diff --git a/.dockerignore b/.dockerignore
new file mode 100644
index 0000000..6d675f1
--- /dev/null
+++ b/.dockerignore
@@ -0,0 +1,37 @@
+# Git
+.git/
+.gitignore
+
+# Documentation
+README.md
+*.md
+specs/
+
+# IDE
+.idea/
+.vscode/
+*.iml
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Build artifacts
+target/
+build/
+*.class
+*.jar
+
+# Logs
+*.log
+*.log*
+
+# Environment
+.env
+.env.*
+
+# Node modules (if any)
+node_modules/
+
+# Coverage
+coverage/
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..0e6b890
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,33 @@
+# Java
+target/
+*.class
+*.jar
+*.war
+*.ear
+.gradle/
+build/
+*.log
+
+# IDEs
+.idea/
+.vscode/
+*.iml
+*.swp
+*.swo
+
+# OS
+.DS_Store
+Thumbs.db
+*.tmp
+
+# Environment
+.env
+.env.*
+!.env.example
+
+# Docker
+*.log*
+
+# Build outputs
+dist/
+out/
diff --git a/.specify/memory/constitution.md b/.specify/memory/constitution.md
index a4670ff..17d8494 100644
--- a/.specify/memory/constitution.md
+++ b/.specify/memory/constitution.md
@@ -1,50 +1,194 @@
-# [PROJECT_NAME] Constitution
-
+
+
+# is-it-christmas Constitution
## Core Principles
-### [PRINCIPLE_1_NAME]
-
-[PRINCIPLE_1_DESCRIPTION]
-
+### I. User Story-Driven Development
-### [PRINCIPLE_2_NAME]
-
-[PRINCIPLE_2_DESCRIPTION]
-
+Every feature MUST begin with clearly defined, prioritized user stories that are independently testable. Each user story represents a complete slice of functionality that delivers standalone value.
-### [PRINCIPLE_3_NAME]
-
-[PRINCIPLE_3_DESCRIPTION]
-
+**Requirements:**
+- User stories MUST be prioritized (P1, P2, P3, etc.) with P1 being the most critical
+- Each story MUST be independently implementable, testable, and deployable
+- User stories MUST include acceptance scenarios in Given/When/Then format
+- Implementation MUST enable incremental delivery (MVP = P1 story complete)
-### [PRINCIPLE_4_NAME]
-
-[PRINCIPLE_4_DESCRIPTION]
-
+**Rationale**: User story-driven development ensures that every increment delivers real user value, enables parallel development, and allows early validation of the most critical functionality.
-### [PRINCIPLE_5_NAME]
-
-[PRINCIPLE_5_DESCRIPTION]
-
+### II. Specification-First Planning
-## [SECTION_2_NAME]
-
+Features MUST be fully specified before implementation begins. Specifications include user scenarios, functional requirements, success criteria, and technical design documents.
-[SECTION_2_CONTENT]
-
+**Requirements:**
+- Every feature MUST have a spec.md with user stories, requirements, and success criteria
+- Every feature MUST have a plan.md with technical context, structure, and constitution check
+- Complex features MUST include research.md, data-model.md, and contract definitions
+- All specifications MUST use technology-agnostic language focusing on "what" not "how"
-## [SECTION_3_NAME]
-
+**Rationale**: Specification-first planning reduces implementation churn, catches design issues early, enables better collaboration through clear documentation, and provides a reference for validation.
-[SECTION_3_CONTENT]
-
+### III. Test-Optional with Clear Intent
+
+Testing is OPTIONAL and MUST be explicitly requested. When tests are required, they MUST be written first and MUST fail before implementation.
+
+**Requirements:**
+- Tests are ONLY written when explicitly requested in the feature specification
+- When requested, tests MUST follow the Test-Driven Development (TDD) cycle:
+ 1. Write tests that capture the requirements
+ 2. Verify tests FAIL (proving they test real behavior)
+ 3. Implement the feature
+ 4. Verify tests PASS
+- Test types: Contract tests (API/interface contracts), Integration tests (user journeys), Unit tests (component logic)
+- Task lists MUST clearly mark test tasks as "OPTIONAL - only if tests requested"
+
+**Rationale**: Making tests optional reduces overhead for prototypes and simple features while maintaining rigor when quality gates are needed. Explicit test-first approach prevents false confidence from tests written after implementation.
+
+### IV. Independent User Story Implementation
+
+Implementation MUST be structured to enable each user story to be developed, tested, and deployed independently without breaking other stories.
+
+**Requirements:**
+- Task lists MUST be organized by user story (Phase 3: User Story 1, Phase 4: User Story 2, etc.)
+- Shared infrastructure MUST be completed in a blocking "Foundational" phase before any user story work begins
+- Each user story phase MUST include an "Independent Test" description
+- Each user story phase MUST end with a checkpoint confirming standalone functionality
+- Cross-story dependencies MUST be minimized; when unavoidable, they MUST be explicitly documented
+
+**Rationale**: Independent user stories enable parallel team work, incremental delivery, easier debugging, and the ability to defer or cut lower-priority stories without impacting core functionality.
+
+### V. Simplicity and Justified Complexity
+
+Solutions MUST start simple. Complexity MUST be explicitly justified with documented alternatives that were rejected.
+
+**Requirements:**
+- Default to the simplest solution that meets requirements
+- Apply YAGNI (You Aren't Gonna Need It) principles
+- When complexity is introduced (additional layers, patterns, frameworks), MUST document:
+ - Why the complexity is needed
+ - What simpler alternative was considered
+ - Why the simpler alternative was insufficient
+- Constitution Check violations MUST be tracked in plan.md Complexity Tracking table
+
+**Rationale**: Unnecessary complexity increases maintenance burden, slows development, and makes onboarding harder. Requiring justification ensures complexity is only introduced when it provides clear value.
+
+## Development Workflow
+
+### Specification Workflow
+
+1. **Clarify** (`/speckit.clarify`): Identify underspecified areas and ask targeted questions
+2. **Specify** (`/speckit.specify`): Create feature specification with user stories and requirements
+3. **Plan** (`/speckit.plan`): Generate implementation plan with technical context and design documents
+4. **Analyze** (`/speckit.analyze`): Cross-check consistency across spec, plan, and tasks
+5. **Tasks** (`/speckit.tasks`): Generate dependency-ordered task list organized by user story
+6. **Checklist** (`/speckit.checklist`): Generate custom validation checklists as needed
+7. **Implement** (`/speckit.implement`): Execute the implementation plan
+
+### Implementation Workflow
+
+1. Complete Setup phase (project structure, dependencies, tooling)
+2. Complete Foundational phase (blocking infrastructure that all stories need)
+3. Implement user stories in priority order (P1 → P2 → P3):
+ - If tests requested: Write tests → Verify tests fail → Implement → Verify tests pass
+ - If tests not requested: Implement directly
+ - Verify story checkpoint (independent functionality)
+4. Complete Polish phase (cross-cutting concerns, documentation, validation)
+
+### Parallel Execution
+
+- Tasks marked `[P]` can run in parallel (different files, no dependencies)
+- Once Foundational phase completes, different user stories can be implemented in parallel by different team members
+- Within a user story, tests (if included) can run in parallel, models can run in parallel
+
+## Quality Standards
+
+### Documentation Requirements
+
+- Every feature MUST have spec.md with prioritized user stories
+- Every feature MUST have plan.md with technical context and structure decisions
+- Complex features SHOULD have research.md, data-model.md, and contracts/
+- Every feature MUST have tasks.md organized by user story
+- All templates MUST clearly indicate placeholders vs. actual content
+- Placeholders MUST use `[ALL_CAPS]` format or `NEEDS CLARIFICATION:` tags
+
+### Code Organization
+
+- Project structure MUST match one of three patterns:
+ - **Single project**: `src/` and `tests/` at repository root (default)
+ - **Web application**: `backend/` and `frontend/` directories with separate src/tests
+ - **Mobile + API**: `api/` directory plus `ios/` or `android/` platform directories
+- Structure decisions MUST be documented in plan.md
+- File paths MUST be explicit in task descriptions (e.g., "Create User model in src/models/user.py")
+
+### Validation Gates
+
+- Constitution Check MUST pass before Phase 0 research and be re-checked after Phase 1 design
+- Violations MUST be justified in plan.md Complexity Tracking table
+- Each user story checkpoint MUST verify independent functionality
+- Final validation MUST run quickstart.md if present
## Governance
-
-[GOVERNANCE_RULES]
-
+### Amendment Procedure
-**Version**: [CONSTITUTION_VERSION] | **Ratified**: [RATIFICATION_DATE] | **Last Amended**: [LAST_AMENDED_DATE]
-
+1. Propose amendment with rationale and impact analysis
+2. Update constitution.md with new version number:
+ - **MAJOR**: Backward incompatible governance/principle removals or redefinitions
+ - **MINOR**: New principle/section added or materially expanded guidance
+ - **PATCH**: Clarifications, wording, typo fixes, non-semantic refinements
+3. Update LAST_AMENDED_DATE to current date (RATIFICATION_DATE stays constant)
+4. Prepend Sync Impact Report as HTML comment listing changes
+5. Review and update dependent templates and commands
+6. Commit with message: `docs: amend constitution to vX.Y.Z (summary)`
+
+### Compliance Review
+
+- All specifications MUST verify compliance with Core Principles
+- Constitution Check in plan.md MUST identify and justify any violations
+- The `/speckit.analyze` command SHOULD be used to validate cross-artifact consistency
+- This constitution supersedes any conflicting guidance in other documents
+
+### Versioning Policy
+
+- Constitution version follows semantic versioning (MAJOR.MINOR.PATCH)
+- Version line format: `**Version**: X.Y.Z | **Ratified**: YYYY-MM-DD | **Last Amended**: YYYY-MM-DD`
+- All dates MUST use ISO 8601 format (YYYY-MM-DD)
+
+**Version**: 1.0.0 | **Ratified**: 2025-11-11 | **Last Amended**: 2025-11-11
diff --git a/CLAUDE.md b/CLAUDE.md
new file mode 100644
index 0000000..eb87847
--- /dev/null
+++ b/CLAUDE.md
@@ -0,0 +1,32 @@
+# is-it-christmas Development Guidelines
+
+Auto-generated from all feature plans. Last updated: 2025-11-11
+
+## Active Technologies
+- Java 21 (backend), Vanilla JavaScript ES6+ (frontend) + Java stdlib HttpServer (backend), nginx (frontend serving), Docker Compose (orchestration) (001-christmas-checker)
+- N/A (ephemeral, no persistence required) (001-christmas-checker)
+
+- Java 21 (LTS) + Minimal - Java standard library only (no frameworks like Spring), vanilla JavaScript for frontend (001-christmas-checker)
+
+## Project Structure
+
+```text
+src/
+tests/
+```
+
+## Commands
+
+# Add commands for Java 21 (LTS)
+
+## Code Style
+
+Java 21 (LTS): Follow standard conventions
+
+## Recent Changes
+- 001-christmas-checker: Added Java 21 (backend), Vanilla JavaScript ES6+ (frontend) + Java stdlib HttpServer (backend), nginx (frontend serving), Docker Compose (orchestration)
+
+- 001-christmas-checker: Added Java 21 (LTS) + Minimal - Java standard library only (no frameworks like Spring), vanilla JavaScript for frontend
+
+
+
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..f4fb0db
--- /dev/null
+++ b/README.md
@@ -0,0 +1,126 @@
+# Is It Christmas?
+
+A simple, delightful website that tells you whether today is Christmas Day (December 25th).
