From 30efe0b70289db941d0bcb392bdb30a46a6cba58 Mon Sep 17 00:00:00 2001
From: Jack Wotherspoon <jackwoth@google.com>
Date: Tue, 2 Jun 2026 13:55:44 -0400
Subject: [PATCH] fix(cli): filter out tool response metadata from resumed
 session history

---
 packages/cli/src/utils/sessionUtils.test.ts | 55 +++++++++++++++++++++
 packages/cli/src/utils/sessionUtils.ts      | 16 +++---
 2 files changed, 63 insertions(+), 8 deletions(-)

diff --git a/packages/cli/src/utils/sessionUtils.test.ts b/packages/cli/src/utils/sessionUtils.test.ts
index cfdadf795f..8c23c98f64 100644
--- a/packages/cli/src/utils/sessionUtils.test.ts
+++ b/packages/cli/src/utils/sessionUtils.test.ts
@@ -1141,4 +1141,59 @@ describe('convertSessionToHistoryFormats', () => {
       throw new Error('Expected tool_group history item');
     }
   });
+
+  it('should NOT include tool response text messages in uiHistory', () => {
+    const messages: MessageRecord[] = [
+      {
+        id: '1',
+        type: 'user',
+        timestamp: new Date().toISOString(),
+        content: [{ text: 'Hello' }],
+      },
+      {
+        id: '2',
+        type: 'gemini',
+        timestamp: new Date().toISOString(),
+        content: [{ text: 'Thinking...' }],
+        toolCalls: [
+          {
+            id: 'call_1',
+            name: 'read_file',
+            args: { path: 'test.ts' },
+            status: CoreToolCallStatus.Success,
+            timestamp: new Date().toISOString(),
+            result: [{ text: 'file content' }],
+          },
+        ],
+      },
+      {
+        id: '3',
+        type: 'user',
+        timestamp: new Date().toISOString(),
+        content: [
+          {
+            functionResponse: {
+              name: 'read_file',
+              response: { content: 'file content' },
+            },
+          },
+        ],
+      },
+    ];
+
+    const { uiHistory } = convertSessionToHistoryFormats(messages);
+
+    const userMessages = uiHistory.filter((item) => item.type === 'user');
+    expect(userMessages).toHaveLength(1);
+    expect(userMessages[0].text).toBe('Hello');
+
+    const toolGroups = uiHistory.filter((item) => item.type === 'tool_group');
+    expect(toolGroups).toHaveLength(1);
+
+    // Verify no message contains the "[Function Response" string which comes from verbose partToString
+    const allText = uiHistory
+      .map((item) => ('text' in item ? item.text : ''))
+      .join(' ');
+    expect(allText).not.toContain('[Function Response');
+  });
 });
diff --git a/packages/cli/src/utils/sessionUtils.ts b/packages/cli/src/utils/sessionUtils.ts
index a2918eae3e..b48a2f9334 100644
--- a/packages/cli/src/utils/sessionUtils.ts
+++ b/packages/cli/src/utils/sessionUtils.ts
@@ -6,13 +6,13 @@
 
 import {
   checkExhaustive,
-  partListUnionToString,
   SESSION_FILE_PREFIX,
   CoreToolCallStatus,
   type Storage,
   type ConversationRecord,
   type MessageRecord,
   loadConversationRecord,
+  partToString,
 } from '@google/gemini-cli-core';
 import * as fs from 'node:fs/promises';
 import path from 'node:path';
@@ -171,7 +171,7 @@ export const extractFirstUserMessage = (messages: MessageRecord[]): string => {
   const userMessage = messages
     // First try filtering out slash commands.
     .filter((msg) => {
-      const content = partListUnionToString(msg.content);
+      const content = partToString(msg.content);
       return (
         !content.startsWith('/') &&
         !content.startsWith('?') &&
@@ -186,9 +186,9 @@ export const extractFirstUserMessage = (messages: MessageRecord[]): string => {
     // Fallback to first user message even if it's a slash command
     const firstMsg = messages.find((msg) => msg.type === 'user');
     if (!firstMsg) return 'Empty conversation';
-    content = cleanMessage(partListUnionToString(firstMsg.content));
+    content = cleanMessage(partToString(firstMsg.content));
   } else {
-    content = cleanMessage(partListUnionToString(userMessage.content));
+    content = cleanMessage(partToString(userMessage.content));
   }
 
   return content;
@@ -312,14 +312,14 @@ export const getAllSessionFiles = async (
 
           if (options.includeFullContent) {
             fullContent = content.messages
-              .map((msg) => partListUnionToString(msg.content))
+              .map((msg) => partToString(msg.content))
               .join(' ');
             messages = content.messages.map((msg) => ({
               role:
                 msg.type === 'user'
                   ? ('user' as const)
                   : ('assistant' as const),
-              content: partListUnionToString(msg.content),
+              content: partToString(msg.content),
             }));
           }
 
@@ -601,9 +601,9 @@ export function convertSessionToHistoryFormats(
 
     // Add the message only if it has content
     const displayContentString = msg.displayContent
-      ? partListUnionToString(msg.displayContent)
+      ? partToString(msg.displayContent)
       : undefined;
-    const contentString = partListUnionToString(msg.content);
+    const contentString = partToString(msg.content);
     const uiText = displayContentString || contentString;
 
     if (uiText.trim()) {