Research: chat-template tags in text the model reads; tips I15 and T33; an open decision

M5a task 04 stopped twice on the chat-template tags the check refuses.
The first time, the model read them in a file and took them for its own
template. The second time, it spelled them out in its own reasoning.

Measured on straylight: the think and tool-call tags are one token
whatever the tokenizer's flag. Inside any chat message, the turn
markers become control tokens, so a tool result can forge a system
turn.

Adds the rule to AGENTS.md, and proposes neutralizing the tags in
loopd as an open decision.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

AGENTS.md

@@ -73,6 +73,10 @@ These come from defects found in review. The evidence is in `docs/implementer-le
   the state a crash leaves behind, not only the states you write on purpose.
 - When two programs must agree about a set of things (which files are a log, which names are ids),
   one of them deciding alone is a bug. Write the case that walks both.
+- Never write the model's chat-template tags out whole (the think and tool-call tags, the
+  angle-bar turn markers), in code, comments, commands or your log. Build them from pieces
+  (`concat!("<", "think")`) and name them in words: text holding them becomes your own control
+  tokens when you read it.
 
 ## The gate