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112 lines
3.7 KiB
Python
112 lines
3.7 KiB
Python
"""Example Finance-domain MCP server (EP-06-T03).
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invoice.get (R1, read-only), payment.create (R2, side-effecting, not yet
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executed), payment.execute (R3, high-impact -- REQUIRE_APPROVAL above
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Finance.Payments' `restrictions.approval_threshold`, enforced entirely by
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config/policies/transaction.rego before the call ever reaches here). Backed
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by static mock data -- this server is deliberately "dumb" (ADR-023): it never
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authorizes anything, only the Gateway/PDP does that, upstream of this process.
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Run directly for local development:
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python -m example_mcp_servers.finance_domain.server
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"""
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from __future__ import annotations
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import itertools
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import os
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from mcp.server.mcpserver import MCPServer
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from starlette.types import ASGIApp
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from emcp_bus.audit.bypass_detection import BackendCredentialGate
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from emcp_bus.audit.sink import JSONLFileAuditSink
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from emcp_bus.common.otel import setup_tracing
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setup_tracing("finance-domain-mcp-server")
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server = MCPServer(name="finance-domain", version="0.1.0")
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_INVOICES: dict[str, dict[str, object]] = {
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"inv-001": {
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"invoice_id": "inv-001",
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"customer_id": "cust-001",
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"amount": 5000,
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"status": "open",
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},
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"inv-002": {
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"invoice_id": "inv-002",
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"customer_id": "cust-002",
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"amount": 25000,
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"status": "overdue",
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},
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}
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_PAYMENTS: dict[str, dict[str, object]] = {}
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_payment_ids = itertools.count(1)
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@server.tool(name="finance.invoice.get", description="Get a single finance invoice by id.")
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def invoice_get(invoice_id: str) -> dict[str, object]:
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invoice = _INVOICES.get(invoice_id)
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if invoice is None:
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return {"error": "not_found", "invoice_id": invoice_id}
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return invoice
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@server.tool(
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name="finance.payment.create", description="Create a draft payment against an invoice."
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)
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def payment_create(invoice_id: str, amount: float) -> dict[str, object]:
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payment_id = f"pay-{next(_payment_ids):03d}"
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payment = {
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"payment_id": payment_id,
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"invoice_id": invoice_id,
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"amount": amount,
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"status": "draft",
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}
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_PAYMENTS[payment_id] = payment
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return payment
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@server.tool(name="finance.payment.execute", description="Execute a previously created payment.")
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def payment_execute(payment_id: str, amount: float) -> dict[str, object]:
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"""`amount` is declared by the caller (not re-derived from the stored
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payment) so it is visible to `config/policies/transaction.rego`'s
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`approval_threshold` check (README.md §26) -- the transaction policy
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inspects call arguments, never backend state, matching `sales.quote.create`'s
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same pattern (EP-06-T02)."""
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payment = _PAYMENTS.get(payment_id)
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if payment is None:
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return {"error": "not_found", "payment_id": payment_id}
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payment["status"] = "executed"
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payment["executed_amount"] = amount
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return payment
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def main() -> None:
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host = os.environ.get("FINANCE_DOMAIN_HOST", "127.0.0.1")
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port = int(os.environ.get("FINANCE_DOMAIN_PORT", "8101"))
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expected_token = os.environ.get("FINANCE_DOMAIN_SERVICE_TOKEN")
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audit_log_path = os.environ.get("EMCP_AUDIT_LOG_PATH", "/tmp/emcp-audit.jsonl")
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app: ASGIApp = server.streamable_http_app(host=host)
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if expected_token:
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# EP-05-T07: reject anything that didn't come through the Gateway's
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# outbound identity (EP-07-T01) with the matching service credential.
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app = BackendCredentialGate(
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app,
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expected_token=expected_token,
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backend="finance-domain",
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audit_sink=JSONLFileAuditSink(audit_log_path),
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)
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import uvicorn
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uvicorn.run(app, host=host, port=port, log_level="info")
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if __name__ == "__main__":
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main()
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