WIP

packages/backend/backend/data/admin_models.py

@@ -289,6 +289,16 @@ class ModelVersion(SQLModel, table=True):
     is_active: bool = Field(default=False, index=True)
     # Only one version can be active at a time for inference
 
+    # Model lineage
+    model_type: str = Field(default="base", max_length=20, index=True)
+    # "base" = trained from pretrained YOLO, "finetune" = fine-tuned from base model
+    base_model_version_id: UUID | None = Field(default=None, index=True)
+    # Points to the base model this was fine-tuned from (None for base models)
+    base_training_dataset_id: UUID | None = Field(default=None, index=True)
+    # The dataset used for original base training (for data mixing old samples)
+    gating_status: str = Field(default="pending", max_length=20, index=True)
+    # Deployment gating: pending, pass, review, reject, skipped
+
     # Training association
     task_id: UUID | None = Field(default=None, foreign_key="training_tasks.task_id", index=True)
     dataset_id: UUID | None = Field(default=None, foreign_key="training_datasets.dataset_id", index=True)
@@ -317,6 +327,64 @@ class ModelVersion(SQLModel, table=True):
     updated_at: datetime = Field(default_factory=datetime.utcnow)
 
 
+# =============================================================================
+# Fine-Tune Pool
+# =============================================================================
+
+
+class FineTunePoolEntry(SQLModel, table=True):
+    """Document in the fine-tune pool for incremental model improvement."""
+
+    __tablename__ = "finetune_pool_entries"
+
+    entry_id: UUID = Field(default_factory=uuid4, primary_key=True)
+    document_id: UUID = Field(foreign_key="admin_documents.document_id", index=True)
+    added_by: str | None = Field(default=None, max_length=255)
+    reason: str | None = Field(default=None, max_length=255)
+    # Reason: user_reported_failure, manual_addition
+    is_verified: bool = Field(default=False, index=True)
+    verified_at: datetime | None = Field(default=None)
+    verified_by: str | None = Field(default=None, max_length=255)
+    created_at: datetime = Field(default_factory=datetime.utcnow)
+
+
+# =============================================================================
+# Deployment Gating
+# =============================================================================
+
+
+class GatingResult(SQLModel, table=True):
+    """Model deployment gating validation result."""
+
+    __tablename__ = "gating_results"
+
+    result_id: UUID = Field(default_factory=uuid4, primary_key=True)
+    model_version_id: UUID = Field(foreign_key="model_versions.version_id", index=True)
+    task_id: UUID | None = Field(default=None, foreign_key="training_tasks.task_id")
+
+    # Gate 1: Regression validation (original test set mAP)
+    gate1_status: str = Field(default="pending", max_length=20)
+    # pending, pass, review, reject
+    gate1_original_mAP: float | None = Field(default=None)
+    gate1_new_mAP: float | None = Field(default=None)
+    gate1_mAP_drop: float | None = Field(default=None)
+
+    # Gate 2: New sample validation (detection rate on pool docs)
+    gate2_status: str = Field(default="pending", max_length=20)
+    gate2_detection_rate: float | None = Field(default=None)
+    gate2_total_samples: int | None = Field(default=None)
+    gate2_detected_samples: int | None = Field(default=None)
+
+    # Overall
+    overall_status: str = Field(default="pending", max_length=20)
+    # pending, pass, review, reject
+    reviewer_notes: str | None = Field(default=None)
+    reviewed_by: str | None = Field(default=None, max_length=255)
+    reviewed_at: datetime | None = Field(default=None)
+
+    created_at: datetime = Field(default_factory=datetime.utcnow)
+
+
 # =============================================================================
 # Annotation History (v2)
 # =============================================================================

packages/backend/backend/data/repositories/__init__.py

@@ -13,6 +13,7 @@ from backend.data.repositories.training_task_repository import TrainingTaskRepos
 from backend.data.repositories.dataset_repository import DatasetRepository
 from backend.data.repositories.model_version_repository import ModelVersionRepository
 from backend.data.repositories.batch_upload_repository import BatchUploadRepository
+from backend.data.repositories.finetune_pool_repository import FineTunePoolRepository
 
 __all__ = [
     "BaseRepository",
@@ -23,4 +24,5 @@ __all__ = [
     "DatasetRepository",
     "ModelVersionRepository",
     "BatchUploadRepository",
+    "FineTunePoolRepository",
 ]

packages/backend/backend/data/repositories/finetune_pool_repository.py

@@ -0,0 +1,131 @@
+"""
+Fine-Tune Pool Repository
+
+Manages the fine-tune pool: accumulated user-reported failure documents
+for incremental model improvement.
+"""
+
+import logging
+from datetime import datetime
+from uuid import UUID
+
+from sqlalchemy import func
+from sqlmodel import select
+
+from backend.data.database import get_session_context
+from backend.data.admin_models import FineTunePoolEntry
+from backend.data.repositories.base import BaseRepository
+
+logger = logging.getLogger(__name__)
+
+
+class FineTunePoolRepository(BaseRepository[FineTunePoolEntry]):
+    """Repository for fine-tune pool management."""
+
+    def add_document(
+        self,
+        document_id: str | UUID,
+        added_by: str | None = None,
+        reason: str | None = None,
+    ) -> FineTunePoolEntry:
+        """Add a document to the fine-tune pool."""
+        with get_session_context() as session:
+            entry = FineTunePoolEntry(
+                document_id=UUID(str(document_id)),
+                added_by=added_by,
+                reason=reason,
+            )
+            session.add(entry)
+            session.commit()
+            session.refresh(entry)
+            session.expunge(entry)
+            return entry
+
+    def get_entry(self, entry_id: str | UUID) -> FineTunePoolEntry | None:
+        """Get a pool entry by ID."""
+        with get_session_context() as session:
+            entry = session.get(FineTunePoolEntry, UUID(str(entry_id)))
+            if entry:
+                session.expunge(entry)
+            return entry
+
+    def get_by_document(self, document_id: str | UUID) -> FineTunePoolEntry | None:
+        """Get pool entry for a document."""
+        with get_session_context() as session:
+            result = session.exec(
+                select(FineTunePoolEntry).where(
+                    FineTunePoolEntry.document_id == UUID(str(document_id))
+                )
+            ).first()
+            if result:
+                session.expunge(result)
+            return result
+
+    def get_paginated(
+        self,
+        verified_only: bool = False,
+        limit: int = 20,
+        offset: int = 0,
+    ) -> tuple[list[FineTunePoolEntry], int]:
+        """List pool entries with pagination."""
+        with get_session_context() as session:
+            query = select(FineTunePoolEntry)
+            count_query = select(func.count()).select_from(FineTunePoolEntry)
+            if verified_only:
+                query = query.where(FineTunePoolEntry.is_verified == True)
+                count_query = count_query.where(FineTunePoolEntry.is_verified == True)
+            total = session.exec(count_query).one()
+            entries = session.exec(
+                query.order_by(FineTunePoolEntry.created_at.desc())
+                .offset(offset)
+                .limit(limit)
+            ).all()
+            for e in entries:
+                session.expunge(e)
+            return list(entries), total
+
+    def get_pool_count(self, verified_only: bool = True) -> int:
+        """Get count of entries in the pool."""
+        with get_session_context() as session:
+            query = select(func.count()).select_from(FineTunePoolEntry)
+            if verified_only:
+                query = query.where(FineTunePoolEntry.is_verified == True)
+            return session.exec(query).one()
+
+    def get_all_document_ids(self, verified_only: bool = True) -> list[UUID]:
+        """Get all document IDs in the pool."""
+        with get_session_context() as session:
+            query = select(FineTunePoolEntry.document_id)
+            if verified_only:
+                query = query.where(FineTunePoolEntry.is_verified == True)
+            results = session.exec(query).all()
+            return list(results)
+
+    def verify_entry(
+        self,
+        entry_id: str | UUID,
+        verified_by: str | None = None,
+    ) -> FineTunePoolEntry | None:
+        """Mark a pool entry as verified."""
+        with get_session_context() as session:
+            entry = session.get(FineTunePoolEntry, UUID(str(entry_id)))
+            if not entry:
+                return None
+            entry.is_verified = True
+            entry.verified_at = datetime.utcnow()
+            entry.verified_by = verified_by
+            session.add(entry)
+            session.commit()
+            session.refresh(entry)
+            session.expunge(entry)
+            return entry
+
+    def remove_entry(self, entry_id: str | UUID) -> bool:
+        """Remove an entry from the pool."""
+        with get_session_context() as session:
+            entry = session.get(FineTunePoolEntry, UUID(str(entry_id)))
+            if not entry:
+                return False
+            session.delete(entry)
+            session.commit()
+            return True

packages/backend/backend/data/repositories/model_version_repository.py

@@ -43,6 +43,10 @@ class ModelVersionRepository(BaseRepository[ModelVersion]):
         training_config: dict[str, Any] | None = None,
         file_size: int | None = None,
         trained_at: datetime | None = None,
+        model_type: str = "base",
+        base_model_version_id: str | UUID | None = None,
+        base_training_dataset_id: str | UUID | None = None,
+        gating_status: str = "pending",
     ) -> ModelVersion:
         """Create a new model version."""
         with get_session_context() as session:
@@ -60,6 +64,10 @@ class ModelVersionRepository(BaseRepository[ModelVersion]):
                 training_config=training_config,
                 file_size=file_size,
                 trained_at=trained_at,
+                model_type=model_type,
+                base_model_version_id=UUID(str(base_model_version_id)) if base_model_version_id else None,
+                base_training_dataset_id=UUID(str(base_training_dataset_id)) if base_training_dataset_id else None,
+                gating_status=gating_status,
             )
             session.add(model)
             session.commit()

packages/backend/backend/pipeline/field_extractor.py

@@ -40,6 +40,7 @@ from .normalizers import (
     EnhancedAmountNormalizer,
     EnhancedDateNormalizer,
 )
+from .value_selector import ValueSelector
 
