fix: uploaded files with no extension become permanently unresolvable (#1275)

* fix: accept extensionless upload ids so files like Dockerfile resolve

* test: upload id validation accepts extensionless ids

tests/test_upload_id_validation.py

@@ -0,0 +1,21 @@
+"""Tests for upload id validation (src/upload_handler.py)."""
+import uuid
+
+from src.upload_handler import is_valid_upload_id
+
+
+def test_extensionless_id_is_valid():
+    # save_upload builds `{uuid.hex}{ext}`; a file with no extension yields a
+    # bare 32-hex id, which used to fail validation and become unresolvable.
+    assert is_valid_upload_id(uuid.uuid4().hex) is True
+
+
+def test_id_with_extension_still_valid():
+    assert is_valid_upload_id(uuid.uuid4().hex + ".png") is True
+
+
+def test_invalid_ids_rejected():
+    assert is_valid_upload_id("not-an-id") is False
+    assert is_valid_upload_id(uuid.uuid4().hex + ".") is False
+    assert is_valid_upload_id("") is False
+    assert is_valid_upload_id(uuid.uuid4().hex + ".tar.gz") is False