ML Training Patterns

Your event store is already a dataset. Editions let you generate synthetic scenarios. PyTorch sees the same proto messages your production code handles.

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The Opportunity

Every event in your system carries:

• The state before the decision
• The decision made (command/action)
• The outcome (resulting events)

For supervised learning, this is labeled data. For reinforcement learning, this is experience replay. For anomaly detection, this is the normal distribution.

And you already have it.

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Event Streams as Training Data

Reading Historical Events

illustrative - PyTorch dataset

import torch
from torch.utils.data import IterableDataset

class EventDataset(IterableDataset):
    def __init__(self, domain: str, event_types: list[str]):
        self.domain = domain
        self.event_types = event_types

    def __iter__(self):
        for event_book in stream_events(self.domain, self.event_types):
            # Extract features from state + event
            features = extract_features(event_book)
            label = extract_label(event_book)
            yield torch.tensor(features), torch.tensor(label)

# Use with DataLoader
dataset = EventDataset("hand", ["PlayerActed", "HandComplete"])
loader = DataLoader(dataset, batch_size=32)

Same Proto, Different Context

The proto messages your aggregate handles are the same messages your training pipeline consumes:

illustrative - shared proto messages

# In aggregate
def handle_player_action(cmd: PlayerAction, state: HandState):
    # Business logic
    ...

# In training pipeline
def extract_features(event_book: EventBook) -> np.ndarray:
    state = rebuild_state(event_book)
    # Same HandState, same fields
    return np.array([
        state.pot_size,
        state.player_stack,
        state.position,
        ...
    ])

No translation layer. No ETL. The types are the contract.

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Generating Counterfactuals with Editions

Real history gives you one path. Editions let you explore alternatives.

Example: Poker Bot Training

illustrative - counterfactual generation

def generate_training_data(hand_ids: list[str], n_alternates: int = 10):
    samples = []

    for hand_id in hand_ids:
        # Get the actual outcome
        actual = get_event_book("hand", hand_id)
        samples.append(extract_sample(actual, is_actual=True))

        # Generate counterfactuals
        for i in range(n_alternates):
            action = sample_alternate_action(actual)
            edition = Edition(name=f"train-{hand_id}-{i}")

            # What would have happened?
            result = speculate(
                command=PlayerAction(hand_id=hand_id, action=action),
                edition=edition,
            )

            samples.append(extract_sample(result, is_actual=False))

            # Cleanup
            delete_edition_events(domain="hand", edition=edition.name)

    return samples

Each counterfactual is a complete simulation through your actual aggregate logic—not a simplified model.

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Training Patterns

Supervised Learning

Predict outcomes from state:

illustrative - supervised learning loop

# Labels: did the player win?
# Features: hand state at decision point

model = HandOutcomePredictor()
for features, label in loader:
    pred = model(features)
    loss = criterion(pred, label)
    loss.backward()
    optimizer.step()

Reinforcement Learning

Event history as experience buffer:

illustrative - RL experience buffer

class PokerExperienceBuffer:
    def __init__(self, domain: str):
        self.domain = domain

    def sample(self, batch_size: int):
        hands = sample_hands(self.domain, batch_size)
        experiences = []
        for hand in hands:
            state = extract_state(hand)
            action = extract_action(hand)
            reward = extract_reward(hand)
            next_state = extract_next_state(hand)
            experiences.append((state, action, reward, next_state))
        return experiences

# Use with any RL algorithm
buffer = PokerExperienceBuffer("hand")
for epoch in range(1000):
    batch = buffer.sample(32)
    train_step(agent, batch)

Anomaly Detection

Learn normal patterns, flag deviations:

illustrative - anomaly detection

# Train on historical events
normal_events = stream_events("transactions", ["TransactionCompleted"])
autoencoder = train_autoencoder(normal_events)

# Flag anomalies in real-time via projector
@handles("TransactionCompleted")
def detect_anomaly(event: TransactionCompleted, state):
    features = extract_features(event)
    reconstruction_error = autoencoder.reconstruction_error(features)
    if reconstruction_error > threshold:
        alert(event, reconstruction_error)

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Integration Architecture

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Why Not a Separate ML Pipeline?

Traditional Approach	Angzarr Approach
ETL from production DB	Read events directly
Schema drift issues	Proto is the contract
Stale training data	Real-time event streams
Simulation != production	Same aggregate logic

The event store is the single source of truth for both production and training.

When You Want Isolation

Direct event access works well for many workloads. But if your training jobs are heavy and you need to isolate load from production, ETL to an external store is straightforward:

• Export events to a data lake (S3, GCS, HDFS)
• Replicate to a read replica dedicated to ML workloads
• Stream to a separate analytical store (ClickHouse, BigQuery)

The proto schema travels with the data. Your training code still sees the same messages—just from a different backing store.

Start by training directly against the event store. When load becomes a concern, migrate to isolated infrastructure. No upfront complexity tax.

Replay from External Sources

Events stored in your data warehouse can flow back through Angzarr. Replay them through the same domains to rebuild state, or route them through entirely different domains to test new aggregate logic, run backtests, or generate derived datasets.

The event store doesn't have to be the origin. Any source that produces valid proto messages can feed the system.

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See Also

• Editions — Temporal branching for counterfactuals
• Projections — Building ML feature stores
• Polyglot — Python for ML, Rust for production