diff --git a/packages/onebot/src/modules/message-actions.ts b/packages/onebot/src/modules/message-actions.ts
index b41ae29e..1cf03dce 100644
--- a/packages/onebot/src/modules/message-actions.ts
+++ b/packages/onebot/src/modules/message-actions.ts
@@ -12,6 +12,29 @@ import type { JsonArray, JsonObject, JsonValue, MessageMeta } from '../types';
 
 const log = createLogger('OneBot');
 
+/**
+ * message_id for a self-sent **c2c (private)** message.
+ *
+ * QQ-NT/Lagrange reference a c2c message in replies by the sender's
+ * `clientSequence`, NOT the server sequence — Lagrange builds the reply source
+ * as `OrigSeqs = ClientSequence != 0 ? ClientSequence : Sequence`
+ * (`dev/Lagrange.Core/.../Message/Entity/ForwardEntity.cs`). So a self-sent
+ * message MUST be keyed by `clientSequence`; otherwise an incoming reply's
+ * resolved id (`hash(clientSequence, peer, private)`) never matches the stored
+ * event and `get_msg` on the quoted message fails ("引用消息" can't be read,
+ * even though replying still works because it only needs the meta row).
+ *
+ * Falls back to the server sequence when `clientSequence` is 0 (e.g. the c2c
+ * file-send receipt), mirroring Lagrange's `||` exactly. Group messages do NOT
+ * use this — their replies reference the (shared) group sequence.
+ */
+function c2cSelfMessageId(
+  receipt: { sequence: number; clientSequence: number },
+  userId: number,
+): number {
+  return hashMessageIdInt32(receipt.clientSequence || receipt.sequence, userId, PRIVATE_MESSAGE_EVENT);
+}
+
 export async function getGroupMsgHistory(
   messageStore: MessageStore,
   groupId: number,
@@ -419,7 +442,7 @@ export async function sendPrivateMessage(
   }
   if (!lastReceipt) throw new Error('message is empty');
 
-  const messageId = hashMessageIdInt32(lastReceipt.sequence, userId, PRIVATE_MESSAGE_EVENT);
+  const messageId = c2cSelfMessageId(lastReceipt, userId);
   ref.cacheMessageMeta(messageId, {
     isGroup: false,
     targetId: userId,
@@ -585,7 +608,7 @@ export async function sendPrivateForwardMessage(
   const forwardId = await ref.bridge.apis.forward.upload(nodes, undefined, userId);
   const previewElement = buildForwardPreviewElement(forwardId, nodes, false, meta);
   const receipt = await ref.bridge.apis.message.sendPrivate(userId, [previewElement]);
-  const messageId = hashMessageIdInt32(receipt.sequence, userId, PRIVATE_MESSAGE_EVENT);
+  const messageId = c2cSelfMessageId(receipt, userId);
 
   ref.cacheMessageMeta(messageId, {
     isGroup: false,
@@ -672,7 +695,7 @@ export async function forwardSingleMessage(
     });
   } else {
     receipt = await ref.bridge.apis.message.sendPrivate(target.userId!, elements);
-    messageIdOut = hashMessageIdInt32(receipt.sequence, target.userId!, PRIVATE_MESSAGE_EVENT);
+    messageIdOut = c2cSelfMessageId(receipt, target.userId!);
     ref.cacheMessageMeta(messageIdOut, {
       isGroup: false,
       targetId: target.userId!,
diff --git a/packages/onebot/tests/send-private-c2c-file.test.ts b/packages/onebot/tests/send-private-c2c-file.test.ts
index fb1e8ab8..e160dc98 100644
--- a/packages/onebot/tests/send-private-c2c-file.test.ts
+++ b/packages/onebot/tests/send-private-c2c-file.test.ts
@@ -18,6 +18,8 @@ import { describe, expect, it, vi } from 'vitest';
 import type { BridgeInterface } from '../../src/bridge/bridge-interface';
 import type { OneBotInstanceContext } from '../src/instance-context';
 import { sendPrivateMessage } from '../src/modules/message-actions';
+import { hashMessageIdInt32, PRIVATE_MESSAGE_EVENT } from '../src/message-id';
+import { resolveReplyId } from '../src/event-converter/utils';
 
