fix: reject REDIS_CACHE_TTL<=0 (kill implicit never-expire)

tests/unit/test_infra_settings.py

@@ -0,0 +1,16 @@
+"""工程配置校验单元测试（Redis 缓存 TTL fail-loud）。"""
+
+from __future__ import annotations
+
+import pytest
+
+
+def test_redis_cache_ttl_zero_rejected() -> None:
+    """REDIS_CACHE_TTL<=0 必须启动即报错，消灭'0=永不过期'隐式语义。"""
+    from adapters.redis_cache import _resolve_cache_ttl
+
+    with pytest.raises(ValueError, match="REDIS_CACHE_TTL"):
+        _resolve_cache_ttl(0)
+    with pytest.raises(ValueError, match="REDIS_CACHE_TTL"):
+        _resolve_cache_ttl(-1)
+    assert _resolve_cache_ttl(86400) == 86400