Initial commit

Add Discord Archive Manager project with:
- Entity Framework Core data models for Discord exports
- JSON import service for processing Discord chat exports
- Archive service for managing imported data
- Docker configuration for containerized deployment

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

README.md

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+# Discord Archive Manager
+
+A .NET 8 console application that parses DiscordChatExporter JSON exports and stores them in MSSQL with content-hashed image storage.
+
+## Features
+
+- Parses DiscordChatExporter JSON exports
+- Stores messages, users, channels, attachments, embeds, and reactions in MSSQL
+- Content-addressed image storage using SHA256 hashing (deduplicates identical files)
+- Tracks user profile changes over time via snapshots
+- Archives processed JSON files
+- Idempotent processing (skips already-processed files)
+
+## Project Structure
+
+```
+DiscordArchiveManager/
+├── src/DiscordArchiveManager/
+│   ├── Program.cs              # Entry point
+│   ├── appsettings.json        # Configuration
+│   ├── Models/
+│   │   ├── DiscordExport.cs    # JSON deserialization models
+│   │   └── Entities/           # EF Core entities
+│   ├── Data/
+│   │   └── DiscordArchiveContext.cs
+│   └── Services/
+│       ├── JsonImportService.cs
+│       ├── ImageHashService.cs
+│       └── ArchiveService.cs
+├── Dockerfile
+├── docker-compose.yml
+└── README.md
+```
+
+## Database Schema
+
+- **Guilds**: Discord servers
+- **Channels**: Text channels within guilds
+- **Users**: Discord users (basic info)
+- **UserSnapshots**: Historical user profile data (nickname, color, avatar)
+- **Messages**: Chat messages
+- **Attachments**: Files attached to messages (stored with content hash)
+- **Embeds**: Rich embeds in messages
+- **Reactions**: Emoji reactions on messages
+- **Mentions**: User mentions in messages
+- **ProcessedFiles**: Tracking for imported files
+
+## Image Storage
+
+Images are stored using a content-addressed system:
+
+1. Calculate SHA256 hash of the file
+2. Store at `/images/{hash[0:2]}/{hash[2:4]}/{hash}.{ext}`
+
+Example: A file with hash `a1b2c3d4e5f6...` and extension `.png` is stored at:
+```
+/images/a1/b2/a1b2c3d4e5f6....png
+```
+
+Benefits:
+- Automatic deduplication (identical files share storage)
+- Even distribution across directories
+- Fast lookup by hash
+
+## Configuration
+
+### appsettings.json
+
+```json
+{
+  "ConnectionStrings": {
+    "Discord": "Server=192.168.10.99;Database=DiscordArchive;User Id=sa;Password=YourPassword;TrustServerCertificate=true"
+  },
+  "Paths": {
+    "InputDirectory": "/app/input",
+    "ArchiveDirectory": "/app/archive",
+    "ImageDirectory": "/app/images"
+  }
+}
+```
+
+### Environment Variables
+
+Configuration can also be set via environment variables:
+- `ConnectionStrings__Discord`: Database connection string
+- `Paths__InputDirectory`: Directory to scan for JSON files
+- `Paths__ArchiveDirectory`: Directory to move processed files
+- `Paths__ImageDirectory`: Directory for content-hashed images
+
+## Usage
+
+### With Docker Compose
+
+1. Create input/archive/images directories:
+   ```bash
+   mkdir -p input archive images
+   ```
+
+2. Place DiscordChatExporter JSON exports in the `input` directory
+
+3. Update the connection string in `docker-compose.yml`
+
+4. Build and run:
+   ```bash
+   docker compose build
+   docker compose up
+   ```
+
+### Without Docker
+
+1. Ensure .NET 8 SDK is installed
+
+2. Update `appsettings.json` with your configuration
+
+3. Build and run:
+   ```bash
+   cd src/DiscordArchiveManager
+   dotnet run
+   ```
+
+## DiscordChatExporter Export Format
+
+This tool expects JSON exports from [DiscordChatExporter](https://github.com/Tyrrrz/DiscordChatExporter).
+
+When exporting, ensure:
+- Format: JSON
+- "Download assets" is enabled (for local attachment storage)
+
+The tool expects the `_Files` directory to be alongside the JSON file:
+```
+exports/
+├── general-2024-01-15.json
+└── general-2024-01-15.json_Files/
+    ├── attachment1.png
+    └── avatar123.webp
+```
+
+## Processing Flow
+
+1. Scan input directory for `*.json` files
+2. For each unprocessed file:
+   - Parse JSON into model objects
+   - Upsert Guild and Channel (idempotent)
+   - Upsert Users and create snapshots for profile changes
+   - Insert Messages (skip if ID exists)
+   - Process attachments:
+     - Calculate SHA256 hash
+     - Copy to content-hashed location if new
+     - Reference existing path if duplicate
+   - Process embeds, reactions, and mentions
+3. Archive JSON file and `_Files` folder
+4. Record in ProcessedFiles table
+
+## Re-running
+
+The tool is safe to run multiple times:
+- Already-processed files are skipped (tracked in ProcessedFiles table)
+- Existing messages are not duplicated (checked by Discord message ID)
+- Duplicate images are not re-copied (checked by content hash)