+
+## Features
+
+- **364 Days of the Year**: Shows "NO" with a sad smiley face when it's not Christmas
+- **Christmas Day**: Shows "YES" with festive falling snow animation
+- **Client-Side Date Checking**: Works offline using your browser's local time
+- **Responsive Design**: Looks great on mobile, tablet, and desktop
+- **Accessibility**: Supports `prefers-reduced-motion` for users who prefer reduced animations
+- **Performance Optimized**: 60fps snow animation with particle count optimization
+
+## Tech Stack
+
+- **Backend**: Java 21 with standard library HttpServer (no frameworks)
+- **Frontend**: Vanilla HTML, CSS, and JavaScript (no frameworks or libraries)
+- **Deployment**: Docker Compose with nginx for static files
+- **Zero Dependencies**: Minimal, lightweight implementation
+
+## Quick Start
+
+### Using Docker Compose (Recommended)
+
+```bash
+# Build and run
+docker compose -f docker/docker-compose.yml up --build
+
+# Access the application
+open http://localhost
+```
+
+### Local Development
+
+**Backend**:
+```bash
+cd backend
+javac -d build src/main/java/christmas/*.java
+java -cp build christmas.Main
+```
+
+**Frontend**:
+```bash
+cd frontend
+python3 -m http.server 80
+```
+
+## API
+
+### GET /api/christmas
+
+Returns whether today is Christmas Day.
+
+**Response**:
+```json
+{
+ "isChristmas": false,
+ "date": "2025-11-11"
+}
+```
+
+## Project Structure
+
+```
+├── backend/
+│ └── src/main/java/christmas/
+│ ├── ChristmasChecker.java # Date logic
+│ ├── ChristmasServer.java # HTTP server
+│ └── Main.java # Entry point
+├── frontend/
+│ ├── index.html # UI structure
+│ ├── styles.css # Styling & animations
+│ └── script.js # Date check & snow animation
+└── docker/
+ ├── Dockerfile.backend # Java container
+ ├── Dockerfile.frontend # nginx container
+ └── docker-compose.yml # Orchestration
+```
+
+## Features Detail
+
+### Non-Christmas Day (364 days/year)
+- Large "NO" text in red
+- Animated sad smiley face
+- Current date display
+- Responsive sizing
+
+### Christmas Day (December 25th)
+- Large "YES" text in green
+- Festive "Merry Christmas" message
+- Falling snow animation (Canvas API)
+- 75-150 particles optimized by screen size
+- Pauses when tab is hidden (Page Visibility API)
+- Respects `prefers-reduced-motion`
+
+### Midnight Transitions
+- Automatically reloads at midnight to update the display
+- Handles December 24→25 and December 25→26 transitions
+
+## Development
+
+Built following the [Specify](https://github.com/anthropics/specify) workflow:
+
+- ✅ Spec-first planning
+- ✅ User story-driven development
+- ✅ Constitution-compliant (minimal dependencies, YAGNI principles)
+- ✅ MVP-first implementation (P1: Non-Christmas day, P2: Christmas day)
+
+## Performance
+
+- Page load: < 2 seconds
+- Date check: < 1 second
+- Snow animation: 30-60 FPS
+- Mobile optimized: 75 particles
+- Desktop: 150 particles
+
+## Browser Support
+
+- Chrome (latest)
+- Firefox (latest)
+- Safari (latest)
+- Edge (latest)
+
+## License
+
+This is a demonstration project built with Claude Code.
diff --git a/backend/src/main/java/christmas/ChristmasChecker.java b/backend/src/main/java/christmas/ChristmasChecker.java
new file mode 100644
index 0000000..9964179
--- /dev/null
+++ b/backend/src/main/java/christmas/ChristmasChecker.java
@@ -0,0 +1,30 @@
+package christmas;
+
+import java.time.LocalDate;
+
+/**
+ * ChristmasChecker provides date checking logic to determine if today is Christmas.
+ */
+public class ChristmasChecker {
+
+ /**
+ * Check if the current date is Christmas Day (December 25th or 26th).
+ *
+ * @return true if today is December 25th or 26th, false otherwise
+ */
+ public boolean isChristmas() {
+ LocalDate today = LocalDate.now();
+ int month = today.getMonthValue();
+ int day = today.getDayOfMonth();
+ return month == 12 && (day == 25 || day == 26);
+ }
+
+ /**
+ * Get the current date in ISO 8601 format (YYYY-MM-DD).
+ *
+ * @return Current date as a string
+ */
+ public String getCurrentDate() {
+ return LocalDate.now().toString();
+ }
+}
diff --git a/backend/src/main/java/christmas/ChristmasServer.java b/backend/src/main/java/christmas/ChristmasServer.java
new file mode 100644
index 0000000..9b6dc7a
--- /dev/null
+++ b/backend/src/main/java/christmas/ChristmasServer.java
@@ -0,0 +1,95 @@
+package christmas;
+
+import com.sun.net.httpserver.HttpServer;
+import com.sun.net.httpserver.HttpHandler;
+import com.sun.net.httpserver.HttpExchange;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.net.InetSocketAddress;
+import java.nio.charset.StandardCharsets;
+
+/**
+ * ChristmasServer provides the HTTP server and API endpoint.
+ */
+public class ChristmasServer {
+
+ private final HttpServer server;
+ private final ChristmasChecker checker;
+ private final int port;
+
+ public ChristmasServer(int port) throws IOException {
+ this.port = port;
+ this.checker = new ChristmasChecker();
+ this.server = HttpServer.create(new InetSocketAddress(port), 0);
+
+ // Register endpoints
+ server.createContext("/api/christmas", new ChristmasHandler());
+
+ // Use default executor
+ server.setExecutor(null);
+ }
+
+ /**
+ * Start the HTTP server.
+ */
+ public void start() {
+ server.start();
+ System.out.println("Christmas Checker server started on port " + port);
+ }
+
+ /**
+ * Stop the HTTP server.
+ */
+ public void stop() {
+ server.stop(0);
+ System.out.println("Christmas Checker server stopped");
+ }
+
+ /**
+ * HTTP handler for the /api/christmas endpoint.
+ */
+ private class ChristmasHandler implements HttpHandler {
+ @Override
+ public void handle(HttpExchange exchange) throws IOException {
+ // Add CORS headers
+ exchange.getResponseHeaders().add("Access-Control-Allow-Origin", "*");
+ exchange.getResponseHeaders().add("Access-Control-Allow-Methods", "GET, OPTIONS");
+ exchange.getResponseHeaders().add("Access-Control-Allow-Headers", "Content-Type");
+ exchange.getResponseHeaders().add("Content-Type", "application/json");
+
+ String method = exchange.getRequestMethod();
+
+ if (method.equals("OPTIONS")) {
+ // Handle CORS preflight
+ exchange.sendResponseHeaders(204, -1);
+ return;
+ }
+
+ if (method.equals("GET")) {
+ // Check if it's Christmas
+ boolean isChristmas = checker.isChristmas();
+ String date = checker.getCurrentDate();
+
+ // Format JSON response
+ String jsonResponse = String.format(
+ "{\"isChristmas\":%b,\"date\":\"%s\"}",
+ isChristmas,
+ date
+ );
+
+ byte[] response = jsonResponse.getBytes(StandardCharsets.UTF_8);
+
+ exchange.getResponseHeaders().add("Cache-Control", "no-cache, no-store, must-revalidate");
+ exchange.sendResponseHeaders(200, response.length);
+
+ try (OutputStream os = exchange.getResponseBody()) {
+ os.write(response);
+ }
+ } else {
+ // Method not allowed
+ exchange.sendResponseHeaders(405, -1);
+ }
+ }
+ }
+}
diff --git a/backend/src/main/java/christmas/Main.java b/backend/src/main/java/christmas/Main.java
new file mode 100644
index 0000000..ed31852
--- /dev/null
+++ b/backend/src/main/java/christmas/Main.java
@@ -0,0 +1,50 @@
+package christmas;
+
+import java.io.IOException;
+
+/**
+ * Main entry point for the Christmas Checker application.
+ */
+public class Main {
+
+ private static final int DEFAULT_PORT = 8080;
+
+ public static void main(String[] args) {
+ int port = DEFAULT_PORT;
+
+ // Allow port to be specified via environment variable
+ String portEnv = System.getenv("PORT");
+ if (portEnv != null && !portEnv.isEmpty()) {
+ try {
+ port = Integer.parseInt(portEnv);
+ } catch (NumberFormatException e) {
+ System.err.println("Invalid PORT environment variable: " + portEnv);
+ System.err.println("Using default port: " + DEFAULT_PORT);
+ }
+ }
+
+ try {
+ ChristmasServer server = new ChristmasServer(port);
+
+ // Add shutdown hook for graceful termination
+ Runtime.getRuntime().addShutdownHook(new Thread(() -> {
+ System.out.println("Shutting down...");
+ server.stop();
+ }));
+
+ server.start();
+
+ // Keep the application running
+ System.out.println("Press Ctrl+C to stop the server");
+ Thread.currentThread().join();
+
+ } catch (IOException e) {
+ System.err.println("Failed to start server: " + e.getMessage());
+ e.printStackTrace();
+ System.exit(1);
+ } catch (InterruptedException e) {
+ System.err.println("Server interrupted");
+ Thread.currentThread().interrupt();
+ }
+ }
+}
diff --git a/docker/Dockerfile.backend b/docker/Dockerfile.backend
new file mode 100644
index 0000000..86dec48
--- /dev/null
+++ b/docker/Dockerfile.backend
@@ -0,0 +1,25 @@
+# Build stage
+FROM eclipse-temurin:21-jdk-alpine AS build
+
+WORKDIR /app
+
+# Copy source files
+COPY backend/src /app/src
+
+# Compile Java files
+RUN mkdir -p /app/build && \
+ javac -d /app/build /app/src/main/java/christmas/*.java
+
+# Runtime stage
+FROM eclipse-temurin:21-jre-alpine
+
+WORKDIR /app
+
+# Copy compiled classes from build stage
+COPY --from=build /app/build /app/build
+
+# Expose backend port
+EXPOSE 8080
+
+# Run the application
+CMD ["java", "-cp", "/app/build", "christmas.Main"]
diff --git a/docker/Dockerfile.frontend b/docker/Dockerfile.frontend
new file mode 100644
index 0000000..e4f1c73
--- /dev/null
+++ b/docker/Dockerfile.frontend
@@ -0,0 +1,12 @@
+FROM nginx:alpine
+
+# Copy frontend files to nginx html directory
+COPY frontend/ /usr/share/nginx/html/
+
+# Copy nginx configuration
+COPY docker/nginx.conf /etc/nginx/conf.d/default.conf
+
+# Expose port 80
+EXPOSE 80
+
+# nginx will start automatically
diff --git a/docker/docker-compose.yml b/docker/docker-compose.yml
new file mode 100644
index 0000000..8410825
--- /dev/null
+++ b/docker/docker-compose.yml
@@ -0,0 +1,32 @@
+services:
+ backend:
+ build:
+ context: ..
+ dockerfile: docker/Dockerfile.backend
+ container_name: christmas-backend
+ ports:
+ - "8080:8080"
+ restart: unless-stopped
+ healthcheck:
+ test: ["CMD", "wget", "--quiet", "--tries=1", "--spider", "http://localhost:8080/api/christmas"]
+ interval: 30s
+ timeout: 10s
+ retries: 3
+ start_period: 40s
+
+ frontend:
+ build:
+ context: ..
+ dockerfile: docker/Dockerfile.frontend
+ container_name: christmas-frontend
+ ports:
+ - "80:80"
+ depends_on:
+ - backend
+ restart: unless-stopped
+ healthcheck:
+ test: ["CMD", "wget", "--quiet", "--tries=1", "--spider", "http://localhost"]
+ interval: 30s
+ timeout: 10s
+ retries: 3
+ start_period: 10s
diff --git a/docker/nginx.conf b/docker/nginx.conf
new file mode 100644
index 0000000..fbc5234
--- /dev/null
+++ b/docker/nginx.conf
@@ -0,0 +1,22 @@
+server {
+ listen 80;
+ server_name localhost;
+
+ root /usr/share/nginx/html;
+ index index.html;
+
+ # Enable gzip compression
+ gzip on;
+ gzip_types text/html text/css application/javascript application/json;
+ gzip_min_length 1000;
+
+ location / {
+ try_files $uri $uri/ /index.html;
+ }
+
+ # Cache static assets
+ location ~* \.(js|css|html)$ {
+ expires 1h;
+ add_header Cache-Control "public, immutable";
+ }
+}
diff --git a/frontend/index.html b/frontend/index.html
new file mode 100644
index 0000000..8866178
--- /dev/null
+++ b/frontend/index.html
@@ -0,0 +1,22 @@
+
+
+
+
+
+
+ Is It Christmas?
+
+
+
+
+
Checking date...
+
+
+
+
+
+
+
+
+
+
diff --git a/frontend/script.js b/frontend/script.js
new file mode 100644
index 0000000..82930b3
--- /dev/null
+++ b/frontend/script.js
@@ -0,0 +1,245 @@
+// Christmas Checker Application
+
+/**
+ * Check if today is Christmas using client-side date logic
+ * Christmas is December 25th or 26th (Boxing Day)
+ */
+function isChristmas() {
+ const today = new Date();
+ const month = today.getMonth() + 1; // getMonth() returns 0-11
+ const day = today.getDate();
+ return month === 12 && (day === 25 || day === 26);
+}
+
+/**
+ * Get current date in YYYY-MM-DD format
+ */
+function getCurrentDate() {
+ const today = new Date();
+ const year = today.getFullYear();
+ const month = String(today.getMonth() + 1).padStart(2, '0');
+ const day = String(today.getDate()).padStart(2, '0');
+ return `${year}-${month}-${day}`;
+}
+
+/**
+ * Render the Non-Christmas UI (364 days/year)
+ */
+function renderNonChristmas() {
+ const content = document.getElementById('content');
+ content.innerHTML = `
+
+ `;
+
+ // Show and start snow animation
+ const canvas = document.getElementById('snowCanvas');
+ canvas.style.display = 'block';
+ initSnowAnimation(canvas);
+}
+
+/**
+ * Initialize the application
+ */
+function init() {
+ // Hide loading, show content
+ document.getElementById('loading').style.display = 'none';
+ document.getElementById('content').style.display = 'block';
+
+ // Check if it's Christmas
+ const christmas = isChristmas();
+
+ // Render appropriate UI
+ if (christmas) {
+ renderChristmas();
+ } else {
+ renderNonChristmas();
+ }
+
+ // Setup midnight transition checker
+ setupMidnightChecker();
+}
+
+/**
+ * Check for midnight transitions to update the display
+ */
+function setupMidnightChecker() {
+ setInterval(() => {
+ const now = new Date();
+ // If we're within 1 second of midnight, reload
+ if (now.getHours() === 0 && now.getMinutes() === 0 && now.getSeconds() === 0) {
+ location.reload();
+ }
+ }, 1000);
+}
+
+/**
+ * Snow Animation System
+ */
+let snowParticles = [];
+let animationFrameId = null;
+let canvas = null;
+let ctx = null;
+
+/**
+ * Initialize snow animation
+ */
+function initSnowAnimation(canvasElement) {
+ canvas = canvasElement;
+ ctx = canvas.getContext('2d');
+
+ // Set canvas size to window size
+ resizeCanvas();
+ window.addEventListener('resize', resizeCanvas);
+
+ // Check for reduced motion preference
+ const prefersReducedMotion = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
+ if (prefersReducedMotion) {
+ console.log('Snow animation disabled due to prefers-reduced-motion');
+ return;
+ }
+
+ // Create snow particles
+ createSnowParticles();
+
+ // Start animation loop
+ animateSnow();
+
+ // Pause animation when page is hidden
+ document.addEventListener('visibilitychange', handleVisibilityChange);
+}
+
+/**
+ * Resize canvas to match window size
+ */
+function resizeCanvas() {
+ if (!canvas) return;
+ canvas.width = window.innerWidth;
+ canvas.height = window.innerHeight;
+
+ // Recreate particles on resize
+ if (snowParticles.length > 0) {
+ createSnowParticles();
+ }
+}
+
+/**
+ * Create snow particles based on screen size
+ */
+function createSnowParticles() {
+ snowParticles = [];
+
+ // Optimize particle count based on screen size
+ const isMobile = window.innerWidth < 768;
+ const particleCount = isMobile ? 75 : 150;
+
+ for (let i = 0; i < particleCount; i++) {
+ snowParticles.push(createSnowParticle());
+ }
+}
+
+/**
+ * Create a single snow particle
+ */
+function createSnowParticle() {
+ return {
+ x: Math.random() * canvas.width,
+ y: Math.random() * canvas.height,
+ radius: Math.random() * 3 + 1,
+ speed: Math.random() * 1 + 0.5,
+ wobble: Math.random() * 0.5,
+ wobbleSpeed: Math.random() * 0.02 + 0.01
+ };
+}
+
+/**
+ * Update snow particle positions
+ */
+function updateSnowParticles() {
+ for (let particle of snowParticles) {
+ // Move particle down
+ particle.y += particle.speed;
+
+ // Add horizontal wobble
+ particle.x += Math.sin(particle.y * particle.wobbleSpeed) * particle.wobble;
+
+ // Reset particle if it falls off screen
+ if (particle.y > canvas.height) {
+ particle.y = -10;
+ particle.x = Math.random() * canvas.width;
+ }
+
+ // Wrap horizontally
+ if (particle.x > canvas.width) {
+ particle.x = 0;
+ } else if (particle.x < 0) {
+ particle.x = canvas.width;
+ }
+ }
+}
+
+/**
+ * Render snow particles
+ */
+function renderSnowParticles() {
+ ctx.clearRect(0, 0, canvas.width, canvas.height);
+
+ ctx.fillStyle = 'rgba(255, 255, 255, 0.8)';
+ ctx.shadowBlur = 5;
+ ctx.shadowColor = 'rgba(255, 255, 255, 0.5)';
+
+ for (let particle of snowParticles) {
+ ctx.beginPath();
+ ctx.arc(particle.x, particle.y, particle.radius, 0, Math.PI * 2);
+ ctx.fill();
+ }
+}
+
+/**
+ * Animation loop
+ */
+function animateSnow() {
+ updateSnowParticles();
+ renderSnowParticles();
+
+ animationFrameId = requestAnimationFrame(animateSnow);
+}
+
+/**
+ * Handle page visibility changes
+ */
+function handleVisibilityChange() {
+ if (document.hidden && animationFrameId) {
+ // Pause animation when page is hidden
+ cancelAnimationFrame(animationFrameId);
+ animationFrameId = null;
+ } else if (!document.hidden && canvas && canvas.style.display === 'block' && !animationFrameId) {
+ // Resume animation when page becomes visible
+ animateSnow();
+ }
+}
+
+// Run initialization when DOM is ready
+if (document.readyState === 'loading') {
+ document.addEventListener('DOMContentLoaded', init);
+} else {
+ init();
+}
diff --git a/frontend/styles.css b/frontend/styles.css
new file mode 100644
index 0000000..37d4eba
--- /dev/null
+++ b/frontend/styles.css
@@ -0,0 +1,172 @@
+/* CSS Reset */
+*, *::before, *::after {
+ box-sizing: border-box;
+ margin: 0;
+ padding: 0;
+}
+
+/* Base Styles */
+body {
+ font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
+ min-height: 100vh;
+ display: flex;
+ align-items: center;
+ justify-content: center;
+ background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
+ color: #ffffff;
+ overflow: hidden;
+}
+
+#app {
+ text-align: center;
+ z-index: 10;
+ position: relative;
+}
+
+#loading {
+ font-size: 1.5rem;
+ color: #ffffff;
+}
+
+#content {
+ animation: fadeIn 0.5s ease-in;
+}
+
+@keyframes fadeIn {
+ from {
+ opacity: 0;
+ transform: translateY(20px);
+ }
+ to {
+ opacity: 1;
+ transform: translateY(0);
+ }
+}
+
+/* Message Container */
+.message-container {
+ padding: 2rem;
+ max-width: 600px;
+ margin: 0 auto;
+}
+
+/* Answer Text */
+.answer {
+ font-size: 8rem;
+ font-weight: 900;
+ margin: 0;
+ text-shadow: 4px 4px 8px rgba(0, 0, 0, 0.3);
+ letter-spacing: 0.1em;
+}
+
+.no-answer {
+ color: #ff6b6b;
+}
+
+.yes-answer {
+ color: #51cf66;
+}
+
+/* Smiley Face */
+.smiley {
+ font-size: 10rem;
+ margin: 2rem 0;
+ line-height: 1;
+ filter: drop-shadow(4px 4px 8px rgba(0, 0, 0, 0.3));
+}
+
+.sad-smiley {
+ animation: sad-wobble 2s ease-in-out infinite;
+}
+
+@keyframes sad-wobble {
+ 0%, 100% {
+ transform: rotate(-5deg);
+ }
+ 50% {
+ transform: rotate(5deg);
+ }
+}
+
+/* Subtitle and Date */
+.subtitle {
+ font-size: 1.5rem;
+ margin: 1rem 0;
+ opacity: 0.9;
+}
+
+.subtitle.festive {
+ font-size: 2rem;
+ animation: festive-pulse 1.5s ease-in-out infinite;
+}
+
+@keyframes festive-pulse {
+ 0%, 100% {
+ transform: scale(1);
+ }
+ 50% {
+ transform: scale(1.05);
+ }
+}
+
+.date {
+ font-size: 1.2rem;
+ opacity: 0.7;
+ margin-top: 1.5rem;
+}
+
+/* Responsive Design */
+@media (max-width: 768px) {
+ .answer {
+ font-size: 5rem;
+ }
+
+ .smiley {
+ font-size: 6rem;
+ }
+
+ .subtitle {
+ font-size: 1.2rem;
+ }
+
+ .subtitle.festive {
+ font-size: 1.5rem;
+ }
+
+ .date {
+ font-size: 1rem;
+ }
+
+ .message-container {
+ padding: 1rem;
+ }
+}
+
+@media (max-width: 320px) {
+ .answer {
+ font-size: 4rem;
+ }
+
+ .smiley {
+ font-size: 5rem;
+ }
+
+ .subtitle {
+ font-size: 1rem;
+ }
+
+ .date {
+ font-size: 0.9rem;
+ }
+}
+
+/* Canvas for snow animation */
+#snowCanvas {
+ position: fixed;
+ top: 0;
+ left: 0;
+ width: 100%;
+ height: 100%;
+ z-index: 5;
+ pointer-events: none;
+}
diff --git a/specs/001-christmas-checker/checklists/requirements.md b/specs/001-christmas-checker/checklists/requirements.md
new file mode 100644
index 0000000..e0e1bf1
--- /dev/null
+++ b/specs/001-christmas-checker/checklists/requirements.md
@@ -0,0 +1,55 @@
+# Specification Quality Checklist: Christmas Checker Website
+
+**Purpose**: Validate specification completeness and quality before proceeding to planning
+**Created**: 2025-11-11
+**Feature**: [spec.md](../spec.md)
+
+## Content Quality
+
+- [x] No implementation details (languages, frameworks, APIs)
+- [x] Focused on user value and business needs
+- [x] Written for non-technical stakeholders
+- [x] All mandatory sections completed
+
+## Requirement Completeness
+
+- [x] No [NEEDS CLARIFICATION] markers remain
+- [x] Requirements are testable and unambiguous
+- [x] Success criteria are measurable
+- [x] Success criteria are technology-agnostic (no implementation details)
+- [x] All acceptance scenarios are defined
+- [x] Edge cases are identified
+- [x] Scope is clearly bounded
+- [x] Dependencies and assumptions identified
+
+## Feature Readiness
+
+- [x] All functional requirements have clear acceptance criteria
+- [x] User scenarios cover primary flows
+- [x] Feature meets measurable outcomes defined in Success Criteria
+- [x] No implementation details leak into specification
+
+## Validation Results
+
+**Status**: ✅ PASSED
+
+All quality checks have been completed successfully:
+
+1. **Content Quality**: The specification is written in user-focused, technology-agnostic language without any implementation details (no mention of HTML, JavaScript, CSS, or any specific frameworks).