 function fakeBridge(overrides: Partial<BridgeInterface> = {}): BridgeInterface {
   return new Proxy(overrides as BridgeInterface, {
@@ -257,3 +259,68 @@ describe('send_private_msg with {type:"file"} segment', () => {
     expect(sendC2cFileMessage).not.toHaveBeenCalled();
   });
 });
+
+// Regression: a friend replied to a bot self-sent private message; the bot
+// called get_msg on the quoted id and got "message not found" (then replied
+// "无法解析申请信息"). c2c replies reference the message by clientSequence
+// (Lagrange OrigSeqs = ClientSequence||Sequence), but the self-sent message was
+// keyed by the server (private) sequence — so the reply's resolved id never
+// matched the stored event. Self-sent c2c messages must be keyed by
+// clientSequence so the two agree.
+describe('send_private_msg self-sent message_id (c2c reply / get_msg resolution)', () => {
+  it('keys a self-sent private message by clientSequence, matching an incoming reply id', async () => {
+    // clientSequence and (server) sequence deliberately differ.
+    const receipt = { messageId: 1, sequence: 888, clientSequence: 21196, random: 7, timestamp: 1700000000 };
+    const sendPrivate = vi.fn(async () => receipt);
+    const cacheMessageMeta = vi.fn();
+    const bridge = fakeBridge({
+      apis: { message: { sendPrivate } } as any,
+      resolveUserUid: vi.fn(async () => 'u_peer'),
+    } as any);
+    const ctx = {
+      uin: '10001', selfId: 10001, bridge,
+      messageStore: { findEvent: () => null } as any,
+      cacheMessageMeta,
+      mediaStore: {} as any,
+      musicSignUrl: '',
+    } as unknown as OneBotInstanceContext;
+
+    const result = await sendPrivateMessage(ctx, 67890, 'hi', false);
+
+    // The id an incoming reply to this message resolves to — the peer quotes it
+    // by clientSequence, so resolveReplyId(...) hashes clientSequence. The
+    // resolver mirrors how instance.ts wires messageIdResolver (4-arg → hash).
+    const messageIdResolver = (_isGroup: boolean, sessionId: number, seq: number, eventName: string) =>
+      hashMessageIdInt32(seq, sessionId, eventName);
+    const incomingReplyId = resolveReplyId(false, 67890, 21196, messageIdResolver);
+    expect(result.messageId).toBe(incomingReplyId);
+    expect(result.messageId).toBe(hashMessageIdInt32(21196, 67890, PRIVATE_MESSAGE_EVENT));
+    // …and specifically NOT the server (private) sequence, which was the bug.
+    expect(result.messageId).not.toBe(hashMessageIdInt32(888, 67890, PRIVATE_MESSAGE_EVENT));
+    // Meta still carries both sequences (recall needs the server seq + clientSeq).
+    expect(cacheMessageMeta).toHaveBeenCalledWith(
+      incomingReplyId,
+      expect.objectContaining({ clientSequence: 21196, sequence: 888 }),
+    );
+  });
+
+  it('falls back to the server sequence when clientSequence is 0 (file-send receipt)', async () => {
+    const receipt = { messageId: 1, sequence: 888, clientSequence: 0, random: 7, timestamp: 1700000000 };
+    const sendPrivate = vi.fn(async () => receipt);
+    const cacheMessageMeta = vi.fn();
+    const bridge = fakeBridge({
+      apis: { message: { sendPrivate } } as any,
+      resolveUserUid: vi.fn(async () => 'u_peer'),
+    } as any);
+    const ctx = {
+      uin: '10001', selfId: 10001, bridge,
+      messageStore: { findEvent: () => null } as any,
+      cacheMessageMeta,
+      mediaStore: {} as any,
+      musicSignUrl: '',
+    } as unknown as OneBotInstanceContext;
+
+    const result = await sendPrivateMessage(ctx, 67890, 'hi', false);
+    expect(result.messageId).toBe(hashMessageIdInt32(888, 67890, PRIVATE_MESSAGE_EVENT));
+  });
+});