mirror of
https://github.com/bretzel-app/crumbs.git
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107 lines
3.8 KiB
Markdown
107 lines
3.8 KiB
Markdown
# Architecture
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## Overview
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Crumbs follows a **local-first** architecture where the client (browser) is the primary data store and the server acts as a sync target and backup.
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```
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┌─────────────────────────────┐
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│ Browser (PWA) │
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│ ┌───────────┐ ┌──────────┐ │
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│ │ Svelte │ │ IndexedDB│ │
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│ │ Stores │◄│ (idb) │ │
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│ └─────┬─────┘ └────┬─────┘ │
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│ │ │ │
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│ ┌─────▼─────────────▼─────┐ │
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│ │ Sync Engine │ │
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│ │ (LWW CRDT + Queue) │ │
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│ └──────────┬──────────────┘ │
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└─────────────┼────────────────┘
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│ HTTP (JSON)
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┌─────────────▼────────────────┐
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│ Server (Node.js) │
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│ ┌──────────┐ ┌────────────┐ │
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│ │ SvelteKit│ │ SQLite │ │
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│ │ API │◄│ (Drizzle) │ │
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│ └──────────┘ └────────────┘ │
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└──────────────────────────────┘
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```
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## Data Flow
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### Read Path
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1. User opens app
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2. Svelte stores read from IndexedDB (instant)
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3. Background sync pulls latest from server
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4. If newer data found, IDB is updated, stores react
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### Write Path
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1. User creates/edits note
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2. Change written to IndexedDB immediately
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3. Change added to sync queue
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4. Background sync pushes queue to server
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5. Server applies changes with LWW resolution
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### Conflict Resolution (LWW)
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For a single-user app with multiple devices:
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- Each note has an `updatedAt` timestamp and `version` number
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- When merging: newer timestamp wins
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- If timestamps match: higher version wins
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- If both match: local version is preferred
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## Tech Stack Rationale
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### SvelteKit
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- Smallest bundle size of major frameworks
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- Built-in SSR, routing, API routes
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- Svelte 5 runes for reactive state
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- Native service worker support via @vite-pwa/sveltekit
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### SQLite + Drizzle
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- Zero-config database (single file)
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- WAL mode for concurrent reads
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- Drizzle provides type-safe queries without ORM overhead
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- Perfect for single-user self-hosted apps
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### IndexedDB (idb)
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- Browser-native storage (no size limits like localStorage)
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- Async API doesn't block main thread
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- `idb` library provides Promise-based wrapper
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- Survives browser restarts
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### Tailwind CSS 4
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- Utility-first, tree-shakeable
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- Built-in dark mode support (`dark:` variants)
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- New v4 uses Vite plugin (faster builds)
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### Argon2
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- Current best practice for password hashing
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- Memory-hard (resists GPU attacks)
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- Winner of the Password Hashing Competition
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## Database Schema
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See `src/lib/server/db/schema.ts` for the complete Drizzle schema.
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Key tables:
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- `users` - Single user (password hash)
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- `sessions` - Auth sessions (30-day TTL)
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- `notes` - Core note data with version tracking
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- `tags` - Unique tag names
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- `note_tags` - Many-to-many note ↔ tag
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- `attachments` - Image file metadata
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- `sync_log` - Sync operation history
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## File Organization
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```
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src/lib/server/ # Server-only code (DB, auth, attachments)
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src/lib/sync/ # Sync engine (shared types, server + client implementations)
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src/lib/stores/ # Svelte reactive stores (notes, theme, auth, search)
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src/lib/components/ # Svelte UI components
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src/lib/utils/ # Pure utility functions (markdown, tags, colors)
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src/lib/types/ # TypeScript type definitions
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src/routes/api/ # REST API endpoints
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src/routes/ # Page routes (SvelteKit file-based routing)
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```
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