docs: record why RG 112(b)/(c)/(d-saint) are unbuilt

They have been carried as a bare 'unbuilt' for weeks. The reason is not
neglect, and it differs per clause -- now measured across 1583-9999 rather
than asserted.

(c) cannot fire in this architecture at all: Temporal_ef.temporal returns one
office per day, so two de Tempore candidates never coexist. Nothing to build.

(b) is already produced by RG 16(a), which is implemented: 0 days in either
direction, because a Lord feast takes an occurring Sunday's place with no
commemoration, and no Class1 Sunday shares a date with any of the four
Lord-subject entries.

(d)'s saint half has no candidate pair. Three apparent pairs are distinct
saints sharing a forename -- recorded so the false positive is not rediscovered
-- and the one real pair, agnes and agnes-secundo, is 7 days apart and
co-occurs 0 times.

(b) and (d) are data-unreachable rather than architecture-unreachable, so an
overlay can make either live. That is the entry_14_movable_band shape. Left as
an explicit open decision rather than silently resolved.

1 files changed, 12 insertions, 2 deletions

diff --git a/CLAUDE.md b/CLAUDE.md
index a749cd7..d38fbb8 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -616,8 +616,18 @@ Boniface 14 May, Evaristus, Theodore); and `romanus`, which should not exist on
 9 August. lectio's ini is **generated from missalemeum**, so the two are one
 lineage, not two independent sources.
 
-**Unbuilt, recorded**: RG 112(b)/(c)/(d, non-BVM half) (only (a) and (d)'s
-BVM half have a live witness this codebase's data can construct). Allow-list
+**Unbuilt, recorded**: RG 112(b)/(c)/(d, non-BVM half). *(2026-08-18: the
+reason is now measured and written down, register §6.29, rather than left as
+a bare "unbuilt".)* **(c) cannot fire at all** — `Temporal_ef.temporal`
+returns one office per day, so two *de Tempore* candidates never coexist;
+0 days domain-wide. **(b) is already produced by RG 16(a)** — 0 days either
+direction across 1583–9999, because the feast takes the Sunday's place
+*"nulla fit commemoratio"* and no Class1 Sunday shares a date with any of the
+4 Lord-subject entries. **(d)'s saint half has no candidate pair** — the only
+genuine one, `agnes`/`agnes-secundo`, is 7 days apart and co-occurs 0 times.
+So (b) and (d) are DATA-unreachable, not architecture-unreachable, and an
+`--overlay` can make either live — the `entry_14_movable_band` shape. Whether
+to build defensively against that is an open judgement call, not an oversight. Allow-list
 entries M11 and M13 are `verdict open` by design. Holy Name of Jesus (RG
 17(a)) and RG 110 (inseparable Peter/Paul commemorations) are **RESOLVED —
 see item 4 above.** The Sacred Triduum's own identity is **RESOLVED — see