feat: use KVNR instead of Nachname in fall_id generation

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/app/services/import_service.py

@@ -1,13 +1,15 @@
 """Import service for DAK Zweitmeinungs-Portal.
 
 Handles:
-- fall_id generation: YYYY-KW02d-fallgruppe-Nachname
+- fall_id generation: YYYY-KW02d-fallgruppe-KVNR (or random suffix)
 - Duplicate detection: by fall_id or (nachname, fallgruppe, datum, vorname, geburtsdatum)
 - Preview/confirm flow: preview_import() checks for duplicates, confirm_import() inserts
 - Import logging: writes ImportLog entry on each confirmed import
 """
 
 import logging
+import random
+import string
 
 from sqlalchemy.orm import Session
 
@@ -19,15 +21,24 @@ from app.services.csv_parser import ParsedCase
 logger = logging.getLogger(__name__)
 
 
+def generate_random_suffix(length: int = 6) -> str:
+    """Generate a random alphanumeric suffix (uppercase + digits)."""
+    charset = string.ascii_uppercase + string.digits
+    return "".join(random.choices(charset, k=length))
+
+
 def generate_fall_id(parsed: ParsedCase) -> str:
-    """Generate unique fall_id: YYYY-KW02d-fallgruppe-Nachname.
+    """Generate unique fall_id: YYYY-KW02d-fallgruppe-KVNR.
+
+    Uses KVNR as identifier. Falls back to 6-char random suffix if
+    KVNR is missing or empty.
 
     Examples:
-        - 2026-06-onko-Tonn
-        - 2026-12-kardio-Mueller
-        - 2026-06-intensiv-Daum
+        - 2026-06-onko-A123456789
+        - 2026-12-kardio-X7K9M2  (random fallback)
     """
-    return f"{parsed.jahr}-{parsed.kw:02d}-{parsed.fallgruppe}-{parsed.nachname}"
+    suffix = parsed.kvnr if parsed.kvnr else generate_random_suffix()
+    return f"{parsed.jahr}-{parsed.kw:02d}-{parsed.fallgruppe}-{suffix}"
 
 
 def check_duplicate(db: Session, parsed: ParsedCase) -> bool:

backend/tests/test_import.py

@@ -16,6 +16,7 @@ from app.services.import_service import (
     check_duplicate,
     confirm_import,
     generate_fall_id,
+    generate_random_suffix,
     preview_import,
 )
 
@@ -55,10 +56,10 @@ def _make_parsed_case(
 
 class TestGenerateFallId:
     def test_format(self):
-        """fall_id matches YYYY-KW-fallgruppe-Nachname format."""
-        pc = _make_parsed_case(nachname="Tonn", fallgruppe="onko", jahr=2026, kw=6)
+        """fall_id matches YYYY-KW-fallgruppe-KVNR format."""
+        pc = _make_parsed_case(nachname="Tonn", kvnr="D410126355", fallgruppe="onko", jahr=2026, kw=6)
         result = generate_fall_id(pc)
-        assert result == "2026-06-onko-Tonn"
+        assert result == "2026-06-onko-D410126355"
 
     def test_kw_padding_single_digit(self):
         """KW < 10 is zero-padded to 2 digits."""
@@ -79,31 +80,40 @@ class TestGenerateFallId:
         assert "-01-" in result
 
     def test_different_cases_produce_different_ids(self):
-        """Different patients/fallgruppen produce unique fall_ids."""
-        pc1 = _make_parsed_case(nachname="Tonn", fallgruppe="onko")
-        pc2 = _make_parsed_case(nachname="Daum", fallgruppe="intensiv")
-        pc3 = _make_parsed_case(nachname="Tonn", fallgruppe="kardio")
-
+        """Different KVNRs/fallgruppen produce unique fall_ids."""
+        pc1 = _make_parsed_case(kvnr="A111111111", fallgruppe="onko")
+        pc2 = _make_parsed_case(kvnr="B222222222", fallgruppe="intensiv")
+        pc3 = _make_parsed_case(kvnr="A111111111", fallgruppe="kardio")
         ids = {generate_fall_id(pc1), generate_fall_id(pc2), generate_fall_id(pc3)}
         assert len(ids) == 3
 
