> ## Documentation Index
> Fetch the complete documentation index at: https://exegia.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Architecture

> How the Supabase-powered backend converts, stores, and serves corpora

The backend converts, stores, and serves 30+ pre-loaded text corpora with a REST API, built on Supabase, PostgreSQL, and Deno.

## System overview

```text theme={null}
┌─────────────┐         ┌──────────────┐         ┌──────────────┐
│   Frontend  │────────▶│   Supabase   │────────▶│  PostgreSQL  │
│  (React)    │  REST   │ Edge Function│   SQL   │   Database   │
└─────────────┘         └──────────────┘         └──────────────┘
                               │
                               ▼
                        ┌──────────────┐
                        │   Storage    │
                        │  (.exg files)│
                        └──────────────┘
```

## Corpus conversion flow

<Steps>
  <Step title="Upload">
    Client sends `POST /functions/v1/convert-corpus` with `multipart/form-data` containing `corpus.zip` plus metadata.
  </Step>

  <Step title="Edge Function receives the request">
    The function validates file type, metadata, and size; generates a `job_id` (UUID); writes the file to ephemeral `/tmp` storage; uploads it to Storage at `uploads/job_id.zip`; and immediately returns **202 Accepted** with the `job_id`.
  </Step>

  <Step title="Background processing">
    Via `EdgeRuntime.waitUntil`, the function reads the zip, detects the format (EPUB, PDF, TEI, XML, or plain text), and builds the `.exg` envelope:

    * `manifest.json` — metadata and node types
    * `index.json` — file listing
    * `corpus.exgc` — compressed source

    It then uploads the result to Storage at `datasets/{name}.exg`, deletes the temporary upload, and inserts a row into the `corpora` table.
  </Step>

  <Step title="Complete">
    The corpus is available via the REST API at `/rest/v1/corpora` and via Storage at `/storage/v1/object/public/corpora/datasets/{name}.exg`.
  </Step>
</Steps>

## The .exg format

Corpora are stored in an internal `.exg` envelope format — a packaged archive containing the manifest, index, and compressed source content. Direct access to raw source files is not exposed in the UI.