diff --git a/src/data/sessions.test.ts b/src/data/sessions.test.ts
index b7a8dcf..c711e8e 100644
--- a/src/data/sessions.test.ts
+++ b/src/data/sessions.test.ts
@@ -2,7 +2,7 @@ import { describe, it, expect, beforeEach, afterEach, vi } from "vitest";
 import { createHash } from "node:crypto";
 import { createDatabase, type BotDatabase } from "./database.js";
 import { createUserStore, type UserStore } from "./users.js";
-import { createSessionStore, type SessionStore, SESSION_TTL_MS, SESSION_TOUCH_INTERVAL_MS, MAX_SESSIONS_PER_USER } from "./sessions.js";
+import { createSessionStore, type SessionStore, SESSION_TTL_MS, SESSION_TOUCH_INTERVAL_MS, MAX_SESSIONS_PER_USER, GUEST_SESSION_TTL_MS } from "./sessions.js";
 
 function sha256(token: string) {
   return createHash("sha256").update(token).digest("hex");
@@ -126,3 +126,38 @@ describe("SessionStore", () => {
     expect(count).toBe(MAX_SESSIONS_PER_USER);
   });
 });
+
+describe("guest sessions", () => {
+  let botDb: BotDatabase;
+  let sessions: SessionStore;
+
+  beforeEach(() => {
+    botDb = createDatabase(":memory:");
+    sessions = createSessionStore(botDb.db);
+    // Create the synthetic guest user row to satisfy the sessions FK.
+    botDb.db
+      .prepare("INSERT INTO users (id, username, passwordHash, createdAt, updatedAt, role) VALUES ('__guest__','游客','!',?,?, 'guest')")
+      .run(Date.now(), Date.now());
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+    botDb.close();
+  });
+
+  it("skipCap lets more than MAX_SESSIONS_PER_USER coexist for one principal", () => {
+    const tokens: string[] = [];
+    for (let i = 0; i < MAX_SESSIONS_PER_USER + 3; i++) {
+      tokens.push(sessions.createSession("__guest__", { ttlMs: GUEST_SESSION_TTL_MS, skipCap: true }).token);
+    }
+    // The first token must STILL validate (not evicted).
+    expect(sessions.validateAndTouch(tokens[0])?.role).toBe("guest");
+    const n = (botDb.db.prepare("SELECT COUNT(*) AS n FROM sessions WHERE userId='__guest__'").get() as { n: number }).n;
+    expect(n).toBe(MAX_SESSIONS_PER_USER + 3);
+  });
+
+  it("ttlMs sets a shorter expiry than the default", () => {
+    const { expiresAt } = sessions.createSession("__guest__", { ttlMs: GUEST_SESSION_TTL_MS, skipCap: true });
+    expect(expiresAt).toBeLessThanOrEqual(Date.now() + GUEST_SESSION_TTL_MS + 50);
+  });
+});
diff --git a/src/data/sessions.ts b/src/data/sessions.ts
index bf446d2..6da5930 100644
--- a/src/data/sessions.ts
+++ b/src/data/sessions.ts
@@ -2,17 +2,18 @@ import { createHash, randomBytes } from "node:crypto";
 import type Database from "better-sqlite3";
 
 export const SESSION_TTL_MS = 7 * 24 * 60 * 60 * 1000; // 7 days
+export const GUEST_SESSION_TTL_MS = 24 * 60 * 60 * 1000; // 1 day — guests are short-lived
 export const SESSION_TOUCH_INTERVAL_MS = 60 * 60 * 1000; // 1 hour
 export const MAX_SESSIONS_PER_USER = 10;
 
 export interface SessionValidation {
   userId: string;
   username: string;
-  role: "admin" | "member";
+  role: "admin" | "member" | "guest";
 }
 
 export interface SessionStore {
-  createSession(userId: string): { token: string; expiresAt: number };
+  createSession(userId: string, opts?: { ttlMs?: number; skipCap?: boolean }): { token: string; expiresAt: number };
   validateAndTouch(rawToken: string): SessionValidation | null;
   deleteSession(rawToken: string): void;
   deleteAllForUser(userId: string, exceptToken?: string): void;
@@ -47,7 +48,7 @@ export function createSessionStore(db: Database.Database): SessionStore {
   );
 
   return {
-    createSession(userId) {
+    createSession(userId, opts) {
       // Cap concurrent sessions per user — oldest gets evicted on overflow.
       // Wrap the count → delete → insert in a transaction so concurrent logins
       // for the same user can't both pass the cap check and both insert,
@@ -55,11 +56,13 @@ export function createSessionStore(db: Database.Database): SessionStore {
       const token = randomBytes(32).toString("base64url");
       const id = hashToken(token);
       const now = Date.now();
-      const expiresAt = now + SESSION_TTL_MS;
+      const expiresAt = now + (opts?.ttlMs ?? SESSION_TTL_MS);
       const tx = db.transaction(() => {
-        const existing = (countForUserStmt.get(userId) as { n: number }).n;
-        if (existing >= MAX_SESSIONS_PER_USER) {
-          deleteOldestForUserStmt.run(userId, existing - MAX_SESSIONS_PER_USER + 1);
+        if (!opts?.skipCap) {
+          const existing = (countForUserStmt.get(userId) as { n: number }).n;
+          if (existing >= MAX_SESSIONS_PER_USER) {
+            deleteOldestForUserStmt.run(userId, existing - MAX_SESSIONS_PER_USER + 1);
+          }
         }
         insertStmt.run(id, userId, now, expiresAt, now);
       });
@@ -82,7 +85,7 @@ export function createSessionStore(db: Database.Database): SessionStore {
       if (now - row.lastSeenAt > SESSION_TOUCH_INTERVAL_MS) {
         touchStmt.run(now, now + SESSION_TTL_MS, id);
       }
-      return { userId: row.userId, username: row.username, role: row.role as "admin" | "member" };
+      return { userId: row.userId, username: row.username, role: row.role as "admin" | "member" | "guest" };
     },
 
     deleteSession(rawToken) {