     def test_same_patient_same_week_same_fallgruppe(self):
-        """Same patient in same week and fallgruppe produces same fall_id."""
-        pc1 = _make_parsed_case(nachname="Mueller", fallgruppe="onko", kw=8)
-        pc2 = _make_parsed_case(nachname="Mueller", fallgruppe="onko", kw=8)
+        """Same KVNR in same week and fallgruppe produces same fall_id."""
+        pc1 = _make_parsed_case(kvnr="A111111111", fallgruppe="onko", kw=8)
+        pc2 = _make_parsed_case(kvnr="A111111111", fallgruppe="onko", kw=8)
         assert generate_fall_id(pc1) == generate_fall_id(pc2)
 
-    def test_umlauts_preserved(self):
-        """German umlauts in Nachname are preserved in fall_id."""
-        pc = _make_parsed_case(nachname="Krölls", fallgruppe="onko")
+    def test_random_suffix_when_no_kvnr(self):
+        """fall_id uses 6-char random suffix when KVNR is missing."""
+        pc = _make_parsed_case(kvnr=None, fallgruppe="onko", jahr=2026, kw=6)
         result = generate_fall_id(pc)
-        assert "Krölls" in result
+        parts = result.split("-")
+        assert parts[0] == "2026"
+        assert parts[1] == "06"
+        assert parts[2] == "onko"
+        suffix = parts[3]
+        assert len(suffix) == 6
+        assert suffix.isalnum()
+        assert suffix == suffix.upper()
 
-    def test_hyphenated_name(self):
-        """Hyphenated names are preserved in fall_id."""
-        pc = _make_parsed_case(nachname="Hähle-Jakelski", fallgruppe="sd")
+    def test_random_suffix_when_empty_kvnr(self):
+        """fall_id uses random suffix when KVNR is empty string."""
+        pc = _make_parsed_case(kvnr="", fallgruppe="onko", jahr=2026, kw=6)
         result = generate_fall_id(pc)
-        assert "Hähle-Jakelski" in result
+        parts = result.split("-")
+        suffix = parts[3]
+        assert len(suffix) == 6
+        assert suffix.isalnum()
 
     def test_all_fallgruppen(self):
         """fall_id works for all valid fallgruppen."""
@@ -120,6 +130,26 @@ class TestGenerateFallId:
         assert result.startswith("2027-")
 
 
+# ── generate_random_suffix tests ───────────────────────────────────────
+
+
+class TestGenerateRandomSuffix:
+    def test_length(self):
+        assert len(generate_random_suffix()) == 6
+
+    def test_charset(self):
+        """Only uppercase letters and digits."""
+        import re
+        for _ in range(50):
+            s = generate_random_suffix()
+            assert re.match(r'^[A-Z0-9]{6}$', s)
+
+    def test_uniqueness(self):
+        """Different calls produce different suffixes."""
+        suffixes = {generate_random_suffix() for _ in range(20)}
+        assert len(suffixes) >= 15
+
+
 # ── ImportRow schema tests ──────────────────────────────────────────────
 
 
@@ -149,10 +179,10 @@ class TestImportRowSchema:
             fallgruppe="kardio",
             datum=date(2026, 2, 2),
             is_duplicate=True,
-            fall_id="2026-06-kardio-Tonn",
+            fall_id="2026-06-kardio-D410126355",
         )
         assert row.is_duplicate is True
-        assert row.fall_id == "2026-06-kardio-Tonn"
+        assert row.fall_id == "2026-06-kardio-D410126355"
 
 
 # ── ImportPreview schema tests ──────────────────────────────────────────