diff --git a/ui/src/ui/chat/build-chat-items.ts b/ui/src/ui/chat/build-chat-items.ts
index 1ceb80230dd..4e01f6a0faa 100644
--- a/ui/src/ui/chat/build-chat-items.ts
+++ b/ui/src/ui/chat/build-chat-items.ts
@@ -1,6 +1,7 @@
 import type { ChatItem, MessageGroup, ToolCard } from "../types/chat-types.ts";
 import { extractTextCached } from "./message-extract.ts";
-import { normalizeMessage, normalizeRoleForGrouping } from "./message-normalizer.ts";
+import { normalizeMessage } from "./message-normalizer.ts";
+import { normalizeRoleForGrouping } from "./role-normalizer.ts";
 import { messageMatchesSearchQuery } from "./search-match.ts";
 import { extractToolCards, extractToolPreview } from "./tool-cards.ts";
 
diff --git a/ui/src/ui/chat/chat-avatar.ts b/ui/src/ui/chat/chat-avatar.ts
index 756a04eae5a..1992ac2e23d 100644
--- a/ui/src/ui/chat/chat-avatar.ts
+++ b/ui/src/ui/chat/chat-avatar.ts
@@ -10,7 +10,7 @@ import {
   isRenderableControlUiAvatarUrl,
   resolveAssistantTextAvatar,
 } from "../views/agents-utils.ts";
-import { normalizeRoleForGrouping } from "./message-normalizer.ts";
+import { normalizeRoleForGrouping } from "./role-normalizer.ts";
 
 export function renderChatAvatar(
   role: string,
diff --git a/ui/src/ui/chat/grouped-render.ts b/ui/src/ui/chat/grouped-render.ts
index f298da6b3c2..4e9e59309eb 100644
--- a/ui/src/ui/chat/grouped-render.ts
+++ b/ui/src/ui/chat/grouped-render.ts
@@ -24,11 +24,8 @@ import {
   extractThinkingCached,
   formatReasoningMarkdown,
 } from "./message-extract.ts";
-import {
-  isToolResultMessage,
-  normalizeMessage,
-  normalizeRoleForGrouping,
-} from "./message-normalizer.ts";
+import { isToolResultMessage, normalizeMessage } from "./message-normalizer.ts";
+import { normalizeRoleForGrouping } from "./role-normalizer.ts";
 import { isTtsSupported, speakText, stopTts, isTtsSpeaking } from "./speech.ts";
 import {
   extractToolCards,
diff --git a/ui/src/ui/chat/message-normalizer.test.ts b/ui/src/ui/chat/message-normalizer.test.ts
index 1b37981d1d4..e8a56c31021 100644
--- a/ui/src/ui/chat/message-normalizer.test.ts
+++ b/ui/src/ui/chat/message-normalizer.test.ts
@@ -1,9 +1,5 @@
 import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
-import {
-  normalizeMessage,
-  normalizeRoleForGrouping,
-  isToolResultMessage,
-} from "./message-normalizer.ts";
+import { normalizeMessage } from "./message-normalizer.ts";
 
