Agent skill

create-classifier

Train task-specific classifiers for the extractor pipeline. Supports vision, text, and hybrid classifiers with GRPO training and execution feedback. Includes data collection, confidence-based routing, and shadow deployment.

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Install this agent skill to your Project

npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/other/other/create-classifier

Metadata

Additional technical details for this skill

short description
Generalized classifier training infrastructure with execution feedback

SKILL.md

Create Classifier Skill

Purpose: Training infrastructure for task-specific classifiers that improve extractor pipeline accuracy through ML-based detection instead of regex/heuristics.

Overview

This skill provides end-to-end infrastructure for creating, training, and deploying classifiers for extraction tasks:

  • Data Collection: Mine labeled data from successful pipeline runs
  • Training Templates: Vision, text, and hybrid classifier architectures
  • Execution Feedback: GRPO-style training with pipeline success as reward
  • Confidence Routing: Automatic fallback to heuristics when confidence is low
  • Shadow Deployment: Compare classifier vs heuristics before full rollout

Success Story: Table Strategy Classifier

The table extraction classifier (S05) achieved:

  • 95.07% accuracy (vs ~75% heuristic baseline)
  • Reduced fallback rate from ~25% to <10%
  • Faster inference than multi-strategy attempts

This skill generalizes that success pattern for other extraction tasks.

Supported Classifier Types

1. Vision Classifiers

Use case: Document-level classification from images

  • Example: S00 document type detection (arxiv, requirements_spec, legal)
  • Input: First 3 pages as images (224x224)
  • Architecture: EfficientNet-B0 or DiT (Document Image Transformer)

2. Text Classifiers

Use case: Sentence or block-level classification from text

  • Example: S08 requirement sentence detection
  • Input: Sentence text + context (headings, modal verbs)
  • Architecture: BERT-base or RoBERTa

3. Hybrid Classifiers

Use case: Combined text + layout features

  • Example: S04 citation vs section header detection
  • Input: Text + font size + bbox + surrounding context
  • Architecture: Multi-modal fusion network

Usage

Step 0: Preflight Assess (Recommended)

Run an initial task/data assessment before training. This recommends classifier family/backbone, checks class imbalance, and can trigger /dogpile research when confidence is low.

bash
./run.sh assess \
  --task document_type \
  --labels data/labels/document_type.jsonl \
  --dogpile-when-uncertain

Step 0b: Benchmark-First Model Selection (Recommended)

Run benchmark-first selection after assess. This attempts classifier-lab first when configured, then uses internal quick benchmarking as deterministic fallback. For production training, make classifier-lab mandatory and fail closed on selection.

bash
./run.sh select-model \
  --labels data/labels/document_type.jsonl \
  --model efficientnet_b0 \
  --candidate-backbones \
    efficientnet_b0,convnextv2_nano.fcmae_ft_in22k_in1k,resnet50 \
  --benchmark-first \
  --classifier-lab-first \
  --require-classifier-lab \
  --require-selection-pass

Step 1: Data Collection

Collect labeled examples from successful pipeline runs:

bash
./run.sh collect \
  --task document_type \
  --source /path/to/corpus \
  --output data/labels/document_type.jsonl

Output format (JSONL):

json
{
  "id": "doc_abc123",
  "task": "document_type",
  "input": {
    "image_paths": ["page_0.png", "page_1.png", "page_2.png"],
    "text_features": { "page_count": 42, "has_formulas": true }
  },
  "label": "arxiv_scientific",
  "confidence": 0.95,
  "source": "successful_extraction"
}

Step 2: Train Classifier

Train using supervised learning or GRPO (with execution feedback):

bash
# Supervised fine-tuning (SFT)
./run.sh train \
  --config configs/document_type.yaml \
  --mode sft \
  --epochs 20

# GRPO with execution feedback
./run.sh train \
  --config configs/document_type.yaml \
  --mode grpo \
  --feedback-fn validate_pipeline_success

# Iterative train with preflight assess, optional HF augmentation, and holdout gate
./run.sh train-iterative \
  --task document_type \
  --model efficientnet_b0 \
  --labels data/labels/document_type.jsonl \
  --output-dir models/document_type \
  --benchmark-first \
  --classifier-lab-first \
  --require-classifier-lab \
  --require-selection-pass \
  --run-preflight-assess \
  --auto-hf-augment \
  --run-hp-search

# Strict quality gate profile (recommended default)
# - holdout macro-F1 >= 0.90
# - holdout accuracy >= 0.90
# - per-class recall floor >= 0.80 (enforce in evaluator/report gate)