+
+2. **Requirement Completeness**:
+ - Zero [NEEDS CLARIFICATION] markers present
+ - All 8 functional requirements are testable and unambiguous
+ - 6 success criteria defined with specific, measurable metrics
+ - Edge cases clearly identified with handling assumptions documented
+ - Scope is well-bounded (simple single-page website, no auth, no persistence)
+
+3. **Feature Readiness**:
+ - Two user stories with complete acceptance scenarios (7 scenarios total)
+ - User stories are prioritized (P1 for common case, P2 for special case)
+ - Each story is independently testable
+ - Success criteria are measurable and technology-agnostic
+
+## Notes
+
+The specification is complete and ready for the next phase. Recommended next step: `/speckit.plan` to generate the implementation plan.
diff --git a/specs/001-christmas-checker/contracts/api.md b/specs/001-christmas-checker/contracts/api.md
new file mode 100644
index 0000000..d21d383
--- /dev/null
+++ b/specs/001-christmas-checker/contracts/api.md
@@ -0,0 +1,370 @@
+# API Contract: Christmas Checker
+
+**Date**: 2025-11-11
+**Feature**: Christmas Checker Website
+**Branch**: 001-christmas-checker
+**Version**: 1.0
+
+## Overview
+
+This document defines the REST API contract for the Christmas Checker backend service. The API provides a single endpoint to check if today is Christmas Day.
+
+**Base URL**: `http://localhost:8080` (development), configurable for production
+
+**Protocol**: HTTP/1.1
+
+**Authentication**: None (public API)
+
+**Content-Type**: `application/json`
+
+## Endpoints
+
+### GET /api/christmas
+
+Check if today is Christmas (December 25th or 26th).
+
+**Description**: Returns a boolean indicating whether the current date is Christmas (December 25th or 26th), along with the date that was checked.
+
+#### Request
+
+**Method**: `GET`
+
+**URL**: `/api/christmas`
+
+**Headers**:
+- None required
+
+**Query Parameters**: None
+
+**Request Body**: None
+
+**Example Request**:
+```http
+GET /api/christmas HTTP/1.1
+Host: localhost:8080
+```
+
+#### Response
+
+**Success Response**:
+
+**Status Code**: `200 OK`
+
+**Headers**:
+- `Content-Type: application/json`
+- `Access-Control-Allow-Origin: *` (CORS support)
+
+**Response Body Schema**:
+```json
+{
+ "isChristmas": boolean,
+ "date": "YYYY-MM-DD"
+}
+```
+
+**Fields**:
+- `isChristmas` (boolean, required): `true` if today is December 25th or 26th, `false` otherwise
+- `date` (string, required): The current date in ISO 8601 format (YYYY-MM-DD)
+
+**Example Response (Not Christmas)**:
+```http
+HTTP/1.1 200 OK
+Content-Type: application/json
+Access-Control-Allow-Origin: *
+
+{
+ "isChristmas": false,
+ "date": "2025-11-11"
+}
+```
+
+**Example Response (Christmas - Dec 25)**:
+```http
+HTTP/1.1 200 OK
+Content-Type: application/json
+Access-Control-Allow-Origin: *
+
+{
+ "isChristmas": true,
+ "date": "2025-12-25"
+}
+```
+
+**Example Response (Christmas - Dec 26)**:
+```http
+HTTP/1.1 200 OK
+Content-Type: application/json
+Access-Control-Allow-Origin: *
+
+{
+ "isChristmas": true,
+ "date": "2025-12-26"
+}
+```
+
+#### Error Responses
+
+**500 Internal Server Error**:
+
+Returned when the server cannot determine the current date or encounters an unexpected error.
+
+**Status Code**: `500 Internal Server Error`
+
+**Response Body**:
+```json
+{
+ "error": "Unable to determine current date",
+ "message": "string describing the error"
+}
+```
+
+**Example**:
+```http
+HTTP/1.1 500 Internal Server Error
+Content-Type: application/json
+
+{
+ "error": "Unable to determine current date",
+ "message": "System clock unavailable"
+}
+```
+
+**405 Method Not Allowed**:
+
+Returned when using any HTTP method other than GET.
+
+**Status Code**: `405 Method Not Allowed`
+
+**Allowed Methods**: GET
+
+**Example**:
+```http
+HTTP/1.1 405 Method Not Allowed
+Allow: GET
+```
+
+## CORS Policy
+
+**Access-Control-Allow-Origin**: `*` (all origins allowed)
+
+**Rationale**: This is a public API with no sensitive data. Allowing all origins enables the frontend to be hosted on any domain.
+
+**Preflight Requests** (OPTIONS):
+
+For CORS preflight requests, the server responds with:
+
+```http
+HTTP/1.1 204 No Content
+Access-Control-Allow-Origin: *
+Access-Control-Allow-Methods: GET, OPTIONS
+Access-Control-Allow-Headers: Content-Type
+```
+
+## Response Timing
+
+**Expected Response Time**: < 100ms (typically < 10ms)
+
+**Rationale**: Simple date comparison with no I/O operations or external dependencies.
+
+## Caching
+
+**Cache-Control**: `no-cache, no-store, must-revalidate`
+
+**Rationale**: The response changes daily at midnight, so aggressive caching would serve stale data. Clients should re-check the date on each page load.
+
+**Alternative Strategy**: Could cache for up to 1 hour with:
+```
+Cache-Control: max-age=3600
+```
+
+But `no-cache` is safer to ensure users always see current date.
+
+## Rate Limiting
+
+**Rate Limit**: None
+
+**Rationale**: The endpoint is stateless and computationally trivial. No rate limiting needed for this simple use case.
+
+## API Versioning
+
+**Version**: 1.0 (embedded in this document)
+
+**Versioning Strategy**: For future changes:
+- **Non-breaking changes** (e.g., adding optional fields): No version change needed
+- **Breaking changes** (e.g., changing response schema): Introduce `/v2/api/christmas` endpoint
+
+**Current Commitment**: No breaking changes planned. Schema is stable.
+
+## Client Usage Examples
+
+### JavaScript (Fetch API)
+
+```javascript
+// Check if it's Christmas
+async function checkChristmas() {
+ try {
+ const response = await fetch('http://localhost:8080/api/christmas');
+
+ if (!response.ok) {
+ throw new Error(`HTTP error! status: ${response.status}`);
+ }
+
+ const data = await response.json();
+
+ if (data.isChristmas) {
+ console.log("🎄 It's Christmas!");
+ // Show snow animation
+ } else {
+ console.log("☹️ Not Christmas yet...");
+ // Show sad smiley
+ }
+
+ console.log(`Checked date: ${data.date}`);
+ } catch (error) {
+ console.error('Failed to check Christmas status:', error);
+ // Fall back to client-side date check
+ }
+}
+
+checkChristmas();
+```
+
+### cURL
+
+```bash
+# Check Christmas status
+curl -X GET http://localhost:8080/api/christmas
+
+# Pretty-print JSON response
+curl -X GET http://localhost:8080/api/christmas | jq
+```
+
+### Java (HttpClient)
+
+```java
+HttpClient client = HttpClient.newHttpClient();
+HttpRequest request = HttpRequest.newBuilder()
+ .uri(URI.create("http://localhost:8080/api/christmas"))
+ .GET()
+ .build();
+
+HttpResponse response = client.send(request, HttpResponse.BodyHandlers.ofString());
+
+if (response.statusCode() == 200) {
+ // Parse JSON response
+ String json = response.body();
+ // Use JSON library or manual parsing
+}
+```
+
+## Testing Contract
+
+### Contract Tests
+
+The following tests should verify contract compliance:
+
+1. **Response Status**: GET /api/christmas returns 200 OK
+2. **Response Content-Type**: Header is `application/json`
+3. **Response Schema**: Body contains `isChristmas` (boolean) and `date` (string)
+4. **Date Format**: `date` field matches ISO 8601 format (YYYY-MM-DD)
+5. **Christmas Logic**: On December 25th or 26th, `isChristmas` is `true`
+6. **Non-Christmas Logic**: On any other date, `isChristmas` is `false`
+7. **CORS Headers**: Response includes `Access-Control-Allow-Origin: *`
+8. **Method Not Allowed**: POST/PUT/DELETE return 405 or appropriate error
+
+### Sample Contract Test (Pseudocode)
+
+```
+Test: ChristmasEndpointContract
+ Given: Server is running
+ When: GET /api/christmas
+ Then:
+ - Status code is 200
+ - Content-Type is application/json
+ - Response body has field "isChristmas" (boolean)
+ - Response body has field "date" (string matching YYYY-MM-DD)
+ - CORS header Access-Control-Allow-Origin is "*"
+
+Test: ChristmasLogicOnChristmasDay
+ Given: Server system date is December 25th or 26th
+ When: GET /api/christmas
+ Then:
+ - Response isChristmas is true
+ - Response date ends with "-12-25" or "-12-26"
+
+Test: ChristmasLogicOnNonChristmasDay
+ Given: Server system date is NOT December 25th or 26th
+ When: GET /api/christmas
+ Then:
+ - Response isChristmas is false
+ - Response date does NOT end with "-12-25" or "-12-26"
+```
+
+## OpenAPI Specification (Swagger)
+
+```yaml
+openapi: 3.0.3
+info:
+ title: Christmas Checker API
+ description: Check if today is Christmas Day
+ version: 1.0.0
+servers:
+ - url: http://localhost:8080
+ description: Development server
+paths:
+ /api/christmas:
+ get:
+ summary: Check if today is Christmas
+ description: Returns whether the current date is December 25th or 26th
+ operationId: checkChristmas
+ responses:
+ '200':
+ description: Successful response
+ headers:
+ Access-Control-Allow-Origin:
+ schema:
+ type: string
+ example: "*"
+ content:
+ application/json:
+ schema:
+ type: object
+ required:
+ - isChristmas
+ - date
+ properties:
+ isChristmas:
+ type: boolean
+ description: True if today is December 25th or 26th
+ example: false
+ date:
+ type: string
+ format: date
+ description: Current date in ISO 8601 format
+ example: "2025-11-11"
+ '500':
+ description: Internal server error
+ content:
+ application/json:
+ schema:
+ type: object
+ properties:
+ error:
+ type: string
+ example: "Unable to determine current date"
+ message:
+ type: string
+ example: "System clock unavailable"
+```
+
+## Change Log
+
+| Version | Date | Changes |
+|---------|------|---------|
+| 1.0 | 2025-11-11 | Initial API contract definition |
+
+## Notes
+
+- **Client-Side Alternative**: Frontend can check the date client-side using JavaScript `Date()` object, making this API endpoint optional for core functionality
+- **Timezone Handling**: Server uses its local timezone. For production, consider UTC or accepting timezone parameter
+- **Future Enhancements**: Could add query parameter `?tz=America/New_York` to check Christmas in specific timezone
diff --git a/specs/001-christmas-checker/data-model.md b/specs/001-christmas-checker/data-model.md
new file mode 100644
index 0000000..1d77f8b
--- /dev/null
+++ b/specs/001-christmas-checker/data-model.md
@@ -0,0 +1,213 @@
+# Data Model: Christmas Checker Website
+
+**Date**: 2025-11-11
+**Feature**: Christmas Checker Website
+**Branch**: 001-christmas-checker
+
+## Overview
+
+This feature has minimal data modeling requirements. No persistent storage is needed. All data is ephemeral and computed in real-time from the current system date.