 
 @dataclass
@@ -169,13 +170,21 @@ class FieldExtractor:
                     overlap_ratio = overlap_area / token_area if token_area > 0 else 0
                     matching_tokens.append((token, overlap_ratio))
 
-        # Sort by overlap ratio and combine text
+        # Sort by overlap ratio
         matching_tokens.sort(key=lambda x: -x[1])
-        raw_text = ' '.join(t[0].text for t in matching_tokens)
 
         # Get field name
         field_name = CLASS_TO_FIELD.get(detection.class_name, detection.class_name)
 
+        # Convert to OCRTokens for value selection, then filter
+        from shared.ocr.paddle_ocr import OCRToken
+        pdf_ocr_tokens = [
+            OCRToken(text=t[0].text, bbox=t[0].bbox, confidence=1.0)
+            for t in matching_tokens
+        ]
+        value_tokens = ValueSelector.select_value_tokens(pdf_ocr_tokens, field_name)
+        raw_text = ' '.join(t.text for t in value_tokens)
+
         # Normalize and validate
         normalized_value, is_valid, validation_error = self._normalize_and_validate(
             field_name, raw_text
@@ -223,13 +232,14 @@ class FieldExtractor:
         # Run OCR on region
         ocr_tokens = self.ocr_engine.extract_from_image(region)
 
-        # Combine all OCR text
-        raw_text = ' '.join(t.text for t in ocr_tokens)
-        ocr_confidence = sum(t.confidence for t in ocr_tokens) / len(ocr_tokens) if ocr_tokens else 0.0
-
         # Get field name
         field_name = CLASS_TO_FIELD.get(detection.class_name, detection.class_name)
 
+        # Select value tokens (filter out label text)
+        value_tokens = ValueSelector.select_value_tokens(ocr_tokens, field_name)
+        raw_text = ' '.join(t.text for t in value_tokens)
+        ocr_confidence = sum(t.confidence for t in ocr_tokens) / len(ocr_tokens) if ocr_tokens else 0.0
+
         # Normalize and validate
         normalized_value, is_valid, validation_error = self._normalize_and_validate(
             field_name, raw_text

packages/backend/backend/pipeline/normalizers/amount.py

@@ -20,26 +20,98 @@ class AmountNormalizer(BaseNormalizer):
     Handles various Swedish amount formats:
     - With decimal: 1 234,56 kr
     - With SEK suffix: 1234.56 SEK
+    - Payment line kronor/ore: 590 00 (space = decimal separator)
     - Multiple amounts (returns the last one, usually the total)
     """
 
+    # Payment line kronor/ore pattern: "590 00" means 590.00 SEK
+    # Only matches when no comma/dot is present (pure digit-space-2digit format)
+    _KRONOR_ORE_PATTERN = re.compile(r'^(\d+)\s+(\d{2})$')
+
     @property
     def field_name(self) -> str:
         return "Amount"
 
+    @classmethod
+    def _try_kronor_ore(cls, text: str) -> NormalizationResult | None:
+        """Try to parse as payment line kronor/ore format.
+
+        Swedish payment lines separate kronor and ore with a space:
+        "590 00" = 590.00 SEK, "15658 00" = 15658.00 SEK
+
+        Only applies when text has no comma or dot (otherwise it's
+        a normal amount format with explicit decimal separator).
+
+        Returns NormalizationResult on success, None if not matched.
+        """
+        if ',' in text or '.' in text:
+            return None
+
+        match = cls._KRONOR_ORE_PATTERN.match(text.strip())
+        if not match:
+            return None
+
+        kronor = match.group(1)
+        ore = match.group(2)
+        try:
+            amount = float(f"{kronor}.{ore}")
+            if amount > 0:
+                return NormalizationResult.success(f"{amount:.2f}")
+        except ValueError:
+            pass
+        return None
+
+    @staticmethod
+    def _parse_amount_str(match: str) -> float | None:
+        """Convert matched amount string to float, detecting European vs Anglo format.
+
+        European: 2.254,50 -> 2254.50 (dot=thousand, comma=decimal)
+        Anglo: 1,234.56 -> 1234.56 (comma=thousand, dot=decimal)
+        Swedish: 1 234,56 -> 1234.56 (space=thousand, comma=decimal)
+        """
+        has_comma = ',' in match
+        has_dot = '.' in match
+        if has_comma and has_dot:
+            if match.rfind(',') > match.rfind('.'):
+                # European: 2.254,50
+                cleaned = match.replace(" ", "").replace(".", "").replace(",", ".")
+            else:
+                # Anglo: 1,234.56
+                cleaned = match.replace(" ", "").replace(",", "")
+        elif has_comma:
+            cleaned = match.replace(" ", "").replace(",", ".")
+        else:
+            cleaned = match.replace(" ", "")
+        try:
+            return float(cleaned)
+        except ValueError:
+            return None
+
     def normalize(self, text: str) -> NormalizationResult:
         text = text.strip()
         if not text:
             return NormalizationResult.failure("Empty text")
 
+        # Early check: payment line kronor/ore format ("590 00" → 590.00)
+        kronor_ore_result = self._try_kronor_ore(text)
+        if kronor_ore_result is not None:
+            return kronor_ore_result
+
         # Split by newlines and process line by line to get the last valid amount
         lines = text.split("\n")
 
         # Collect all valid amounts from all lines
         all_amounts: list[float] = []
 
-        # Pattern for Swedish amount format (with decimals)
-        amount_pattern = r"(\d[\d\s]*[,\.]\d{2})\s*(?:kr|SEK)?"
+        # Separate patterns for European and Anglo formats
+        # (?!\d) lookahead prevents partial matches (e.g. "1,23" in "1,234.56")
+        # European: dot=thousand, comma=decimal (2.254,50 or 1 234,56)
+        # Anglo: comma=thousand, dot=decimal (1,234.56 or 1234.56)
+        amount_pattern = (
+            r"(\d[\d\s.]*,\d{2})(?!\d)\s*(?:kr|SEK)?"
+            r"|"
+            r"(\d[\d\s,]*\.\d{2})(?!\d)\s*(?:kr|SEK)?"
+        )
 
         for line in lines:
             line = line.strip()
@@ -47,15 +119,13 @@ class AmountNormalizer(BaseNormalizer):
                 continue
 
             # Find all amounts in this line
-            matches = re.findall(amount_pattern, line, re.IGNORECASE)
-            for match in matches:
-                amount_str = match.replace(" ", "").replace(",", ".")
-                try:
-                    amount = float(amount_str)
-                    if amount > 0:
-                        all_amounts.append(amount)
-                except ValueError:
+            for m in re.finditer(amount_pattern, line, re.IGNORECASE):
+                match = m.group(1) or m.group(2)
+                if not match:
                     continue
+                amount = self._parse_amount_str(match)
+                if amount is not None and amount > 0:
+                    all_amounts.append(amount)
 
         # Return the last amount found (usually the total)
         if all_amounts:
@@ -122,31 +192,33 @@ class EnhancedAmountNormalizer(AmountNormalizer):
         if not text:
             return NormalizationResult.failure("Empty text")
 
+        # Early check: payment line kronor/ore format ("590 00" → 590.00)
+        kronor_ore_result = self._try_kronor_ore(text)
+        if kronor_ore_result is not None:
+            return kronor_ore_result
+
         # Strategy 1: Apply OCR corrections first
         corrected_text = OCRCorrections.correct_digits(text, aggressive=False).corrected
 
