Initial implementation of IRC LLM bot

Full implementation from spec: ZNC/IRC client with TLS, Ollama LLM backend,
per-user SQLite conversation memory, and Flask web admin portal with 7 pages.

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

bot/message_handler.py

@@ -0,0 +1,99 @@
+import logging
+import re
+from collections import deque
+
+from bot import memory as mem
+from bot import llm_client
+
+logger = logging.getLogger(__name__)
+
+# Per-channel rolling context buffer: {channel: deque}
+_context_buffers: dict[str, deque] = {}
+
+
+def _get_context(channel: str, window: int) -> deque:
+    if channel not in _context_buffers:
+        _context_buffers[channel] = deque(maxlen=window)
+    else:
+        _context_buffers[channel] = deque(_context_buffers[channel], maxlen=window)
+    return _context_buffers[channel]
+
+
+def handle_privmsg(nick: str, channel: str, text: str, config: dict) -> str | None:
+    """
+    Returns a reply string if the bot should respond, else None.
+    Also maintains the context buffer as a side effect.
+    """
+    window = config.get("context_window", 5)
+    ctx = _get_context(channel, window)
+
+    ignored = [n.lower() for n in config.get("ignored_nicks", [])]
+    if nick.lower() in ignored:
+        return None
+
+    bot_nick = config.get("bot_nick", "avcbot").lower()
+    trigger_prefix = config.get("trigger_prefix")
+    trigger_on_nick = config.get("trigger_on_nick", True)
+
+    # Detect "forget me" command before trigger check
+    forget_pattern = re.compile(
+        rf"^{re.escape(bot_nick)}\s*[:,]\s*forget\s+me\s*$", re.IGNORECASE
+    )
+    if forget_pattern.match(text.strip()):
+        mem.delete_user_history(channel, nick)
+        logger.info(f"[MEMORY] Forgot history for {nick} in {channel}")
+        return f"{nick}: Done, I've cleared your history."
+
+    # Determine if triggered
+    stripped = None
+
+    if trigger_on_nick:
+        nick_pattern = re.compile(
+            rf"^{re.escape(bot_nick)}\s*[:,]\s*", re.IGNORECASE
+        )
+        m = nick_pattern.match(text)
+        if m:
+            stripped = text[m.end():].strip()
+
+    if stripped is None and trigger_prefix:
+        if text.startswith(trigger_prefix):
+            stripped = text[len(trigger_prefix):].strip()
+
+    # Add to context buffer regardless
+    ctx.append(f"<{nick}> {text}")
+
+    if stripped is None:
+        return None
+
+    # Build and send to LLM
+    history = []
+    if config.get("memory_enabled", True):
+        limit = config.get("memory_history_limit", 8)
+        history = mem.load_history(channel, nick, limit)
+
+    prompt = llm_client.build_prompt(
+        user_message=stripped,
+        nick=nick,
+        persistent_history=history,
+        context_buffer=list(ctx)[:-1],  # exclude the current message already in buffer
+    )
+
+    system = config.get(
+        "system_prompt",
+        "You are a helpful IRC assistant for Active Blue. Keep responses concise and under 3 sentences when possible.",
+    )
+
+    logger.info(f"[LLM] Request from {nick} in {channel}: {stripped[:80]}")
+
+    try:
+        reply = llm_client.generate(prompt, system, config)
+    except TimeoutError:
+        return f"{nick}: [LLM timeout — try again]"
+    except Exception as e:
+        logger.error(f"[LLM] Generation error: {e}")
+        return f"{nick}: [LLM error — check logs]"
+
+    if config.get("memory_enabled", True):
+        mem.save_exchange(channel, nick, stripped, reply)
+
+    return f"{nick}: {reply}"