Domain Fintech

This is your checklist for building anything that touches money. It pushes you away from f64 (precision loss) toward rust_decimal, shows you how to model immutable transactions with Arc for audit trails, and maps fintech domain rules (double-entry accounting, regulatory compliance) directly to Rust patterns. The trace-down tables connect constraints like "money can't disappear" to specific designs like newtypes and RAII transaction scopes. Most valuable if you're building payment systems, trading platforms, or ledgers where getting the money math wrong isn't just a bug, it's a legal problem. Covers currency types, event sourcing for transactions, and the common mistakes that break audit requirements.

skills.sh installs: 581
GitHub stars: 1.3K
last updated: Jul 14, 2026

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Install

$ npx -y skills add zhanghandong/rust-skills --skill domain-fintech --agent claude-code

Installs into .claude/skills of the current project.

Files

FinTech Domain

Layer 3: Domain Constraints

Domain Constraints → Design Implications

Domain Rule	Design Constraint	Rust Implication
Audit trail	Immutable records	Arc, no mutation
Precision	No floating point	rust_decimal
Consistency	Transaction boundaries	Clear ownership
Compliance	Complete logging	Structured tracing
Reproducibility	Deterministic execution	No race conditions

Critical Constraints

Financial Precision

RULE: Never use f64 for money
WHY: Floating point loses precision
RUST: Use rust_decimal::Decimal

Audit Requirements

RULE: All transactions must be immutable and traceable
WHY: Regulatory compliance, dispute resolution
RUST: Arc<T> for sharing, event sourcing pattern

Consistency

RULE: Money can't disappear or appear
WHY: Double-entry accounting principles
RUST: Transaction types with validated totals

Trace Down ↓

From constraints to design (Layer 2):

"Need immutable transaction records"
    ↓ m09-domain: Model as Value Objects
    ↓ m01-ownership: Use Arc for shared immutable data

SKILL.md on GitHub

Details

Repository: github.com/zhanghandong/rust-skills
Category: Rust
First seen: Jun 3, 2026