Research: present-head flag 1 reaches target span only after its last update (no new kappa)

[VictorLiwentao]

Change and scope

One-flag follow-up under priority revision 6, card p104-side-correction. #3349 names present-head class (0,1,9,43). #3392 pins absent-head flag 2. #3443 pins present-head flag 9 late hosting. This package pins flag 1 (X0 → Y7, basis head 232) with both literal-frame and GF(2)-span chronology.

On the published 4,058-event word:

• the head enters Y7 (listed and in span) only at the terminal transport after-frame at event 3473
• all six Y7 adds (last at event 2797) run in head-free charts (head_free_target_updates=6/6)
• X0's literal drop at event 591 is a nested chart change that keeps 232 in span (8 ^ 32 ^ 64 ^ 128); source_span_drops=0
• preterminal_hosting=0 and preterminal_span_hosting=0; zero joint endpoint events; frames unrestored

Chronological dirty restoration therefore cannot use co-hosted basis-head geometry on this word. Flag 1 is not a reprint of flag 9 (drop/arrive/gap 591/3473/2882 vs 500/3489/2989; different target/head/frames).

Scoped obstruction. No new kappa. Selected κ stays 0.001672660197076918. Coefficient delivery (flag-0 cascade on Y34) is outside this package.

Result

Package: research/p104-present-head-flag1-audit/.
Tip: 818c303a9740b8704bbb0dfd06fb42af28b06c69.
Content tip: 112436d9be29b668c9306901843c440dafac3755.
Base: 6f100d4bb5083f8c35d96fd95a539811c62f245c.

Validation

python3.12 -I -B research/p104-present-head-flag1-audit/verify.py
python3.12 -I -O -Werror -B research/p104-present-head-flag1-audit/verify.py
python3.12 -I -O -Werror -B research/p104-present-head-flag1-audit/independent.py
python3.12 -I -O -Werror -B research/p104-present-head-flag1-audit/test_package.py
python3.12 -B scripts/research_package.py --package research/p104-present-head-flag1-audit

Expected:

PASS_P104_PRESENT_HEAD_FLAG1 flag=1 head=232 preterminal_hosting=0 preterminal_span_hosting=0 drop_event=591 arrive_event=3473 source_span_drops=0 head_free_target_updates=6/6 no_new_kappa
PASS_P104_PRESENT_HEAD_FLAG1_INDEPENDENT flag=1 head=232 preterminal_hosting=0 preterminal_span_hosting=0 drop_event=591 arrive_event=3473 source_span_drops=0 head_free_target_updates=6/6 no_new_kappa
PASS_P104_PRESENT_HEAD_FLAG1_TESTS groups=6
PASS_REGISTERED_RESEARCH_PACKAGE research/p104-present-head-flag1-audit outcome=completed

Default verify is read-only. Admission uses need() and still fires under -O.

Overlap and credit

Closest priors: #3443 (flag 9 method), #3349 (present-head census), #3392 (absent-head flag 2), merged #3242 (X0 first touched at 591). Does not reopen those packages, #3441/#3436/#3421/#3411, deferred V45/rho=0, or the merged readout series through #2883. Soft-overlap checked against open #3363/#3365/#3371/#3372 (coefficient delivery on flag 0 / Y34): this package recomputes no coefficient and says nothing about Y34.

Credit Nick Petalas / #2981, jwr404 / #3242, #3349, #3392, and #3443. Prepared by Wentao Li (VictorLiwentao, @Is__Victor) with substantial AI assistance, under Apache-2.0.