| name | extract-formulas |
| description | Extract mathematical formulas (F-*) from requirements - calculations, algorithms, conversions. Enables autogeneration of calculation functions with tests. Use when requirements involve math, dates, percentages, or algorithms. |
| allowed-tools | ["Read","Write","Edit"] |
extract-formulas
Skill Type: Actuator (Requirements Disambiguation)
Purpose: Extract F-* formulas from REQ-* requirements
Prerequisites: REQ-* requirement exists
Agent Instructions
You are extracting formulas (F-*) from requirements.
Formulas are:
- Mathematical calculations (fee = amount * rate)
- Date/time calculations (expiry = issue_time + duration)
- Conversions (celsius = (fahrenheit - 32) * 5/9)
- Algorithms (hash, scoring, ranking)
Goal: Identify formulas precise enough for code autogeneration.
F-* Categories
1. Arithmetic Formulas
F-001: Stripe processing fee
- Formula: fee = (amount * 0.029) + 0.30
- Inputs: amount (float)
- Output: fee (float, rounded to 2 decimals)
- Autogenerate: calculate_stripe_fee(amount) -> float
2. Date/Time Calculations
F-010: Token expiry time
- Formula: expiry = issue_time + (60 * 60) seconds
- Inputs: issue_time (datetime)
- Output: expiry (datetime)
- Autogenerate: calculate_token_expiry(issue_time) -> datetime
3. Percentage/Ratio Calculations
F-020: Discount amount
- Formula: discount = original_price * discount_percentage
- Inputs: original_price (float), discount_percentage (float 0.0-1.0)
- Output: discount (float, rounded to 2 decimals)
- Autogenerate: calculate_discount(price, percentage) -> float
4. Hash/Checksum Algorithms
F-030: Idempotency key
- Formula: key = SHA256(merchant_id + timestamp + amount)
- Inputs: merchant_id (str), timestamp (int), amount (float)
- Output: key (hex string, 64 chars)
- Autogenerate: generate_idempotency_key(...) -> str
Extraction Process
Identify formulas by looking for:
- Calculations: "calculate", "compute", "determine"
- Operators: +, -, *, /, %, ^
- Functions: SHA256, round, abs, max, min
- Time: "expires after", "duration", "timeout"
- Money: "fee", "tax", "discount", "total"
Output Format
[EXTRACT FORMULAS - <REQ-ID>]
Requirement: Payment processing
Formulas Extracted (3):
✓ F-001: Stripe processing fee calculation
✓ F-002: Idempotency key generation
✓ F-003: Transaction timeout calculation
Updated: docs/requirements/payments.md
Added: Formulas section with 3 F-*
✅ Formula Extraction Complete!
"Excellence or nothing" 🔥