         # Strategy 2: Look for labeled amounts (highest priority)
+        # Use two capture groups: group(1) = European, group(2) = Anglo
         labeled_patterns = [
-            # Swedish patterns
-            (r"(?:att\s+betala|summa|total|belopp)\s*[:\s]*(\d[\d\s]*[,\.]\d{2})", 1.0),
+            # Swedish patterns ((?!\d) prevents partial matches like "1,23" in "1,234.56")
+            (r"(?:att\s+betala|summa|total|belopp)\s*[:\s]*(\d[\d\s.]*,\d{2}(?!\d)|\d[\d\s,]*\.\d{2}(?!\d))", 1.0),
             (
-                r"(?:moms|vat)\s*[:\s]*(\d[\d\s]*[,\.]\d{2})",
+                r"(?:moms|vat)\s*[:\s]*(\d[\d\s.]*,\d{2}(?!\d)|\d[\d\s,]*\.\d{2}(?!\d))",
                 0.8,
             ),  # Lower priority for VAT
             # Generic pattern
-            (r"(\d[\d\s]*[,\.]\d{2})\s*(?:kr|sek|kronor)?", 0.7),
+            (r"(\d[\d\s.]*,\d{2}(?!\d)|\d[\d\s,]*\.\d{2}(?!\d))\s*(?:kr|sek|kronor)?", 0.7),
         ]
 
         candidates: list[tuple[float, float, int]] = []
         for pattern, priority in labeled_patterns:
             for match in re.finditer(pattern, corrected_text, re.IGNORECASE):
-                amount_str = match.group(1).replace(" ", "").replace(",", ".")
-                try:
-                    amount = float(amount_str)
-                    if 0 < amount < 10_000_000:  # Reasonable range
-                        candidates.append((amount, priority, match.start()))
-                except ValueError:
-                    continue
+                amount = self._parse_amount_str(match.group(1))
+                if amount is not None and 0 < amount < 10_000_000:
+                    candidates.append((amount, priority, match.start()))
 
         if candidates:
             # Sort by priority (desc), then by position (later is usually total)

packages/backend/backend/pipeline/pipeline.py

@@ -301,6 +301,27 @@ class InferencePipeline:
             all_extracted = []
             all_ocr_text = []  # Collect OCR text for VAT extraction
 
+            # Check if PDF has readable text layer (avoids OCR for text PDFs)
+            from shared.pdf.extractor import PDFDocument
+            is_text_pdf = False
+            pdf_tokens_by_page: dict[int, list] = {}
+            try:
+                with PDFDocument(pdf_path) as pdf_doc:
+                    is_text_pdf = pdf_doc.is_text_pdf()
+                    if is_text_pdf:
+                        for pg in range(pdf_doc.page_count):
+                            pdf_tokens_by_page[pg] = list(
+                                pdf_doc.extract_text_tokens(pg)
+                            )
+                        logger.info(
+                            "Text PDF detected, extracted %d tokens from %d pages",
+                            sum(len(t) for t in pdf_tokens_by_page.values()),
+                            len(pdf_tokens_by_page),
+                        )
+            except Exception as e:
+                logger.warning("PDF text detection failed, falling back to OCR: %s", e)
+                is_text_pdf = False
+
             # Process each page
             for page_no, image_bytes in render_pdf_to_images(pdf_path, dpi=self.dpi):
                 # Convert to numpy array
@@ -313,7 +334,17 @@ class InferencePipeline:
 
                 # Extract fields from detections
                 for detection in detections:
-                    extracted = self.extractor.extract_from_detection(detection, image_array)
+                    if is_text_pdf and page_no in pdf_tokens_by_page:
+                        extracted = self.extractor.extract_from_detection_with_pdf(
+                            detection,
+                            pdf_tokens_by_page[page_no],
+                            image.width,
+                            image.height,
+                        )
+                    else:
+                        extracted = self.extractor.extract_from_detection(
+                            detection, image_array
+                        )
                     all_extracted.append(extracted)
 
                 # Collect full-page OCR text for VAT extraction (only if business features enabled)

packages/backend/backend/pipeline/value_selector.py

@@ -0,0 +1,172 @@
+"""
+Value Selector Module.
+
+Selects the most likely value token(s) from OCR output per field type,
+filtering out label text before sending to normalizer.
+
+Stateless and pure -- easy to test, no side effects.
+"""
+
+import re
+from typing import Final
+
+from shared.ocr.paddle_ocr import OCRToken
+
+
+# Swedish label keywords commonly found near field values
+LABEL_KEYWORDS: Final[frozenset[str]] = frozenset({
+    "fakturanummer", "fakturanr", "fakturadatum", "forfallodag", "forfalldatum",
+    "bankgiro", "plusgiro", "bg", "pg", "ocr", "belopp", "summa",
+    "total", "att", "betala", "kundnummer", "organisationsnummer",
+    "org", "nr", "datum", "nummer", "ref", "referens",
+    "momsreg", "vat", "moms", "sek", "kr",
+    "org.nr", "kund", "faktura", "invoice",
+})
+
+# Patterns
+_DATE_PATTERN = re.compile(
+    r"\d{4}[-./]\d{2}[-./]\d{2}"   # 2024-01-15, 2024.01.15
+    r"|"
+    r"\d{2}[-./]\d{2}[-./]\d{4}"   # 15/01/2024
+    r"|"
+    r"\d{8}"                        # 20240115
+)
+
+_AMOUNT_PATTERN = re.compile(
+    r"\d[\d\s.]*,\d{2}(?:\s*(?:kr|SEK))?$"   # European: 2.254,50 SEK
+    r"|"
+    r"\d[\d\s,]*\.\d{2}(?:\s*(?:kr|SEK))?$"  # Anglo: 1,234.56 SEK
+)
+
+_BANKGIRO_PATTERN = re.compile(
+    r"^\d{3,4}-\d{4}$"             # 123-4567
+    r"|"
+    r"^\d{7,8}$"                    # 1234567 or 12345678
+)
+
+_PLUSGIRO_PATTERN = re.compile(
+    r"^\d+-\d$"                     # 12345-6
+    r"|"
+    r"^\d{2,8}$"                    # 1234567
+)
+
+_ORG_NUMBER_PATTERN = re.compile(
+    r"\d{6}-?\d{4}"                 # 556123-4567 or 5561234567
+)
+
+
+def _is_label(text: str) -> bool:
+    """Check if token text is a known Swedish label keyword."""
+    cleaned = text.lower().rstrip(":").strip()
+    return cleaned in LABEL_KEYWORDS
+
+
+def _count_digits(text: str) -> int:
+    """Count digit characters in text."""
+    return sum(c.isdigit() for c in text)
+
+
+class ValueSelector:
+    """Selects value token(s) from OCR output, filtering label text.
+
+    Pure static methods -- no state, no side effects.
+    Fallback: always returns all tokens if no pattern matches,
+    so this can never make results worse than current behavior.
+    """
+
+    @staticmethod
+    def select_value_tokens(
+        tokens: list[OCRToken],
+        field_name: str,
+    ) -> list[OCRToken]:
+        """Select the most likely value token(s) for a given field.
+
+        Args:
+            tokens: OCR tokens from the detected region.
+            field_name: Normalized field name (e.g. "InvoiceDate", "Amount").
+
+        Returns:
+            Filtered list of value tokens. Falls back to all tokens
+            if no field-specific pattern matches.
+        """
+        if not tokens:
+            return []
+
+        selector = _FIELD_SELECTORS.get(field_name, _fallback_selector)
+        selected = selector(tokens)
+
+        # Safety: never return empty if we had input tokens
+        if not selected:
+            return list(tokens)
+
+        return selected
+
+    @staticmethod
+    def _select_date(tokens: list[OCRToken]) -> list[OCRToken]:
+        return _select_by_pattern(tokens, _DATE_PATTERN)
+
+    @staticmethod
+    def _select_amount(tokens: list[OCRToken]) -> list[OCRToken]:
+        return _select_by_pattern(tokens, _AMOUNT_PATTERN)
+
+    @staticmethod
+    def _select_bankgiro(tokens: list[OCRToken]) -> list[OCRToken]:
+        return _select_by_pattern(tokens, _BANKGIRO_PATTERN)
+
+    @staticmethod
+    def _select_plusgiro(tokens: list[OCRToken]) -> list[OCRToken]:
+        return _select_by_pattern(tokens, _PLUSGIRO_PATTERN)
+
+    @staticmethod
+    def _select_org_number(tokens: list[OCRToken]) -> list[OCRToken]:
+        return _select_by_pattern(tokens, _ORG_NUMBER_PATTERN)
+
+    @staticmethod
+    def _select_ocr_number(tokens: list[OCRToken]) -> list[OCRToken]:
+        """Select token with the longest digit sequence (min 5 digits)."""
+        best: OCRToken | None = None
+        best_count = 0
+        for token in tokens:
+            digit_count = _count_digits(token.text)
+            if digit_count >= 5 and digit_count > best_count:
+                best = token
+                best_count = digit_count
+        return [best] if best else []
+
+    @staticmethod
+    def _select_by_label_exclusion(tokens: list[OCRToken]) -> list[OCRToken]:
+        """Remove label keywords, keep remaining tokens."""
+        return [t for t in tokens if not _is_label(t.text)]
+
+    @staticmethod
+    def _select_payment_line(tokens: list[OCRToken]) -> list[OCRToken]:
+        """Payment line keeps all tokens (needs full text)."""
+        return list(tokens)
+
+
+def _select_by_pattern(
+    tokens: list[OCRToken],
+    pattern: re.Pattern[str],
+) -> list[OCRToken]:
+    """Select tokens matching a regex pattern."""
+    return [t for t in tokens if pattern.search(t.text.strip())]
+
+
+def _fallback_selector(tokens: list[OCRToken]) -> list[OCRToken]:
+    """Default: return all tokens unchanged."""
+    return list(tokens)
+
+
+# Map field names to selector functions
+_FIELD_SELECTORS: Final[dict[str, callable]] = {
+    "InvoiceDate": ValueSelector._select_date,
+    "InvoiceDueDate": ValueSelector._select_date,
+    "Amount": ValueSelector._select_amount,
+    "Bankgiro": ValueSelector._select_bankgiro,
+    "Plusgiro": ValueSelector._select_plusgiro,
+    "OCR": ValueSelector._select_ocr_number,
+    "InvoiceNumber": ValueSelector._select_by_label_exclusion,
+    "supplier_org_number": ValueSelector._select_org_number,
+    "customer_number": ValueSelector._select_by_label_exclusion,
+    "payment_line": ValueSelector._select_payment_line,
+}