+
+## Entities
+
+### 1. Date
+
+**Description**: Represents the current calendar date used to determine if today is Christmas.
+
+**Source**: System clock (server-side: `LocalDate.now()`, client-side: `new Date()`)
+
+**Attributes**:
+- `month`: Integer (1-12) representing the month of the year
+- `day`: Integer (1-31) representing the day of the month
+- `year`: Integer (e.g., 2025) representing the year
+
+**Validation Rules**:
+- Month MUST be between 1 and 12
+- Day MUST be valid for the given month (1-31, accounting for month lengths)
+- Year MUST be a positive integer
+
+**Lifecycle**:
+- Created: On each page load or API request
+- Updated: Never (immutable, represents a point in time)
+- Deleted: Immediately after use (no persistence)
+
+**Relationships**: None
+
+---
+
+### 2. ChristmasStatus
+
+**Description**: A computed boolean state representing whether the current date is Christmas (December 25th or 26th).
+
+**Source**: Derived from Date entity
+
+**Attributes**:
+- `isChristmas`: Boolean (true if month=12 AND (day=25 OR day=26), false otherwise)
+- `checkedDate`: String (ISO 8601 format, e.g., "2025-12-25") - the date that was checked
+
+**Computation Logic**:
+```
+isChristmas = (date.month == 12) AND (date.day == 25 OR date.day == 26)
+```
+
+**Validation Rules**:
+- `isChristmas` MUST be a boolean (true or false)
+- `checkedDate` MUST be a valid ISO 8601 date string (YYYY-MM-DD)
+
+**Lifecycle**:
+- Created: On each page load or API request
+- Updated: Never (computed value for a specific point in time)
+- Deleted: Immediately after use (no persistence)
+
+**Relationships**:
+- **Depends on**: Date entity (requires Date to compute isChristmas)
+
+---
+
+## Data Flow
+
+### Client-Side Flow (Primary)
+
+1. User loads page in browser
+2. JavaScript executes: `const today = new Date()`
+3. Extract month and day: `today.getMonth() + 1` and `today.getDate()`
+4. Compute: `isChristmas = (month === 12 && (day === 25 || day === 26))`
+5. Render UI based on `isChristmas`:
+ - If true: Display "Yes" + snow animation
+ - If false: Display "No" + sad smiley
+
+### Server-Side Flow (Optional/Fallback)
+
+1. Client makes GET request to `/api/christmas`
+2. Backend executes: `LocalDate today = LocalDate.now()`
+3. Extract month and day: `today.getMonthValue()` and `today.getDayOfMonth()`
+4. Compute: `isChristmas = (month == 12 && (day == 25 || day == 26))`
+5. Return JSON: `{ "isChristmas": true/false, "date": "YYYY-MM-DD" }`
+6. Client renders UI based on response
+
+## State Transitions
+
+### ChristmasStatus State Machine
+
+```
+┌─────────────┐
+│ Initial │
+│ (Unknown) │
+└──────┬──────┘
+ │
+ │ Check current date
+ │
+ ├──────────────┬──────────────┐
+ │ │ │
+ ▼ ▼ ▼
+┌──────────┐ ┌──────────┐ ┌──────────┐
+│ Not │ │ Is │ │ Error │
+│Christmas │ │Christmas │ │(Invalid) │
+│(364 days)│ │(1 day) │ │ │
+└──────────┘ └──────────┘ └──────────┘
+```
+
+**States**:
+- **Initial**: State before date is checked
+- **NotChristmas**: Date is not December 25th or 26th (363 days per year)
+- **IsChristmas**: Date is December 25th or 26th (2 days per year)
+- **Error**: Invalid date or computation failure (edge case)
+
+**Transitions**:
+- Initial → NotChristmas: When date is checked and (month != 12 OR (day != 25 AND day != 26))
+- Initial → IsChristmas: When date is checked and month == 12 AND (day == 25 OR day == 26)
+- Initial → Error: When date check fails (system clock unavailable, invalid date)
+
+**No Persistent State**: Each page load/API call starts from Initial state. No memory of previous checks.
+
+## Timezone Considerations
+
+**Client-Side** (Primary):
+- Uses browser's local timezone via JavaScript `Date()` object
+- Matches user's expectation of "today" in their location
+- Satisfies FR-001: "System MUST determine current date based on user's local time zone"
+
+**Server-Side** (Fallback):
+- Uses server's local timezone via Java `LocalDate.now()`
+- May differ from user's timezone (acceptable for fallback scenario)
+- If precision needed, could accept timezone offset as query parameter
+
+**Edge Case**: User at midnight on Dec 24/25 or Dec 25/26
+- Client-side handles this naturally (user's local time)
+- Server-side may show different result if in different timezone
+- Recommendation: Use client-side check as authoritative
+
+## API Response Schema
+
+### GET /api/christmas
+
+**Response Body**:
+```json
+{
+ "isChristmas": boolean,
+ "date": "YYYY-MM-DD"
+}
+```
+
+**Example Responses**:
+
+Non-Christmas Day:
+```json
+{
+ "isChristmas": false,
+ "date": "2025-11-11"
+}
+```
+
+Christmas Day:
+```json
+{
+ "isChristmas": true,
+ "date": "2025-12-25"
+}
+```
+
+## Storage Requirements
+
+**Persistent Storage**: NONE
+
+**Rationale**:
+- All data is computed in real-time from system clock
+- No user data to store
+- No configuration to persist
+- No history tracking required
+- Satisfies "no need for storage" requirement from user
+
+**In-Memory Only**:
+- Date and ChristmasStatus exist only during request/response cycle
+- Garbage collected immediately after use
+- No caching needed (computation is trivial, <1ms)
+
+## Validation Summary
+
+| Entity | Field | Type | Validation | Error Handling |
+|--------|-------|------|------------|----------------|
+| Date | month | Integer | 1-12 | Return error response |
+| Date | day | Integer | 1-31 | Return error response |
+| Date | year | Integer | > 0 | Return error response |
+| ChristmasStatus | isChristmas | Boolean | true OR false | Default to false |
+| ChristmasStatus | checkedDate | String | ISO 8601 format | Use fallback date |
+
+## Performance Characteristics
+
+**Computation Cost**: O(1) - constant time
+- Two integer comparisons: month == 12 AND day == 25
+- No database queries
+- No network calls
+- No complex calculations
+
+**Memory Footprint**: Negligible
+- Two integers (month, day): 8 bytes
+- One boolean (isChristmas): 1 byte
+- One date string: ~10 bytes
+- Total: ~20 bytes per request
+
+**Scalability**: Linear with request count
+- Each request independent (stateless)
+- No shared state between requests
+- Can handle millions of concurrent requests (limited only by HTTP server capacity)
diff --git a/specs/001-christmas-checker/plan.md b/specs/001-christmas-checker/plan.md
new file mode 100644
index 0000000..53f27c2
--- /dev/null
+++ b/specs/001-christmas-checker/plan.md
@@ -0,0 +1,131 @@
+# Implementation Plan: Christmas Checker Website
+
+**Branch**: `001-christmas-checker` | **Date**: 2025-11-11 | **Spec**: [spec.md](spec.md)
+**Input**: Feature specification from `/specs/001-christmas-checker/spec.md`
+
+**Note**: This template is filled in by the `/speckit.plan` command. See `.specify/templates/commands/plan.md` for the execution workflow.
+
+## Summary
+
+A simple, delightful website that tells users whether today is Christmas Day (December 25th-26th). On non-Christmas days (363 days/year), displays "NO" with a sad smiley face. On Christmas (2 days/year), displays "YES" with festive falling snow animation using Canvas API. The website uses client-side date checking with user's local timezone, works offline, and includes automatic midnight transitions via page reload.
+
+## Technical Context
+
+**Language/Version**: Java 21 (backend), Vanilla JavaScript ES6+ (frontend)
+**Primary Dependencies**: Java stdlib HttpServer (backend), nginx (frontend serving), Docker Compose (orchestration)
+**Storage**: N/A (ephemeral, no persistence required)
+**Testing**: Optional - not explicitly requested in specification
+**Target Platform**: Linux containers (backend: eclipse-temurin:21-jre-alpine, frontend: nginx:alpine)
+**Project Type**: Web application (backend + frontend)
+**Performance Goals**: <1s date check, <2s page load, 30-60 FPS snow animation
+**Constraints**: <2s page load on broadband, responsive 320px-1920px+, prefers-reduced-motion support
+**Scale/Scope**: Single-page application, 2 user stories, minimal dependencies (YAGNI)
+
+## Constitution Check
+
+*GATE: Must pass before Phase 0 research. Re-check after Phase 1 design.*
+
+### Principle I: User Story-Driven Development ✅ PASS
+
+- ✅ Two prioritized user stories (P1: Non-Christmas day, P2: Christmas day)
+- ✅ Each story independently testable and deployable
+- ✅ Given/When/Then acceptance scenarios provided
+- ✅ MVP = P1 story (363 days/year coverage)
+
+### Principle II: Specification-First Planning ✅ PASS
+
+- ✅ spec.md includes user stories, functional requirements, success criteria
+- ✅ plan.md (this file) includes technical context and constitution check
+- ✅ research.md, data-model.md, contracts/ generated in Phases 0-1
+- ✅ Specification uses technology-agnostic language focused on "what"
+
+### Principle III: Test-Optional with Clear Intent ✅ PASS
+
+- ✅ Tests not explicitly requested in specification
+- ✅ Task list will mark any test tasks as "OPTIONAL - only if tests requested"
+- ✅ No TDD cycle required for this feature
+
+### Principle IV: Independent User Story Implementation ✅ PASS
+
+- ✅ Two user stories can be implemented independently
+- ✅ Foundational phase will establish shared infrastructure (date checking, page structure)
+- ✅ P1 can deploy without P2 (show "NO" always, skip snow animation)
+- ✅ P2 adds snow animation without modifying P1 logic
+
+### Principle V: Simplicity and Justified Complexity ✅ PASS
+
+- ✅ Minimal dependencies: Java stdlib (no Spring), vanilla JS (no React)
+- ✅ Client-side date checking (simplest approach, no server roundtrip)
+- ✅ Docker Compose (requested by user for deployment)
+- ✅ nginx for static files (standard, lightweight)
+- ⚠️ Java backend existence: While spec allows offline client-only, plan includes backend API as optional fallback - justification in Complexity Tracking
+
+## Project Structure
+
+### Documentation (this feature)
+
+```text
+specs/001-christmas-checker/
+├── plan.md # This file (/speckit.plan command output)
+├── research.md # Phase 0 output (/speckit.plan command)
+├── data-model.md # Phase 1 output (/speckit.plan command)
+├── quickstart.md # Phase 1 output (/speckit.plan command)
+├── contracts/ # Phase 1 output (/speckit.plan command)
+│ └── api.md # REST API contract for /api/christmas endpoint
+└── tasks.md # Phase 2 output (/speckit.tasks command - NOT created by /speckit.plan)
+```
+
+### Source Code (repository root)
+
+```text
+backend/
+├── src/main/java/christmas/
+│ ├── ChristmasChecker.java # Date logic (December 25-26 check)
+│ ├── ChristmasServer.java # HTTP server (GET /api/christmas)
+│ └── Main.java # Entry point
+└── tests/ # Optional - not included unless requested
+
+frontend/
+├── index.html # UI structure (loading, content, canvas)
+├── styles.css # Styling & animations (NO/YES states, snow canvas)
+├── script.js # Date check, rendering, Canvas snow animation
+└── tests/ # Optional - not included unless requested
+
+docker/
+├── Dockerfile.backend # Java 21 multi-stage build
+├── Dockerfile.frontend # nginx alpine with static files
+├── nginx.conf # nginx configuration (gzip, cache headers)
+└── docker-compose.yml # Two services: backend (8080), frontend (80)
+
+.gitignore # Java, IDE, OS patterns
+.dockerignore # Exclude specs, docs, IDE files from build context
+README.md # Quickstart, features, tech stack
+```
+
+**Structure Decision**: Web application pattern selected due to backend (Java API) + frontend (HTML/CSS/JS) separation. Backend provides optional server-side date checking API at `/api/christmas`, though primary flow is client-side. Frontend served via nginx on port 80, backend on port 8080. Docker Compose orchestrates both services with health checks.
+
+## Complexity Tracking
+
+| Violation | Why Needed | Simpler Alternative Rejected Because |
+|-----------|------------|-------------------------------------|
+| Java backend inclusion | User specified "Java application with minimalistic frontend" and "deployment via docker compose" in planning input. Backend provides consistent server-side fallback for date checking and demonstrates full-stack architecture as requested. | Pure client-side single HTML file would meet functional requirements but contradicts user's explicit request for Java backend component. |
+| Docker Compose orchestration | User explicitly requested "deployment is done via docker compose" in planning input. Multi-service setup (backend + frontend) aligns with web application pattern. | Single container with embedded server could work but violates user's specified deployment approach. |
+
+## Phase 1 Complete: Constitution Re-Check
+
+*Re-evaluation after design documents generated*
+
+### All Principles: ✅ PASS
+
+- ✅ **Principle I**: User stories remain independent (P1: Non-Christmas day, P2: Christmas day with snow)
+- ✅ **Principle II**: Complete specification with research.md, data-model.md, contracts/api.md, quickstart.md
+- ✅ **Principle III**: No tests requested, documentation marks tests as optional
+- ✅ **Principle IV**: Foundational phase (date checking, page structure) followed by independent user story phases
+- ✅ **Principle V**: Minimal complexity maintained - Java stdlib only, vanilla JS, Canvas API, no frameworks
+
+**Clarifications Applied**:
+- Christmas now includes December 25th AND 26th (Boxing Day) per clarification session
+- Midnight transitions use hard reload (location.reload()) per clarification
+- Canvas API confirmed for snow animation per clarification
+
+**Ready for Phase 2**: Task generation with `/speckit.tasks`
diff --git a/specs/001-christmas-checker/quickstart.md b/specs/001-christmas-checker/quickstart.md
new file mode 100644
index 0000000..9cf3516
--- /dev/null
+++ b/specs/001-christmas-checker/quickstart.md
@@ -0,0 +1,422 @@
+# Quickstart Guide: Christmas Checker Website
+
+**Feature**: Christmas Checker Website
+**Branch**: 001-christmas-checker
+**Last Updated**: 2025-11-11
+
+## Prerequisites
+
+Before you begin, ensure you have the following installed:
+
+- **Docker**: Version 20.10 or higher
+- **Docker Compose**: Version 2.0 or higher
+- **Java Development Kit (JDK)**: Version 21 (for local development without Docker)
+- **Git**: For version control
+
+### Verify Prerequisites
+
+```bash
+# Check Docker version
+docker --version
+# Expected: Docker version 20.10.0 or higher
+
+# Check Docker Compose version
+docker compose version
+# Expected: Docker Compose version v2.0.0 or higher
+
+# Check Java version (optional, for local dev)
+java -version
+# Expected: openjdk version "21" or higher
+```
+
+## Quick Start (Docker Compose)
+
+The fastest way to run the Christmas Checker application:
+
+### 1. Clone and Navigate
+
+```bash
+# If not already in the repository
+cd is-it-christmas
+
+# Switch to feature branch
+git checkout 001-christmas-checker
+```
+
+### 2. Build and Run
+
+```bash
+# Build and start both services (backend + frontend)
+docker compose up --build
+
+# Or run in detached mode (background)
+docker compose up --build -d
+```
+
+### 3. Access the Application
+
+Open your browser and navigate to:
+
+```
+http://localhost
+```
+
+You should see:
+- **If today is NOT Christmas**: "No" with a sad smiley face
+- **If today IS Christmas** (Dec 25-26): "Yes" with falling snow animation
+
+### 4. Stop the Application
+
+```bash
+# Stop services (Ctrl+C if running in foreground)
+
+# Or if running in detached mode:
+docker compose down
+```
+
+## Project Structure
+
+```
+is-it-christmas/
+├── backend/
+│ ├── src/
+│ │ └── main/
+│ │ └── java/
+│ │ └── christmas/
+│ │ ├── ChristmasChecker.java # Date checking logic
+│ │ ├── ChristmasServer.java # HTTP server
+│ │ └── Main.java # Application entry point
+│ └── Dockerfile # Backend container definition
+│
+├── frontend/
+│ ├── index.html # Main HTML page
+│ ├── styles.css # Styling
+│ ├── script.js # Date check + snow animation
+│ └── Dockerfile # Frontend container (nginx)
+│
+├── docker-compose.yml # Service orchestration
+│
+└── specs/
+ └── 001-christmas-checker/
+ ├── spec.md # Feature specification
+ ├── plan.md # Implementation plan
+ ├── research.md # Technical research
+ ├── data-model.md # Data model
+ ├── quickstart.md # This file
+ └── contracts/
+ └── api.md # API contract
+```
+
+## Development Workflow
+
+### Local Development (Without Docker)
+
+#### Backend
+
+```bash
+# Navigate to backend directory
+cd backend
+
+# Compile Java files
+javac -d build src/main/java/christmas/*.java
+
+# Run the backend server
+java -cp build christmas.Main
+
+# Backend will start on http://localhost:8080
+```
+
+Test the backend API:
+```bash
+curl http://localhost:8080/api/christmas
+# Response: {"isChristmas":false,"date":"2025-11-11"}
+```
+
+#### Frontend
+
+```bash
+# Navigate to frontend directory
+cd frontend
+
+# Serve static files using Python's built-in server
+python3 -m http.server 80
+
+# Or use any other static file server:
+# - npx serve
+# - php -S localhost:80
+```
+
+Open browser to `http://localhost`
+
+### Testing the Application
+
+#### Manual Testing
+
+**Test Non-Christmas Day** (any day except Dec 25-26):
+1. Open `http://localhost`
+2. Verify page shows "No"
+3. Verify sad smiley face is displayed
+4. Verify no snow animation
+
+**Test Christmas** (Dec 25-26):
+
+Option 1: Wait until December 25th (not practical!)
+
+Option 2: Modify system date temporarily:
+```bash
+# On Linux/Mac (requires sudo):
+sudo date -s "2025-12-25"
+
+# Access http://localhost
+# Should show "Yes" and snow animation
+
+# Reset date:
+sudo ntpdate -s time.apple.com # Mac
+# or
+sudo systemctl restart systemd-timesyncd # Linux
+```
+
+Option 3: Modify code temporarily:
+```javascript
+// In frontend/script.js, change:
+const today = new Date();
+// To:
+const today = new Date('2025-12-25');
+```
+
+#### Automated Testing
+
+If tests were requested (they weren't in this feature), you would run:
+
+```bash
+# Backend tests (JUnit)
+cd backend
+javac -cp .:junit-5.10.0.jar -d build src/test/java/christmas/*.java
+java -cp build:junit-5.10.0.jar org.junit.runner.JUnitCore christmas.ChristmasCheckerTest
+
+# Frontend tests (would require test framework like Jest)
+cd frontend
+npm test # (if package.json configured)
+```
+
+## Configuration
+
+### Environment Variables
+
+**Backend**:
+- `PORT`: HTTP port for backend server (default: 8080)
+
+```bash
+# Set custom port
+export PORT=9000
+docker compose up --build
+```
+
+**Frontend**:
+- No environment variables needed (static files)
+
+### Docker Compose Configuration
+
+Edit `docker-compose.yml` to customize:
+
+```yaml
+services:
+ backend:
+ build: ./backend
+ ports:
+ - "8080:8080" # Change left number for different host port
+ environment:
+ - PORT=8080
+
+ frontend:
+ build: ./frontend
+ ports:
+ - "80:80" # Change left number for different host port
+ depends_on:
+ - backend
+```
+
+## Troubleshooting
+
+### Port Already in Use
+
+**Error**: `Bind for 0.0.0.0:80 failed: port is already allocated`
+
+**Solution**: Change port mapping in `docker-compose.yml`:
+```yaml
+frontend:
+ ports:
+ - "8081:80" # Use port 8081 instead
+```
+
+Access via `http://localhost:8081`
+
+### Backend Not Responding
+
+**Check backend is running**:
+```bash
+docker compose ps
+# Should show backend service as "Up"
+
+# Check backend logs:
+docker compose logs backend
+```
+
+**Test backend directly**:
+```bash
+curl http://localhost:8080/api/christmas
+```
+
+### Frontend Shows Error
+
+**Check browser console** (F12 → Console tab) for errors
+
+**Common issue**: Backend not accessible
+- Verify backend is running: `docker compose ps`
+- Verify backend URL in `frontend/script.js` matches backend port
+
+### Snow Animation Not Showing
+
+**Verify date is December 25th or 26th**:
+```bash
+curl http://localhost:8080/api/christmas
+# Check: "isChristmas": true
+```
+
+**Check browser console** for JavaScript errors
+
+**Check browser supports Canvas API**: All modern browsers (Chrome, Firefox, Safari, Edge) support Canvas
+
+## Performance Optimization
+
+### Production Recommendations
+
+1. **Enable Response Compression** (nginx):
+```nginx
+gzip on;
+gzip_types text/html text/css application/javascript;
+```
+
+2. **Add Cache Headers** for static assets:
+```nginx
+location ~* \.(js|css|html)$ {
+ expires 1h;
+ add_header Cache-Control "public, immutable";
+}
+```
+
+3. **Optimize Snow Particle Count**:
+Edit `frontend/script.js`:
+```javascript
+// Reduce particles for better performance
+const maxParticles = window.innerWidth < 768 ? 50 : 100; // Instead of 200
+```
+
+4. **Use Production Docker Images**:
+- Multi-stage builds to reduce image size
+- Alpine-based images for smaller footprint
+
+## Deployment
+
+### Deploy to Production
+
+1. **Set production environment variables**
+2. **Use production Docker Compose file**:
+
+```yaml
+# docker-compose.prod.yml
+services:
+ backend:
+ build: ./backend
+ restart: always
+ environment:
+ - PORT=8080
+
+ frontend:
+ build: ./frontend
+ restart: always
+ ports:
+ - "80:80"
+ depends_on:
+ - backend
+```
+
+3. **Deploy**:
+```bash
+docker compose -f docker-compose.prod.yml up -d
+```
+
+### Deploy to Cloud
+
+**AWS ECS / Azure Container Instances / Google Cloud Run**:
+- Push Docker images to container registry
+- Deploy using cloud-specific Docker Compose support or orchestration tools
+
+**Kubernetes**:
+```bash
+# Generate Kubernetes manifests from Docker Compose
+kompose convert -f docker-compose.yml
+
+# Deploy to Kubernetes
+kubectl apply -f backend-deployment.yaml
+kubectl apply -f frontend-deployment.yaml
+```
+
+## Monitoring
+
+### Health Checks
+
+**Backend**:
+```bash
+# Check if backend is responding
+curl http://localhost:8080/api/christmas
+
+# Expected: 200 OK with JSON response
+```
+
+**Frontend**:
+```bash
+# Check if frontend is accessible
+curl -I http://localhost
+
+# Expected: 200 OK with HTML content
+```
+
+### Logs
+
+**View real-time logs**:
+```bash
+# All services
+docker compose logs -f
+
+# Backend only
+docker compose logs -f backend
+
+# Frontend only
+docker compose logs -f frontend
+```
+
+## Next Steps
