Phase 3 fixed two of the twelve branches of `_inflect_predicate` by hand and
pinned them with a hand-written oracle. The other ten kept handing whole
predicate phrases to single-verb functions, so the same root cause was still
live on **57 of 96** (branch x multi-word predicate) pairs, 9 of 12 branches:
"belongs to" --perfective--> "has belongs toed"
"belongs to" --imperfective--> "is belongs toing"
"belongs to" --past--> "belongs toed"
"is defined as" --future--> "will is defined a"
"contrasts with" --negated--> "does not contrasts with"
Every branch now routes through `morphology.inflect_phrase_head`, which applies
a single-verb inflection to the finite verb and carries tokens 2..n through
byte-identically. Two closed tables were needed because `_base_form` is a
suffix stripper and the head of every copular predicate is a form of BE:
`base_form("is")` returned "i" and `present_participle("is")` returned "iing".
Also fixes predicate-nominal object agreement. `render_step` pluralized the
subject and never the object, so it wrote "all dogs are a mammal". The object
agrees only for a predicate nominal -- a closed set of two -- because a
prepositional object carries its own number and a productive rule would write
"all claims are grounded in evidences".
Measured
--------
tail-mangling pairs 57/96 -> 0/96
g_read_rate (round-trip) 0.0 -> 0.003413 first non-zero in the arc
grammatical_coverage v1 49/49 (2 cases corrected, see below)
english_fluency_ood 117/117 + 39/39 + 13/13 unchanged
discourse_paragraph 12/12 + 6/6 + 5/5 + 1/1 unchanged
zero_code_domain_acquisition 18/18 + 30/30 + 21/21 unchanged
`gram_C14_p01` and `gram_C14_p10` expected "...defined as compound", which is
not English. Corrected, and the old string moved into `reject_surfaces` so the
case now actively rejects what it used to accept. The correction is not my
judgment: the reader independently READS "all molecules are defined as
compounds" and REFUSES the singular form, and that is precisely what took
g_read_rate off zero.
Why the invariant instead of a bigger oracle
--------------------------------------------
A per-branch oracle has to be extended by hand for each new branch, and a
branch added without one is invisible -- which is how eight survived Phase 3.
The pin is structural instead: English marks tense, number and aspect on the
finite verb, so inflection must leave tokens 2..n byte-identical. It needs no
oracle and covers branches nobody has written yet.
It is necessary, not sufficient: "does not contrasts with" preserves its tail
perfectly and is still wrong. `test_do_support_puts_the_head_in_the_bare_
infinitive` is the sufficiency half.
Mutation
--------
baseline 84 pass
inflect_phrase_head applied to the whole phrase 39 FAIL
_IRREGULAR_BASE emptied 2 FAIL
_IRREGULAR_PARTICIPLE auxiliaries removed 2 FAIL
PREDICATIVE_NOMINAL emptied 3 FAIL
PREDICATIVE_NOMINAL widened to every copular predicate 2 FAIL
The last row is the one that matters: the plausible-but-wrong fix -- "pluralize
the object under a plural subject" -- is caught by the mass-noun control.
Not fixed here, deliberately: "has not the following steps" is archaic rather
than wrong, and modernizing it to do-support is a separate judgment call.
[Verification]: smoke 621, deductive 406, lane pins 11/11 unchanged
(grammatical_coverage is not a pinned lane; no pin was edited).
_inflect_predicate applied base_form — a SINGLE-VERB function — to whole
humanized predicate phrases, stripping the final word's last character
class, and its plural branch never consulted `copular`. Nine of the 26 seed
predicates came out wrong and every multi-word one did:
is defined as -> "is defined a" want "are defined as"
has the following ... -> "...step" want "have the following steps"
belongs to -> "belongs to" want "belong to"
causes -> "caus" want "cause"
Root causes, both single-point as §1.4 predicted:
1. morphology.agree_plural_phrase inflects the HEAD (the finite verb is the
first token of every humanized predicate) and carries the rest through.
base_form stays single-verb and is PINNED as still wrong on a phrase, so
nobody "fixes" the symptom in the wrong place.
2. The plural branch now agrees the phrase. The plural NEGATED branch had the
same defect ("do not is defined a") and is fixed with it: a plural copula
takes a bare "not", everything else takes do-support.
Two further defects found while writing the eval cases, both fixed here:
base_form("causes") -> "caus". The -es sibilant rule fired on a stem
ending in a single "s"; it must require a doubled "ss" ("passes"->"pass"),
because a single "s" is nearly always a stem ending in "e" that took a
plain -s ("causes"->"cause").
pluralize("proof") -> "prooves". f/fe -> ves is NOT productive in English
(proof->proofs, chief->chiefs, roof->roofs); it is a closed set. Now
derived as lexicon.VES_PLURAL_SINGULARS from the ves-rows of
IRREGULAR_SINGULARS, so the rule cannot claim a word the table does not
know. Phase 2B had put pluralize on the SERVING path, so this one was live
— and the surface-hashing pin from #133 confirms no served surface moved,
which is that guard's first real use.
New construction C14 quantified_copular, 13 cases: the combination that was
broken was the one never tested. Measured before: 152 corpus cases carry a
quantifier and ZERO combine it with a copular predicate.
MY FIRST DRAFT OF THOSE CASES COULD NOT FAIL. must_contain/word_order listed
quantifier, subject and object but NOT THE VERB, so "all molecules is
defined a compound" passed and reverting the fix left 47/47 green. Rewritten
with the agreed verb in both constraints plus reject_surfaces carrying the
ACTUAL pre-fix output, computed by running the reverted code rather than
guessed. Mutation now:
baseline 13/13 C14
revert phrase-head agreement 4/13
revert -es stem rule 12/13
revert closed ves set 11/13
The 4 survivors of the first mutation are the mass-noun controls, which is
correct — "all evidence is grounded in truth" must NOT pluralize.
Same lesson as the lane pins in #133: a pin that cannot fail guards nothing,
and the only way to know is to break the thing on purpose.
grammar_roundtrip's graph corpus is harvested from the committed case files,
so it grew 280 -> 293. Updated exactly rather than loosened to an inequality:
a corpus that grows or shrinks should require a deliberate edit.
[Verification]: in-worktree on CPython 3.12.13, uv sync --locked —
agreement 26/26 (from 17/26); english_fluency_ood 117/117 + 39/39 + dev
13/13 unchanged; grammatical_coverage v1 49/49; smoke 621 unchanged;
deductive 405; scripts/verify_lane_shas.py 11/11, no pin edited.
The ratified, flag-ON v1b categorical band served "all dog are mammal" for
every noun: the A/E/I/O templates supply all/no/some + are, which demand a
plural, and the slots were filled with singular canonical entity ids. Four
of the 47 ratified corpus cases were affected, and wrong=0 never noticed
because every verdict was correct — only the prose was wrong.
Two fixes that compose into a closed round trip:
1. generate/morphology.py becomes the single owner of the number RULES
(Phase 2A gave the TABLES one owner). Both directions live there:
pluralize + singularize, over lexicon.IRREGULAR_PLURALS /
IRREGULAR_SINGULARS, with mass-noun and compound-head handling.
templates.pluralize and reader._singularize were two independent copies
of the regular suffix rules that disagreed about which irregulars they
knew; both now delegate.
2. render._display_noun re-inflects at render time and swaps _ for a space,
so compound ids read "guard dogs" rather than "guards dog" or
"guard_dog".
Result: reader gives wolves -> wolf, renderer gives wolf -> wolves. The
round trip closes.
0 malformed of 47 (from 4)
reader-vs-reader singularization 20/20 (from 8/20), 0 silently wrong
s_surface_match_rate 0.0 -> 0.625, now EQUAL to s_renderable_rate, so the
only remaining losses are surfaces the renderer cannot express at all
NEAR-MISS — widening a reader broke soundness, caught by the lane:
Routing the reader through the full 29-entry table first produced wrong=1 on
band v6-EX. ds-ex-0012 ("No fish are mammals. Therefore some fish are
mammals.") answered invalid where gold is refuted.
_singularize returning None makes the reader REFUSE, and the serving
composer tries the categorical band FIRST, falling through to more capable
bands. "fish" previously returned None (it matches no suffix rule), so v6-EX
got the case and decided it correctly. Resolving "fish" made v1b accept a
sentence it cannot decide.
Fixed by a principle, not a patch: a number-INVARIANT form is ambiguous in
number — "fish are mammals" is plural, "a fish is a mammal" is singular, and
the token cannot tell you which — so a reader that must not guess number
declines it. lexicon.INVARIANT_NUMBER is derived from the singularizer's own
key == value rows, so the rule cannot drift from the table.
=> Coverage and correctness are different axes. Fixing a corrupted VALUE is
safe; widening ACCEPTANCE changes which band answers, and in a
first-match composer that turns a right answer into a wrong one. Same
family as ADR-0261 5.1 refuse-don't-drop.
Also fixed, found by testing the inverse law: the two number tables were not
mutual inverses. The pluralizer lacked cactus->cacti, fungus->fungi,
die->dice and the invariants aircraft/means/offspring, so CORE could read
"cacti" but wrote "cactuses", and would have written "aircrafts", "meanses",
"offsprings". No round trip can close across a non-invertible table.
THE LANE SHA PINS ARE BLIND TO SERVED ENGLISH:
2B changed 4 served surfaces and the pins came back 11/11 byte-identical.