packages/backend/backend/web/api/v1/admin/training/__init__.py

@@ -12,6 +12,7 @@ from .documents import register_document_routes
 from .export import register_export_routes
 from .datasets import register_dataset_routes
 from .models import register_model_routes
+from .pool import register_pool_routes
 
 
 def create_training_router() -> APIRouter:
@@ -23,6 +24,7 @@ def create_training_router() -> APIRouter:
     register_export_routes(router)
     register_dataset_routes(router)
     register_model_routes(router)
+    register_pool_routes(router)
 
     return router
 

packages/backend/backend/web/api/v1/admin/training/datasets.py

@@ -12,6 +12,7 @@ from backend.web.core.auth import (
     AnnotationRepoDep,
     ModelVersionRepoDep,
     TrainingTaskRepoDep,
+    FineTunePoolRepoDep,
 )
 from backend.web.schemas.admin import (
     DatasetCreateRequest,
@@ -233,6 +234,7 @@ def register_dataset_routes(router: APIRouter) -> None:
         datasets_repo: DatasetRepoDep,
         models: ModelVersionRepoDep,
         tasks: TrainingTaskRepoDep,
+        pool: FineTunePoolRepoDep,
     ) -> TrainingTaskResponse:
         """Create a training task from a dataset.
 
@@ -261,13 +263,39 @@ def register_dataset_routes(router: APIRouter) -> None:
                     status_code=404,
                     detail=f"Base model version not found: {base_model_version_id}",
                 )
+            # Chain prevention: never fine-tune from a fine-tuned model
+            if getattr(base_model, "model_type", "base") == "finetune":
+                original_base_id = getattr(base_model, "base_model_version_id", None)
+                raise HTTPException(
+                    status_code=400,
+                    detail=(
+                        f"Cannot chain fine-tunes. Model {base_model.version} is already "
+                        f"a fine-tuned model. Select the original base model instead"
+                        f"{f' (base_model_version_id: {original_base_id})' if original_base_id else ''}."
+                    ),
+                )
+            # Pool threshold: require minimum verified pool entries for fine-tuning
+            from backend.web.services.data_mixer import MIN_POOL_SIZE
+
+            verified_count = pool.get_pool_count(verified_only=True)
+            if verified_count < MIN_POOL_SIZE:
+                raise HTTPException(
+                    status_code=400,
+                    detail=(
+                        f"Fine-tuning requires at least {MIN_POOL_SIZE} verified pool entries "
+                        f"(currently {verified_count}). Add more documents to the fine-tune "
+                        f"pool and verify them before starting fine-tuning."
+                    ),
+                )
+
             # Store the resolved model path for the training worker
             config_dict["base_model_path"] = base_model.model_path
             config_dict["base_model_version"] = base_model.version
             logger.info(
-                "Incremental training: using model %s (%s) as base",
+                "Fine-tuning: using base model %s (%s) with %d verified pool entries",
                 base_model.version,
                 base_model.model_path,
+                verified_count,
             )
 
         task_id = tasks.create(

packages/backend/backend/web/api/v1/admin/training/export.py

@@ -124,16 +124,11 @@ def register_export_routes(router: APIRouter) -> None:
                             x1 = ann.x_center * img_width + half_w
                             y1 = ann.y_center * img_height + half_h
 
-                            # Use manual_mode for manual/imported annotations
-                            manual_mode = ann.source in ("manual", "imported")
-
-                            # Apply field-specific bbox expansion
+                            # Apply uniform bbox expansion
                             ex0, ey0, ex1, ey1 = expand_bbox(
                                 bbox=(x0, y0, x1, y1),
                                 image_width=img_width,
                                 image_height=img_height,
-                                field_type=ann.class_name,
-                                manual_mode=manual_mode,
                             )
 
                             # Convert back to normalized YOLO format

packages/backend/backend/web/api/v1/admin/training/models.py

@@ -88,6 +88,9 @@ def register_model_routes(router: APIRouter) -> None:
                     name=m.name,
                     status=m.status,
                     is_active=m.is_active,
+                    model_type=getattr(m, "model_type", "base"),
+                    base_model_version_id=str(m.base_model_version_id) if getattr(m, "base_model_version_id", None) else None,
+                    gating_status=getattr(m, "gating_status", "pending"),
                     metrics_mAP=m.metrics_mAP,
                     document_count=m.document_count,
                     trained_at=m.trained_at,
@@ -121,6 +124,9 @@ def register_model_routes(router: APIRouter) -> None:
                 name=model.name,
                 status=model.status,
                 is_active=model.is_active,
+                model_type=getattr(model, "model_type", "base"),
+                base_model_version_id=str(model.base_model_version_id) if getattr(model, "base_model_version_id", None) else None,
+                gating_status=getattr(model, "gating_status", "pending"),
                 metrics_mAP=model.metrics_mAP,
                 document_count=model.document_count,
                 trained_at=model.trained_at,
@@ -153,6 +159,10 @@ def register_model_routes(router: APIRouter) -> None:
             model_path=model.model_path,
             status=model.status,
             is_active=model.is_active,
+            model_type=getattr(model, "model_type", "base"),
+            base_model_version_id=str(model.base_model_version_id) if getattr(model, "base_model_version_id", None) else None,
+            base_training_dataset_id=str(model.base_training_dataset_id) if getattr(model, "base_training_dataset_id", None) else None,
+            gating_status=getattr(model, "gating_status", "pending"),
             task_id=str(model.task_id) if model.task_id else None,
             dataset_id=str(model.dataset_id) if model.dataset_id else None,
             metrics_mAP=model.metrics_mAP,
@@ -209,6 +219,25 @@ def register_model_routes(router: APIRouter) -> None:
     ) -> ModelVersionResponse:
         """Activate a model version for inference."""
         _validate_uuid(version_id, "version_id")
+
+        # Check gating status before activation (for fine-tuned models)
+        pre_check = models.get(version_id)
+        if not pre_check:
+            raise HTTPException(status_code=404, detail="Model version not found")
+        model_type = getattr(pre_check, "model_type", "base")
+        gating_status = getattr(pre_check, "gating_status", "skipped")
+        if model_type == "finetune":
+            if gating_status == "reject":
+                raise HTTPException(
+                    status_code=400,
+                    detail="Model failed deployment gating validation. Cannot activate a rejected model.",
+                )
+            if gating_status == "pending":
+                raise HTTPException(
+                    status_code=400,
+                    detail="Model gating validation not yet completed. Wait for validation to finish.",
+                )
+
         model = models.activate(version_id)
         if not model:
             raise HTTPException(status_code=404, detail="Model version not found")
@@ -227,6 +256,8 @@ def register_model_routes(router: APIRouter) -> None:
         message = "Model version activated for inference"
         if model_reloaded:
             message += " (model reloaded)"
+        if gating_status == "review":
+            message += " (WARNING: gating status is REVIEW - manual inspection recommended)"
 
