Add review stage coverage and fix XML tax deduplication

- Reviewer now sends all pages to the review VLM alongside extracted JSON.

- XML builder deduplicates account.tax records by rate.

- XML builder raises on confidence below min_confidence_threshold.

- Adds fractional tax-rate support with stable external IDs.

- Adds expected_invoice.xml fixture, reviewer tests, and XML regression tests.

tests/test_xml_builder.py

@@ -1,15 +1,20 @@
 """Tests for the Odoo XML builder."""
 
+from __future__ import annotations
+
 from decimal import Decimal
+from pathlib import Path
+
+import pytest
+from lxml import etree
 
 from odoo_ocr.config import Settings
 from odoo_ocr.pipeline.xml_builder import build_odoo_xml
 from odoo_ocr.schemas import ExtractedInvoice, InvoiceLineItem, ReviewResult
 
 
-def test_build_odoo_xml() -> None:
-    settings = Settings()
-    invoice = ExtractedInvoice(
+def _fixture_invoice() -> ExtractedInvoice:
+    return ExtractedInvoice(
         vendor_name="Acme Supplies",
         vendor_vat="GB123456789",
         invoice_number="INV-2024-001",
@@ -30,9 +35,12 @@ def test_build_odoo_xml() -> None:
         tax_total=Decimal("200.00"),
         total=Decimal("1200.00"),
     )
-    review = ReviewResult(valid=True, confidence=0.95)
 
-    xml = build_odoo_xml(invoice, review, settings)
+
+def test_build_odoo_xml() -> None:
+    settings = Settings()
+    invoice = _fixture_invoice()
+    xml = build_odoo_xml(invoice, ReviewResult(valid=True, confidence=0.95), settings)
 
     assert xml.startswith("<?xml version=")
     assert 'model="res.partner"' in xml
@@ -43,6 +51,60 @@ def test_build_odoo_xml() -> None:
     assert "in_invoice" in xml
 
 
+def test_xml_parses_with_lxml() -> None:
+    invoice = _fixture_invoice()
+    xml = build_odoo_xml(invoice, ReviewResult(valid=True, confidence=0.95), Settings())
+
+    root = etree.fromstring(xml.encode("utf-8"))
+    models = {record.get("model") for record in root.iter("record")}
+    assert models == {"res.partner", "account.tax", "account.move", "account.move.line"}
+
+
+def test_xml_matches_expected_fixture() -> None:
+    invoice = _fixture_invoice()
+    xml = build_odoo_xml(invoice, ReviewResult(valid=True, confidence=0.95), Settings())
+
+    expected = (Path(__file__).parent / "fixtures" / "expected_invoice.xml").read_text(
+        encoding="utf-8"
+    )
+
+    def _normalize(doc: str) -> dict:
+        root = etree.fromstring(doc.encode("utf-8"))
+
+        def _el(element) -> dict:
+            return {
+                "tag": element.tag,
+                "attrs": dict(element.attrib.items()),
+                "text": (element.text or "").strip(),
+                "children": [_el(child) for child in element],
+            }
+
+        return _el(root)
+
+    assert _normalize(xml) == _normalize(expected)
+
+
+def test_fractional_tax_rate_ids_are_distinct() -> None:
+    invoice = ExtractedInvoice(
+        vendor_name="X",
+        invoice_number="1",
+        invoice_date="2024-01-01",
+        line_items=[
+            InvoiceLineItem(description="A", tax_rate=Decimal("19.79")),
+            InvoiceLineItem(description="B", tax_rate=Decimal("15.2")),
+            InvoiceLineItem(description="C", tax_rate=Decimal("15.7")),
+        ],
+    )
+    xml = build_odoo_xml(invoice, ReviewResult(valid=True, confidence=0.95), Settings())
+
+    assert 'id="purchase_vat_19_79"' in xml
+    assert 'id="purchase_vat_15_2"' in xml
+    assert 'id="purchase_vat_15_7"' in xml
+    assert xml.count('model="account.tax"') == 3
+    assert "Purchase VAT 19.79%" in xml
+    assert "<field name=\"amount\">19.79</field>" in xml
+
+
 def test_xml_adds_review_comment_for_low_confidence() -> None:
     settings = Settings()
     invoice = ExtractedInvoice(
@@ -58,3 +120,39 @@ def test_xml_adds_review_comment_for_low_confidence() -> None:
 
     xml = build_odoo_xml(invoice, review, settings)
     assert "HUMAN REVIEW ADVISED" in xml
+
+
+def test_duplicate_tax_rates_emit_one_record() -> None:
+    """Multiple lines sharing the same tax rate must produce a single account.tax record."""
+    invoice = ExtractedInvoice(
+        vendor_name="X",
+        invoice_number="1",
+        invoice_date="2024-01-01",
+        line_items=[
+            InvoiceLineItem(description="A", tax_rate=Decimal("20")),
+            InvoiceLineItem(description="B", tax_rate=Decimal("20")),
+            InvoiceLineItem(description="C", tax_rate=Decimal("0")),
+        ],
+    )
+    xml = build_odoo_xml(invoice, ReviewResult(valid=True, confidence=0.95), Settings())
+
+    assert xml.count('id="purchase_vat_20"') == 1
+    assert xml.count('id="purchase_vat_0"') == 1
+    assert xml.count('model="account.tax"') == 2
+
+
+def test_xml_refuses_low_confidence() -> None:
+    settings = Settings()
+    invoice = ExtractedInvoice(
+        vendor_name="X",
+        invoice_number="1",
+        invoice_date="2024-01-01",
+        line_items=[],
+        subtotal=Decimal("0"),
+        tax_total=Decimal("0"),
+        total=Decimal("0"),
+    )
+    review = ReviewResult(valid=False, confidence=0.70)
+
+    with pytest.raises(ValueError, match="below the minimum threshold"):
+        build_odoo_xml(invoice, review, settings)