Add read_file skill, session persistence, and update script

- New read_file skill: paginated file reading with line ranges,
  path restricted to /workspace, binary detection, directory listing
- Session persistence via SQLite + FTS5: conversation history survives
  agent restarts, last N messages restored into deque on boot,
  auto-prune to 1000 messages
- Update truncation hint to reference read_file instead of run_command
- New scripts/update.sh for patching rootfs + rebuilding snapshot

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

agent/agent.py

@@ -12,6 +12,7 @@ from collections import deque
 
 from skills import discover_skills, execute_skill, set_logger as set_skills_logger
 from tools import load_memory, query_ollama, set_logger as set_tools_logger
+from sessions import init_db, save_message, load_recent, set_logger as set_sessions_logger
 
 # ─── Config ──────────────────────────────────────────────────────────
 
@@ -63,6 +64,7 @@ def log(msg):
 # Inject logger into submodules
 set_skills_logger(log)
 set_tools_logger(log)
+set_sessions_logger(log)
 
 # ─── Init ────────────────────────────────────────────────────────────
 
@@ -70,6 +72,11 @@ AGENT_MEMORY = load_memory(WORKSPACE)
 TOOLS, SKILL_SCRIPTS = discover_skills(SKILL_DIRS)
 log(f"Loaded {len(TOOLS)} skills: {', '.join(SKILL_SCRIPTS.keys())}")
 
+db_conn = init_db(f"{WORKSPACE}/sessions.db")
+for msg in load_recent(db_conn, CONTEXT_SIZE):
+    recent.append(msg)
+log(f"Session: restored {len(recent)} messages")
+
 
 def reload_memory():
     global AGENT_MEMORY
@@ -212,6 +219,7 @@ def handle_message(irc, source_nick, target, text):
     reply_to = source_nick if is_dm else target
 
     recent.append({"nick": source_nick, "text": text, "channel": channel})
+    save_message(db_conn, source_nick, channel, text)
 
     if source_nick == NICK:
         return
@@ -249,6 +257,7 @@ def handle_message(irc, source_nick, target, text):
 
             irc.say(reply_to, "\n".join(lines))
             recent.append({"nick": NICK, "text": response[:200], "channel": channel})
+            save_message(db_conn, NICK, channel, response[:200], full_text=response)
         except Exception as e:
             log(f"Error handling message: {e}")
             try: