Spec Package Template

## Story
As a [role], I want [goal], so that [benefit].

## Acceptance Criteria
1. Given [...], when [...], then [...]

## Mockup
Layout: [structure]
Components: [key elements]
States: default | loading | error | empty

## Technical Constraints
Stack: [tech]
Libraries: [specific libs]
Patterns: [follow existing X]

## Story
As a user, I want to save articles to a reading list
so that I can return to them later.

## Acceptance Criteria
1. Given I enter a valid URL and title and click Save,
   then the article appears at the top of my list
2. Given the URL field is empty, when I click Save,
   then an inline error "URL is required" appears
3. Given no articles are saved, when I view the list,
   then I see an empty state with "Save your first article"

## Mockup
Layout: Header (logo + Add button) + filter bar + card list
Components: ArticleCard (title, domain, tags, read indicator)
States: empty (illustration + CTA), loading (skeleton cards)

## Technical Constraints
Stack: React, TypeScript, Tailwind CSS, localStorage
Pattern: Follow existing Card component pattern
Validation: URL must match https?:// pattern