+
+After completing the quickstart:
+
+1. **Generate Tasks**: Run `/speckit.tasks` to create implementation task list
+2. **Implement**: Follow tasks.md to build the feature
+3. **Validate**: Test against acceptance scenarios in spec.md
+4. **Deploy**: Use production deployment steps above
+
+## Additional Resources
+
+- **Feature Specification**: [spec.md](spec.md)
+- **Implementation Plan**: [plan.md](plan.md)
+- **API Contract**: [contracts/api.md](contracts/api.md)
+- **Data Model**: [data-model.md](data-model.md)
+- **Research**: [research.md](research.md)
+
+## Support
+
+For issues or questions:
+1. Check this quickstart guide
+2. Review feature specification and plan
+3. Check Docker Compose logs
+4. Consult research.md for technical decisions
diff --git a/specs/001-christmas-checker/research.md b/specs/001-christmas-checker/research.md
new file mode 100644
index 0000000..dc89f2f
--- /dev/null
+++ b/specs/001-christmas-checker/research.md
@@ -0,0 +1,202 @@
+# Research: Christmas Checker Website
+
+**Date**: 2025-11-11
+**Feature**: Christmas Checker Website
+**Branch**: 001-christmas-checker
+
+## Research Questions
+
+Based on the Technical Context, the following areas required research:
+
+1. Best approach for minimal Java HTTP server (no frameworks)
+2. JavaScript snow animation best practices for performance
+3. Docker Compose setup for Java + static files
+4. Date handling in Java for timezone-aware date comparison
+5. Frontend-backend communication patterns
+
+## Findings
+
+### 1. Minimal Java HTTP Server
+
+**Decision**: Use `com.sun.net.httpserver.HttpServer` from Java standard library
+
+**Rationale**:
+- Built into Java SE since Java 6, no external dependencies
+- Sufficient for simple REST endpoints
+- Lightweight and easy to configure
+- Supports both HTTP and HTTPS
+- Perfect for minimal dependency requirement
+
+**Alternatives Considered**:
+- **Spring Boot**: Rejected - too heavy for this simple use case, violates "minimal dependencies" requirement
+- **Jetty embedded**: Rejected - external dependency, overkill for single endpoint
+- **Undertow**: Rejected - external dependency
+- **Raw sockets**: Rejected - too low-level, would require manual HTTP parsing
+
+**Implementation Approach**:
+```java
+HttpServer server = HttpServer.create(new InetSocketAddress(8080), 0);
+server.createContext("/api/christmas", new ChristmasHandler());
+server.start();
+```
+
+### 2. JavaScript Snow Animation
+
+**Decision**: Use Canvas API with RequestAnimationFrame for snow particles
+
+**Rationale**:
+- Canvas provides excellent performance for particle effects
+- RequestAnimationFrame ensures smooth 60fps animation
+- No external libraries needed (vanilla JS)
+- Can easily optimize particle count based on screen size
+- Respects `prefers-reduced-motion` for accessibility
+
+**Alternatives Considered**:
+- **CSS animations**: Rejected - limited control over particle physics, harder to optimize particle count
+- **SVG**: Rejected - poor performance with many particles (hundreds of snowflakes)
+- **WebGL**: Rejected - overkill for 2D particles, complexity violation
+- **Libraries (particles.js, etc.)**: Rejected - violates "minimal dependencies"
+
+**Implementation Approach**:
+- Create canvas overlay covering full viewport
+- Generate 100-200 snowflake particles (adjust based on screen size)
+- Use simple physics: constant downward velocity + slight horizontal wobble
+- Recycle particles when they fall off screen
+- Clear and redraw on each frame using requestAnimationFrame
+
+**Performance Optimizations**:
+- Limit particle count on mobile (50-100 vs 150-200 on desktop)
+- Use simple circles instead of complex shapes
+- Batch drawing operations
+- Pause animation when page not visible (Page Visibility API)
+
+### 3. Docker Compose Architecture
+
+**Decision**: Two-service architecture with nginx for frontend, Java for backend
+
+**Rationale**:
+- Separation of concerns: static files vs dynamic API
+- nginx excellent for serving static files efficiently
+- Java service only handles API endpoint
+- Both services lightweight and minimal
+- Easy to scale independently if needed
+
+**Alternatives Considered**:
+- **Single Java service serving both**: Rejected - mixing concerns, Java not optimized for static file serving
+- **Node.js for frontend**: Rejected - introduces another language/runtime unnecessarily
+- **Apache instead of nginx**: Rejected - nginx lighter and more modern
+
+**Docker Compose Structure**:
+```yaml
+services:
+ backend:
+ build: ./docker/backend
+ ports:
+ - "8080:8080"
+
+ frontend:
+ build: ./docker/frontend
+ ports:
+ - "80:80"
+ depends_on:
+ - backend
+```
+
+### 4. Java Date/Time Handling
+
+**Decision**: Use `java.time.LocalDate` for date comparisons
+
+**Rationale**:
+- Modern Java 8+ time API (java.time package)
+- Immutable and thread-safe
+- Clear separation of date (LocalDate) vs time (LocalTime)
+- Easy comparison: `LocalDate.now().getMonthValue() == 12 && LocalDate.now().getDayOfMonth() == 25`
+
+**Alternatives Considered**:
+- **java.util.Date**: Rejected - deprecated, mutable, poor API design
+- **java.util.Calendar**: Rejected - verbose, mutable, confusing API
+- **Joda-Time**: Rejected - external dependency, java.time is standard now
+
+**Implementation Approach**:
+```java
+LocalDate today = LocalDate.now();
+boolean isChristmas = today.getMonthValue() == 12 && today.getDayOfMonth() == 25;
+```
+
+**Timezone Consideration**:
+- Backend uses server's local timezone (acceptable for simple deployment)
+- Frontend could alternatively check date client-side for user's local timezone
+- Decision: Frontend checks date client-side using JavaScript `Date()` object
+- Backend endpoint becomes optional/redundant but kept for architecture demonstration
+
+### 5. Frontend-Backend Communication
+
+**Decision**: Simple REST GET endpoint returning JSON
+
+**Rationale**:
+- RESTful pattern is standard and well-understood
+- GET request is idempotent and cacheable
+- JSON is lightweight and universally supported
+- CORS headers allow cross-origin requests if needed
+
+**Endpoint Design**:
+```
+GET /api/christmas
+Response: { "isChristmas": true|false, "date": "2025-12-25" }
+```
+
+**Alternatives Considered**:
+- **WebSocket**: Rejected - overkill for simple one-time check
+- **GraphQL**: Rejected - too complex for single field
+- **Plain text response**: Rejected - JSON is more structured and extensible
+
+**CORS Configuration**:
+- Allow all origins (`Access-Control-Allow-Origin: *`) since this is a public API
+- No authentication needed
+
+### 6. Client-Side vs Server-Side Date Check
+
+**Decision**: Implement BOTH with client-side as primary
+
+**Rationale**:
+- Client-side JS can check date using user's local timezone (matches spec requirement FR-001)
+- Server-side endpoint demonstrates backend capability and provides fallback
+- Offline capability: once page loads, works without backend
+- Simplifies architecture while meeting all requirements
+
+**Implementation Strategy**:
+1. Frontend loads and immediately checks date client-side
+2. Displays result without waiting for backend
+3. Backend endpoint available but not strictly necessary for functionality
+4. This approach satisfies the "offline-capable" requirement from spec
+
+## Technology Stack Summary
+
+| Component | Technology | Version | Rationale |
+|-----------|-----------|---------|-----------|
+| Backend Language | Java | 21 (LTS) | User requirement, minimal dependencies |
+| Backend HTTP | com.sun.net.httpserver | Standard library | No external dependencies |
+| Backend Date/Time | java.time.LocalDate | Standard library | Modern, immutable, clear API |
+| Frontend HTML/CSS/JS | Vanilla (no frameworks) | ES6+ | User requirement: minimal dependencies |
+| Snow Animation | Canvas + RequestAnimationFrame | Browser standard | Best performance for particles |
+| Frontend Server | nginx | alpine | Lightweight static file serving |
+| Container Platform | Docker + Docker Compose | Latest | User requirement |
+| Testing | JUnit 5 | 5.10+ | Standard Java testing (if tests requested) |
+
+## Open Questions Resolved
+
+All NEEDS CLARIFICATION items from Technical Context have been resolved:
+
+✅ HTTP server approach: Java standard library HttpServer
+✅ Snow animation: Canvas API with RequestAnimationFrame
+✅ Docker structure: Two services (nginx + Java)
+✅ Date handling: java.time.LocalDate
+✅ Frontend-backend: REST JSON API (optional, client-side primary)
+
+## Next Steps
+
+Proceed to Phase 1:
+1. Generate data-model.md (minimal - just Date and ChristmasStatus entities)
+2. Generate contracts/api.md (REST endpoint specification)
+3. Generate quickstart.md (how to build and run)
+4. Update agent context files
diff --git a/specs/001-christmas-checker/spec.md b/specs/001-christmas-checker/spec.md
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+# 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**:
+
+1. **Given** it is November 11th, **When** a user visits the website, **Then** the page displays "No" and shows a sad smiley face
+2. **Given** it is December 24th, **When** a user visits the website, **Then** the page displays "No" and shows a sad smiley face
+3. **Given** it is December 27th, **When** a user visits the website, **Then** the page displays "No" and shows a sad smiley face
+4. **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**:
+
+1. **Given** it is December 25th, **When** a user visits the website, **Then** the page displays "Yes" and shows snow falling animation
+2. **Given** it is December 26th, **When** a user visits the website, **Then** the page displays "Yes" and shows snow falling animation
+3. **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
+4. **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
diff --git a/specs/001-christmas-checker/tasks.md b/specs/001-christmas-checker/tasks.md
new file mode 100644
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+++ b/specs/001-christmas-checker/tasks.md
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+# Tasks: Christmas Checker Website
+
+**Input**: Design documents from `/specs/001-christmas-checker/`
+**Prerequisites**: plan.md (required), spec.md (required for user stories), research.md, data-model.md, contracts/
+
+**Tests**: No tests requested in the feature specification, so tests are NOT included.
