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Ghost in the Droid

🔗 Hello World — LangChain

Ghost tools inside a LangChain agent. In the video, a LangChain agent harvests subreddits into SQLite — the phone does the browsing, the framework does the orchestrating.

Prerequisites

Section titled “Prerequisites”
  • A phone connected over ADB with USB debugging on (adb devices shows it)
  • Python 3.11+ and an Anthropic (or other LangChain-supported) API key

Step 1 — Install with the LangChain extra

Section titled “Step 1 — Install with the LangChain extra”
Terminal window
pip install "ghost-in-the-droid[langchain]"

Ghost’s core never imports the adapter — the framework dependency is an optional extra, so plain installs stay lean.

Step 2 — Give your agent a body

Section titled “Step 2 — Give your agent a body”
from langchain.chat_models import init_chat_model
from langgraph.prebuilt import create_react_agent
from integrations.langchain import ghost_langchain_tools


tools = ghost_langchain_tools("emulator-5554")   # bound to one device
agent = create_react_agent(init_chat_model("anthropic:claude-sonnet-4"), tools)


agent.invoke({"messages": "Open Settings and turn on Wi-Fi"})
# → the agent taps its way through the real phone

Every Ghost tool (tap, type_text, launch_app, get_screen_tree, find_on_screen, screenshots, OCR, …) arrives as a native LangChain tool, so it slots straight into LangGraph or any existing agent loop.

Step 3 — Verify

Section titled “Step 3 — Verify”

Swap the prompt for something observable:

agent.invoke({"messages": "Read the top post on r/LocalLLaMA in the Reddit app and summarize it"})

The video runs exactly this pattern in a loop — five harvests, results written to a local SQLite table.

Two things worth knowing

Section titled “Two things worth knowing”
  • Device binding is locked. The serial you pass to ghost_langchain_tools(...) can’t be overridden by a tool call — one toolset drives exactly one phone.
  • Dangerous tools are opt-in. Raw shell and run_skill are excluded unless you pass include_dangerous=True. The allow-list fails closed.

What next?

Section titled “What next?”

Try another approach →

Section titled “Try another approach →”

MCP + Claude Code · MCP + Codex · MCP + Antigravity · Ghost CLI · Web Chat · On-Device Android · On-Device iPhone · iPhone Duolingo