         return ModelVersionResponse(
             version_id=str(model.version_id),

packages/backend/backend/web/api/v1/admin/training/pool.py

@@ -0,0 +1,159 @@
+"""Fine-Tune Pool Endpoints."""
+
+import logging
+from typing import Annotated
+
+from fastapi import APIRouter, HTTPException, Query
+
+from backend.web.core.auth import AdminTokenDep, FineTunePoolRepoDep, DocumentRepoDep
+from backend.web.schemas.admin.pool import (
+    PoolAddRequest,
+    PoolEntryItem,
+    PoolEntryResponse,
+    PoolListResponse,
+    PoolStatsResponse,
+)
+
+from ._utils import _validate_uuid
+
+logger = logging.getLogger(__name__)
+
+
+def register_pool_routes(router: APIRouter) -> None:
+    """Register fine-tune pool endpoints on the router."""
+
+    @router.post(
+        "/pool",
+        response_model=PoolEntryResponse,
+        summary="Add document to fine-tune pool",
+        description="Add a labeled document to the fine-tune pool for future fine-tuning.",
+    )
+    async def add_to_pool(
+        request: PoolAddRequest,
+        admin_token: AdminTokenDep,
+        pool: FineTunePoolRepoDep,
+        docs: DocumentRepoDep,
+    ) -> PoolEntryResponse:
+        """Add a document to the fine-tune pool."""
+        _validate_uuid(request.document_id, "document_id")
+
+        # Verify document exists
+        doc = docs.get(request.document_id)
+        if not doc:
+            raise HTTPException(status_code=404, detail="Document not found")
+
+        # Check if already in pool
+        existing = pool.get_by_document(request.document_id)
+        if existing:
+            raise HTTPException(
+                status_code=409,
+                detail=f"Document already in fine-tune pool (entry_id: {existing.entry_id})",
+            )
+
+        entry = pool.add_document(
+            document_id=request.document_id,
+            added_by=admin_token,
+            reason=request.reason,
+        )
+
+        return PoolEntryResponse(
+            entry_id=str(entry.entry_id),
+            message="Document added to fine-tune pool",
+        )
+
+    @router.get(
+        "/pool",
+        response_model=PoolListResponse,
+        summary="List fine-tune pool entries",
+    )
+    async def list_pool_entries(
+        admin_token: AdminTokenDep,
+        pool: FineTunePoolRepoDep,
+        verified_only: Annotated[bool, Query(description="Filter to verified only")] = False,
+        limit: Annotated[int, Query(ge=1, le=100)] = 20,
+        offset: Annotated[int, Query(ge=0)] = 0,
+    ) -> PoolListResponse:
+        """List entries in the fine-tune pool."""
+        entries, total = pool.get_paginated(
+            verified_only=verified_only,
+            limit=limit,
+            offset=offset,
+        )
+
+        return PoolListResponse(
+            total=total,
+            limit=limit,
+            offset=offset,
+            entries=[
+                PoolEntryItem(
+                    entry_id=str(e.entry_id),
+                    document_id=str(e.document_id),
+                    added_by=e.added_by,
+                    reason=e.reason,
+                    is_verified=e.is_verified,
+                    verified_at=e.verified_at,
+                    verified_by=e.verified_by,
+                    created_at=e.created_at,
+                )
+                for e in entries
+            ],
+        )
+
+    @router.get(
+        "/pool/stats",
+        response_model=PoolStatsResponse,
+        summary="Get fine-tune pool statistics",
+    )
+    async def get_pool_stats(
+        admin_token: AdminTokenDep,
+        pool: FineTunePoolRepoDep,
+    ) -> PoolStatsResponse:
+        """Get statistics about the fine-tune pool."""
+        total = pool.get_pool_count(verified_only=False)
+        verified = pool.get_pool_count(verified_only=True)
+
+        return PoolStatsResponse(
+            total_entries=total,
+            verified_entries=verified,
+            unverified_entries=total - verified,
+            is_ready=verified >= 50,
+        )
+
+    @router.post(
+        "/pool/{entry_id}/verify",
+        response_model=PoolEntryResponse,
+        summary="Verify a pool entry",
+        description="Mark a pool entry as verified (human-reviewed).",
+    )
+    async def verify_pool_entry(
+        entry_id: str,
+        admin_token: AdminTokenDep,
+        pool: FineTunePoolRepoDep,
+    ) -> PoolEntryResponse:
+        """Mark a pool entry as verified."""
+        _validate_uuid(entry_id, "entry_id")
+        entry = pool.verify_entry(entry_id, verified_by=admin_token)
+        if not entry:
+            raise HTTPException(status_code=404, detail="Pool entry not found")
+
+        return PoolEntryResponse(
+            entry_id=str(entry.entry_id),
+            message="Pool entry verified",
+        )
+
+    @router.delete(
+        "/pool/{entry_id}",
+        summary="Remove from fine-tune pool",
+    )
+    async def remove_from_pool(
+        entry_id: str,
+        admin_token: AdminTokenDep,
+        pool: FineTunePoolRepoDep,
+    ) -> dict:
+        """Remove a document from the fine-tune pool."""
+        _validate_uuid(entry_id, "entry_id")
+        success = pool.remove_entry(entry_id)
+        if not success:
+            raise HTTPException(status_code=404, detail="Pool entry not found")
+
+        return {"message": "Entry removed from fine-tune pool"}

packages/backend/backend/web/core/auth.py

@@ -17,6 +17,7 @@ from backend.data.repositories import (
     TrainingTaskRepository,
     ModelVersionRepository,
     BatchUploadRepository,
+    FineTunePoolRepository,
 )
 
 
@@ -95,6 +96,12 @@ def get_batch_upload_repository() -> BatchUploadRepository:
     return BatchUploadRepository()
 
 
+@lru_cache(maxsize=1)
+def get_finetune_pool_repository() -> FineTunePoolRepository:
+    """Get the FineTunePoolRepository instance (thread-safe singleton)."""
+    return FineTunePoolRepository()
+
+
 def reset_all_repositories() -> None:
     """Reset all repository instances (for testing)."""
     get_token_repository.cache_clear()
@@ -104,6 +111,7 @@ def reset_all_repositories() -> None:
     get_training_task_repository.cache_clear()
     get_model_version_repository.cache_clear()
     get_batch_upload_repository.cache_clear()
+    get_finetune_pool_repository.cache_clear()
 
 
 # Repository dependency type aliases
@@ -113,3 +121,4 @@ DatasetRepoDep = Annotated[DatasetRepository, Depends(get_dataset_repository)]
 TrainingTaskRepoDep = Annotated[TrainingTaskRepository, Depends(get_training_task_repository)]
 ModelVersionRepoDep = Annotated[ModelVersionRepository, Depends(get_model_version_repository)]
 BatchUploadRepoDep = Annotated[BatchUploadRepository, Depends(get_batch_upload_repository)]
+FineTunePoolRepoDep = Annotated[FineTunePoolRepository, Depends(get_finetune_pool_repository)]

packages/backend/backend/web/core/scheduler.py

@@ -16,6 +16,7 @@ from backend.data.repositories import (
     ModelVersionRepository,
     DocumentRepository,
     AnnotationRepository,
+    FineTunePoolRepository,
 )
 from backend.web.core.task_interface import TaskRunner, TaskStatus
 from backend.web.services.storage_helpers import get_storage_helper
@@ -47,6 +48,7 @@ class TrainingScheduler(TaskRunner):
         self._model_versions = ModelVersionRepository()
         self._documents = DocumentRepository()
         self._annotations = AnnotationRepository()
+        self._pool = FineTunePoolRepository()
 
     @property
     def name(self) -> str:
@@ -168,7 +170,7 @@ class TrainingScheduler(TaskRunner):
 
         try:
             # Get training configuration
-            model_name = config.get("model_name", "yolo11n.pt")
+            model_name = config.get("model_name", "yolo26s.pt")
             base_model_path = config.get("base_model_path")  # For incremental training
             epochs = config.get("epochs", 100)
             batch_size = config.get("batch_size", 16)
@@ -182,14 +184,19 @@ class TrainingScheduler(TaskRunner):
             augmentation_multiplier = config.get("augmentation_multiplier", 2)
 
             # Determine which model to use as base
-            if base_model_path:
-                # Incremental training: use existing trained model
+            is_finetune = bool(base_model_path)
+            if is_finetune:
+                # Fine-tuning: use existing trained model as base
                 if not Path(base_model_path).exists():
                     raise ValueError(f"Base model not found: {base_model_path}")
                 effective_model = base_model_path
+                # Override parameters for fine-tuning (best practices)
+                epochs = config.get("epochs", 10)
+                learning_rate = config.get("learning_rate", 0.001)
                 self._training_tasks.add_log(
                     task_id, "INFO",
-                    f"Incremental training from: {base_model_path}",
+                    f"Fine-tuning from: {base_model_path} "
+                    f"(epochs={epochs}, freeze=10, cos_lr=true)",
                 )
             else:
                 # Train from pretrained model
@@ -229,10 +236,16 @@ class TrainingScheduler(TaskRunner):
                         f"(total: {aug_result['total_images']})",
                     )
 
+            # Build mixed dataset for fine-tuning (pool samples + old data)
+            if is_finetune and dataset_id:
+                data_yaml, dataset_path = self._build_mixed_finetune_dataset(
+                    task_id, dataset_path, data_yaml,
+                )
+
             # Run YOLO training
             result = self._run_yolo_training(
                 task_id=task_id,
-                model_name=effective_model,  # Use base model or pretrained model
+                model_name=effective_model,
                 data_yaml=data_yaml,
                 epochs=epochs,
                 batch_size=batch_size,
@@ -240,6 +253,8 @@ class TrainingScheduler(TaskRunner):
                 learning_rate=learning_rate,
                 device=device,
                 project_name=project_name,
+                freeze=10 if is_finetune else 0,
+                cos_lr=is_finetune,
             )
 
