diff --git a/src/domain/threads/reference.ts b/src/domain/threads/reference.ts
index f006af7b..ffaab660 100644
--- a/src/domain/threads/reference.ts
+++ b/src/domain/threads/reference.ts
@@ -1,6 +1,7 @@
 import type { Thread } from "../../generated/app-server/v2/Thread";
 import type { ThreadItem } from "../../generated/app-server/v2/ThreadItem";
 import type { Turn } from "../../generated/app-server/v2/Turn";
+import type { UserInput } from "../../generated/app-server/v2/UserInput";
 import { inputToText, shortThreadId } from "../../utils";
 import { getThreadTitle } from "./model";
 
@@ -18,6 +19,12 @@ export interface ReferencedThreadTurn {
   assistantText: string | null;
 }
 
+export interface ReferencedThreadInput {
+  input: UserInput[];
+  referencedThread: ReferencedThreadDisplay;
+  status: string;
+}
+
 export function referencedThreadTurns(turns: Turn[]): ReferencedThreadTurn[] {
   return [...turns]
     .sort((a, b) => (a.startedAt ?? 0) - (b.startedAt ?? 0))
@@ -69,6 +76,20 @@ export function referencedThreadDisplay(thread: Thread, count: number): Referenc
   };
 }
 
+export function referencedThreadInput(
+  thread: Thread,
+  turns: readonly ReferencedThreadTurn[],
+  userRequest: string,
+  messageInput: UserInput[],
+): ReferencedThreadInput {
+  const prompt = referencedThreadPrompt(thread, [...turns], userRequest);
+  return {
+    input: [{ type: "text", text: prompt, text_elements: [] }, ...messageInput.filter((item) => item.type !== "text")],
+    referencedThread: referencedThreadDisplay(thread, turns.length),
+    status: referencedThreadStatus(thread, turns.length),
+  };
+}
+
 export function referencedThreadDisplayFromPrompt(text: string): { text: string; reference: ReferencedThreadDisplay } | null {
   const headerStart = text.indexOf("[Codex Panel referenced thread]");
   const headerEnd = text.indexOf("[/Codex Panel referenced thread]");
diff --git a/src/features/chat/view.ts b/src/features/chat/view.ts
index 453d3c27..6d8e8605 100644
--- a/src/features/chat/view.ts
+++ b/src/features/chat/view.ts
@@ -31,9 +31,7 @@ import {
   type ChatState,
 } from "./chat-state";
 import {
-  referencedThreadDisplay,
-  referencedThreadPrompt,
-  referencedThreadStatus,
+  referencedThreadInput as buildReferencedThreadInput,
   referencedThreadTurns,
   REFERENCED_THREAD_TURN_LIMIT,
   type ReferencedThreadDisplay,
@@ -910,13 +908,9 @@ export class CodexChatView extends ItemView {
         this.addSystemMessage("Referenced thread has no readable conversation turns.");
         return null;
       }
-      const prompt = referencedThreadPrompt(thread, turns, message);
-      const messageInput = this.composerController.codexInput(message);
-      this.setStatus(referencedThreadStatus(thread, turns.length));
-      return {
-        input: [{ type: "text", text: prompt, text_elements: [] }, ...messageInput.filter((item) => item.type !== "text")],
-        referencedThread: referencedThreadDisplay(thread, turns.length),
-      };
+      const reference = buildReferencedThreadInput(thread, turns, message, this.composerController.codexInput(message));
+      this.setStatus(reference.status);
+      return reference;
     } catch (error) {
       this.addSystemMessage(error instanceof Error ? error.message : String(error));
       return null;
diff --git a/tests/domain/threads/reference.test.ts b/tests/domain/threads/reference.test.ts
index 07266bf8..41326c31 100644
--- a/tests/domain/threads/reference.test.ts
+++ b/tests/domain/threads/reference.test.ts
@@ -2,7 +2,12 @@ import { describe, expect, it } from "vitest";
 
 import type { Thread } from "../../../src/generated/app-server/v2/Thread";
 import type { Turn } from "../../../src/generated/app-server/v2/Turn";
-import { referencedThreadDisplayFromPrompt, referencedThreadPrompt, referencedThreadTurns } from "../../../src/domain/threads/reference";
+import {
+  referencedThreadDisplayFromPrompt,
+  referencedThreadInput,
+  referencedThreadPrompt,
+  referencedThreadTurns,
+} from "../../../src/domain/threads/reference";
 
 function thread(overrides: Partial<Thread> = {}): Thread {
   return {
@@ -97,4 +102,17 @@ describe("thread reference context", () => {
       },
     });
   });
+
+  it("builds slash command input while preserving non-text attachments", () => {
+    const source = thread();
+    const input = referencedThreadInput(source, [{ userText: "元の依頼", assistantText: "回答" }], "この続きです", [
+      { type: "text", text: "この続きです", text_elements: [] },
+      { type: "mention", name: "Note", path: "Note.md" },
+    ]);
+
+    expect(input.status).toBe("Referencing 019abcde (1/20 turns).");
+    expect(input.referencedThread).toMatchObject({ threadId: source.id, title: "参照元", includedTurns: 1 });
+    expect(input.input[0]).toMatchObject({ type: "text" });
+    expect(input.input[1]).toEqual({ type: "mention", name: "Note", path: "Note.md" });
+  });
 });