Fix thumbnail backoff and watchlist fallback matching

title_matching.py

@@ -0,0 +1,83 @@
+#!/usr/bin/env python3
+
+"""Shared anime title normalization and matching helpers."""
+
+import re
+import unicodedata
+
+
+def normalize_title_key(value):
+    text = unicodedata.normalize("NFKD", str(value or ""))
+    text = "".join(char for char in text if not unicodedata.combining(char))
+    text = text.lower()
+    text = re.sub(r"\((19|20)\d{2}\)", " ", text)
+    text = re.sub(r"[^a-z0-9]+", " ", text)
+    return re.sub(r"\s+", " ", text).strip()
+
+
+def normalize_identity_title_key(value):
+    text = normalize_title_key(value)
+    if not text:
+        return ""
+    text = re.sub(r"\b(\d+)(st|nd|rd|th)\s+season\b", r"season \1", text)
+    return re.sub(r"\s+", " ", text).strip()
+
+
+def base_title_variants(value):
+    text = str(value or "").strip()
+    variants = []
+    if text:
+        variants.append(text)
+    patterns = [
+        r"\s+\((19|20)\d{2}\)\s*$",
+        r"\s+season\s+\d+\s*$",
+        r"\s+part\s+\d+\s*$",
+        r"\s+cour\s+\d+\s*$",
+        r"\s+\d+(st|nd|rd|th)\s+season\s*$",
+    ]
+    changed = True
+    current = text
+    while current and changed:
+        changed = False
+        for pattern in patterns:
+            trimmed = re.sub(pattern, "", current, flags=re.IGNORECASE).strip(" -:")
+            if trimmed and trimmed != current:
+                current = trimmed
+                if current not in variants:
+                    variants.append(current)
+                changed = True
+    return variants
+
+
+def title_match_variants(value):
+    variants = set()
+    for raw_value in base_title_variants(value):
+        normalized = normalize_title_key(raw_value)
+        if normalized:
+            variants.add(normalized)
+        stripped = re.sub(r"\b(19|20)\d{2}\b", " ", normalized)
+        stripped = re.sub(r"\s+", " ", stripped).strip()
+        if stripped:
+            variants.add(stripped)
+    return variants
+
+
+def identity_title_variants(value):
+    variants = set()
+    normalized = normalize_identity_title_key(value)
+    if normalized:
+        variants.add(normalized)
+        stripped = re.sub(r"\b(19|20)\d{2}\b", " ", normalized)
+        stripped = re.sub(r"\s+", " ", stripped).strip()
+        if stripped:
+            variants.add(stripped)
+    return variants
+
+
+def title_lookup_queries(value):
+    queries = []
+    for raw_value in base_title_variants(value):
+        text = str(raw_value or "").strip()
+        if text and text not in queries:
+            queries.append(text)
+    return queries