             # Update task with results
@@ -261,13 +276,23 @@ class TrainingScheduler(TaskRunner):
                 )
 
             # Auto-create model version for the completed training
-            self._create_model_version_from_training(
+            model_version = self._create_model_version_from_training(
                 task_id=task_id,
                 config=config,
                 dataset_id=dataset_id,
                 result=result,
             )
 
+            # Auto-run gating validation for fine-tuned models
+            if is_finetune and model_version:
+                self._run_gating_after_finetune(
+                    task_id=task_id,
+                    model_version=model_version,
+                    config=config,
+                    data_yaml=data_yaml,
+                    result=result,
+                )
+
         except Exception as e:
             logger.error(f"Training task {task_id} failed: {e}")
             self._training_tasks.add_log(task_id, "ERROR", f"Training failed: {e}")
@@ -286,13 +311,16 @@ class TrainingScheduler(TaskRunner):
         config: dict[str, Any],
         dataset_id: str | None,
         result: dict[str, Any],
-    ) -> None:
-        """Create a model version entry from completed training."""
+    ) -> Any | None:
+        """Create a model version entry from completed training.
+
+        Returns the created model version, or None on failure.
+        """
         try:
             model_path = result.get("model_path")
             if not model_path:
                 logger.warning(f"No model path in training result for task {task_id}")
-                return
+                return None
 
             # Get task info for name
             task = self._training_tasks.get(task_id)
@@ -322,6 +350,12 @@ class TrainingScheduler(TaskRunner):
                 if dataset:
                     document_count = dataset.total_documents
 
+            # Determine model lineage
+            is_finetune = bool(config.get("base_model_path"))
+            model_type = "finetune" if is_finetune else "base"
+            base_model_version_id = config.get("base_model_version_id") if is_finetune else None
+            gating_status = "pending" if is_finetune else "skipped"
+
             # Create model version
             model_version = self._model_versions.create(
                 version=version,
@@ -337,6 +371,10 @@ class TrainingScheduler(TaskRunner):
                 training_config=config,
                 file_size=file_size,
                 trained_at=datetime.utcnow(),
+                model_type=model_type,
+                base_model_version_id=base_model_version_id,
+                base_training_dataset_id=dataset_id if not is_finetune else None,
+                gating_status=gating_status,
             )
 
             logger.info(
@@ -349,12 +387,105 @@ class TrainingScheduler(TaskRunner):
                 f"Model version {version} created (mAP: {mAP_display})",
             )
 
+            return model_version
+
         except Exception as e:
             logger.error(f"Failed to create model version for task {task_id}: {e}")
             self._training_tasks.add_log(
                 task_id, "WARNING",
                 f"Failed to auto-create model version: {e}",
             )
+            return None
+
+    def _build_mixed_finetune_dataset(
+        self,
+        task_id: str,
+        base_dataset_path: Path,
+        original_data_yaml: str,
+    ) -> tuple[str, Path]:
+        """Build a mixed dataset for fine-tuning.
+
+        Combines verified pool samples with randomly sampled old training data.
+
+        Returns:
+            Tuple of (data_yaml path, dataset_path) for the mixed dataset.
+            Falls back to original if mixing fails or pool is empty.
+        """
+        try:
+            from backend.web.services.data_mixer import build_mixed_dataset
+
+            pool_doc_ids = self._pool.get_all_document_ids(verified_only=True)
+            if not pool_doc_ids:
+                self._training_tasks.add_log(
+                    task_id, "INFO",
+                    "No verified pool entries found, using original dataset",
+                )
+                return original_data_yaml, base_dataset_path
+
+            mixed_output = base_dataset_path.parent / f"mixed_{task_id[:8]}"
+            mix_result = build_mixed_dataset(
+                pool_document_ids=pool_doc_ids,
+                base_dataset_path=base_dataset_path,
+                output_dir=mixed_output,
+            )
+
+            self._training_tasks.add_log(
+                task_id, "INFO",
+                f"Data mixing: {mix_result['new_images']} new + "
+                f"{mix_result['old_images']} old = {mix_result['total_images']} total "
+                f"(ratio: {mix_result['mixing_ratio']}x)",
+            )
+
+            return mix_result["data_yaml"], mixed_output
+
+        except Exception as e:
+            logger.error(f"Data mixing failed for task {task_id}: {e}")
+            self._training_tasks.add_log(
+                task_id, "WARNING",
+                f"Data mixing failed: {e}. Using original dataset.",
+            )
+            return original_data_yaml, base_dataset_path
+
+    def _run_gating_after_finetune(
+        self,
+        task_id: str,
+        model_version: Any,
+        config: dict[str, Any],
+        data_yaml: str,
+        result: dict[str, Any],
+    ) -> None:
+        """Run gating validation after a fine-tune training completes."""
+        try:
+            from backend.web.services.gating_validator import run_gating_validation
+
+            model_path = result.get("model_path")
+            base_model_version_id = config.get("base_model_version_id")
+            version_id = str(model_version.version_id)
+
+            self._training_tasks.add_log(
+                task_id, "INFO", "Running deployment gating validation...",
+            )
+
+            gating_result = run_gating_validation(
+                model_version_id=version_id,
+                new_model_path=model_path,
+                base_model_version_id=base_model_version_id,
+                data_yaml=data_yaml,
+                task_id=task_id,
+            )
+
+            self._training_tasks.add_log(
+                task_id, "INFO",
+                f"Gating result: {gating_result.overall_status} "
+                f"(gate1={gating_result.gate1_status}, gate2={gating_result.gate2_status})",
+            )
+
+        except Exception as e:
+            logger.error(f"Gating validation failed for task {task_id}: {e}")
+            self._training_tasks.add_log(
+                task_id, "WARNING",
+                f"Gating validation failed: {e}. Model remains in 'pending' state.",
+            )
 
     def _export_training_data(self, task_id: str) -> dict[str, Any] | None:
         """Export training data for a task."""
@@ -456,6 +587,8 @@ names: {list(FIELD_CLASSES.values())}
         learning_rate: float,
         device: str,
         project_name: str,
+        freeze: int = 0,
+        cos_lr: bool = False,
     ) -> dict[str, Any]:
         """Run YOLO training using shared trainer."""
         from shared.training import YOLOTrainer, TrainingConfig as SharedTrainingConfig
@@ -479,6 +612,8 @@ names: {list(FIELD_CLASSES.values())}
             project="runs/train",
             name=f"{project_name}/task_{task_id[:8]}",
             workers=0,
+            freeze=freeze,
+            cos_lr=cos_lr,
         )
 
         # Run training using shared trainer

packages/backend/backend/web/schemas/admin/__init__.py

@@ -11,6 +11,7 @@ from .annotations import *  # noqa: F401, F403
 from .training import *  # noqa: F401, F403
 from .datasets import *  # noqa: F401, F403
 from .models import *  # noqa: F401, F403
+from .pool import *  # noqa: F401, F403
 from .dashboard import *  # noqa: F401, F403
 
 # Resolve forward references for DocumentDetailResponse

packages/backend/backend/web/schemas/admin/models.py

@@ -40,6 +40,9 @@ class ModelVersionItem(BaseModel):
     name: str = Field(..., description="Model name")
     status: str = Field(..., description="Status (active, inactive, archived)")
     is_active: bool = Field(..., description="Is currently active for inference")
+    model_type: str = Field(default="base", description="Model type (base or finetune)")
+    base_model_version_id: str | None = Field(None, description="Base model version UUID (for fine-tuned models)")
+    gating_status: str = Field(default="pending", description="Deployment gating status")
     metrics_mAP: float | None = Field(None, description="Mean Average Precision")
     document_count: int = Field(..., description="Documents used in training")
     trained_at: datetime | None = Field(None, description="Training completion time")
@@ -66,6 +69,10 @@ class ModelVersionDetailResponse(BaseModel):
     model_path: str = Field(..., description="Path to model file")
     status: str = Field(..., description="Status (active, inactive, archived)")
     is_active: bool = Field(..., description="Is currently active for inference")
+    model_type: str = Field(default="base", description="Model type (base or finetune)")
+    base_model_version_id: str | None = Field(None, description="Base model version UUID")
+    base_training_dataset_id: str | None = Field(None, description="Base training dataset UUID")
+    gating_status: str = Field(default="pending", description="Deployment gating status")
     task_id: str | None = Field(None, description="Training task UUID")
     dataset_id: str | None = Field(None, description="Dataset UUID")
     metrics_mAP: float | None = Field(None, description="Mean Average Precision")

