feat: multi-instance support with --config parameter

Add support for running multiple nanobot instances with complete isolation:

- Add --config parameter to gateway command for custom config file path
- Implement set_config_path() in config/loader.py for dynamic config path
- Derive data directory from config file location (e.g., ~/.nanobot-xxx/)
- Update get_data_path() to use unified data directory from config loader
- Ensure cron jobs use instance-specific data directory

This enables running multiple isolated nanobot instances by specifying
different config files, with each instance maintaining separate:
- Configuration files
- Workspace (memory, sessions, skills)
- Cron jobs
- Logs and media

Example usage:
  nanobot gateway --config ~/.nanobot-instance2/config.json --port 18791

nanobot/cli/commands.py

@@ -244,15 +244,24 @@ def _make_provider(config: Config):
 @app.command()
 def gateway(
     port: int = typer.Option(18790, "--port", "-p", help="Gateway port"),
-    workspace: str | None = typer.Option(None, "--workspace", "-w", help="Workspace directory"),
-    config: str | None = typer.Option(None, "--config", "-c", help="Config file path"),
     verbose: bool = typer.Option(False, "--verbose", "-v", help="Verbose output"),
+    config: str = typer.Option(None, "--config", "-c", help="Path to config file"),
 ):
     """Start the nanobot gateway."""
+    # Set config path if provided (must be done before any imports that use get_data_dir)
+    if config:
+        from nanobot.config.loader import set_config_path
+        config_path = Path(config).expanduser().resolve()
+        if not config_path.exists():
+            console.print(f"[red]Error: Config file not found: {config_path}[/red]")
+            raise typer.Exit(1)
+        set_config_path(config_path)
+        console.print(f"[dim]Using config: {config_path}[/dim]")
+    
     from nanobot.agent.loop import AgentLoop
     from nanobot.bus.queue import MessageBus
     from nanobot.channels.manager import ChannelManager
-    from nanobot.config.loader import load_config
+    from nanobot.config.loader import get_data_dir, load_config
     from nanobot.cron.service import CronService
     from nanobot.cron.types import CronJob
     from nanobot.heartbeat.service import HeartbeatService
@@ -262,20 +271,16 @@ def gateway(
         import logging
         logging.basicConfig(level=logging.DEBUG)
 
-    config_path = Path(config) if config else None
-    config = load_config(config_path)
-    if workspace:
-        config.agents.defaults.workspace = workspace
-
     console.print(f"{__logo__} Starting nanobot gateway on port {port}...")
+
+    config = load_config()
     sync_workspace_templates(config.workspace_path)
     bus = MessageBus()
     provider = _make_provider(config)
     session_manager = SessionManager(config.workspace_path)
 
     # Create cron service first (callback set after agent creation)
-    # Use workspace path for per-instance cron store
-    cron_store_path = config.workspace_path / "cron" / "jobs.json"
+    cron_store_path = get_data_dir() / "cron" / "jobs.json"
     cron = CronService(cron_store_path)
 
     # Create agent with cron service

nanobot/config/loader.py

@@ -6,15 +6,29 @@ from pathlib import Path
 from nanobot.config.schema import Config
 
 
+# Global variable to store current config path (for multi-instance support)
+_current_config_path: Path | None = None
+
+
+def set_config_path(path: Path) -> None:
+    """Set the current config path (used to derive data directory)."""
+    global _current_config_path
+    _current_config_path = path
+
+
 def get_config_path() -> Path:
-    """Get the default configuration file path."""
+    """Get the configuration file path."""
+    if _current_config_path:
+        return _current_config_path
     return Path.home() / ".nanobot" / "config.json"
 
 
 def get_data_dir() -> Path:
-    """Get the nanobot data directory."""
-    from nanobot.utils.helpers import get_data_path
-    return get_data_path()
+    """Get the nanobot data directory (derived from config path)."""
+    config_path = get_config_path()
+    # If config is ~/.nanobot-xxx/config.json, data dir is ~/.nanobot-xxx/
+    # If config is ~/.nanobot/config.json, data dir is ~/.nanobot/
+    return config_path.parent
 
 
 def load_config(config_path: Path | None = None) -> Config:

nanobot/utils/helpers.py

@@ -12,8 +12,9 @@ def ensure_dir(path: Path) -> Path:
 
 
 def get_data_path() -> Path:
-    """~/.nanobot data directory."""
-    return ensure_dir(Path.home() / ".nanobot")
+    """Get nanobot data directory (derived from config path)."""
+    from nanobot.config.loader import get_data_dir
+    return ensure_dir(get_data_dir())
 
 
 def get_workspace_path(workspace: str | None = None) -> Path: