[ARCH] User-facing broker selector and trading-mode indicator

[Ibrahim-3d]

Context

The codebase supports multiple brokers via pt_exchange_abstraction.py and ExchangeFactory.register_exchange() (Robinhood, Binance, Kraken, KuCoin, plus ccxt-backed exchanges). We are not replacing Robinhood; we are giving users the ability to pick the broker they already use.

What's missing is a clear user-facing mechanism to:

1. Pick which broker is active for live trading.
2. See at a glance whether the app is in Paper or Live mode, and which broker is wired up.
3. Persist that selection across restarts.

This mirrors the existing paper-mode visibility pattern but extends it to broker choice.

Goal

A dedicated Trading Mode settings panel plus a always-visible status indicator. No order, balance fetch, or position call may bypass the active-broker selector.

Scope

Settings panel (in pt_settings_manager.py and a new Settings tab section)

• Trading Mode radio group: Paper Trading (default) | Live Trading
• Active Broker radio group (enabled only when Live): Robinhood | Binance | Kraken | KuCoin
  • Each broker row shows: connection status (Connected as: ****<last 4> / Not configured)
  • Each broker row has a Test connection button
  • Binance row adds a Testnet toggle (uses testnet.binance.vision base URL)
• Confirm switch to Live modal: explicit Yes, I understand real money is at risk checkbox before activating Live mode

Persistent settings keys (new)

• trading.mode enum: paper | live (default paper)
• trading.active_broker enum: robinhood | binance | kraken | kucoin | null (null = paper only)
• trading.binance_testnet bool (default true when first enabling Binance)

Always-visible status bar widget (pt_hub.py)

A new widget in the main window header, distinct colors:

• [PAPER] green background when paper
• [LIVE: Binance (testnet)] amber background when live + testnet
• [LIVE: Binance] red background when live + real money
• [LIVE: Robinhood] red background when live + Robinhood

Clicking the widget opens the Trading Mode settings panel.

Backend routing

• Add get_active_broker() -> AbstractExchange to pt_settings_manager.py (or a thin pt_broker_router.py). Looks up persisted broker, instantiates via ExchangeFactory, returns it.
• Audit and update every order/balance/position call site in:
  • pt_trader.py
  • order_execution_engine.py
  • dca_automation.py
  • advanced_order_automation.py
  • conditional_order_logic.py
  • pt_paper_trading.py (paper mode shortcut)
• Paper mode: route to PaperTradingAccount. Live mode: route to get_active_broker(). Never bypass.

Tests

• Settings round-trip (encrypt/decrypt mode + active broker)
• get_active_broker() returns correct concrete class
• Switching mid-session does not lose in-flight orders (drain queue before swap)
• UI test: status-bar color/text matches persisted state

Security/audit

• Log every Trading Mode change via pt_security_logger.log_config_change() with correlation ID
• Log every Active Broker change with correlation_context() so audit trail links the switch to subsequent orders

Out of scope

• New broker implementations (Binance's spot completion is tracked in [FEATURE] Implement Binance order execution (place_order, get_balance, cancel_order) #85 / PR [FEATURE] Implement Binance authenticated order execution - closes #85 #92)
• Migration of legacy hard-coded Robinhood call sites to the abstraction layer (separate refactor)
• Multi-broker simultaneous trading (one active broker at a time for v1)

Acceptance criteria

• User can pick Paper or Live mode and persist selection
• User can pick active broker when Live, with per-broker connection status visible
• Status bar visible on every screen, color-coded, click-through to settings
• Binance testnet toggle works and routes orders to testnet.binance.vision
• All order/balance/position call sites route through get_active_broker() or paper account, never directly
• Audit log shows mode + broker change events with correlation IDs
• Confirm modal blocks accidental Live activation
• Switching mode mid-session drains in-flight orders cleanly

Why this blocks Binance live

PR #92 implements the Binance REST surface, but until this issue lands there is no way for a user to actually choose Binance as their broker without code changes. Merging Binance live without the selector risks orders going to the wrong venue.

Related

• [TESTING] Create end-to-end paper trading demo script #87 paper trading demo (closes via PR [FEATURE] Paper mode in hub: blue palette, banner, sample runner - closes #86 #87 #90)
• [FEATURE] Implement Binance order execution (place_order, get_balance, cancel_order) #85 Binance order execution (in progress via PR [FEATURE] Implement Binance authenticated order execution - closes #85 #92)
• Phase 2 [FEATURE] Complete order execution engine integration #56 order execution