fix(webchat): show sessions_send handoffs as forwarded

Fix WebChat display projection for sessions_send inter-session handoffs. Forwarded messages now render assistant-side with source attribution while keeping transcript user-role semantics, stripping generated inter-session envelopes from display text, and preserving heartbeat/TTS/message-tool cleanup boundaries. Fixes #89161.

ui/src/ui/chat/build-chat-items.test.ts

@@ -67,6 +67,66 @@ describe("buildChatItems", () => {
     expect(groups.map((group) => group.senderLabel)).toEqual(["Iris", "Joaquin De Rojas"]);
   });
 
+  it("keeps differently cased user roles in one group", () => {
+    const groups = messageGroups({
+      messages: [
+        {
+          role: "user",
+          content: "first",
+          timestamp: 1000,
+        },
+        {
+          role: "User",
+          content: "second",
+          timestamp: 1001,
+        },
+      ],
+    });
+
+    expect(groups).toHaveLength(1);
+    expect(groups[0].role).toBe("user");
+    expect(groups[0].messages).toHaveLength(2);
+  });
+
+  it("keeps forwarded assistant display messages separate from local assistant replies", () => {
+    const groups = messageGroups({
+      messages: [
+        {
+          role: "assistant",
+          content: "local reply",
+          timestamp: 1000,
+        },
+        {
+          role: "assistant",
+          content: "forwarded report",
+          senderLabel: "Forwarded from main",
+          timestamp: 1001,
+        },
+      ],
+    });
+
+    expect(groups).toHaveLength(2);
+    expect(groups.map((group) => group.senderLabel)).toEqual([null, "Forwarded from main"]);
+  });
+
+  it("keeps empty forwarded assistant display groups", () => {
+    const groups = messageGroups({
+      messages: [
+        {
+          role: "assistant",
+          content: [{ type: "text", text: "" }],
+          senderLabel: "Forwarded from main",
+          timestamp: 1000,
+        },
+      ],
+    });
+
+    expect(groups).toHaveLength(1);
+    expect(groups[0].role).toBe("assistant");
+    expect(groups[0].senderLabel).toBe("Forwarded from main");
+    expect(groups[0].messages).toHaveLength(1);
+  });
+
   it("collapses consecutive duplicate text messages into one rendered item with a count", () => {
     const groups = messageGroups({
       messages: [

ui/src/ui/chat/build-chat-items.ts

@@ -191,13 +191,17 @@ function groupMessages(items: ChatItem[]): Array<ChatItem | MessageGroup> {
 
     const normalized = normalizeMessage(item.message);
     const role = normalizeRoleForGrouping(normalized.role);
-    const senderLabel = role.toLowerCase() === "user" ? (normalized.senderLabel ?? null) : null;
+    const senderLabel =
+      role.toLowerCase() === "user" || role.toLowerCase() === "assistant"
+        ? (normalized.senderLabel ?? null)
+        : null;
     const timestamp = normalized.timestamp || Date.now();
+    const shouldSplitBySender = role.toLowerCase() === "user" || role.toLowerCase() === "assistant";
 
     if (
       !currentGroup ||
       currentGroup.role !== role ||
-      (role.toLowerCase() === "user" && currentGroup.senderLabel !== senderLabel)
+      (shouldSplitBySender && currentGroup.senderLabel !== senderLabel)
     ) {
       if (currentGroup) {
         result.push(currentGroup);
@@ -253,7 +257,8 @@ function collapseDuplicateDisplaySignature(message: unknown): string | null {
   if (!text) {
     return null;
   }
-  const senderLabel = role === "user" ? (normalized.senderLabel ?? "").trim() : "";
+  const senderLabel =
+    role === "user" || role === "assistant" ? (normalized.senderLabel ?? "").trim() : "";
   return `${role}:${senderLabel}:${text}`;
 }
 
