# 06 · Data engine

The engine turns sources into delivered, provenance-tagged data. It is the legal motor — the whole product positioning depends on it. Build on existing `src/workers/` (`adaptive_router`, `browser_worker`, `ocr_worker`, `db`) but enforce the sourcing boundary below.

## Sourcing chain (strict priority — this is the law)

For each field × market, acquire in this order; stop at the first that works:

1. **Official API / bulk** — registries with programmatic/bulk access (highest confidence).
2. **Authorized public web** — clearly public pages, **respecting `robots.txt` and rate limits**, no auth walls.
3. **Licensed partner data** — contractually obtained.
4. **Otherwise → "not available / licensed only"** — delivered honestly as level 0. **Never guessed.**

### Prohibited (do not build, keep, or extend)
- WAF/bot-detection bypass — **including FlareSolverr**, "stealth"/patched browsers, undetected-* used to defeat detection.
- Proxy/fingerprint rotation to evade bans; scraping behind login walls; automated fake-account creation (Apollo etc.).
- **Reconciliation:** if `browser_worker.py` has an `HTTP → FlareSolverr → Playwright` chain, **drop the FlareSolverr stage** and keep only: polite HTTP fetch (identifies itself, obeys robots + rate limits) → optional Playwright for genuinely public JS-rendered pages (same politeness). The `adaptive_router` then chooses among **compliant** methods only (API > bulk > authorized fetch), not bypass tiers.

## Pipeline stages (per job)

```
sourcing → extraction/OCR → structuring → enrichment/fusion → QA
```

1. **Sourcing** — `adaptive_router` picks the compliant method per source; "source-racing" = query several *authorized* sources and take the fastest/freshest. Writes raw payloads + which source answered.
2. **Extraction / OCR** — API JSON parsed directly; documents (PDF/HTML/images) via **Unstructured** + OCR cascade (PaddleOCR → Tesseract → LLM fallback) in `ocr_worker`. Output: candidate fields.
3. **Structuring** — NER + entity resolution (spaCy / transformers, sv/no/da/fi/de/fr), normalize to schema, link entities across markets via **LEI** (GLEIF golden key). Dedup with **RapidFuzz**.
4. **Enrichment / fusion** — combine fields from multiple sources; compute **multi-source agreement** → confidence + level; append optional enrichment (NACE/SNI, sanctions/PEP flag from official lists, website/tech).
5. **QA** — quality checks (**Great Expectations** or equivalent, run inside the worker): validity (format/range), completeness, freshness, uniqueness (post-dedup), corroboration. Drop rows below the order's `confidence_target` (deliver fewer, never fabricate). Emit the quality report stored on `deliveries`.

Each stage updates `jobs` (`stage`, `pct`, `metrics` incl. per-market progress, running counts, climbing confidence) so the production tracker / SSE can render it live.

## Confidence & provenance scoring

- Per field, write a `bridge_provenance` row: `source_id`, `freshness`, `confidence` (0–1), `level` (0–3), `agreed_sources`.
- Level: 0 = unavailable/licensed; 1 = single source; 2 = partial corroboration; 3 = ≥2 independent sources agree.
- `est_confidence` on the order = aggregate target; delivered `avg_confidence` = actual.

## `sources.yaml` (machine-readable registry)

Single registry that drives the router, the `/sources` API, and the public sourcing-map page. Schema per entry:

```yaml
- source_id: gleif
  name: GLEIF (LEI)
  market: global
  access: api            # api | bulk | authorized_web | licensed
  cadence: daily
  licence: "open (CC0) — VERIFY current terms"
  entities: [company]
  fields: [lei, legal_name, address]
  base_url: https://api.gleif.org
  robots_ok: true        # for authorized_web only; must be honored
  rate_limit: "per provider terms"
  notes: "cross-border key"
```

### Starter set (VERIFY current access/licence per source before relying — terms change)
- **GLEIF / LEI** — typically open; cross-border key. *(verify)*
- **Brønnøysund (Brreg, NO)** — typically open API. *(verify)*
- **Companies House (UK)** — free API (key required). *(verify)*
- **CVR / Virk (DK)** — API access with terms. *(verify)*
- **PRH (FI)** — varies. *(verify)*
- **Bolagsverket (SE)** — more restricted for bulk; plan licensed/partner route. *(verify)*
- Vehicle: **RDW (NL)** open-ish, **Traficom (FI)**, **Transportstyrelsen (SE)**, **DVLA (UK)** — *(verify each; vehicle/PII rules differ)*

> Do not hardcode access terms as fact. When building each connector, confirm the current API/licence/robots status and record it in `sources.yaml`. If unclear or disallowed for bulk, route to licensed/partner or mark fields level 0.

## Libraries used here
Crawlee or Scrapy (orchestration of **authorized** fetches) · Playwright (public JS pages, politely) · Unstructured (document parsing) · PaddleOCR/Tesseract (OCR) · spaCy / HF transformers (NER, multilingual) · Polars (fast tabular) · RapidFuzz (dedup/matching) · Great Expectations (quality) · dbt (optional transform layer). Versions/install: `docs/07-dependencies.md`.