 describe("message-normalizer", () => {
   describe("normalizeMessage", () => {
@@ -390,69 +386,4 @@ describe("message-normalizer", () => {
       expect(result.senderLabel).toBe("Iris");
     });
   });
-
-  describe("normalizeRoleForGrouping", () => {
-    it("returns tool for toolresult", () => {
-      expect(normalizeRoleForGrouping("toolresult")).toBe("tool");
-      expect(normalizeRoleForGrouping("toolResult")).toBe("tool");
-      expect(normalizeRoleForGrouping("TOOLRESULT")).toBe("tool");
-    });
-
-    it("returns tool for tool_result", () => {
-      expect(normalizeRoleForGrouping("tool_result")).toBe("tool");
-      expect(normalizeRoleForGrouping("TOOL_RESULT")).toBe("tool");
-    });
-
-    it("returns tool for tool", () => {
-      expect(normalizeRoleForGrouping("tool")).toBe("tool");
-      expect(normalizeRoleForGrouping("Tool")).toBe("tool");
-    });
-
-    it("returns tool for function", () => {
-      expect(normalizeRoleForGrouping("function")).toBe("tool");
-      expect(normalizeRoleForGrouping("Function")).toBe("tool");
-    });
-
-    it("preserves user role", () => {
-      expect(normalizeRoleForGrouping("user")).toBe("user");
-      expect(normalizeRoleForGrouping("User")).toBe("User");
-    });
-
-    it("preserves assistant role", () => {
-      expect(normalizeRoleForGrouping("assistant")).toBe("assistant");
-    });
-
-    it("preserves system role", () => {
-      expect(normalizeRoleForGrouping("system")).toBe("system");
-    });
-  });
-
-  describe("isToolResultMessage", () => {
-    it("returns true for toolresult role", () => {
-      expect(isToolResultMessage({ role: "toolresult" })).toBe(true);
-      expect(isToolResultMessage({ role: "toolResult" })).toBe(true);
-      expect(isToolResultMessage({ role: "TOOLRESULT" })).toBe(true);
-    });
-
-    it("returns true for tool_result role", () => {
-      expect(isToolResultMessage({ role: "tool_result" })).toBe(true);
-      expect(isToolResultMessage({ role: "TOOL_RESULT" })).toBe(true);
-    });
-
-    it("returns false for other roles", () => {
-      expect(isToolResultMessage({ role: "user" })).toBe(false);
-      expect(isToolResultMessage({ role: "assistant" })).toBe(false);
-      expect(isToolResultMessage({ role: "tool" })).toBe(false);
-    });
-
-    it("returns false for missing role", () => {
-      expect(isToolResultMessage({})).toBe(false);
-      expect(isToolResultMessage({ content: "test" })).toBe(false);
-    });
-
-    it("returns false for non-string role", () => {
-      expect(isToolResultMessage({ role: 123 })).toBe(false);
-      expect(isToolResultMessage({ role: null })).toBe(false);
-    });
-  });
 });
diff --git a/ui/src/ui/chat/message-normalizer.ts b/ui/src/ui/chat/message-normalizer.ts
index 697cd39377a..dc090e97daa 100644
--- a/ui/src/ui/chat/message-normalizer.ts
+++ b/ui/src/ui/chat/message-normalizer.ts
@@ -13,6 +13,7 @@ import { mediaKindFromMime } from "../../../../src/media/constants.js";
 import { splitMediaFromOutput } from "../../../../src/media/parse.js";
 import { parseInlineDirectives } from "../../../../src/utils/directive-tags.js";
 import type { NormalizedMessage, MessageContentItem } from "../types/chat-types.ts";
+export { isToolResultMessage, normalizeRoleForGrouping } from "./role-normalizer.ts";
 
