---
name: a5c-ai/behavior-contract
source: https://app.decimal.ai/s/a5c-ai-behavior-contract@1/SKILL.md
source_sha256: a4acc70643bd
---

- "Positive amounts still process correctly"
- "Negative amounts still throw `InvalidAmountError`"
- "Receipt format remains unchanged for all amount types"

## Contract Document Template

```markdown
# Behavior Contract: [Bug Title]

## Bug Condition
[Precise description of triggering conditions]

## Postcondition
[Expected correct behavior after fix]

## Invariants
- [ ] Invariant 1: [existing behavior to preserve]
- [ ] Invariant 2: [existing behavior to preserve]

## Testable Assertions
1. `expect(processPayment(0)).toEqual({ amount: 0, status: 'completed' })`
2. `expect(processPayment(100)).toEqual({ amount: 100, status: 'completed' })`
3. `expect(() => processPayment(-1)).toThrow(InvalidAmountError)`
```

## Usage in Bugfix Workflow

1. Bug analysis identifies root cause at file:line
2. This skill formalizes the contract from the analysis
3. tdd-enforcer writes failing test from Bug Condition
4. tdd-enforcer writes preservation tests from Invariants
5. Minimal fix applied, contract audited