diff --git a/internal/cloud/access-control-preset-users.test.ts b/internal/cloud/access-control-preset-users.test.ts
new file mode 100644
index 00000000..bd84b677
--- /dev/null
+++ b/internal/cloud/access-control-preset-users.test.ts
@@ -0,0 +1,76 @@
+import assert from "node:assert/strict";
+import { createHash } from "node:crypto";
+import { test } from "bun:test";
+
+import { createCloudApiServer } from "./server.ts";
+
+test("preset user login keeps YAML nav claims when OpenFGA tuple sync is unavailable", async () => {
+  const password = "preset-user-password";
+  const server = createCloudApiServer({
+    env: {
+      HWLAB_ACCESS_CONTROL_REQUIRED: "1",
+      HWLAB_ACCESS_CONTROL_USERS_JSON: JSON.stringify([
+        {
+          id: "usr_v03_huiggao",
+          username: "huiggao@163.com",
+          displayName: "huiggao@163.com",
+          email: "huiggao@163.com",
+          role: "user",
+          status: "active",
+          navProfile: "code-mdtodo-only",
+          passwordHashEnv: "HWLAB_PRESET_USER_HUIGGAO_PASSWORD_HASH"
+        }
+      ]),
+      HWLAB_ACCESS_CONTROL_NAV_PROFILES_JSON: JSON.stringify([
+        { id: "code-mdtodo-only", allowedIds: ["workbench.code", "project.mdtodo"] }
+      ]),
+      HWLAB_PRESET_USER_HUIGGAO_PASSWORD_HASH: stablePasswordHash(password)
+    },
+    openFgaAuthorizer: throwingOpenFgaAuthorizer()
+  });
+  await listen(server);
+  try {
+    const { port } = server.address() as { port: number };
+    const login = await fetch(`http://127.0.0.1:${port}/auth/login`, {
+      method: "POST",
+      headers: { "content-type": "application/json" },
+      body: JSON.stringify({ username: "huiggao@163.com", password })
+    });
+    assert.equal(login.status, 200);
+    const loginBody = await login.json();
+    assert.deepEqual(loginBody.access.nav.allowedIds, ["workbench.code", "project.mdtodo"]);
+
+    const cookie = login.headers.get("set-cookie")?.split(";")[0] ?? "";
+    assert.match(cookie, /^hwlab_session=/u);
+    const session = await fetch(`http://127.0.0.1:${port}/auth/session`, { headers: { cookie } });
+    assert.equal(session.status, 200);
+    const sessionBody = await session.json();
+    assert.equal(sessionBody.actor.username, "huiggao@163.com");
+    assert.deepEqual(sessionBody.access.nav.allowedIds, ["workbench.code", "project.mdtodo"]);
+  } finally {
+    await close(server);
+  }
+});
+
+function stablePasswordHash(password: string) {
+  const salt = "preset-user-test-salt";
+  return `sha256:${salt}:${createHash("sha256").update(`${salt}:${password}`).digest("hex")}`;
+}
+
+function throwingOpenFgaAuthorizer() {
+  const error = Object.assign(new Error("openfga unavailable"), { code: "openfga_unavailable" });
+  return {
+    async describe() { return { ok: false, code: "openfga_unavailable" }; },
+    async check() { throw error; },
+    async writeTuple() { throw error; },
+    async deleteTuple() { throw error; }
+  };
+}
+
+function listen(server: any) {
+  return new Promise<void>((resolve) => server.listen(0, "127.0.0.1", resolve));
+}
+
+function close(server: any) {
+  return new Promise<void>((resolve, reject) => server.close((error: Error | undefined) => (error ? reject(error) : resolve())));
+}
diff --git a/internal/cloud/access-control.ts b/internal/cloud/access-control.ts
index d42e3cb2..39465d7b 100644
--- a/internal/cloud/access-control.ts
+++ b/internal/cloud/access-control.ts
@@ -569,7 +569,7 @@ class AccessController {
 
   async syncExistingAdminTuples() {
     const users = await this.store.listUsers?.() ?? [];
-    for (const user of users.filter((item) => item.role === "admin")) await this.syncUserAdminTuple(user, user);
+    for (const user of users.filter((item) => item.role === "admin")) await this.syncUserAdminTupleBestEffort(user, user);
   }
 
   async syncPresetUsers() {
@@ -589,13 +589,36 @@ class AccessController {
         email: spec.email || null,
         now: this.now()
       });
-      await this.syncUserAdminTuple(user, user);
+      await this.syncUserAdminTupleBestEffort(user, user);
       if (user?.role === "admin") {
-        for (const toolId of HWLAB_TOOL_IDS) await this.grantAccessTuple({ userId: user.id, relation: "can_use", object: openFgaObject("tool", toolId), admin: user });
+        for (const toolId of HWLAB_TOOL_IDS) {
+          await this.grantAccessTupleBestEffort(
+            { userId: user.id, relation: "can_use", object: openFgaObject("tool", toolId), admin: user },
+            "preset_admin_tool_tuple_sync_failed"
+          );
+        }
       }
     }
   }
 
+  async syncUserAdminTupleBestEffort(user, admin) {
+    try {
+      return await this.syncUserAdminTuple(user, admin);
+    } catch (error) {
+      warnAccessControlBootstrap("admin_tuple_sync_failed", error);
+      return { ok: false, degradedReason: "openfga_tuple_sync_failed" };
+    }
+  }
+
+  async grantAccessTupleBestEffort(input, code = "tuple_sync_failed") {
+    try {
+      return await this.grantAccessTuple(input);
+    } catch (error) {
+      warnAccessControlBootstrap(code, error);
+      return { ok: false, degradedReason: "openfga_tuple_sync_failed" };
+    }
+  }
+
   async grantAccessTuple({ userId, relation, object, admin }) {
     const result = await this.openFga.writeTuple({ userId, relation, object });
     if (result.ok !== false) await this.store.upsertAccessTuple?.({ userId, relation, object, createdByAdminId: admin?.id ?? userId, now: this.now() });
@@ -1795,6 +1818,17 @@ function navProfileByIdFromEnv(env = process.env, profileId) {
   if (!found) return null;
   return { id, allowedIds: uniqueTextList(found.allowedIds) };
 }
+function warnAccessControlBootstrap(code, error) {
+  const message = error instanceof Error ? error.message : String(error ?? "");
+  console.warn(JSON.stringify({
+    event: "hwlab.access-control.bootstrap.warning",
+    code,
+    errorName: error?.name ?? null,
+    errorCode: error?.code ?? null,
+    message: message.slice(0, 300),
+    valuesRedacted: true
+  }));
+}
 function uniqueTextList(value) {
   if (!Array.isArray(value)) return [];
   return [...new Set(value.map((item) => textOr(item, "")).filter(Boolean))];