Known limitations

wardcat is a best-effort detector: false negatives and false positives are expected, and using it does not by itself make a system compliant. The cases below are known, and each has a mitigation. The security policy lists the behaviours that are inherent to the design rather than bugs.

Case	Description	Mitigation
Homoglyph domain	Confusable folding (normalize_confusables, on by default) catches Cyrillic/Greek lookalikes and fullwidth/Arabic digits (ali@tеst.com, ４111…), but it is a curated skeleton, not the full Unicode table — an exotic lookalike may slip through	Add an allowlist/extra validation for high-stakes fields; the LLM layer can flag suspicious text
US_ZIP_CODE	A bare 5-digit ZIP is matched only with a ZIP: keyword; otherwise ZIP+4 (12345-6789) is required, to avoid false positives	Enable POSTAL_CODE (catches any bare 5-digit), or the LLM layer for contextual ZIPs
EU_NATIONAL_ID	Spanish DNI/NIE, French INSEE, Dutch BSN and Polish PESEL are matched by regex; German IDs are not	Enable the LLM layer — it catches German (and other) national IDs contextually
PASSPORT	Regex needs a passport keyword (passport no:, pasaport, Reisepass, passeport) — bare passport numbers are too generic to match safely	Enable the LLM layer — it catches unlabeled passport numbers
FINANCIAL_AMOUNT / VAT_NUMBER	FINANCIAL_AMOUNT is off by default; a bare Turkish Vergi No needs a keyword	Enable FINANCIAL_AMOUNT for confidential docs; use a Vergi No/VKN keyword or the LLM layer for VAT
Multilingual NER	One SpaCy model loads per language; wardcat bundles no language detection by design (keeps the core dependency-light)	Detect the language yourself (check supported_languages()) and pass several models via language=[...], or use the language-agnostic LLM layer
European addresses	Regex needs a street-type keyword (Straße, Rue, Calle…); unnumbered informal addresses may be missed	Use the NER ADDRESS / LLM layer, or add a custom_patterns rule for your address format
Turkish NER (tr_core_news_trf)	The transformer model is incompatible with SpaCy 3.5+	Use tr_core_news_md or tr_core_news_lg
Lower-cased text	Where the document carries no capitals, the "a name has a capital" rule is switched off, so a common-word sequence can surface as a PERSON	Preserve the original casing if you want the stricter rule, or drop the phrase with add_allowlist([...]) / with_llm(adjudicate=True)
Weak checksums	The ABA routing, NHS and IMEI checks each let roughly one bare digit run in ten through, so an uncued match is scored 0.70 and the default floor leaves it alone	Write the number with its keyword (IMEI: …, routing number …), or call with_min_confidence(0.6) to act on uncued matches
Ethereum addresses	The 0x + 40-hex form is checked on its shape; EIP-55 mixed-case checksumming needs keccak-256, which the standard library does not carry	Bitcoin addresses are fully checksum-verified; for Ethereum, pair the match with the LLM layer if a stricter check matters
NER types that moved	GPE/LOC used to be reported as ADDRESS, and NORP as ORG. A configuration written before that keeps working but stops covering them	Add LOCATION and/or NRP on the NER layer. The first scan of an affected guard says so once
Turkish NER quality	tr_core_news_md/lg are news-trained and may miss names in non-standard contexts	Combine with .with_llm(...) — the LLM catches names NER misses
Phone numbers outside TR/FR/DE	The built-in PHONE pattern deliberately refuses a bare 123 456 7890; an unlabelled number in another national format falls through it	Name the regions you serve with with_phone_regions(), or label the number (Phone: …)
Prompt injection	Scanned text is interpolated into the LLM prompt, so adversarial input can try to suppress the LLM layer's findings	Keep regex and NER in front of it; see security