### Step 2b: Train with Docker

Run training in a container (recommended for reproducibility):

```bash
docker-compose up classifier

This mounts the corpus and output directories automatically.


### Step 3: Evaluate

Compare classifier against heuristic baseline:

```bash
./run.sh evaluate \
  --model models/document_type \
  --baseline heuristic \
  --test-set data/test/document_type.jsonl

Success criteria:

  • Overall accuracy >90%
  • Per-class precision >80%
  • Inference time <100ms

Step 4: Shadow Deploy

Run classifier in parallel with heuristics (log differences, no changes to pipeline):

bash
./run.sh shadow-deploy \
  --model models/document_type \
  --target s00_profile_detector \
  --duration 7d \
  --log-path logs/shadow_deploy.jsonl

Step 5: Deploy

If metrics pass, deploy to production:

bash
./run.sh deploy \
  --model models/document_type \
  --target extractor \
  --confidence-threshold 0.8

Configuration Files

Document Type Classifier (configs/document_type.yaml)

yaml
task: document_type
type: vision

classes:
  - arxiv_scientific
  - requirements_spec
  - legal_contract
  - general

model:
  architecture: efficientnet_b0
  pretrained: true
  input_size: 224
  num_pages: 3 # First 3 pages

training:
  epochs: 20
  batch_size: 16
  learning_rate: 0.001
  optimizer: adam

confidence:
  threshold: 0.8 # Route to heuristic if below

feedback:
  mode: grpo # or 'sft'
  reward_fn: validate_preset_accuracy
  baseline: heuristic

Requirements Classifier (configs/requirements.yaml)

yaml
task: requirement_detection
type: text

classes:
  - requirement
  - non_requirement

model:
  architecture: bert-base-uncased
  max_length: 256

training:
  epochs: 10
  batch_size: 32
  learning_rate: 2e-5

confidence:
  threshold: 0.9 # High precision needed

Architecture Details

Vision Classifier Template

python
import timm
import torch.nn as nn

class VisionClassifier(nn.Module):
    def __init__(self, num_classes, backbone="efficientnet_b0"):
        super().__init__()
        self.backbone = timm.create_model(
            backbone,
            pretrained=True,
            num_classes=0
        )
        self.classifier = nn.Linear(
            self.backbone.num_features,
            num_classes
        )
        self.confidence_head = nn.Sequential(
            nn.Linear(self.backbone.num_features, 1),
            nn.Sigmoid()
        )

    def forward(self, x):
        features = self.backbone(x)
        logits = self.classifier(features)
        confidence = self.confidence_head(features)
        return logits, confidence

Confidence-Based Routing

python
class ConfidenceRouter:
    def __init__(self, classifier, heuristic_fn, threshold=0.8):
        self.classifier = classifier
        self.heuristic = heuristic_fn
        self.threshold = threshold

    def predict(self, input_data):
        pred, confidence = self.classifier(input_data)

        if confidence >= self.threshold:
            return {"prediction": pred, "source": "classifier"}
        else:
            # Fallback to heuristic
            return {
                "prediction": self.heuristic(input_data),
                "source": "heuristic",
                "classifier_confidence": confidence  # Log anyway
            }

Data Collection Strategy

Automatic Labeling

Mine labels from successful pipeline outputs:

S00 (Document Type):

  • Extract preset from 00_profile.json → label
  • Extract first 3 pages as images → input

S05 (Table Strategy):

  • Extract strategy from 05_tables.json → label
  • Extract table region image → input
  • Use success/failure as GRPO reward

S08 (Requirements):

  • Bootstrap with regex-matched sentences → positive examples
  • Random sentences without modal verbs → negative examples
  • Manual review of edge cases

Label Validation

python
def validate_labels(labels_path, sample_size=100):
    """Manual review of random sample for quality check."""
    labels = load_jsonl(labels_path)
    sample = random.sample(labels, sample_size)

    correct = 0
    for item in sample:
        print(f"Input: {item['input']}")
        print(f"Predicted label: {item['label']}")
        response = input("Correct? (y/n): ")
        if response.lower() == 'y':
            correct += 1

    accuracy = correct / sample_size
    print(f"Label quality: {accuracy:.1%}")
    return accuracy >= 0.95  # Threshold for good labels

GRPO Training (Execution Feedback)

Reward Functions

S00 Document Type:

python
def reward_preset_accuracy(predicted_preset, pdf_path):
    """Reward = 1.0 if pipeline succeeds, 0.0 if fails."""
    result = run_pipeline(pdf_path, preset=predicted_preset)
    return 1.0 if result.success else 0.0

