06/15 Phase 1 + 2 codes

app/utils/text.py

@@ -0,0 +1,26 @@
+"""Text normalization for accent-insensitive search.
+
+Strips diacritics so "phở" -> "pho" and "ñandú" -> "nandu".
+Used now for display/utility; drives `title_norm` shadow column in Phase 2 listings.
+"""
+import unicodedata
+
+# Vietnamese đ/Đ do not decompose via NFKD, map explicitly.
+_EXPLICIT = {
+    "đ": "d", "Đ": "d",
+    "ð": "d", "Ð": "d",
+}
+
+
+def normalize(text: str) -> str:
+    if not text:
+        return ""
+    out = []
+    for ch in text:
+        if ch in _EXPLICIT:
+            out.append(_EXPLICIT[ch])
+            continue
+        decomposed = unicodedata.normalize("NFKD", ch)
+        stripped = "".join(c for c in decomposed if not unicodedata.combining(c))
+        out.append(stripped)
+    return "".join(out).lower().strip()