fix(post_rules): a maiden name makes the lone name word the family (#445)

docs/design/decisions.md

@@ -535,6 +535,20 @@ Declined:
 - 2026-08-26 #335 — M3 makes the marker vocabulary act in a THIRD position. M2's claim acts on the word after a name word; M1's on the content of a configured pair; M3's now on the first word of any bracketed clause, under the default policy. #vocabulary-collisions C-i is keyed on the position a claim acts on, so extending where a rule acts re-asks C-i of the whole set it reads, and nothing in the process prompts that — the rule was designed, reviewed and approved without the set being re-examined. Review afterwards found one entry that fails C-i, the Czech abbreviation roz, and its disposition is this file's Excluded (MAIDEN_MARKERS) block, which is keyed to the vocabulary set rather than to any rule: it was removed. Two things worth separating, since the finding surfaced during this work and is easy to file under it — the defect was M2's and predates #335 (bare "Rosalind Roz Smith" lost its family name on master), and M3's own boundary already excluded the common one-word "(Roz)" spelling. What belongs to M3 is only the widening, and the lesson is the general one: re-ask C-i of a vocabulary set whenever a rule extends where its claim acts.
 - 2026-08-26 #335 — what configuring maiden_delimiters still buys, since M3 removes the commonest reason to reach for it: markerless clauses, and one-word clauses. "Cherice J. (Johnson) Williams" is a real US convention and a corpus name, and nothing in that clause says maiden, so it stays a nickname by default — only a caller who knows their data can say otherwise. The knob is a declaration about the DATA; M3 is a reading of what a clause declares about itself.
 
+### M4 — a maiden marker makes the lone name word the family
+
+- 2026-08-27 #445 (M4, PR on fix/445-maiden-marked-lone-name) — Derek's rationale, in his terms: normally if there is only one name we assume it is a given name because we have to pick one, but maiden markers mark a previous surname before marriage, so it would not make sense to include one if there was no other surname for it to clarify — and given that, when a marker leaves only one name word we switch the assumption and read that word as the family name. `parse("Smith née Jones")` reported given 'Smith' with an EMPTY family through 2.1 and reads family 'Smith', maiden 'Jones' since. The rule is written in post_rules as H1's sibling and placed directly under it, so the interaction is decidable by reading rather than by running: where H1 fired there is no GIVEN left for M4 to move, and where H1 declined because the title addresses by given name ("Sir John née Jones") the `not titles` guard keeps M4 off the same word. A titled name is H1's at both outcomes, which is what keeps H1's given-name-title carve-out intact.
+- 2026-08-27 #445 — the third time in the 2.2 bundle that a name carrying a maiden clause reported no family, and the three share a SYMPTOM rather than a cause. State that carefully, because the first draft of this entry claimed one cause for all three and was wrong. #410 (H1): a title plus one name word reported no family the moment a suffix, nickname or maiden name stood beside it. #411 (P5's reserve): the bound given-name join counted the marker and the maiden name as words it could spend, and spent the family name. Those two ARE one cause -- a count that included words which are no part of the name -- and the grep that would find a fourth is a rule counting name words without first asking which of them are name words. #445 is not that: it changes no count anywhere (post_rules gains a new block, assign gains only a comment), and `parse("Smith")` with no clause beside it at all already read given 'Smith' with an empty family, so nothing was being swallowed. Its cause is the one the next entry gives: O4 decides nothing at one name word, and the reading came from a convention nobody had written down. The site that grep would miss is `_name_positions`'s `count == 1` branch, silent for every order and every name -- which is exactly what O5 now records.
+- 2026-08-27 #445 — O4 was SILENT at exactly one name word, which is why the shipped reading had no rule to point at and why O5 now exists. O4 reads a name by comparing where its words stand ("the first name word is the given name, the last is the family name"); with one word the first IS the last, so there is nothing to compare and the rule decides nothing. O5 records the reading as the convention it is — a guess fixed in advance so that the same input always reads the same way, not a determination about the word — and names H1, N3 and M4 as the rules that DO decide such a name. Written that way deliberately: a rule asserting "a lone name word is the given name" as a fact would have made #445 a contradiction of the documented behavior instead of an exception to a documented guess, and would make #449 one too.