packages/backend/backend/web/schemas/admin/pool.py

@@ -0,0 +1,72 @@
+"""Admin Fine-Tune Pool Schemas."""
+
+from datetime import datetime
+
+from pydantic import BaseModel, Field
+
+
+class PoolAddRequest(BaseModel):
+    """Request to add a document to the fine-tune pool."""
+
+    document_id: str = Field(..., description="Document UUID to add")
+    reason: str = Field(
+        default="user_reported_failure",
+        description="Reason: user_reported_failure, manual_addition",
+    )
+
+
+class PoolEntryItem(BaseModel):
+    """Fine-tune pool entry."""
+
+    entry_id: str = Field(..., description="Entry UUID")
+    document_id: str = Field(..., description="Document UUID")
+    added_by: str | None = Field(None, description="Who added this entry")
+    reason: str | None = Field(None, description="Reason for adding")
+    is_verified: bool = Field(..., description="Whether entry has been verified")
+    verified_at: datetime | None = Field(None, description="Verification timestamp")
+    verified_by: str | None = Field(None, description="Who verified")
+    created_at: datetime = Field(..., description="Creation timestamp")
+
+
+class PoolListResponse(BaseModel):
+    """Paginated pool entry list."""
+
+    total: int = Field(..., ge=0, description="Total entries")
+    limit: int = Field(..., ge=1, description="Page size")
+    offset: int = Field(..., ge=0, description="Current offset")
+    entries: list[PoolEntryItem] = Field(default_factory=list, description="Pool entries")
+
+
+class PoolStatsResponse(BaseModel):
+    """Pool statistics."""
+
+    total_entries: int = Field(..., ge=0, description="Total pool entries")
+    verified_entries: int = Field(..., ge=0, description="Verified entries")
+    unverified_entries: int = Field(..., ge=0, description="Unverified entries")
+    is_ready: bool = Field(..., description="Whether pool has >= 50 verified entries for fine-tuning")
+    min_required: int = Field(default=50, description="Minimum verified entries required")
+
+
+class PoolEntryResponse(BaseModel):
+    """Response for pool entry operation."""
+
+    entry_id: str = Field(..., description="Entry UUID")
+    message: str = Field(..., description="Status message")
+
+
+class GatingResultItem(BaseModel):
+    """Gating validation result."""
+
+    result_id: str = Field(..., description="Result UUID")
+    model_version_id: str = Field(..., description="Model version UUID")
+    gate1_status: str = Field(..., description="Gate 1 status")
+    gate1_original_mAP: float | None = Field(None, description="Original model mAP")
+    gate1_new_mAP: float | None = Field(None, description="New model mAP")
+    gate1_mAP_drop: float | None = Field(None, description="mAP drop percentage")
+    gate2_status: str = Field(..., description="Gate 2 status")
+    gate2_detection_rate: float | None = Field(None, description="Detection rate on new samples")
+    gate2_total_samples: int | None = Field(None, description="Total new samples tested")
+    gate2_detected_samples: int | None = Field(None, description="Samples correctly detected")
+    overall_status: str = Field(..., description="Overall gating status")
+    reviewer_notes: str | None = Field(None, description="Reviewer notes")
+    created_at: datetime = Field(..., description="Creation timestamp")

packages/backend/backend/web/schemas/admin/training.py

@@ -12,7 +12,7 @@ from .enums import TrainingStatus, TrainingType
 class TrainingConfig(BaseModel):
     """Training configuration."""
 
-    model_name: str = Field(default="yolo11n.pt", description="Base model name (used if no base_model_version_id)")
+    model_name: str = Field(default="yolo26s.pt", description="Base model name (used if no base_model_version_id)")
     base_model_version_id: str | None = Field(
         default=None,
         description="Model version UUID to use as base for incremental training. If set, uses this model instead of model_name.",

packages/backend/backend/web/services/data_mixer.py

@@ -0,0 +1,199 @@
+"""
+Data Mixing Service
+
+Mixes fine-tune pool samples with randomly sampled old training data
+following best practices for incremental YOLO fine-tuning.
+"""
+
+import logging
+import random
+import shutil
+from pathlib import Path
+from typing import Any
+from uuid import UUID
+
+logger = logging.getLogger(__name__)
+
+# Mixing ratios: (max_new_samples, old_data_multiplier)
+# Fewer new samples require higher old data ratio to prevent catastrophic forgetting
+MIXING_RATIOS: list[tuple[int, int]] = [
+    (10, 50),   # <= 10 new samples: 50x old
+    (50, 20),   # <= 50 new samples: 20x old
+    (200, 10),  # <= 200 new samples: 10x old
+    (500, 5),   # <= 500 new samples: 5x old
+]
+
+# Default multiplier for 500+ samples
+DEFAULT_MULTIPLIER = 5
+
+# Maximum old samples to include (cap for performance)
+MAX_OLD_SAMPLES = 3000
+
+# Minimum pool size for fine-tuning
+MIN_POOL_SIZE = 50
+
+
+def get_mixing_ratio(new_sample_count: int) -> int:
+    """Determine old data multiplier based on new sample count.
+
+    Args:
+        new_sample_count: Number of new samples in the fine-tune pool.
+
+    Returns:
+        Multiplier for old data sampling.
+    """
+    for threshold, multiplier in MIXING_RATIOS:
+        if new_sample_count <= threshold:
+            return multiplier
+    return DEFAULT_MULTIPLIER
+
+
+def build_mixed_dataset(
+    pool_document_ids: list[UUID],
+    base_dataset_path: Path,
+    output_dir: Path,
+    seed: int = 42,
+) -> dict[str, Any]:
+    """Build a mixed dataset for fine-tuning.
+
+    Combines ALL fine-tune pool samples with randomly sampled old data
+    from the base training dataset.
+
+    Args:
+        pool_document_ids: Document IDs from the fine-tune pool.
+        base_dataset_path: Path to the base training dataset directory.
+        output_dir: Output directory for the mixed dataset.
+        seed: Random seed for reproducible sampling.
+
+    Returns:
+        Dictionary with dataset info (data_yaml path, counts).
+    """
+    new_count = len(pool_document_ids)
+    multiplier = get_mixing_ratio(new_count)
+    old_target = min(new_count * multiplier, MAX_OLD_SAMPLES)
+
+    logger.info(
+        "Building mixed dataset: %d new samples, %dx multiplier, "
+        "targeting %d old samples",
+        new_count, multiplier, old_target,
+    )
+
+    # Create output directory structure
+    output_dir.mkdir(parents=True, exist_ok=True)
+    for split in ("train", "val"):
+        (output_dir / "images" / split).mkdir(parents=True, exist_ok=True)
+        (output_dir / "labels" / split).mkdir(parents=True, exist_ok=True)
+
+    # Collect old training images from base dataset
+    old_train_images = _collect_images(base_dataset_path / "images" / "train")
+    old_val_images = _collect_images(base_dataset_path / "images" / "val")
+
+    # Randomly sample old data
+    rng = random.Random(seed)
+    all_old_images = old_train_images + old_val_images
+    if len(all_old_images) > old_target:
+        sampled_old = rng.sample(all_old_images, old_target)
+    else:
+        sampled_old = all_old_images
+
+    # Split old samples: 80% train, 20% val
+    rng.shuffle(sampled_old)
+    old_train_count = int(len(sampled_old) * 0.8)
+    old_train = sampled_old[:old_train_count]
+    old_val = sampled_old[old_train_count:]
+
+    # Copy old samples to mixed dataset
+    old_copied = 0
+    for split_name, images in [("train", old_train), ("val", old_val)]:
+        for img_path in images:
+            label_path = _image_to_label_path(img_path)
+            dst_img = output_dir / "images" / split_name / img_path.name
+            dst_label = output_dir / "labels" / split_name / label_path.name
+            if img_path.exists():
+                shutil.copy2(img_path, dst_img)
+                old_copied += 1
+            if label_path.exists():
+                shutil.copy2(label_path, dst_label)
+
+    # Copy new pool samples (from base dataset, identified by document_id prefix)
+    # Pool documents go into train split (80%) and val split (20%)
+    pool_id_strs = {str(doc_id) for doc_id in pool_document_ids}
+    new_images = _find_pool_images(base_dataset_path, pool_id_strs)
+
+    rng.shuffle(new_images)
+    new_train_count = int(len(new_images) * 0.8)
+    new_train = new_images[:new_train_count]
+    new_val = new_images[new_train_count:]
+
+    new_copied = 0
+    for split_name, images in [("train", new_train), ("val", new_val)]:
+        for img_path in images:
+            label_path = _image_to_label_path(img_path)
+            dst_img = output_dir / "images" / split_name / img_path.name
+            dst_label = output_dir / "labels" / split_name / label_path.name
+            if img_path.exists() and not dst_img.exists():
+                shutil.copy2(img_path, dst_img)
+                new_copied += 1
+            if label_path.exists() and not dst_label.exists():
+                shutil.copy2(label_path, dst_label)
+
+    # Generate data.yaml
+    from shared.fields import FIELD_CLASSES
+
+    yaml_path = output_dir / "data.yaml"
+    yaml_content = (
+        f"path: {output_dir.absolute()}\n"
+        f"train: images/train\n"
+        f"val: images/val\n"
+        f"\n"
+        f"nc: {len(FIELD_CLASSES)}\n"
+        f"names: {list(FIELD_CLASSES.values())}\n"
+    )
+    yaml_path.write_text(yaml_content)
+
+    total_images = old_copied + new_copied
+    logger.info(
+        "Mixed dataset built: %d old + %d new = %d total images",
+        old_copied, new_copied, total_images,
+    )
+
+    return {
+        "data_yaml": str(yaml_path),
+        "total_images": total_images,
+        "old_images": old_copied,
+        "new_images": new_copied,
+        "mixing_ratio": multiplier,
+    }
+
+
+def _collect_images(images_dir: Path) -> list[Path]:
+    """Collect all image files from a directory."""
+    if not images_dir.exists():
+        return []
+    return sorted(images_dir.glob("*.png")) + sorted(images_dir.glob("*.jpg"))
+
+
+def _image_to_label_path(image_path: Path) -> Path:
+    """Convert image path to corresponding label path."""
+    labels_dir = image_path.parent.parent.parent / "labels" / image_path.parent.name
+    return labels_dir / image_path.with_suffix(".txt").name
+
+
+def _find_pool_images(
+    base_dataset_path: Path,
+    pool_doc_ids: set[str],
+) -> list[Path]:
+    """Find images in base dataset that belong to pool documents."""
+    images: list[Path] = []
+    for split in ("train", "val", "test"):
+        split_dir = base_dataset_path / "images" / split
+        if not split_dir.exists():
+            continue
+        for img_path in split_dir.iterdir():
+            if not img_path.is_file():
+                continue
+            # Image filenames are like: {doc_id}_page{N}.png
+            doc_id = img_path.stem.rsplit("_page", 1)[0]
+            if doc_id in pool_doc_ids:
+                images.append(img_path)
+    return images

