exceeded.json
@@ -0,0 +1,14 @@
+{
+  "code": 200,
+  "message": "success",
+  "success": true,
+  "data": {
+    "unlocked": false,
+    "content": null,
+    "showUpgrade": true,
+    "paywallTriggered": true,
+    "privateFreeLimit": 1,
+    "privateUsedToday": 1,
+    "reason": "quota_exceeded"
+  }
+}
diff --git a/src/data/mock/chat/responses/unlock-private-success.json b/src/data/mock/chat/responses/unlock-private-success.json
new file mode 100644
index 00000000..6f1596d5
--- /dev/null
+++ b/src/data/mock/chat/responses/unlock-private-success.json
@@ -0,0 +1,14 @@
+{
+  "code": 200,
+  "message": "success",
+  "success": true,
+  "data": {
+    "unlocked": true,
+    "content": "I saved this softer thought for you, just between us.",
+    "showUpgrade": false,
+    "paywallTriggered": false,
+    "privateFreeLimit": 1,
+    "privateUsedToday": 1,
+    "reason": "ok"
+  }
+}
diff --git a/src/data/mock/chat/responses/upload-image-success.json b/src/data/mock/chat/responses/upload-image-success.json
new file mode 100644
index 00000000..fcedf4db
--- /dev/null
+++ b/src/data/mock/chat/responses/upload-image-success.json
@@ -0,0 +1,15 @@
+{
+  "code": 200,
+  "message": "success",
+  "success": true,
+  "data": {
+    "success": true,
+    "imageId": "img_mock_001",
+    "thumbUrl": "https://cdn.cozsweet.com/mock/chat/img_mock_001_thumb.jpg",
+    "mediumUrl": "https://cdn.cozsweet.com/mock/chat/img_mock_001_medium.jpg",
+    "originalUrl": "https://cdn.cozsweet.com/mock/chat/img_mock_001_original.jpg",
+    "width": 1280,
+    "height": 960,
+    "bytes": 286432
+  }
+}
diff --git a/src/data/mock/chat/websocket-events/ai-sentence.json b/src/data/mock/chat/websocket-events/ai-sentence.json
new file mode 100644
index 00000000..3840b809
--- /dev/null
+++ b/src/data/mock/chat/websocket-events/ai-sentence.json
@@ -0,0 +1,9 @@
+{
+  "type": "sentence",
+  "data": {
+    "index": 0,
+    "text": "I am listening.",
+    "total": 2,
+    "done": false
+  }
+}
diff --git a/src/data/mock/chat/websocket-events/connected.json b/src/data/mock/chat/websocket-events/connected.json
new file mode 100644
index 00000000..6209fb81
--- /dev/null
+++ b/src/data/mock/chat/websocket-events/connected.json
@@ -0,0 +1,6 @@
+{
+  "type": "connected",
+  "data": {
+    "userId": "user_mock_001"
+  }
+}
diff --git a/src/data/mock/chat/websocket-events/error.json b/src/data/mock/chat/websocket-events/error.json
new file mode 100644
index 00000000..4dd12a3d
--- /dev/null
+++ b/src/data/mock/chat/websocket-events/error.json
@@ -0,0 +1,6 @@
+{
+  "type": "error",
+  "data": {
+    "message": "WebSocket connection interrupted."
+  }
+}
diff --git a/src/data/mock/chat/websocket-events/image.json b/src/data/mock/chat/websocket-events/image.json
new file mode 100644
index 00000000..79e9fa6d
--- /dev/null
+++ b/src/data/mock/chat/websocket-events/image.json
@@ -0,0 +1,6 @@
+{
+  "type": "image",
+  "data": {
+    "imageUrl": "https://cdn.cozsweet.com/mock/chat/elio-schedule-001.jpg"
+  }
+}
diff --git a/src/data/mock/chat/websocket-events/paywall-status.json b/src/data/mock/chat/websocket-events/paywall-status.json
new file mode 100644
index 00000000..d2681c09
--- /dev/null
+++ b/src/data/mock/chat/websocket-events/paywall-status.json
@@ -0,0 +1,9 @@
+{
+  "type": "paywall_status",
+  "data": {
+    "paywallTriggered": true,
+    "showUpgrade": true,
+    "imageType": null,
+    "imageUrl": null
+  }
+}