Should Juan Sta. Maria read family Sta. Maria? Today it reads middle Sta., family Maria #725

What happens today. Filipino surnames that begin with Santa or Santo are commonly written abbreviated: Sta. Maria, Sta. Ana, Sto. Domingo, Sta. Cruz. In a name written without a comma, the parser splits the surname:

Juan Sta. Maria        →  given 'Juan', middle 'Sta.', family 'Maria'
Juan Sta Maria         →  given 'Juan', middle 'Sta', family 'Maria'
Juan Sto. Tomas Jr.    →  given 'Juan', middle 'Sto.', family 'Tomas', suffix 'Jr.'
Sta. Maria, Juan       →  given 'Juan', family 'Sta. Maria'      (the comma keeps it whole)
Jean Ste. Marie        →  given 'Jean', family 'Ste. Marie'      (ste is a particle)

So the comma and no-comma writings of the same name disagree on the family. sta and sto are in no vocabulary set, while ste is a particle.

Evidence. US Census 2010 surname bearers, from uv run python tools/name_usage.py "Sta. Maria" and likewise for the others (2026-10-18): Sta. Ana 408, Sta. Maria 376, Sto. Domingo 163, Sta. Cruz 110, each over 90% Asian/Pacific Islander. The Census strips punctuation, but Santa Maria is its own entry (12,375), so these are bearers recorded with the abbreviation. Background is in decisions/H6's 2026-10-18 entry (PR #724).

Proposal. Add sta and sto to particles as ambiguous particles, the way van is listed. Measured with Lexicon.default().add(particles={"sta", "sto"}, particles_ambiguous={"sta", "sto"}):

Juan Sta. Maria        →  family 'Sta. Maria'
Juan Sta Maria         →  family 'Sta Maria'
Juan Sto. Tomas Jr.    →  family 'Sto. Tomas', suffix 'Jr.'
JUAN STA. MARIA        →  family 'STA. MARIA'
Sta. Maria, Juan       →  family 'Sta. Maria'      (unchanged)
Sta Juan               →  given 'Sta', family 'Juan', plus a particle-or-given report
John Sta               →  family 'Sta'             (unchanged)
Sta. Maria Juan        →  title 'Sta.'             (unchanged: H2's shape takes a leading period-marked word)

Why ambiguous rather than never-given: as never-given particles, P1's fold would take a bare leading one, so Sta Juan would read family Sta Juan. Bare Sta is a surname in its own right (120 Census bearers, 2 Tunisian family-name bearers on Wikidata). Sto has under 100 Census bearers, and neither shows up as a given name (SSA under 5 a year).

Costs to settle:

• capitalized(): particles render lowercase, so Juan Sta. Maria would render Juan sta. Maria. ste already does this (juan ste. marie → Juan ste. Marie). Should these get a capitalization exception, or is lowercase acceptable?
• initials(): particles are left out, so J. S. M. becomes J. M., as with de la Cruz → J. C..
• Particle runs: Juan dela Cruz Sta. Ana reads family dela Cruz Sta. Ana today. With the listing it reads middle dela Cruz, family Sta. Ana. Which is right for a Filipino double surname?
• Trailing particle after a comma (P6): Smith, Juan Sta. would read family Sta. Smith with a report, where today it reads middle Sta.. That input is probably garbage.

Corpus. Of the 5,716 corpus names, only one holds the word: Sta. Maria, Juan, the H6 example from #724. Its fields don't move, only initials() (J. S. M. → J. M.). So the snapshot can't show this change, and the evidence has to come from rows written for it.

Exclusions. This doesn't change H6 (a title before a family comma): a period-marked word in front of a family comma is still read by vocabulary alone. It also doesn't cover a leading Sta. with no comma (H2's shape), or other abbreviated surname heads (Mt., Ft., both under 100 Census bearers).