diff --git a/docs/port/HANDOFF.md b/docs/port/HANDOFF.md
index 3350d80d..701c27ba 100644
--- a/docs/port/HANDOFF.md
+++ b/docs/port/HANDOFF.md
@@ -39,10 +39,27 @@ archive gives **1**, `EXTRAS` → another archive gives **3**. Same kind of
 destination, gap set by the outgoing screen — the strongest support for that
 dependence, since it removes the destination as the variable.
 
-🔴 **But the clean ordering is gone.** `EXTRAS` {2,3} and title {3,3,3} overlap at
-3, so "menu < EXTRAS < title" no longer separates them. What survives is weaker:
-the outgoing screen constrains the gap to a ~2-wide band, and the bands are not
-disjoint.
+🔴 **Superseded again, and this time sharpened.** With eight transitions the gap
+is a property of the **ordered pair**, not the origin:
+
+| transition | gaps | n | repeats agree? |
+|---|---|---|---|
+| title → menu | 3, 3, 3 | 3 | **yes** |
+| `EXTRAS` → menu | 2, 2 | 2 | **yes** |
+| menu → title | 0 | 1 | — |
+| menu → `EXTRAS` | 1 | 1 | — |
+| menu → another archive | 1 | 1 | — |
+| `EXTRAS` → another archive | 3 | 1 | — |
+
+**Every repeated pair is identical** — five replicates, no variation — and **every
+differing value comes from a different pair**. The same origin gives different
+values to different destinations (menu 0 vs 1, `EXTRAS` 2 vs 3), so the origin
+constrains but the pair determines.
+
+📌 **For `black_hold_units`:** a constant is excluded, and keying on the outgoing
+screen is excluded too. Any keyed version would have to be keyed on the **ordered
+pair**, with a measured value for each — six pairs known, two of them replicated,
+and nothing declared predicting any of them.
 
 📌 **The gap tracks the screen being LEFT — but CONSTRAINS rather than determines
 it.** ⚠️ Corrected the same day, prompted by `sylpheed-port` asking for *"a second
diff --git a/docs/re/data/fade-four-transitions.txt b/docs/re/data/fade-four-transitions.txt
index c6eb255a..e2c3ff82 100644
--- a/docs/re/data/fade-four-transitions.txt
+++ b/docs/re/data/fade-four-transitions.txt
@@ -246,3 +246,40 @@ frame  untextured full-screen   textured (distinct)        draws tex
 # the outgoing screen constrains the gap to a 2-wide band, and different outgoing
 # screens have different bands that are not disjoint. Still not predictive, and
 # now not even cleanly ordered.
+
+################################################################################
+# EIGHTH TRANSITION: a SECOND EXTRAS -> menu, via (B). 2026-08-30.
+# Taken to verify the fixed effective-config guard on the one screen screen_id.py
+# cannot resolve, and to replicate the table's weakest cell at the same time.
+#
+# ✅ THE GUARD WORKS, verified in a run rather than asserted:
+#     arming on       = menu  [screen_id: cannot separate menu/EXTRAS]
+#     discriminator   = extras  rmse=18.94  (other main_menu 30.09, margin 11.15)
+#   Before the fix this run would have announced "arming on = menu" while armed on
+#   EXTRAS. The ambiguity is now visible instead of hidden.
+#
+#   frames 29-31   outgoing quad 229, 255, 255
+#   frames 32, 33  EMPTY: 3 draws, 0 textured
+#   frames 34-38   incoming menu's quad decaying 169, 148, 106, 63, 21
+#   GAP = 2, identical to the first EXTRAS -> menu.
+#
+################################################################################
+# 📌 EIGHT TRANSITIONS: THE GAP IS A PROPERTY OF THE ORDERED PAIR, NOT THE ORIGIN
+#
+#   transition        gaps       n   repeats agree?
+#   title  -> menu    3, 3, 3    3   YES
+#   EXTRAS -> menu    2, 2       2   YES
+#   menu   -> title   0          1   -
+#   menu   -> EXTRAS  1          1   -
+#   menu   -> other   1          1   -
+#   EXTRAS -> other   3          1   -
+#
+# EVERY repeated pair is identical -- 3/3 and 2/2, five replicates, no variation.
+# EVERY differing value comes from a DIFFERENT pair. And the same origin gives
+# different values to different destinations: menu 0 vs 1, EXTRAS 2 vs 3.
+#
+# 🔴 So "the outgoing screen determines the gap" is superseded a second time. The
+# origin CONSTRAINS it (menu {0,1}, EXTRAS {2,3}, title {3}); the ORDERED PAIR
+# determines it, reproducibly. Still nothing declared predicts which value a pair
+# gets, so this remains a description with five replicates behind it rather than a
+# rule.