# services/ — business logic

Each module holds the domain logic behind the asset extraction endpoint.
Routers stay thin; heavy lifting lives here so it can be unit-tested in
isolation.

## Services

| File | What it does |
|------|--------------|
| `fetcher.py`       | Safe async HTML fetch: SSRF block-list, redirect/size/timeout caps, content-type check. |
| `resolver.py`      | Turn `src`/`href`/CSS `url()` references into absolute URLs. |
| `asset_service.py` | Orchestrates fetch → parse → extract → group. |

## `extractors/` — asset category extractors

Each extractor parses the (BeautifulSoup) document and returns absolute URLs
for one category. See [`extractors/README.md`](./extractors/README.md).

## Conventions

- Services raise a domain-specific exception (e.g. `FetchError`,
  `AssetExtractError`) that the router maps to an HTTP response.
- URL resolution is centralized in `resolver.py` — every extractor should
  funnel its raw references through it to avoid duplicated/drifted logic.