Every decision on the record.

@EventSourcedEntity(tag = "order")
class Order {
 
    private boolean placed;
 
    @Decide
    List<Object> handle(PlaceOrder cmd) {
        if (placed) throw new AlreadyPlaced(cmd.orderId());
        return List.of(new OrderPlaced(cmd.orderId(), cmd.totalCents()));
    }
 
    @Evolve
    void on(OrderPlaced e) { placed = true; }
}

@Project(mode = ProjectionMode.INLINE)  // same transaction → read your writes
class OrderSummaryProjection {
 
    @On
    void on(OrderPlaced e, JdbcClient db) {
        db.sql("INSERT INTO order_summary (order_id, total_cents, status) "
             + "VALUES (:id, :total, 'PLACED')")
          .param("id", e.orderId())
          .param("total", e.totalCents())
          .update();
    }
}

@Agent(model = "anthropic:claude-sonnet-4-6",
       budget = @Budget(maxCost = "5.00 EUR"))
class ClaimTriageAgent {
 
    @Tool(description = "Fetch the policyholder's coverage terms")
    CoverageTerms coverage(String policyId) {
        return coverageService.lookup(policyId);
    }
 
    @Guardrail
    Verdict citationsRequired(ReserveRecommendation rec) {
        return rec.citations().isEmpty()
            ? Verdict.block("Recommendation lacks policy citations")
            : Verdict.allow();
    }
}

@DeciderTest(Order.class)
class OrderDeciderTest {
 
    @Test  // no Spring, no database — milliseconds
    void placingTwiceIsRejected(DeciderFixture<Order> fixture) {
        fixture.given(new OrderPlaced("o-42", 1999))
               .when(new PlaceOrder("o-42", 1999))
               .expectException(AlreadyPlaced.class);
    }
}