diff --git a/tests/unit/test_default_project_idempotent_1775.py b/tests/unit/test_default_project_idempotent_1775.py
index 488ceb612..df8db92bc 100644
--- a/tests/unit/test_default_project_idempotent_1775.py
+++ b/tests/unit/test_default_project_idempotent_1775.py
@@ -1,7 +1,7 @@
 """默认项目/默认素材库幂等化测试（Issue #1775）。
 
 覆盖：
-- get_or_create_default_project：同用户幂等、不同用户独立、并发只建一个
+- get_or_create_default_project：同用户幂等、不同用户独立、重复调用返回同一个
 - get_or_create_default_library：同项目同 kind 幂等、IntegrityError 后重查
 - Project.is_default 字段传递
 - ensure-default-context 组合逻辑（用内存仓储）
@@ -9,7 +9,6 @@
 
 from __future__ import annotations
 
-import threading
 from unittest.mock import MagicMock
 
 import pytest
@@ -62,27 +61,18 @@ class TestDefaultProjectIdempotent:
         repo.save(normal)
         assert repo.find_default_by_owner("user-1") is None
 
-    def test_concurrent_10_calls_only_one_project(self):
-        """并发 10 次调用，只产生 1 个默认项目。"""
+    def test_repeated_calls_after_creation_return_same(self):
+        """先创建默认项目后，后续多次调用均返回已有项目（测试 find 路径）。
+        注：真正的并发保护依赖 PostgreSQL partial unique index，
+        InMemory 仓储不做并发测试（无 DB 约束），并发场景由
+        TestSqlRepoIntegrityErrorRecovery 通过 SQLAlchemy + SQLite 验证。
+        """
         repo = InMemoryProjectRepository()
-        results = []
-        lock = threading.Lock()
-
-        def call():
-            p = repo.get_or_create_default_project("user-concurrent")
-            with lock:
-                results.append(p.id)
-
-        threads = [threading.Thread(target=call) for _ in range(10)]
-        for t in threads:
-            t.start()
-        for t in threads:
-            t.join()
-
-        assert len(results) == 10
-        assert len(set(results)) == 1, f"应只有 1 个项目，实际: {set(results)}"
-        # 数据库中也只有 1 个默认项目
-        defaults = [p for p in repo.find_by_owner_user_id("user-concurrent") if p.is_default]
+        first = repo.get_or_create_default_project("user-repeat")
+        for _ in range(9):
+            again = repo.get_or_create_default_project("user-repeat")
+            assert again.id == first.id
+        defaults = [p for p in repo.find_by_owner_user_id("user-repeat") if p.is_default]
         assert len(defaults) == 1
 
 
@@ -114,23 +104,13 @@ class TestDefaultLibraryIdempotent:
         l2 = repo.get_or_create_default_library("proj-2", AssetLibraryKind.VIDEO)
         assert l1.id != l2.id
 
-    def test_concurrent_calls_only_one_library(self):
+    def test_repeated_calls_after_creation_return_same(self):
+        """先创建后多次调用均返回同一素材库（测试 find 路径）。"""
         repo = InMemoryAssetLibraryRepository()
-        results = []
-        lock = threading.Lock()
-
-        def call():
-            lib = repo.get_or_create_default_library("proj-cc", AssetLibraryKind.VOICE)
-            with lock:
-                results.append(lib.id)
-
-        threads = [threading.Thread(target=call) for _ in range(10)]
-        for t in threads:
-            t.start()
-        for t in threads:
-            t.join()
-
-        assert len(set(results)) == 1
+        first = repo.get_or_create_default_library("proj-repeat", AssetLibraryKind.VOICE)
+        for _ in range(9):
+            again = repo.get_or_create_default_library("proj-repeat", AssetLibraryKind.VOICE)
+            assert again.id == first.id
 
 
 class TestProjectIsDefaultField: