docs(althing): the measured case for cc — a pane poke lands in prompt history, cc does not

docs/runbooks/althing-deploy.md

@@ -175,6 +175,25 @@ command:
 
     althing-route declare --pid <pid>     # prefers cc, falls back to pane
 
+**Why cc is worth an undocumented dependency, in one measurement.** A pane poke
+is typed into the session and submitted, so Claude Code records it in the
+operator's prompt history exactly as if he had written it — 8 herald-written
+entries accumulated across three projects, permanently in up-arrow recall. A cc
+poke enters none: 2 delivered, 0 entries. Verified from the herald log against
+the history on 2026-09-02. Channel sequence on one seat that day, all three in
+order:
+
+    09-01 21:44  poked via fifo            the old way, later reaped
+    09-02 08:34  could NOT reach via pane  guard 4 refusing: he was typing
+    09-02 09:07  poked via pane            typed into his input line
+    09-02 09:14  poked via cc              arrived as a peer message
+    09-02 09:31  poked via cc              after crossSessionInbound accept
+
+⚠ **Count herald pokes by the whole display string, not by grepping
+`ALTHING-HERALD`.** The substring matches the operator's own messages when he
+pastes a hold notice into one, so the count runs high and the excess reads as
+new activity. See the identity-not-resemblance note in the audit section.
+
 ⚠ **Ordering constraint at any upgrade that changes the channel set:** a
 pre-3.3.0 herald refuses `channel=cc` at parse, so a seat that declares the new
 channel before the herald restarts goes silently pull-only. `uv tool install