DLP: regional identifiers and templates

Phase 2b of the DLP and mail flow rules spec: every identifier in the
§2.3 catalog, each implemented from its issuer's published rules and
tested against published examples.

US (SSN, ITIN, EIN, ABA routing, driver's licenses, MBI, NPI, DEA), UK
(NI number, NHS number, UTR), Canada (SIN), Australia (TFN, Medicare),
the EU (Germany's tax ID and ID card, France's NIR, Spain's DNI/NIE,
Italy's codice fiscale, the Dutch BSN, Belgium's national number,
Poland's PESEL, Sweden's personnummer, Denmark's CPR, Finland's HETU,
Ireland's PPS, Portugal's NIF, Austria's SVNR), Norway, Switzerland,
India (Aadhaar, PAN), China, Japan, Singapore, South Korea, Brazil (CPF,
CNPJ), Mexico (CURP) and South Africa. 49 detectors in all, plus seven
templates named for what they find.

An identifier that is only digits and whose check about one random
number in ten passes counts alone only in its written form
(536-22-1234, 943 476 5919) and as bare digits only beside a word; ABA
routing numbers and NPIs always need one. Spec §2.3 records this.

A test runs every detector over an ordinary business email (order,
invoice and tracking numbers, dates, amounts, an address) and requires
nothing to fire but the contact detectors. 47 unit tests.

crates/features/src/mailflow/detectors/mod.rs

@@ -19,8 +19,18 @@
 //! same card number pasted twice counts once. They stay in memory: callers
 //! read only [`Findings::len`].
 
+pub mod africa;
+pub mod americas;
 pub mod any;
+pub mod asia;
+pub mod australia;
+pub mod canada;
 pub mod checks;
+pub mod eu;
+pub mod europe;
+pub mod templates;
+pub mod uk;
+pub mod us;
 
 use ahash::AHashSet;
 
@@ -108,7 +118,20 @@ impl Detector {
 
 /// Every detector, in the order the console lists them.
 pub fn all() -> impl Iterator<Item = &'static Detector> {
-    any::DETECTORS.iter()
+    [
+        any::DETECTORS,
+        us::DETECTORS,
+        uk::DETECTORS,
+        canada::DETECTORS,
+        australia::DETECTORS,
+        eu::DETECTORS,
+        europe::DETECTORS,
+        asia::DETECTORS,
+        americas::DETECTORS,
+        africa::DETECTORS,
+    ]
+    .into_iter()
+    .flatten()
 }
 
 pub fn by_id(id: &str) -> Option<&'static Detector> {
@@ -159,6 +182,38 @@ pub fn stands_alone(text: &str, start: usize, end: usize) -> bool {
     before.is_none_or(|c| !c.is_alphanumeric()) && after.is_none_or(|c| !c.is_alphanumeric())
 }
 
+/// Days in `month` of `year` (0 for a month that doesn't exist).
+pub fn days_in(year: u32, month: u32) -> u32 {
+    match month {
+        1 | 3 | 5 | 7 | 8 | 10 | 12 => 31,
+        4 | 6 | 9 | 11 => 30,
+        2 if year.is_multiple_of(4) && (!year.is_multiple_of(100) || year.is_multiple_of(400)) => {
+            29
+        }
+        2 => 28,
+        _ => 0,
+    }
+}
+
+/// Whether `year`-`month`-`day` is a real date between 1900 and 2100.
+pub fn valid_date(year: u32, month: u32, day: u32) -> bool {
+    (1900..=2100).contains(&year) && (1..=days_in(year, month)).contains(&day)
+}
+
+/// Whether a two-digit year, month and day make a real date in either the
+/// 1900s or the 2000s.
+pub fn valid_short_date(yy: u32, month: u32, day: u32) -> bool {
+    valid_date(1900 + yy, month, day) || valid_date(2000 + yy, month, day)
+}
+
+/// The value of each digit in `s`.
+pub fn digit_values(s: &str) -> Vec<u32> {
+    s.bytes()
+        .filter(u8::is_ascii_digit)
+        .map(|b| u32::from(b - b'0'))
+        .collect()
+}
+
 /// The ASCII digits of `s`.
 pub fn digits(s: &str) -> String {
     s.chars().filter(char::is_ascii_digit).collect()
@@ -188,6 +243,30 @@ mod tests {
         assert!(word_near(&text, start, start + 8, &["passport"]));
     }
 
+    /// An ordinary business email: order, invoice and tracking numbers,
+    /// dates, amounts, a street address. Nothing here is an identifier, so
+    /// no detector may fire, except the contact ones on the signature.
+    #[test]
+    fn ordinary_mail_finds_nothing() {
+        let text = "Hi Dana,\n\nThanks for order 4471-2290 placed 2026-09-14. Invoice INV-2026-00917 \
+            for $12,480.00 is due 10/31/2026; PO 7731902 covers lines 1-14. Tracking \
+            1Z999AA10123456784, parcel 3 of 5, 12.5 kg, box 40x30x20 cm. Meeting moved to \
+            Tuesday 9:30-10:15 in room 2B, building 1177. Ticket #5520318, case 20260914-0042. \
+            Version 2026.9.28.4, build 118822, commit 5a73a118. Serial SN-88213-X. \
+            Ship to 1600 Amphitheatre Pkwy, Mountain View, CA 94043. Revenue grew 18% to \
+            1,204,332 units; see figures 3.1-3.4 and table 12.\n\nBest,\nSam\n\
+            Sam Rivera | +1 (415) 555-2671 | [email protected]";
+        let quiet = ["email-addresses", "phone-numbers"];
+        for detector in all().filter(|d| !quiet.contains(&d.id)) {
+            assert_eq!(
+                detector.count(text),
+                0,
+                "{} fired on ordinary mail",
+                detector.id
+            );
+        }
+    }
+
     #[test]
     fn ids_are_unique() {
         let mut seen = AHashSet::new();