run 27

docs/pt2-protocol-summary.md

@@ -290,6 +290,10 @@ Current caution:
   opening their known `7A` branches.
 - At the same time, `A0` is not sufficient to make every branch deterministic:
   a later `A0 -> E9` control repeat returned heartbeat only.
+- A broader non-`A0` context ladder showed that `A0` is not the only opener:
+  `90` opened `E8`, `E9`, and `EC`; `AF` opened `E9` and `EC`, and shifted
+  `E8` into the sibling `07 80 FA 50 26 51` family; bare heartbeat opened `E8`
+  and `E9` but not `EC`.
 
 ## What We Know
 
@@ -327,8 +331,9 @@ Current caution:
 - Overall, the evidence is getting stronger for selector-like host entries that
   open related response families, but weaker for a fully reproducible multi-turn
   "conversation" state.
-- `A0` now looks more like part of the selection context than a purely generic
-  primer, but its effect is branch-dependent and not fully deterministic.
+- There appears to be a small family of context openers rather than a single
+  magic gate byte; `EC` is stricter than `E8/E9`, and heartbeat alone was not
+  enough to open it.
 
 ## What We Do Not Know