Offer the assistant the same formatting the mesh composer has, and drop the mark lower

Colour is chosen by name and mapped to a fixed value here, so the model never writes a style property — the same closed-set rule the mesh store uses.

Plugin/unraid/Tools/ai_chat_worker.php

@@ -915,6 +915,32 @@ if ($profile === 'chat' && vv_ai_chat_needs_varaverk($question)) {
 
 if ($context !== '') $system .= "PASSAGES\n" . $context;
 
+// What the transcript can render, offered rather than required.
+//
+// Appended to every profile at the single point they all pass through, so a new profile cannot
+// be added without it. The set is the one the mesh composer already offers, and the renderer
+// maps colour NAMES to fixed values — the model never writes a colour, only chooses one, so
+// nothing it emits can become a style property.
+//
+// Deliberately permissive in tone. The interesting question is whether it reaches for these at
+// all and where; an instruction to use them would answer that question by force and tell us
+// nothing. Prose stays prose.
+$system .= "\n\nFORMATTING AVAILABLE TO YOU\n"
+         . "The transcript renders a small set of marks. Use them where they genuinely help a "
+         . "reader — a warning that must not be skimmed, a value worth picking out of a "
+         . "sentence — and not otherwise. Plain prose is the default and needs no marking.\n"
+         . "  **bold**            emphasis\n"
+         . "  *italic*            aside or term\n"
+         . "  __underline__       rarely; reserve for something that must not be missed\n"
+         . "  {big}…{/big}        one size up\n"
+         . "  {small}…{/small}    one size down, for asides\n"
+         . "  {green}…{/green}    also blue, amber, red, violet, grey\n"
+         . "Colour carries meaning here: green for confirmed-good, amber for caution, red for "
+         . "something broken or destructive. Do not colour text decoratively — a coloured word "
+         . "that means nothing costs the colours their meaning everywhere else. Code fences and "
+         . "`inline code` work as before and remain the right choice for anything typed at a "
+         . "shell.\n";
+
 $messages = [['role' => 'system', 'content' => $system]];
 $hist = json_decode($historyJson ?: '[]', true);
 if (is_array($hist)) {