Extract Formulas

extract-formulas

Skill Type: Actuator (Requirements Disambiguation) Purpose: Extract F-* formulas from REQ-* requirements Prerequisites: REQ-* requirement exists

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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.

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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

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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"

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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!

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