Marchward — Python SDK

Runtime authority for AI agents. Gate every tool call through a cost cap, approval gates on irreversible actions, and a tamper-evident audit log.

Python is the primary Marchward SDK — the wedge persona builds on LangGraph / LangChain (both Python). Zero runtime dependencies (stdlib only).

Install

pip install marchward

Quickstart

from marchward import MarchwardClient

marchward = MarchwardClient(api_key="tnt_...")   # or set MARCHWARD_API_KEY

decision = marchward.execute(
    service="github",
    tool_name="github.repos.delete",
    arguments={"owner": "acme", "repo": "old-experiment"},
    context={"env": "production"},
)

if decision.allowed:
    do_the_delete()
elif decision.escalated:
    print(f"Paused for approval — review {decision.review_id}")
elif decision.blocked:
    print(f"Blocked: {decision.reason_codes}")

With LangGraph (the persona's stack)

from langchain_core.tools import tool
from marchward import MarchwardClient

marchward = MarchwardClient()

@tool
def delete_repo(owner: str, repo: str) -> str:
    """Delete a GitHub repository."""
    d = marchward.execute(service="github", tool_name="github.repos.delete",
                      arguments={"owner": owner, "repo": repo})
    if not d.allowed:
        return f"Refused by Marchward ({d.outcome.value})."
    # ... real delete here ...
    return "deleted"

How it works (Model B)

You send a logical tool call — service + tool_name + arguments. Marchward resolves the real downstream HTTP request from its tool catalog, governs it, injects your stored credential server-side, and executes it. Your agent holds only MARCHWARD_API_KEY; it never touches downstream credentials. Connect those once in the dashboard (Settings → Connected services).

API

• MarchwardClient(api_key=None, *, api_url=None, default_agent_id="python-sdk", timeout=30.0, poll_timeout=120.0, poll_interval=0.75)
• .execute(*, service, tool_name, arguments=None, context=None, agent_id=None, request_id=None, wait=True) -> Decision
• .get_job(job_id) -> dict — poll one async job manually (for wait=False).
• Decision: .allowed / .escalated / .blocked / .executed, plus .outcome, .decision_id, .review_id, .reason_codes, .http_status, .raw, .job_id, .execution, .execution_error.

Contract

.executed is True only when an ALLOW actually ran its downstream — an ALLOW with no connected credential, a failed downstream, or a still-pending job is allowed-but-not-executed.

Risk classification

Risk is classified by the resolved HTTP method, not the tool name — any DELETE (or a flagged destructive POST like stripe.charges.create) is treated as irreversible and gated, regardless of what the tool is named. So a custom-named destructive tool can't slip past the approval gate.

Tests

cd packages/sdk-python && python -m unittest discover -s tests