Feature Specification: Christmas Checker Website

Feature Branch: 001-christmas-checker Created: 2025-11-11 Status: Draft Input: User description: "i am building a simple webpage website that informs the user whether it is christmas or not. If it not christmas, the page says no and a sad smiley face is shown to the user. IF it is christmas, the website says yes and snow falls on the screen."

Clarifications

Session 2025-11-11

Q: Should December 26th be considered Christmas? → A: Yes - Both December 25th and 26th are Christmas
Q: How should the midnight transition behavior work when users keep the page open? → A: Hard reload at midnight (page refreshes automatically)
Q: What implementation approach should be used for the snow animation? → A: Canvas API with particle system

User Scenarios & Testing (mandatory)

User Story 1 - Check Christmas Status on Non-Christmas Day (Priority: P1)

A visitor opens the website on any day that is not Christmas (December 25th or 26th) to find out if it's Christmas. The website displays a clear "No" message with a sad smiley face, informing them that today is not Christmas.

Why this priority: This is the most common scenario (363 days per year) and represents the core functionality. Without this story working, the website fails its primary purpose for the vast majority of visits.

Independent Test: Can be fully tested by visiting the website on any non-Christmas day and verifying the "No" message and sad smiley face appear.

Acceptance Scenarios:

Given it is November 11th, When a user visits the website, Then the page displays "No" and shows a sad smiley face
Given it is December 24th, When a user visits the website, Then the page displays "No" and shows a sad smiley face
Given it is December 27th, When a user visits the website, Then the page displays "No" and shows a sad smiley face
Given it is any date from January 1st to December 24th or December 27th onwards, When a user visits the website, Then the page displays "No" and shows a sad smiley face

User Story 2 - Check Christmas Status on Christmas Day (Priority: P2)

A visitor opens the website on Christmas (December 25th or 26th) to confirm it's Christmas. The website displays a festive "Yes" message with animated snow falling on the screen, creating a celebratory experience.

Why this priority: This is the special case that happens twice per year and provides the delightful experience that makes the website memorable. While less frequent than P1, it's what makes the website fun and shareable.

Independent Test: Can be fully tested by setting the system date to December 25th or 26th and verifying the "Yes" message and snow animation appear.

Acceptance Scenarios:

Given it is December 25th, When a user visits the website, Then the page displays "Yes" and shows snow falling animation
Given it is December 26th, When a user visits the website, Then the page displays "Yes" and shows snow falling animation
Given it is December 25th at midnight (00:00), When a user visits the website, Then the page displays "Yes" and shows snow falling animation
Given it is December 26th at 11:59 PM, When a user visits the website, Then the page displays "Yes" and shows snow falling animation

Edge Cases

What happens when the user visits the website exactly at midnight transitioning from December 24th to December 25th? (System performs automatic page reload to update from "No" to "Yes")
What happens when the user visits the website exactly at midnight transitioning from December 26th to December 27th? (System performs automatic page reload to update from "Yes" to "No")
How does the system determine "today's date" for users in different time zones? (Assumption: Use the user's local browser time zone)
What happens if the user's system clock is incorrect or manipulated? (System trusts client-side clock; no validation)
What happens if snow animation causes performance issues on older devices? (Respect prefers-reduced-motion; optimize particle count by device screen size)

Requirements (mandatory)

Functional Requirements

FR-001: System MUST determine the current date based on the user's local time zone
FR-002: System MUST display "No" when the current date is not December 25th or 26th
FR-003: System MUST display a sad smiley face visual element when showing "No"
FR-004: System MUST display "Yes" when the current date is December 25th or 26th
FR-005: System MUST display a snow falling animation using Canvas API with particle system when showing "Yes"
FR-006: System MUST update the displayed state automatically via page reload if the user keeps the page open across midnight on December 24th/25th or December 26th/27th
FR-007: Page MUST be accessible via standard web browsers (Chrome, Firefox, Safari, Edge)
FR-008: Visual elements (text, smiley face, snow) MUST be clearly visible and legible

Key Entities

Date: Represents the current calendar date, determined from the user's local system time. Key attributes include month (1-12) and day (1-31).
Christmas Status: A boolean state representing whether the current date matches December 25th or 26th. This drives which UI elements are displayed.

Success Criteria (mandatory)

Measurable Outcomes

SC-001: Users can determine if it's Christmas within 1 second of page load
SC-002: The correct status (Yes/No) is displayed with 100% accuracy based on the current date
SC-003: Page loads and displays content in under 2 seconds on standard broadband connections
SC-004: Visual elements (smiley face and snow animation) render correctly on screens ranging from mobile devices (320px width) to desktop displays (1920px+ width)
SC-005: Users can understand the Christmas status without reading instructions (self-evident design)
SC-006: Snow animation (when active) runs smoothly at a minimum of 30 frames per second on devices from the past 5 years

Assumptions

The definition of "Christmas" is December 25th and 26th (Boxing Day) in the user's local time zone
"Snow falling" refers to a Canvas API particle-based visual animation effect, not actual weather data
The website is a single-page application with no navigation or additional pages
No user authentication or data persistence is required
The website should work offline once initially loaded (date check can be done client-side)
Accessibility considerations follow standard web practices (e.g., alt text for smiley face, reduced motion preferences for snow animation)
Snow animation uses 75 particles on mobile devices (width < 768px) and 150 particles on desktop

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