@@ -285,7 +290,9 @@ function hasRenderableNormalizedMessage(message: unknown): boolean {
   if (!normalized) {
     return false;
   }
-  return normalized.content.length > 0 || Boolean(normalized.replyTarget);
+  const role = normalizeRoleForGrouping(normalized.role);
+  const hasVisibleSenderLabel = role === "assistant" && Boolean(normalized.senderLabel?.trim());
+  return normalized.content.length > 0 || Boolean(normalized.replyTarget) || hasVisibleSenderLabel;
 }
 
 function sanitizeStreamText(text: string): string {

ui/src/ui/chat/grouped-render.test.ts

@@ -934,6 +934,37 @@ describe("grouped chat rendering", () => {
     expect(avatar?.tagName).toBe("DIV");
   });
 
+  it("uses assistant senderLabel for forwarded assistant-side groups", () => {
+    const container = document.createElement("div");
+    const group: MessageGroup = {
+      kind: "group",
+      key: "forwarded-group",
+      role: "assistant",
+      senderLabel: "Forwarded from main",
+      messages: [
+        {
+          key: "forwarded-message",
+          message: { role: "assistant", content: "forwarded report", timestamp: 1000 },
+        },
+      ],
+      timestamp: 1000,
+      isStreaming: false,
+    };
+
+    render(
+      renderMessageGroup(group, {
+        showReasoning: true,
+        showToolCalls: true,
+        assistantName: "OpenClaw",
+        assistantAvatar: null,
+      }),
+      container,
+    );
+
+    const sender = container.querySelector<HTMLElement>(".chat-group.assistant .chat-sender-name");
+    expect(sender?.textContent).toBe("Forwarded from main");
+  });
+
   it("collapses consecutive tool results into an activity group", () => {
     const container = document.createElement("div");
     const group: MessageGroup = {

ui/src/ui/chat/grouped-render.ts

@@ -442,7 +442,7 @@ export function renderMessageGroup(
     normalizedRole === "user"
       ? (userLabel ?? resolvedUserName)
       : normalizedRole === "assistant"
-        ? assistantName
+        ? (userLabel ?? assistantName)
         : normalizedRole === "tool"
           ? "Tool"
           : normalizedRole;

ui/src/ui/chat/heartbeat-display.ts

@@ -100,6 +100,9 @@ export function isAssistantHeartbeatAckForDisplay(message: unknown): boolean {
   if (role !== "assistant") {
     return false;
   }
+  if (typeof entry.senderLabel === "string" && entry.senderLabel.trim()) {
+    return false;
+  }
 
   const content =
     typeof entry.content === "string" || Array.isArray(entry.content) ? entry.content : entry.text;

ui/src/ui/chat/role-normalizer.test.ts

@@ -17,11 +17,13 @@ describe("normalizeRoleForGrouping", () => {
     expect(normalizeRoleForGrouping("Function")).toBe("tool");
   });
 
-  it("preserves core roles", () => {
+  it("normalizes core roles", () => {
     expect(normalizeRoleForGrouping("user")).toBe("user");
-    expect(normalizeRoleForGrouping("User")).toBe("User");
+    expect(normalizeRoleForGrouping("User")).toBe("user");
     expect(normalizeRoleForGrouping("assistant")).toBe("assistant");
+    expect(normalizeRoleForGrouping("Assistant")).toBe("assistant");
     expect(normalizeRoleForGrouping("system")).toBe("system");
+    expect(normalizeRoleForGrouping("System")).toBe("system");
   });
 
   it("detects only tool result role variants", () => {

ui/src/ui/chat/role-normalizer.ts

@@ -3,14 +3,14 @@
  */
 export function normalizeRoleForGrouping(role: string): string {
   const lower = role.toLowerCase();
-  // Preserve original casing when it's already a core role.
-  if (role === "user" || role === "User") {
-    return role;
+  // Core roles drive grouping and layout; casing variants should not split groups.
+  if (lower === "user") {
+    return "user";
   }
-  if (role === "assistant") {
+  if (lower === "assistant") {
     return "assistant";
   }
-  if (role === "system") {
+  if (lower === "system") {
     return "system";
   }
   // Keep tool-related roles distinct so the UI can style/toggle them.