Order Lifecycle

If you're building an OMS or EMS, this walks you through order state machines, FIX protocol flows, and all the edge cases that bite you in production. It covers the full lifecycle from order entry through fills, cancels, and replacements, including the race conditions between cancel requests and executions that cause most bugs. You'll find the canonical state definitions (New, Pending New, Accepted, Partially Filled, and the terminal states), valid transitions, ClOrdID chaining for cancel/replace workflows, and pre-submission validation patterns. The material on CAT audit trails and order persistence for failover is solid. This is the reference you want when debugging why an order hit an impossible state or designing recovery logic.

skills.sh installs: 780
GitHub stars: 224
last updated: Aug 21, 2026

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Install

$ npx -y skills add joellewis/finance_skills --skill order-lifecycle --agent claude-code

Installs into .claude/skills of the current project.

Files

Order Lifecycle

Core Concepts

Order State Machine

The order state machine is the central abstraction in any order management system. It defines every state an order can occupy and every valid transition between states. A correctly implemented state machine prevents impossible transitions (such as filling a canceled order), ensures audit trail completeness, and provides the foundation for order status reporting to clients, counterparties, and regulators.

Canonical order states:

SKILL.md on GitHub

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