The deduction_serve_v1 hashed report holds only n/counts/by_gold/
correct_by_gold/all_cases_correct/mismatch_examples — no prose at all.
Confirmed by sabotage: with _display_noun returning "SABOTAGE_" + ..., so
every clause reads "all SABOTAGE_dogs are SABOTAGE_animals",
11 lane SHA pins -> 11/11 byte-identical, blind
test_deduction_serve_lane + _license -> 20 passed, blind
Phase 1 grammar_roundtrip -> 3 tests RED, caught it
This corrects #129: byte-identity of the pins is the arbiter for values and
verdicts, NOT for surface text, so the 2A/2B split is not a partition of
"changes users can see." Phase 2A's 11/11 conclusion still stands on its own
independent evidence (24/24 table-equality checks vs the pre-migration
literals), but the justification was thinner than stated.
Before Phase 1 no test in the tree would have noticed CORE's served prose
turning into word salad. That is exactly how "all dog are mammal" survived
on a ratified flag-ON band with wrong=0 intact.
Deliberately not fixed: mass-noun verb agreement ("all evidence ARE truth"
should be "is"). The copula is fixed text inside the templates, so agreeing
it changes the template shape rather than a slot, and no mass noun reaches a
categorical clause in any serve corpus. Recorded in render.py.
No lane pin edited — none moved.
[Verification]: in-worktree on CPython 3.12.13, uv sync --locked —
smoke 621 unchanged; deductive 403 passed (383 + 20 new/rewritten);
scripts/verify_lane_shas.py 11/11 (see blindness note above — gate on
grammar_roundtrip for surface work, not on these pins).
The measurement foundation for docs/plans/grammar-unification-2026-07-26.md.
WHY: evals/deterministic_fluency reports 1.00 on all six predicates and
still passes "banana does the.", "wet ground rains the is." and
"is is is is." — it checks terminal punctuation, presence of a verb-shaped
token, and two anti-shape regexes. Heuristic predicates will always have
that failure mode, because grammaticality cannot be measured without a
grammar. So this lane measures agreement between the two halves of CORE
that already encode grammar, and requires the measurement to FAIL on salad.
Two directions, reported separately because they fail for different
reasons and have different remedies:
G-round-trip graph -> realize_target -> surface -> comprehend -> graph
S-round-trip surface -> comprehend -> graph -> categorical renderer -> surface
v1 baseline on main @ 9696443a:
graph_cases 280 surface_cases 8
g_write_rate 1.000 s_read_rate 1.000
g_read_rate 0.000 s_renderable_rate 0.625
g_exact_rate 0.000 s_surface_match_rate 0.000
negative_cases 16
reject_rate 1.000
g_read_rate and s_surface_match_rate are pins on measured DEFECTS, not
goals; they may be revised upward only. s_surface_match_rate = 0 is the
§1.7 categorical render defect caught by construction — the lane found it
without being told to look.
g_args_rate and g_predicates_rate are deliberately separate: high argument
agreement with low predicate agreement would mean the grammars align and
only the vocabulary is split, a materially different remedy from both
being low. That distinction decides the arc's direction (plan §6).
Design notes:
- The committed cases.jsonl is the SINGLE source for authored surfaces —
no in-module duplicate, since a second copy of a corpus is the defect
this arc exists to remove. Negative shuffles are DERIVED at run time so
they cannot drift from the positives.
- The shuffles are lexically identical to positives (same vocabulary, same
length, order destroyed) so the lane cannot pass by vocabulary-checking.
- Fixed rotation, not a PRNG, so reject_rate is byte-reproducible.
- The lane keeps a local copy of the reader's quantifier map ON PURPOSE so
it never becomes a consumer of what it measures;
test_quantifier_map_matches_reader fails loudly if the reader changes.
- _render_categorical deliberately reaches a private serving function: a
lane measuring a private copy would measure what users never see.
Every guarantee is paired with a mutation test. The load-bearing one is
test_reject_rate_goes_red_when_the_reader_accepts_everything: an
accept-everything reader must drive reject_rate to 0.0. Without it,
reject_rate == 1.0 would be unfalsifiable — precisely the defect that
makes the existing fluency lane decoration.
Also documents plainly what round-trip does NOT prove: it measures mutual
intelligibility, not English quality. english_fluency_ood accepts "river
flows valley" and round-trip would be happy with it. No metric here may be
cited as evidence of prose quality.
scripts/measure_grammar_seam.py reproduces every number in the plan's §1
so a reader can check them instead of trusting them.
[Verification]: in-worktree on CPython 3.12.13, uv sync --locked —
smoke 621 (unchanged), deductive 364 (349 + 15 new). Lane SHA pins
verified separately. No serving code touched; new files plus one suite
registration line.
Shay