port: the ordered pair determines the gap; nothing declared predicts it

Their run gives five replicates with no variation -- title->menu 3,3,3 and
EXTRAS->menu 2,2 -- while every differing value comes from a different ordered
pair, and the same origin gives different values to different destinations. The
origin constrains; the ordered pair determines.

That excludes a second model for black_hold_units: a constant was already out, and
keying on the outgoing screen is now out too. Only an ordered-pair key survives,
needing a measured value per pair.

Checked their 'nothing declared predicts it' from my export rather than taking it.
Outgoing close (15,10,10,10), incoming clear (12,12,16,12), outgoing span
(269,74,80,80) and incoming span (80,80,269,74) each have two rows sharing a value
with different gaps, so no single declared quantity determines it.

Did not search combinations, deliberately: four intra-archive pairs against many
candidate two-screen functions fits by construction, which is the error this
corpus has catalogued five times including my own 16/16/18. A formula found here
would be indistinguishable from one found in noise.

black_hold_units stays 0 meaning not modelled, now with two candidate models
positively excluded rather than one.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N7FiFFFwbvG2uxdcEh8HyF

docs/port/DECISIONS.md

@@ -9,7 +9,7 @@ dies, which is what this file is for.
 
 <!-- INDEX: generated by tools/port/index-decisions -- do not hand-edit -->
 
-219 sections. Search this before re-deriving anything.
+220 sections. Search this before re-deriving anything.
 
 * [P0 — the exporter, 2026-08-28](#p0--the-exporter-2026-08-28)
 * [P1 — Godot draws the screen, 2026-08-28](#p1--godot-draws-the-screen-2026-08-28)
@@ -230,6 +230,7 @@ dies, which is what this file is for.
 * [Every documented invocation verified — and one runs forever without saying so](#every-documented-invocation-verified--and-one-runs-forever-without-saying-so)
 * [🔴 I promoted an unverified claim of theirs to a fact, against data I had authored](#i-promoted-an-unverified-claim-of-theirs-to-a-fact-against-data-i-had-authored)
 * [The half-guard they named, tested — and it found a real gap on first use](#the-half-guard-they-named-tested--and-it-found-a-real-gap-on-first-use)
+* [The ordered pair determines the gap — and nothing declared predicts it](#the-ordered-pair-determines-the-gap--and-nothing-declared-predicts-it)
 
 <!-- /INDEX -->
 ## P0 — the exporter, 2026-08-28
@@ -11556,3 +11557,43 @@ caught your `--no-hold` no-op, and you'd never have caught my 'sole exit'."*
 Neither of us is the right auditor of our own retiring words. I had written the
 doubt about this guard into my own file and left it there; it took someone else
 repeating it back for me to run the test.
+
+## The ordered pair determines the gap — and nothing declared predicts it
+
+Their latest run gives **five replicates with no variation** — `title→menu` 3,3,3
+and `EXTRAS→menu` 2,2 — while every *differing* value comes from a different
+ordered pair. The same origin gives different values to different destinations
+(menu 0 vs 1, EXTRAS 2 vs 3). **The origin constrains; the ordered pair
+determines, reproducibly.**
+
+🔴 **That excludes a second model for `black_hold_units`.** A constant was already
+out; **keying on the outgoing screen is now out too.** Only an ordered-pair key
+survives, needing a measured value per pair — six known, two replicated.
+
+### My independent check: no declared quantity predicts it
+
+They said nothing declared predicts the values. Checked from my export rather than
+taken:
+
+| pair | gap | out.close | in.clear | out.span | in.span |
+|---|---|---|---|---|---|
+| title → menu | 3 | 15 | 12 | 269 | 80 |
+| EXTRAS → menu | 2 | 10 | 12 | 74 | 80 |
+| menu → title | 0 | 10 | 16 | 80 | 269 |
+| menu → EXTRAS | 1 | 10 | 12 | 80 | 74 |
+
+✅ **Each column has two rows sharing a value with different gaps** — `out.close`
+10 gives 2, 0 and 1; `in.clear` 12 gives 3, 2 and 1; `out.span` 80 gives 0 and 1;
+`in.span` 80 gives 3 and 2. **No single declared quantity determines the gap**,
+independently from my side.
+
+⚠️ **And I did not search combinations of them, deliberately.** Four intra-archive
+pairs against many candidate two-screen functions fits **by construction** — the
+error this corpus has catalogued five times, most recently my own 16/16/18. A
+formula found here would be indistinguishable from one found in noise, and I would
+have no way to tell the difference with the data that exists.
+
+📌 So the position is now: **`black_hold_units` = 0, meaning not modelled**, with
+*two* candidate models positively excluded rather than one, and the surviving
+shape harder than when I escalated the decision. Their advice stands and I agree:
+don't key it.