packages/backend/backend/web/services/gating_validator.py

@@ -0,0 +1,198 @@
+"""
+Gating Validation Service
+
+Validates fine-tuned models before deployment using quality gates:
+- Gate 1: Regression validation (mAP drop on original test set)
+- Gate 2: New sample validation (detection rate on pool documents)
+"""
+
+import logging
+from pathlib import Path
+from uuid import UUID
+
+from backend.data.admin_models import GatingResult
+from backend.data.database import get_session_context
+from backend.data.repositories.model_version_repository import ModelVersionRepository
+
+logger = logging.getLogger(__name__)
+
+# Gate 1 thresholds (mAP drop)
+GATE1_PASS_THRESHOLD = 0.01  # < 1% drop = PASS
+GATE1_REVIEW_THRESHOLD = 0.03  # 1-3% drop = REVIEW, > 3% = REJECT
+
+# Gate 2 thresholds (detection rate)
+GATE2_PASS_THRESHOLD = 0.80  # > 80% detection rate = PASS
+
+
+def classify_gate1(mAP_drop: float) -> str:
+    """Classify Gate 1 result based on mAP drop.
+
+    Args:
+        mAP_drop: Absolute mAP drop (positive means degradation).
+
+    Returns:
+        "pass", "review", or "reject"
+    """
+    if mAP_drop < GATE1_PASS_THRESHOLD:
+        return "pass"
+    if mAP_drop < GATE1_REVIEW_THRESHOLD:
+        return "review"
+    return "reject"
+
+
+def classify_gate2(detection_rate: float) -> str:
+    """Classify Gate 2 result based on detection rate.
+
+    Args:
+        detection_rate: Fraction of new samples correctly detected (0-1).
+
+    Returns:
+        "pass" or "review"
+    """
+    if detection_rate >= GATE2_PASS_THRESHOLD:
+        return "pass"
+    return "review"
+
+
+def compute_overall_status(gate1_status: str, gate2_status: str) -> str:
+    """Compute overall gating status from individual gates.
+
+    Rules:
+    - Any "reject" -> overall "reject"
+    - Any "review" (and no reject) -> overall "review"
+    - All "pass" -> overall "pass"
+    """
+    if gate1_status == "reject" or gate2_status == "reject":
+        return "reject"
+    if gate1_status == "review" or gate2_status == "review":
+        return "review"
+    return "pass"
+
+
+def run_gating_validation(
+    model_version_id: str | UUID,
+    new_model_path: str,
+    base_model_version_id: str | UUID | None,
+    data_yaml: str,
+    task_id: str | UUID | None = None,
+) -> GatingResult:
+    """Run deployment gating validation for a fine-tuned model.
+
+    Args:
+        model_version_id: The fine-tuned model version to validate.
+        new_model_path: Path to the new model weights.
+        base_model_version_id: The base model version to compare against.
+        data_yaml: Path to the dataset YAML (for validation).
+        task_id: Optional training task ID.
+
+    Returns:
+        GatingResult with gate statuses.
+    """
+    model_versions = ModelVersionRepository()
+
+    # Gate 1: Regression validation
+    gate1_status = "pending"
+    gate1_original_mAP = None
+    gate1_new_mAP = None
+    gate1_mAP_drop = None
+
+    try:
+        if base_model_version_id:
+            base_model = model_versions.get(str(base_model_version_id))
+            if base_model and base_model.metrics_mAP is not None:
+                gate1_original_mAP = base_model.metrics_mAP
+
+                # Run validation with new model
+                from shared.training import YOLOTrainer, TrainingConfig
+
+                val_config = TrainingConfig(
+                    model_path=new_model_path,
+                    data_yaml=data_yaml,
+                )
+                trainer = YOLOTrainer(config=val_config)
+                val_metrics = trainer.validate(split="val")
+                gate1_new_mAP = val_metrics.get("mAP50")
+
+                if gate1_new_mAP is not None:
+                    gate1_mAP_drop = gate1_original_mAP - gate1_new_mAP
+                    gate1_status = classify_gate1(gate1_mAP_drop)
+                    logger.info(
+                        "Gate 1: original_mAP=%.4f, new_mAP=%.4f, drop=%.4f -> %s",
+                        gate1_original_mAP, gate1_new_mAP, gate1_mAP_drop, gate1_status,
+                    )
+                else:
+                    gate1_status = "review"
+                    logger.warning("Gate 1: Could not compute new mAP, marking as review")
+            else:
+                gate1_status = "pass"
+                logger.info("Gate 1: No base model metrics available, skipping (pass)")
+        else:
+            gate1_status = "pass"
+            logger.info("Gate 1: No base model specified, skipping (pass)")
+    except Exception as e:
+        gate1_status = "review"
+        logger.error("Gate 1 failed: %s", e)
+
+    # Gate 2: New sample validation
+    # For now, we use the training metrics as a proxy
+    # Full implementation would run inference on pool documents
+    gate2_status = "pass"
+    gate2_detection_rate = None
+    gate2_total_samples = None
+    gate2_detected_samples = None
+
+    try:
+        new_model = model_versions.get(str(model_version_id))
+        if new_model and new_model.metrics_mAP is not None:
+            # Use mAP as proxy for detection rate on new samples
+            gate2_detection_rate = new_model.metrics_mAP
+            if gate2_detection_rate is not None:
+                gate2_status = classify_gate2(gate2_detection_rate)
+                logger.info(
+                    "Gate 2: detection_rate=%.4f -> %s",
+                    gate2_detection_rate, gate2_status,
+                )
+    except Exception as e:
+        gate2_status = "review"
+        logger.error("Gate 2 failed: %s", e)
+
+    # Compute overall status
+    overall_status = compute_overall_status(gate1_status, gate2_status)
+    logger.info("Gating overall: %s (gate1=%s, gate2=%s)", overall_status, gate1_status, gate2_status)
+
+    # Save result
+    with get_session_context() as session:
+        result = GatingResult(
+            model_version_id=UUID(str(model_version_id)),
+            task_id=UUID(str(task_id)) if task_id else None,
+            gate1_status=gate1_status,
+            gate1_original_mAP=gate1_original_mAP,
+            gate1_new_mAP=gate1_new_mAP,
+            gate1_mAP_drop=gate1_mAP_drop,
+            gate2_status=gate2_status,
+            gate2_detection_rate=gate2_detection_rate,
+            gate2_total_samples=gate2_total_samples,
+            gate2_detected_samples=gate2_detected_samples,
+            overall_status=overall_status,
+        )
+        session.add(result)
+        session.commit()
+        session.refresh(result)
+        session.expunge(result)
+
+    # Update model version gating status
+    _update_model_gating_status(str(model_version_id), overall_status)
+
+    return result
+
+
+def _update_model_gating_status(version_id: str, status: str) -> None:
+    """Update the gating_status field on a ModelVersion."""
+    from backend.data.admin_models import ModelVersion
+
+    with get_session_context() as session:
+        model = session.get(ModelVersion, UUID(version_id))
+        if model:
+            model.gating_status = status
+            session.add(model)
+            session.commit()

packages/backend/requirements.txt

@@ -3,6 +3,6 @@ fastapi>=0.104.0
 uvicorn[standard]>=0.24.0
 python-multipart>=0.0.6
 sqlmodel>=0.0.22
-ultralytics>=8.1.0
+ultralytics>=8.4.0
 httpx>=0.25.0
 openai>=1.0.0