Use Case Template

Use Case: [Verb phrase — sea level goal]
Actor: [Primary actor]
Goal: [What they want to accomplish]
Preconditions: [Must be true to start]
Postconditions: [True after success]
Main Success Scenario:
  1. [Step]
  ...
Extensions:
  [step][letter]. [Condition]: [Response]

Use Case: User Resets Password
Actor: Registered User
Goal: Regain account access after forgetting password
Preconditions: User has a registered account
Postconditions: User has a new password; old sessions invalidated

Main Scenario:
1. User clicks "Forgot Password"
2. User enters their email address
3. System sends reset email with 60-min link
4. User clicks the link
5. User enters and confirms new password
6. System validates and saves new password
7. System redirects to login with success message

Extensions:
2a. Email not found: show generic "If registered, you'll receive an email"
4a. Link expired: show error + option to request new link
6a. Passwords do not match: show inline error