Reorganize codebase: separate server architecture from business logic

- Created feed_parser.py module with YouTubeFeedParser and FeedEntry classes
- Refactored main.py to focus on Flask routing with two endpoints:
  - GET / for homepage
  - GET /api/feed for REST API with query parameters
- Updated CLAUDE.md with new architecture documentation
- Implemented clean separation between core logic and web server layers

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

CLAUDE.md

@@ -0,0 +1,86 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project Overview
+
+`yottob` is a Flask-based web application for processing YouTube RSS feeds. The project provides both a REST API and CLI interface for fetching and parsing YouTube channel feeds, with filtering logic to exclude YouTube Shorts.
+
+## Development Setup
+
+This project uses `uv` for dependency management.
+
+**Install dependencies:**
+```bash
+uv sync
+```
+
+**Activate virtual environment:**
+```bash
+source .venv/bin/activate  # On macOS/Linux
+```
+
+## Running the Application
+
+**Run the CLI feed parser:**
+```bash
+python main.py
+```
+This executes the `main()` function which fetches and parses a YouTube channel RSS feed for testing.
+
+**Run the Flask web application:**
+```bash
+flask --app main run
+```
+The web server exposes:
+- `/` - Main page (renders `index.html`)
+- `/api/feed` - API endpoint for fetching feeds
+
+**API Usage Example:**
+```bash
+# Fetch default channel feed
+curl http://localhost:5000/api/feed
+
+# Fetch specific channel (without filtering Shorts)
+curl "http://localhost:5000/api/feed?channel_id=CHANNEL_ID&filter_shorts=false"
+```
+
+## Architecture
+
+The codebase follows a clean separation between business logic and web server:
+
+### Core Logic Layer
+**`feed_parser.py`** - Reusable YouTube feed parsing module
+- `YouTubeFeedParser`: Main parser class that encapsulates channel-specific logic
+- `FeedEntry`: Data model for individual feed entries
+- Independent of Flask - can be imported and used in any Python context
+
+### Web Server Layer
+**`main.py`** - Flask application and routes
+- `app`: Flask application instance (main.py:7)
+- `index()`: Homepage route handler (main.py:14)
+- `get_feed()`: REST API endpoint (main.py:20) that uses `YouTubeFeedParser`
+- `main()`: CLI entry point for testing (main.py:42)
+
+### Templates
+**`templates/index.html`** - Frontend HTML (currently static placeholder)
+
+## Feed Parsing Implementation
+
+The `YouTubeFeedParser` class in `feed_parser.py`:
+- Constructs YouTube RSS feed URLs from channel IDs
+- Uses feedparser to fetch and parse feeds
+- Validates HTTP 200 status before processing
+- Optionally filters out YouTube Shorts (any entry with "shorts" in URL)
+- Returns structured dictionary with feed metadata and entries
+
+**YouTube RSS Feed URL Format:**
+```
+https://www.youtube.com/feeds/videos.xml?channel_id={CHANNEL_ID}
+```
+
+## Dependencies
+
+- **Flask 3.1.2+**: Web framework
+- **feedparser 6.0.12+**: RSS/Atom feed parsing
+- **Python 3.14+**: Required runtime version