🧠 Domain & Feature State

Status: Implemented (Feb 2026)

The Domain & Feature State houses the heavy computational stores that implement core business logic, such as portfolio calculation, transaction ledgers, and foreign exchange (FX) graph routing. These stores often consume data from both Reference State and Registries.

🗂️ Stores

Store	Location	Purpose
portfolioStore	portfolio/portfolioStore.svelte.ts	The most complex store. Calculates holdings, performance, and allocations by combining user transactions with live asset prices and FX rates.
txStore	transactions/txStore.svelte.ts	The master ledger of user transactions. Supports infinite scrolling, complex filtering, and bulk operations.
currencyGraphStore	currencyGraphStore.ts	Caches the multi-directed currency graph used by the DFS algorithm to find conversion routes (FX Chain Algorithm).
fxCardInversionStore	fx/fxCardInversionStore.ts	UI-specific domain state tracking which FX pairs the user has "flipped" visually (e.g., viewing USD/EUR instead of EUR/USD).

📐 Architecture & Flow (Portfolio Calculation)

The portfolioStore acts as a central aggregator. It does not fetch data directly; instead, it observes other stores and reactively recalculates the entire portfolio whenever inputs change.

---
config:
  layout: elk
---
graph TD
    subgraph Inputs ["Data Sources"]
        TX["📝 txStore (User Ledger)"]
        Rates["⚡ fxStoreRegistry (Live FX Rates)"]
        Prices["📈 assetPriceRegistry (Live Asset Prices)"]
        Set["⚙️ settingsStore (Base Currency)"]
    end

    Port["🧠 portfolioStore.svelte.ts ($derived aggregations)"]

    subgraph Outputs ["UI Views"]
        Dash["📊 Dashboard (Total Value, Allocations)"]
        Hold["💼 Holdings Table (Per-Asset PL, Value)"]
    end

    TX -->|Raw Trades| Port
    Rates -->|Conversion Factors| Port
    Prices -->|Current Valuation| Port
    Set -->|Target Currency| Port

    Port ===>|Computed Metrics| Dash
    Port ===>|Computed Metrics| Hold

🧮 Portfolio Reactivity

Because portfolioStore is built using Svelte 5 Runes ($derived), it recalculates automatically and efficiently: 1. When txStore adds a new transaction, the total shares for that asset are updated. 2. When the WebSocket pushes a new price to the assetPriceRegistry for that asset, the "Current Value" metric recalculates. 3. If the asset is in USD and the user's settingsStore base currency is EUR, the value is passed through the live rate provided by fxStoreRegistry. 4. The Dashboard instantly reflects the new Net Worth.