## Context

trails.cool ships features regularly but has no user-facing changelog. The
project philosophy values transparency and simplicity. We need a changelog
that's low-friction to write (just add a markdown file), works in-app, and
produces shareable social links.

## Goals / Non-Goals

**Goals:**
- Zero-friction authoring: drop a `.md` file, deploy, done
- Public page at `/changelog` listing all entries newest-first
- Individual entry pages at `/changelog/:slug` with OG meta for social sharing
- "What's New" indicator in nav for returning users
- Works without JavaScript (SSR)

**Non-Goals:**
- CMS or admin interface for writing entries
- RSS feed (future, not now)
- Email notifications for new entries
- Per-entry images or rich media (just markdown text)
- Bilingual entries (English only for now)

## Decisions

### D1: Markdown files in the repo, loaded at build time

Changelog entries live in `apps/journal/changelog/` as markdown files named
by date: `2026-03-25.md`. Vite's `import.meta.glob` loads them at build time.
No runtime file system access needed.

Each file has YAML frontmatter:

```yaml
---
title: "Collaborative route planning goes live"
date: 2026-03-25
---
```

### D2: Single route with dynamic slug

`/changelog` shows all entries. `/changelog/:date` shows a single entry.
Both are one route file using an optional param or two route files. The list
page shows titles + dates + first paragraph preview.

### D3: "What's New" via localStorage timestamp

Store `changelog:lastSeen` timestamp in localStorage. If the newest entry's
date is after this timestamp, show a dot on the nav "Changelog" link. Clicking
the changelog page updates the timestamp. No server state needed.

### D4: Open Graph meta for social sharing

Each `/changelog/:date` page sets `og:title`, `og:description` (first
paragraph), and `og:url`. No og:image for now — text previews are fine.

## Risks / Trade-offs

- **Build-time loading means deploy to publish** → Acceptable. We deploy on
  every merge to main. Adding a changelog entry is: write file, PR, merge,
  deployed.
- **No rich media** → Keeps it simple. Can add images later if needed.
- **localStorage "what's new" doesn't sync across devices** → Fine for now.
  Server-side tracking would require auth and a DB table — overkill.