+- 2026-08-27 #445 — the two carve-outs are not inventions, and both rest on mechanisms.md#TWO-LAYER-ASSIGN: the positional layer never overrides a vocabulary claim, and M4 changes only what POSITION decided. A word the vocabulary claims as a given name keeps that reading ('abd née Jones' — `vocab:bound-given`), and so does a word written as an initial ('J. née Jones Smith V' — the `initial` shape tag). Both are read off tags classify already recorded rather than off a predicate of M4's own, and both witnesses are real corpus names rather than constructed cases, so each carve-out has something in the differential that would notice its loss. Mutation-checked on a scratch copy: dropping the `initial` carve-out fails that name's case row, its facade twin, M4's own boundary example and the pre-existing assertion in test_the_chain_and_the_walk_stop_where_the_peel_begins; dropping `vocab:bound-given` fails the other name's two runners, M4's boundary, P5's own doc example, O5's own `abd née Jones` line and the corpus-wide maiden-clause property on 'abdul' -- six in all, the O5 line having been added by the review round, and the list is exhaustive as re-run against the final tree.
+- 2026-08-27 #445 — the two halves of Derek's answer differ in their relationship to 1.4.0, and a reader should not have to re-derive it. The bracketed spelling RESTORES v1: `Smith (née Jones)` read family 'Smith', nickname 'née Jones' on 1.4.0, 2.0.0 and 2.1.0 alike, and now reads family 'Smith', maiden 'Jones' — the clause changes hands and the family name stays put, so the 1.4.0 gate's diff on that name SHRANK to {nickname, maiden}. The interior spelling is a NEW reading: `Jane née Jones Smith` read first 'Jane', middle 'née Jones', last 'Smith' on 1.4.0 and reads family 'Jane', maiden 'Jones Smith' now, the real surname being inside the maiden value by M2's greedy take. That the marker stands inside the name changes nothing for M4, which counts what the take LEAVES rather than where the marker stood — one name word left that way is one name word, which is the widest half of the decision and the half no earlier version agrees with.
+- 2026-08-27 #445 — a precedence claim corrected while drafting, and it is exactly the class this bundle keeps producing. The first draft of M4 said a name carrying a nickname is N3's rather than this rule's. Measured false: `'Smitty' Jones Jr. née Smith` reads family 'Jones', because N3's count does not set a suffix aside, so N3 declines and M4 fires. A nickname holds nothing off — where N3 has already named the family M4 finds nothing left to move, and where N3 declined M4 names it. The general lesson is the one #410 and #411 already taught from the other side: a rule that counts name words and a rule that counts something else will disagree at the edges, and the disagreement is only visible if the interaction is measured rather than asserted.
+- 2026-08-27 #445 — what the ledger's `# revisit when #445 lands` markers bought, and what they got wrong. Four blocks carried them, and each predicted that a "keep the family" fix would leave the diff a subset of the fields its rule already declared, so the rule would go on explaining the name and the change would be absorbed with the gate green. That was wrong in a way the rule's own shape settles: M4 MOVES the one name word rather than adding one, so `given` empties as `family` fills, the diff outgrows every declaration, and eight names arrived UNEXPLAINED at all three baselines. Two counts run through this and they are different sets, so name which is which: NINE corpus names change reading, of which eight arrive as new diffs — the ninth, 'Smith (née Jones)', has its 1.4.0 diff SHRINK instead, its family agreeing with v1 again. The four markers between them named NINE names to re-measure, of which seven moved: the two that did not are M4's carve-outs, and the two movers the markers could not name were not corpus names until this change's own examples added them. The markers earned their keep all the same — they named the right rule, the right field and very nearly the right set — so they are corrected in place rather than deleted, and the correction says what actually happened. THREE of the four moved in the opposite direction from their own prediction, and getting that number right took two passes. The fix(#335) rule for 'Smith (née Jones)' appears in all three ledgers, and every copy feared absorbing a WIDENED diff while the diff in fact SHRANK to {nickname, maiden}. The first pass narrowed only the 1.4.0 copy, on a measurement of that wheel, and left the other two at four fields on the reasoning that 2.0.0 and 2.1.0 'read `given`, and the baseline cannot move'. They did not: only the BARE spelling ever read `given`, and this rule holds the bracketed one, which reads family 'Smith', nickname 'née Jones' on every released version. So two rules stood over a two-field diff declaring four, and classify's subset test would have explained a `given`/`family` regression on that name in silence -- the absorption those very notes existed to prevent, surviving the round that answered them. A third reviewer found it by instrumenting the comparator to dump real diff-field sets, and that is the lesson worth keeping: ledger prose cannot be checked by reading it, and the round that corrects a marker is exactly where a wrong premise gets written down with confidence.
