Quickstart¶

1. Write an agent¶

A LangStage agent is just a LangGraph CompiledGraph exported from a Python file or module. Nothing LangStage-specific is required.

my_agent.py

from deepagents import create_deep_agent
from langgraph.checkpoint.memory import MemorySaver

graph = create_deep_agent(
    model="anthropic:claude-sonnet-4-5",
    checkpointer=MemorySaver(),
)

2. Point any stage at it with one spec string¶

The agent spec is path/to/file.py:attr or module:attr. Every stage understands the same form:

langstage run --agent my_agent.py:graph          # web
langstage-cli --agent my_agent.py:graph          # terminal  (-a for short)
langstage-jupyter --agent my_agent.py:graph      # JupyterLab launcher

Prefer not to pass it each time? Set it once in the environment or langstage.toml (see Configuration) and every stage picks it up:

export LANGSTAGE_AGENT_SPEC="my_agent.py:graph"

3. Try a stage with no API key¶

Every surface has a --demo flag that swaps in a deterministic, keyless echo agent — great for a first run or for screenshots/tests:

langstage run --demo
langstage-cli --demo "ping"
langstage-jupyter --demo
python -m langstage_vscode --demo

On the web stage, the empty screen offers a few starter-prompt chips — click one to begin without typing.

4. See exactly what's configured¶

When you're not sure which value won, every stage can print the fully resolved configuration — each value, where it came from, and the env var / TOML key that sets it:

langstage config            # web: a subcommand, like `langstage run`
langstage-cli --show-config
langstage-hermes --show-config

Resolved config  (value  [source]):

  agent_spec       = my_agent.py:graph          [env:LANGSTAGE_AGENT_SPEC]   (env: LANGSTAGE_AGENT_SPEC, toml: agent.spec)
  workspace_root   = .                          [default]                    (env: LANGSTAGE_WORKSPACE_ROOT, toml: workspace.root)
  port             = 8050                        [default]                    (env: LANGSTAGE_PORT, toml: server.port)
  ...

Now pick the stage you want: Web · Terminal · JupyterLab · VS Code · Reference agent