BUG: don't modify case of surnames

src/citeable/_keys.py

@@ -17,7 +17,7 @@ def generate_key(author: list[str], year: int) -> str:
 
     Algorithm:
     1. Extract surname from the first author (before comma, or last token).
-    2. Strip non-ASCII and spaces; title-case.
+    2. Strip non-ASCII and spaces; preserve original case.
     3. Return ``"{surname}.{year}"``.
     """
     surname = extract_surname(author[0])

src/citeable/_validate.py

@@ -27,11 +27,11 @@ def extract_surname(name: str) -> str:
     """Extract surname from an author name string.
 
     Handles both ``"Last, First"`` and ``"First Last"`` formats.
-    Returns the surname stripped of non-ASCII characters and title-cased.
+    Returns the surname stripped of non-ASCII characters, preserving original case.
     """
     if "," in name:
         surname = name.split(",", maxsplit=1)[0].strip()
     else:
         surname = name.rsplit(maxsplit=1)[-1].strip()
     surname = re.sub(r"[^A-Za-z]", "", surname)
-    return surname.title()
+    return surname

tests/test_keys.py

@@ -4,6 +4,7 @@
 
 from citeable import Article, Misc, Software, assign_unique_keys
 from citeable._keys import generate_key
+from citeable._validate import extract_surname
 
 # ── generate_key ─────────────────────────────────────────────────────────
 
@@ -20,8 +21,18 @@ def test_generate_key_strips_non_ascii():
     assert generate_key(["Müller, Hans"], 2020) == "Mller.2020"
 
 
-def test_generate_key_title_cases():
-    assert generate_key(["van der berg, Jan"], 2020) == "Vanderberg.2020"
+def test_generate_key_preserves_case():
+    assert generate_key(["van der berg, Jan"], 2020) == "vanderberg.2020"
+
+
+def test_generate_key_camel_case_preserved():
+    assert generate_key(["McArthur, Robert"], 2021) == "McArthur.2021"
+    assert generate_key(["McDonald, Daniel"], 2022) == "McDonald.2022"
+
+
+def test_extract_surname_preserves_case():
+    assert extract_surname("McArthur, Robert") == "McArthur"
+    assert extract_surname("McDonald, Daniel") == "McDonald"
 
 
 # ── assign_unique_keys ──────────────────────────────────────────────────