+- 2026-08-27 #445 — the corpus-wide property test is the repair worth copying. tests/v2/test_parser.py's `test_a_maiden_clause_changes_nothing_else` asserts over the corpus that appending " née Jones" adds a maiden name and moves no other field, and M4 falsifies it for fourteen names. Skipping them would have bought a green suite and lost the check; instead the test computes M4's guard from the base parse's tokens and asserts the flip — family takes what `given` held, every other field standing still — so the class that used to be a hole is now the strongest witness the rule has, fourteen names against the six rows cases.py carries. It is also what executes M4's nickname precedence, `'Smitty' Jones Jr.` being one of the fourteen.
+- 2026-08-27 #445 (review round) — M4 is keyed on the maiden NAME, not on a marker, and the statement was corrected to say so after two reviewers measured the same defect independently. The guard tests for a token in the MAIDEN role, and M1's caller-configured pair produces one with no marker anywhere: under `Policy(maiden_delimiters=frozenset({("(", ")")}))`, `Smith (Jones)` reads family 'Smith', maiden 'Jones', and so do M1's own boundary examples `Smith (Nee)` and `Smith (z domu)`. The BEHAVIOUR is right — the rationale transfers to a declared pair without a word of change, since what announces a former surname is the clause, not the vocabulary that marked it — so the fix was to the rule, which had said "a recognized maiden marker that takes its name and leaves exactly one name word" and now says "a maiden name standing beside exactly one name word". That covers M1, M2 and M3 uniformly, M1 is in M4's `interacts:` and M4 in M1's, and the configured path has an example line of its own. The general lesson is the one this bundle keeps teaching from a new angle: a statement written from the case that prompted the change describes that case, not the code, and only measuring the OTHER paths into the same guard finds the difference.
+- 2026-08-27 #445 (review round) — a known gap recorded rather than closed, the way H1 carries its own. M4's guard counts GIVEN tokens; H1 counts nothing at all (it tests which roles are unoccupied). So a name word another rule has joined counts as several here and M4 declines where H1 fires: `Dr. Dean of Chemistry` reads family 'Dean of Chemistry' while `Dean of Chemistry née Jones` keeps given 'Dean of Chemistry', the connective join (P3) having left three GIVEN tokens. rules.md#P3 says the joined part is one name word wherever another rule counts them, so the two siblings genuinely disagree and this is a gap rather than a boundary. Not closed here: widening the count to units moves zero corpus names (measured), and a behaviour change nobody has approved does not belong in a branch whose blast radius was settled. The sibling claim in the code comment and in this entry is narrowed to match — sibling except in what it counts.
+- 2026-08-27 #445 — the relationship to #449, briefly, because the two look like the same question and are not. #449 asks whether a lone name word with nothing to decide it should REPORT an ambiguity; #445 removes a class of names from that population by giving them something that decides. So #445 reduces #449's reach rather than competing with it, and #449's measurement — a naive "one name word, nothing decided it" condition fires on 19 of 1,085 corpus names, only three or four of them the case it is about — is re-taken after this lands. O5 cites #449 in prose and deliberately carries no `deviates:` marker: that marker asserts an intended output the runner then checks strictly, and #449 has not decided one.
+
 ### O1 — East Slavic rotation
 
 - (v1 era, PR #154) — why patronymic handling is OPT-IN at all: unconditional detection breaks ordinary Latin names whose endings collide (Martin, Franklin, Benjamin), the finding that forced v1's Russian work behind a flag and set the opt-in shape v2 inherited.