 function coerceCanvasPreview(
   value: unknown,
@@ -389,39 +390,3 @@ export function normalizeMessage(message: unknown): NormalizedMessage {
     ...(replyTarget ? { replyTarget } : {}),
   };
 }
-
-/**
- * Normalize role for grouping purposes.
- */
-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;
-  }
-  if (role === "assistant") {
-    return "assistant";
-  }
-  if (role === "system") {
-    return "system";
-  }
-  // Keep tool-related roles distinct so the UI can style/toggle them.
-  if (
-    lower === "toolresult" ||
-    lower === "tool_result" ||
-    lower === "tool" ||
-    lower === "function"
-  ) {
-    return "tool";
-  }
-  return role;
-}
-
-/**
- * Check if a message is a tool result message based on its role.
- */
-export function isToolResultMessage(message: unknown): boolean {
-  const m = message as Record<string, unknown>;
-  const role = typeof m.role === "string" ? m.role.toLowerCase() : "";
-  return role === "toolresult" || role === "tool_result";
-}
diff --git a/ui/src/ui/chat/role-normalizer.test.ts b/ui/src/ui/chat/role-normalizer.test.ts
new file mode 100644
index 00000000000..014de0e5fc8
--- /dev/null
+++ b/ui/src/ui/chat/role-normalizer.test.ts
@@ -0,0 +1,41 @@
+import { describe, expect, it } from "vitest";
+import { isToolResultMessage, normalizeRoleForGrouping } from "./role-normalizer.ts";
+
+describe("normalizeRoleForGrouping", () => {
+  it("returns tool for tool result role variants", () => {
+    expect(normalizeRoleForGrouping("toolresult")).toBe("tool");
+    expect(normalizeRoleForGrouping("toolResult")).toBe("tool");
+    expect(normalizeRoleForGrouping("TOOLRESULT")).toBe("tool");
+    expect(normalizeRoleForGrouping("tool_result")).toBe("tool");
+    expect(normalizeRoleForGrouping("TOOL_RESULT")).toBe("tool");
+  });
+
+  it("returns tool for tool and function roles", () => {
+    expect(normalizeRoleForGrouping("tool")).toBe("tool");
+    expect(normalizeRoleForGrouping("Tool")).toBe("tool");
+    expect(normalizeRoleForGrouping("function")).toBe("tool");
+    expect(normalizeRoleForGrouping("Function")).toBe("tool");
+  });
+
+  it("preserves core roles", () => {
+    expect(normalizeRoleForGrouping("user")).toBe("user");
+    expect(normalizeRoleForGrouping("User")).toBe("User");
+    expect(normalizeRoleForGrouping("assistant")).toBe("assistant");
+    expect(normalizeRoleForGrouping("system")).toBe("system");
+  });
+
+  it("detects only tool result role variants", () => {
+    expect(isToolResultMessage({ role: "toolresult" })).toBe(true);
+    expect(isToolResultMessage({ role: "toolResult" })).toBe(true);
+    expect(isToolResultMessage({ role: "TOOLRESULT" })).toBe(true);
+    expect(isToolResultMessage({ role: "tool_result" })).toBe(true);
+    expect(isToolResultMessage({ role: "TOOL_RESULT" })).toBe(true);
+    expect(isToolResultMessage({ role: "user" })).toBe(false);
+    expect(isToolResultMessage({ role: "assistant" })).toBe(false);
+    expect(isToolResultMessage({ role: "tool" })).toBe(false);
+    expect(isToolResultMessage({})).toBe(false);
+    expect(isToolResultMessage({ content: "test" })).toBe(false);
+    expect(isToolResultMessage({ role: 123 })).toBe(false);
+    expect(isToolResultMessage({ role: null })).toBe(false);
+  });
+});
diff --git a/ui/src/ui/chat/role-normalizer.ts b/ui/src/ui/chat/role-normalizer.ts
new file mode 100644
index 00000000000..952e6a736fc
--- /dev/null
+++ b/ui/src/ui/chat/role-normalizer.ts
@@ -0,0 +1,35 @@
+/**
+ * Normalize role for grouping purposes.
+ */
+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;
+  }
+  if (role === "assistant") {
+    return "assistant";
+  }
+  if (role === "system") {
+    return "system";
+  }
+  // Keep tool-related roles distinct so the UI can style/toggle them.
+  if (
+    lower === "toolresult" ||
+    lower === "tool_result" ||
+    lower === "tool" ||
+    lower === "function"
+  ) {
+    return "tool";
+  }
+  return role;
+}
+
+/**
+ * Check if a message is a tool result message based on its role.
+ */
+export function isToolResultMessage(message: unknown): boolean {
+  const m = message as Record<string, unknown>;
+  const role = typeof m.role === "string" ? m.role.toLowerCase() : "";
+  return role === "toolresult" || role === "tool_result";
+}
diff --git a/ui/src/ui/chat/tool-cards.ts b/ui/src/ui/chat/tool-cards.ts
index f1844a454dd..2ef78533242 100644
--- a/ui/src/ui/chat/tool-cards.ts
+++ b/ui/src/ui/chat/tool-cards.ts
@@ -7,7 +7,7 @@ import type { SidebarContent } from "../sidebar-content.ts";
 import { formatToolDetail, resolveToolDisplay } from "../tool-display.ts";
 import type { ToolCard } from "../types/chat-types.ts";
 import { extractTextCached } from "./message-extract.ts";
-import { isToolResultMessage } from "./message-normalizer.ts";
+import { isToolResultMessage } from "./role-normalizer.ts";
 import { formatToolOutputForSidebar, getTruncatedPreview } from "./tool-helpers.ts";
 
 export type ToolPreview = NonNullable<ToolCard["preview"]>;
diff --git a/ui/src/ui/chat/tool-expansion-state.ts b/ui/src/ui/chat/tool-expansion-state.ts
index 7f0a6c8da81..214caa980a4 100644
--- a/ui/src/ui/chat/tool-expansion-state.ts
+++ b/ui/src/ui/chat/tool-expansion-state.ts
@@ -1,5 +1,5 @@
 import type { ChatItem, MessageGroup } from "../types/chat-types.ts";
-import { isToolResultMessage, normalizeRoleForGrouping } from "./message-normalizer.ts";
+import { isToolResultMessage, normalizeRoleForGrouping } from "./role-normalizer.ts";
 import { getOrCreateSessionCacheValue } from "./session-cache.ts";
 import { extractToolCards } from "./tool-cards.ts";