Hot Reload¶

Modify DevDuck's code while it's running. Changes apply instantly without losing context.

How It Works¶

flowchart TD
    A["File Watcher Thread"] -->|Every 1s| B{"__init__.py changed?"}
    B -->|No| A
    B -->|Yes| C{"Agent executing?"}
    C -->|Yes| D["Set _reload_pending = True"]
    D --> E["Wait for agent to finish"]
    E --> F["os.execv() → Full restart"]
    C -->|No| G{"Debounce (3s)?"}
    G -->|Wait| A
    G -->|Ready| F

A background thread watches devduck/__init__.py. When a change is detected:

Agent idle → Immediate restart via os.execv()
Agent executing → _reload_pending flag set, reload triggers after completion
Debounce → 3-second window prevents rapid reloads

Live Demo¶

🦆 # DevDuck running normally...

# You edit devduck/__init__.py in another terminal

🦆 Detected changes in __init__.py!
🦆 Restarting process with fresh code...
🦆 DevDuck
📝 Logs: /tmp/devduck/logs
🦆 ✓ Zenoh peer: hostname-abc123
🦆 # Ready with your changes!

During Agent Execution¶

🦆 run a complex task...
🛠️ Tool #1: shell

# You edit code while agent is working...

🦆 Agent is currently executing - reload will trigger after completion

✅ Tool completed successfully

[Agent finishes response]
🦆 Agent finished - triggering pending hot-reload...
🦆 Restarting process with fresh code...

Safe Reload

Hot reload never interrupts a running agent. The _reload_pending flag ensures no lost work or corrupted state.

Tool Hot Loading¶

Create new tools by saving .py files to the ./tools/ directory:

# ./tools/weather.py
from strands import tool
import requests

@tool
def weather(city: str) -> str:
    """Get weather for a city."""
    return requests.get(f"https://wttr.in/{city}?format=%C+%t").text

The tool is immediately available — no restart needed. DevDuck's load_tools_from_directory=True picks it up automatically.

Configuration¶

Variable	Default	Description
`DEVDUCK_LOAD_TOOLS_FROM_DIR`	`true`	Auto-load `./tools/*.py`

The file watcher monitors devduck/__init__.py specifically. Tool directory loading is handled by the Strands Agent SDK's built-in mechanism.