新增PDF生成并发设置

backend/tests/test_pdf_limiter.py

@@ -0,0 +1,13 @@
+import pytest
+
+from app.services.pdf import PdfGenerationBusy, PdfGenerationLimiter
+
+
+def test_pdf_generation_limiter_times_out_when_full():
+    limiter = PdfGenerationLimiter()
+    limiter.acquire(limit=1)
+    with pytest.raises(PdfGenerationBusy):
+        limiter.acquire(limit=1, timeout_seconds=0)
+    limiter.release()
+    limiter.acquire(limit=1, timeout_seconds=0)
+    limiter.release()

backend/tests/test_system_settings.py

@@ -0,0 +1,8 @@
+from app.services.system_settings import _coerce_limit
+
+
+def test_pdf_concurrency_limit_is_clamped():
+    assert _coerce_limit(None) == 2
+    assert _coerce_limit(0) == 1
+    assert _coerce_limit(6) == 6
+    assert _coerce_limit(99) == 10