fix: tag context messages with [CONTEXT] to prevent LLM from scoring them

The triage LLM was blending context message content into its reasoning
for new messages (e.g., citing profanity from context when the new
message was just "I'll be here"). Added per-message [CONTEXT] tags
inline and strengthened the prompt to explicitly forbid referencing
context content in reasoning/scores.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

utils/llm_client.py

@@ -399,6 +399,7 @@ class LLMClient:
 
         lines = [f"[Current time: {now.strftime('%I:%M %p')}]", ""]
         last_user = None
+        in_new_section = new_message_start is None or new_message_start == 0
 
         for idx, (username, content, ts, reply_to) in enumerate(messages):
             if new_message_start is not None and idx == new_message_start:
@@ -406,8 +407,10 @@ class LLMClient:
                 lines.append("--- NEW MESSAGES (score only these) ---")
                 lines.append("")
                 last_user = None  # reset collapse so first new msg gets full header
+                in_new_section = True
             delta = now - ts.replace(tzinfo=timezone.utc) if ts.tzinfo is None else now - ts
             rel = LLMClient._format_relative_time(delta)
+            tag = "" if in_new_section else " [CONTEXT]"
 
             if username == last_user:
                 # Continuation from same user — indent
@@ -416,9 +419,9 @@ class LLMClient:
             else:
                 # New user block
                 if reply_to:
-                    prefix = f"[{rel}] {username} → {reply_to}: "
+                    prefix = f"[{rel}] {username} → {reply_to}:{tag} "
                 else:
-                    prefix = f"[{rel}] {username}: "
+                    prefix = f"[{rel}] {username}:{tag} "
                 msg_lines = content.split("\n")
                 lines.append(prefix + msg_lines[0])
                 for line in msg_lines[1:]: