> ## Documentation Index
> Fetch the complete documentation index at: https://docs.quantdesk.app/llms.txt
> Use this file to discover all available pages before exploring further.

# Unified zero-copy portfolio architecture in V2

> How QuantDesk V2 consolidates balances, positions, and orders into one zero-copy PortfolioAccount PDA for sub-millisecond reads and atomic execution.

# Unified zero-copy portfolio

QuantDesk V2 introduces a **unified zero-copy portfolio** architecture. Unlike V1, which managed separate Program Derived Addresses (PDAs) for balances, positions, and orders, V2 consolidates all trader state into a single, high-performance account.

## The V1 to V2 shift

### V1: fragmented state

In V1, every position and open order required its own account creation and rent payment. This led to:

* **Higher latency:** multiple RPC calls to fetch complete state.
* **Complexity:** higher risk of state divergence.
* **Cost:** multiple rent-exempt deposits.

### V2: the unified advantage

V2 uses a single `PortfolioAccount` PDA that acts as a high-density, zero-copy buffer.

* **Atomic execution:** balances, positions, and open orders update in a single transaction.
* **Sub-ms parsing:** with zero-copy (via `bytemuck`), the UI and bots read the entire account state without expensive deserialization.
* **Deterministic PDAs:** each user has one `PortfolioAccount` per subaccount index, derived from `[portfolio, wallet_pubkey, subaccount_index]` seeds.

## Architectural benefits

### Performance

Zero-copy means the SBF program interacts directly with the account's memory. For you, that means faster order placement and liquidation protection.

### Reliability

With all state consolidated, there is no "position drift." If the account exists, the state is consistent across balances, margins, and active trades.

### Devnet readiness

The V2 unified portfolio is the core of our devnet deployment, so what you see in the terminal is a faithful representation of your on-chain state.

## Execution and matching

V2 pairs the unified portfolio with **crankless on-chain matching** — trades settle atomically against BST order-book slabs inside each `MarketV2` account. For execution flow, seat gates, and depth reading, see [Reading the order book](../trading/order-book#v2-crankless-bst-matching).

## Architecture diagram (V2 unified model)

```mermaid theme={"theme":{"light":"github-light","dark":"dracula"}}
flowchart TB
  subgraph UserState["Per user"]
    PA[PortfolioAccount PDA<br/>balances · positions · orders]
  end

  subgraph MarketState["Per market"]
    MV[MarketV2 account]
    BID[Bids BST slab]
    ASK[Asks BST slab]
    MV --- BID
    MV --- ASK
  end

  subgraph Social["Quant Hub optional"]
    QV[Quant Vault]
    VP[Vault portfolio PDA]
    LD[Authorized leader]
    LD --> QV
    QV --> VP
  end

  PA <-->|place_order_v2| MV
```

This replaces the V1 pattern of separate position PDAs per trade. One portfolio, one atomic update path.