S08 Requirements:

python
def reward_requirement_extraction(predicted_requirements, ground_truth):
    """Reward = F1 score vs ground truth."""
    precision = len(predicted & ground_truth) / len(predicted)
    recall = len(predicted & ground_truth) / len(ground_truth)
    f1 = 2 * (precision * recall) / (precision + recall)
    return f1

Training Loop

python
from trl import GRPOTrainer

trainer = GRPOTrainer(
    model=classifier,
    reward_fn=reward_preset_accuracy,
    baseline_fn=heuristic_preset_detection,
    num_iterations=100,
    batch_size=16
)

trainer.train()

Integration Example: S00 Document Type

Before (Heuristics Only)

python
def detect_preset(pdf_path):
    # 47 regex patterns for section numbering
    # Formula detection regex
    # Font-size analysis
    # ~85% accuracy, confidence often <0.8
    return {"preset": "arxiv", "confidence": 0.7}

After (Classifier + Fallback)

python
def detect_preset(pdf_path):
    # Try classifier first
    result = preset_classifier.predict(pdf_path)

    if result["confidence"] >= 0.8:
        return result  # Use classifier
    else:
        # Fallback to heuristics
        return detect_preset_heuristic(pdf_path)

Benefits:

  • Higher accuracy (90%+ vs 85%)
  • Faster (single forward pass vs 47 regex patterns)
  • Continuous improvement (retrain with production data)

Observability

Metrics Logged

json
{
  "timestamp": "2026-02-08T10:53:00Z",
  "task": "document_type",
  "input_id": "doc_abc123",
  "classifier_prediction": "arxiv_scientific",
  "classifier_confidence": 0.92,
  "heuristic_prediction": "general",
  "heuristic_confidence": 0.65,
  "source_used": "classifier",
  "execution_result": "success",
  "inference_time_ms": 45
}

Monitoring Dashboard

Track over time:

  • Classifier usage rate (% using classifier vs fallback)
  • Accuracy comparison (classifier vs heuristic)
  • Inference latency (p50, p95, p99)
  • Fallback rate (low confidence → heuristic)

Files

create-classifier/
├── SKILL.md                    # This file
├── run.sh                      # CLI wrapper
├── .env.example               # Configuration template
├── scripts/
│   ├── collect_labels.py      # Mine labels from pipeline
│   ├── train_vision.py        # Vision classifier training
│   ├── train_text.py          # Text classifier training
│   ├── evaluate.py            # Evaluation & comparison
│   └── deploy.py              # Generate inference code
├── templates/
│   ├── vision_classifier.py   # EfficientNet/DiT template
│   ├── text_classifier.py     # BERT/RoBERTa template
│   └── hybrid_classifier.py   # Multi-modal template
├── configs/
│   ├── document_type.yaml     # S00 preset detection
│   ├── requirements.yaml      # S08 requirement detection
│   └── citation_filter.yaml   # S04 citation filtering
└── utils/
    ├── data_collection.py     # Dataset utilities
    ├── confidence_routing.py  # Routing logic
    └── shadow_deploy.py       # Parallel testing

Dependencies

toml
[tool.uv.dependencies]
torch = "^2.0.0"
timm = "^0.9.0"              # Vision models
transformers = "^4.30.0"     # Text models
trl = "^0.7.0"               # GRPO training
pillow = "^10.0.0"           # Image processing
pyyaml = "^6.0"
loguru = "^0.7.0"

Troubleshooting

Low Accuracy (<90%)

Causes:

  • Insufficient training data (need >1000 examples per class)
  • Class imbalance (e.g., 90% arxiv, 10% legal)
  • Poor label quality

Solutions:

  • Collect more data from corpus
  • Apply class balancing (oversample minority, undersample majority)
  • Manual review and relabeling of subset

Slow Inference (>100ms)

Causes:

  • Large model (DiT is 85M params)
  • CPU inference (no GPU available)

Solutions:

  • Use smaller model (EfficientNet-B0 is 5M params)
  • Quantize to ONNX (2-3x speedup)
  • Batch inference (process multiple pages together)
  • Cache predictions (don't re-classify same document)

High Fallback Rate (>30%)

Causes:

  • Classifier not confident on edge cases
  • Threshold too high (>0.9)

Solutions:

  • Lower confidence threshold (try 0.7)
  • Add more diverse training data
  • Ensemble multiple models (vote on prediction)

Next Steps

  1. Collect data for S00 document type classifier
  2. Train baseline EfficientNet-B0 model
  3. Shadow deploy for 1 week, compare vs heuristics
  4. Deploy if accuracy >90%
  5. Repeat for S08 requirements classifier

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