From a24d601b86ab188e672868c6aa8672b6a53246d6 Mon Sep 17 00:00:00 2001
From: Fusion <noreply@runfusion.ai>
Date: Fri, 15 May 2026 01:52:29 -0700
Subject: [PATCH] =?UTF-8?q?feat(FN-4583):=20complete=20Step=201=20?=
 =?UTF-8?q?=E2=80=94=20add=20chat=20room=20message=20tail=20ordering?=
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Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Fusion-Task-Id: FN-4583
Fusion-Task-Lineage: 4d9b088d-a705-4376-b547-15b37e5370aa
---
 .../src/__tests__/chat-store.rooms.test.ts    | 19 +++++++++++++++++++
 packages/core/src/chat-store.ts               |  6 ++++--
 packages/core/src/chat-types.ts               |  1 +
 3 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/packages/core/src/__tests__/chat-store.rooms.test.ts b/packages/core/src/__tests__/chat-store.rooms.test.ts
index 672b6d707..8cb29e946 100644
--- a/packages/core/src/__tests__/chat-store.rooms.test.ts
+++ b/packages/core/src/__tests__/chat-store.rooms.test.ts
@@ -146,6 +146,25 @@ describe("ChatStore — rooms (FN-3805..FN-3811 contract)", () => {
       expect(store.listRoomMessagesSince(room.id, new Date().toISOString())).toEqual([]);
     });
 
+    it("returns newest limited room window when order is desc while preserving ascending output", () => {
+      const room = store.createRoom({ name: "window-test" });
+
+      for (let i = 1; i <= 107; i += 1) {
+        store.addRoomMessage(room.id, { role: "user", content: `message-${i}` });
+      }
+
+      const newestWindow = store.getRoomMessages(room.id, { limit: 100, order: "desc" });
+      expect(newestWindow).toHaveLength(100);
+      expect(newestWindow[0]?.content).toBe("message-8");
+      expect(newestWindow.at(-1)?.content).toBe("message-107");
+      expect(newestWindow.some((message) => message.content === "message-1")).toBe(false);
+
+      const legacyWindow = store.getRoomMessages(room.id, { limit: 100 });
+      expect(legacyWindow).toHaveLength(100);
+      expect(legacyWindow[0]?.content).toBe("message-1");
+      expect(legacyWindow.at(-1)?.content).toBe("message-100");
+    });
+
     it("keeps cross-room and direct-vs-room histories isolated", () => {
       const session = store.createSession({ agentId: "agent-1" });
       store.addMessage(session.id, { role: "user", content: "direct" });
diff --git a/packages/core/src/chat-store.ts b/packages/core/src/chat-store.ts
index d08e59448..450e5ddcf 100644
--- a/packages/core/src/chat-store.ts
+++ b/packages/core/src/chat-store.ts
@@ -926,14 +926,16 @@ export class ChatStore extends EventEmitter<ChatStoreEvents> {
       params.push(filter.before);
     }
 
+    const order = filter?.order === "desc" ? "DESC" : "ASC";
     const rows = this.db.prepare(`
       SELECT * FROM chat_room_messages
       WHERE ${whereClauses.join(" AND ")}
-      ORDER BY createdAt ASC
+      ORDER BY createdAt ${order}
       LIMIT ? OFFSET ?
     `).all(...params, filter?.limit ?? 100, filter?.offset ?? 0) as ChatRoomMessageRow[];
 
-    return rows.map((row) => this.rowToRoomMessage(row));
+    const normalizedRows = filter?.order === "desc" ? [...rows].reverse() : rows;
+    return normalizedRows.map((row) => this.rowToRoomMessage(row));
   }
 
   listRoomMessagesSince(
diff --git a/packages/core/src/chat-types.ts b/packages/core/src/chat-types.ts
index fa7be410a..cdfc7ec78 100644
--- a/packages/core/src/chat-types.ts
+++ b/packages/core/src/chat-types.ts
@@ -263,4 +263,5 @@ export interface ChatRoomMessagesFilter {
   limit?: number;
   offset?: number;
   before?: string;
+  order?: "asc" | "desc";
 }