+
+**Organization**: Tasks are grouped by user story to enable independent implementation and testing of each story.
+
+## Format: `[ID] [P?] [Story] Description`
+
+- **[P]**: Can run in parallel (different files, no dependencies)
+- **[Story]**: Which user story this task belongs to (e.g., US1, US2)
+- Include exact file paths in descriptions
+
+## Path Conventions
+
+- **Web app**: `backend/` and `frontend/` directories at repository root
+- Backend: Java source in `backend/src/main/java/christmas/`
+- Frontend: HTML/CSS/JS in `frontend/`
+- Docker: Configuration in `docker/`
+
+---
+
+## Phase 1: Setup (Shared Infrastructure)
+
+**Purpose**: Project initialization and basic structure
+
+- [x] T001 Create backend directory structure at backend/src/main/java/christmas/
+- [x] T002 Create frontend directory structure at frontend/
+- [x] T003 [P] Create docker directory structure at docker/
+- [x] T004 [P] Create backend Dockerfile at docker/Dockerfile.backend for Java 21 application
+- [x] T005 [P] Create frontend Dockerfile at docker/Dockerfile.frontend for nginx static file serving
+- [x] T006 Create docker-compose.yml at docker/docker-compose.yml orchestrating backend and frontend services
+
+---
+
+## Phase 2: Foundational (Blocking Prerequisites)
+
+**Purpose**: Core infrastructure that MUST be complete before ANY user story can be implemented
+
+**⚠️ CRITICAL**: No user story work can begin until this phase is complete
+
+- [x] T007 Create ChristmasChecker class in backend/src/main/java/christmas/ChristmasChecker.java with date checking logic
+- [x] T008 [P] Create ChristmasServer class in backend/src/main/java/christmas/ChristmasServer.java with HttpServer setup
+- [x] T009 [P] Create Main class in backend/src/main/java/christmas/Main.java as application entry point
+- [x] T010 Implement GET /api/christmas endpoint handler in backend/src/main/java/christmas/ChristmasServer.java
+- [x] T011 [P] Add CORS headers support in backend/src/main/java/christmas/ChristmasServer.java
+- [x] T012 [P] Create base HTML structure in frontend/index.html with viewport and meta tags
+- [x] T013 [P] Create base CSS file at frontend/styles.css with reset and common styles
+- [x] T014 [P] Create base JavaScript file at frontend/script.js with date checking function
+
+**Checkpoint**: Foundation ready - user story implementation can now begin in parallel
+
+---
+
+## Phase 3: User Story 1 - Check Christmas Status on Non-Christmas Day (Priority: P1) 🎯 MVP
+
+**Goal**: Display "No" message with sad smiley face when it's not Christmas (364 days/year)
+
+**Independent Test**: Visit website on any non-Christmas day and verify "No" message and sad smiley face appear
+
+### Implementation for User Story 1
+
+- [x] T015 [P] [US1] Implement isChristmas() method in backend/src/main/java/christmas/ChristmasChecker.java using LocalDate
+- [x] T016 [P] [US1] Implement JSON response formatting in backend/src/main/java/christmas/ChristmasServer.java
+- [x] T017 [P] [US1] Add client-side date check logic in frontend/script.js using JavaScript Date()
+- [x] T018 [P] [US1] Create HTML structure for "No" message display in frontend/index.html
+- [x] T019 [P] [US1] Create HTML structure for sad smiley face in frontend/index.html
+- [x] T020 [US1] Add CSS styles for "No" message in frontend/styles.css
+- [x] T021 [US1] Add CSS styles for sad smiley face in frontend/styles.css
+- [x] T022 [US1] Implement renderNonChristmas() function in frontend/script.js to display "No" + smiley
+- [x] T023 [US1] Wire up date check to call renderNonChristmas() when not December 25th in frontend/script.js
+- [x] T024 [US1] Add responsive design for mobile screens (320px-768px) in frontend/styles.css
+- [x] T025 [US1] Ensure text and smiley are clearly visible on all screen sizes in frontend/styles.css
+
+**Checkpoint**: At this point, User Story 1 should be fully functional and testable independently
+
+---
+
+## Phase 4: User Story 2 - Check Christmas Status on Christmas Day (Priority: P2)
+
+**Goal**: Display "Yes" message with falling snow animation when it's Christmas (1 day/year)
+
+**Independent Test**: Set system date to December 25th and verify "Yes" message and snow animation appear
+
+### Implementation for User Story 2
+
+- [x] T026 [P] [US2] Create HTML structure for "Yes" message display in frontend/index.html
+- [x] T027 [P] [US2] Create canvas element for snow animation in frontend/index.html
+- [x] T028 [P] [US2] Add CSS styles for "Yes" message in frontend/styles.css
+- [x] T029 [P] [US2] Add CSS styles for canvas overlay in frontend/styles.css
+- [x] T030 [US2] Implement renderChristmas() function in frontend/script.js to display "Yes"
+- [x] T031 [US2] Implement snow particle system initialization in frontend/script.js
+- [x] T032 [US2] Implement snow particle update logic (falling + wobble) in frontend/script.js
+- [x] T033 [US2] Implement snow rendering loop using requestAnimationFrame in frontend/script.js
+- [x] T034 [US2] Wire up date check to call renderChristmas() when December 25th in frontend/script.js
+- [x] T035 [US2] Optimize particle count based on screen size (50-100 mobile, 150-200 desktop) in frontend/script.js
+- [x] T036 [US2] Add Page Visibility API integration to pause animation when tab not visible in frontend/script.js
+- [x] T037 [US2] Add prefers-reduced-motion support to disable animation for accessibility in frontend/script.js
+
+**Checkpoint**: All user stories should now be independently functional
+
+---
+
+## Phase 5: Polish & Cross-Cutting Concerns
+
+**Purpose**: Improvements that affect multiple user stories
+
+- [x] T038 [P] Add error handling for date check failures in frontend/script.js
+- [x] T039 [P] Add midnight transition logic (FR-006) to auto-update display in frontend/script.js
+- [x] T040 [P] Ensure cross-browser compatibility (Chrome, Firefox, Safari, Edge) by testing all features
+- [x] T041 [P] Add alt text for smiley face for screen reader accessibility in frontend/index.html
+- [x] T042 [P] Optimize CSS for performance (minimize repaints, use transforms) in frontend/styles.css
+- [x] T043 [P] Add meta description and title tags in frontend/index.html
+- [x] T044 [P] Configure nginx cache headers and gzip compression in docker/Dockerfile.frontend
+- [x] T045 Validate Docker Compose setup by running docker compose up --build
+- [x] T046 Test MVP (User Story 1) manually on non-Christmas day
+- [x] T047 Test User Story 2 manually by changing system date to December 25th
+- [x] T048 Validate performance goals (page load <2s, animation >30fps, date check <1s)
+- [x] T049 Run quickstart.md validation steps
+
+---
+
+## Dependencies & Execution Order
+
+### Phase Dependencies
+
+- **Setup (Phase 1)**: No dependencies - can start immediately
+- **Foundational (Phase 2)**: Depends on Setup completion - BLOCKS all user stories
+- **User Stories (Phase 3+)**: All depend on Foundational phase completion
+ - User stories can then proceed in parallel (if staffed)
+ - Or sequentially in priority order (P1 → P2)
+- **Polish (Final Phase)**: Depends on all desired user stories being complete
+
+### User Story Dependencies
+
+- **User Story 1 (P1)**: Can start after Foundational (Phase 2) - No dependencies on other stories
+- **User Story 2 (P2)**: Can start after Foundational (Phase 2) - Independent from US1, but builds on same HTML structure
+
+**Key Independence**: User Story 1 can be deployed without User Story 2. US1 provides full MVP functionality.
+
+### Within Each User Story
+
+- **User Story 1 (P1)**: Date logic → HTML structure → CSS styles → JavaScript rendering → Integration
+- **User Story 2 (P2)**: HTML structure for "Yes" → Canvas setup → CSS styles → Snow physics → Animation loop → Integration
+
+### Parallel Opportunities
+
+- All Setup tasks marked [P] can run in parallel (T001-T006, except T006 depends on T004-T005)
+- All Foundational tasks marked [P] can run in parallel (within Phase 2: T008-T009, T011-T014)
+- Once Foundational phase completes, US1 and US2 can be worked on in parallel by different team members
+- Within US1: T015-T019 and T020-T021 can run in parallel
+- Within US2: T026-T029 can run in parallel
+- All Polish tasks marked [P] can run in parallel (T038-T044)
+
+---
+
+## Parallel Example: User Story 1
+
+```bash
+# Launch models and HTML structure together:
+Task: "Implement isChristmas() method in backend/src/main/java/christmas/ChristmasChecker.java"
+Task: "Implement JSON response formatting in backend/src/main/java/christmas/ChristmasServer.java"
+Task: "Add client-side date check logic in frontend/script.js"
+Task: "Create HTML structure for 'No' message in frontend/index.html"
+Task: "Create HTML structure for sad smiley face in frontend/index.html"
+
+# Then launch CSS styling tasks together:
+Task: "Add CSS styles for 'No' message in frontend/styles.css"
+Task: "Add CSS styles for sad smiley face in frontend/styles.css"
+```
+
+---
+
+## Implementation Strategy
+
+### MVP First (User Story 1 Only)
+
+1. Complete Phase 1: Setup
+2. Complete Phase 2: Foundational (CRITICAL - blocks all stories)
+3. Complete Phase 3: User Story 1
+4. **STOP and VALIDATE**: Test User Story 1 independently
+5. Deploy/demo if ready
+
+At this point, you have a working Christmas Checker that handles 364 days of the year correctly!
+
+### Incremental Delivery
+
+1. Complete Setup + Foundational → Foundation ready
+2. Add User Story 1 → Test independently → Deploy/Demo (MVP! ✅)
+3. Add User Story 2 → Test independently → Deploy/Demo (Full feature ✨)
+4. Each story adds value without breaking previous stories
+
+### Parallel Team Strategy
+
+With multiple developers:
+
+1. Team completes Setup + Foundational together
+2. Once Foundational is done:
+ - Developer A: User Story 1 (backend + frontend for "No" case)
+ - Developer B: User Story 2 (snow animation)
+3. Stories complete and integrate independently
+
+---
+
+## Notes
+
+- **[P] tasks** = different files, no dependencies, can run in parallel
+- **[Story] label** maps task to specific user story for traceability
+- Each user story should be independently completable and testable
+- **No tests included**: Feature specification did not request tests
+- Commit after each task or logical group
+- Stop at any checkpoint to validate story independently
+- **File paths are exact**: All tasks include precise file locations
+- **Backend is optional**: Frontend can work standalone with client-side date checking (FR-001)
+- **Docker deployment**: Final validation requires docker compose up
+
+---
+
+## Task Count Summary
+
+- **Setup**: 6 tasks
+- **Foundational**: 8 tasks
+- **User Story 1 (P1 - MVP)**: 11 tasks
+- **User Story 2 (P2)**: 12 tasks
+- **Polish**: 12 tasks
+
+**Total**: 49 tasks
+
+**Parallel Opportunities**: 30 tasks marked [P] can run concurrently with appropriate staffing
+
+**MVP Scope**: Setup (6) + Foundational (8) + User Story 1 (11) = **25 tasks** for complete MVP