[codex] Tighten REST retries and exchange factory

docs/ARCHITECTURE.md

@@ -105,8 +105,8 @@ Risks and debt:
 - `ExchangeConnector` is not the best documentation surface today; prefer the smaller capability traits when writing examples or new code.
 - `src/lib.rs` re-exports only part of the exchange surface. The reliable public namespace is still `lotusx::exchanges::<exchange>`.
 - Some legacy compatibility constructors keep old names or parameters while delegating to the new builders. Prefer the direct `build_connector*` functions in new code.
-- `ExchangeFactory` is for latency tests and demos, not the canonical construction path for every production connector. In particular, check exchange-specific builders when credentials, passphrases, testnet URLs, or custom base URLs matter.
-- `RestClientConfig::max_retries` is currently configuration intent, not a guarantee that every request path retries.
+- `ExchangeFactory` is for latency tests and demos. It now delegates Bybit and OKX creation through the exchange builders, but production code should still prefer exchange-specific builders when credentials, passphrases, or custom behavior matter.
+- `RestClientConfig::max_retries` applies to retryable GET and DELETE failures. POST requests are not automatically retried to avoid repeating order-style side effects.
 - `KlineInterval` includes exchange-specific formatting helpers, so a small amount of exchange dialect knowledge leaks into the shared type layer.
 - `src/exchanges/okx/` is implemented, but `src/exchanges/okx_perp/` is an empty, unregistered directory. Treat OKX perpetual as not implemented.
 - Some tests depend on public exchange APIs and can fail because of network or upstream API changes.

examples/custom_latency_test.rs

@@ -56,7 +56,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
             markets_metrics: markets_metrics.clone(),
             klines_metrics: markets_metrics.clone(), // Simplified for demo
             websocket_connection_time: std::time::Duration::from_millis(100),
-            websocket_first_message: std::time::Duration::from_millis(1000),
+            websocket_first_message: std::time::Duration::from_secs(1),
             websocket_success_rate: 1.0,
             tick_to_trade_latency: std::time::Duration::from_millis(50),
             market_impact_bps: calculate_market_impact(&markets_metrics),

examples/okx_example.rs

@@ -53,9 +53,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
 
 /// Create OKX configuration from environment variables or use defaults
 fn create_config() -> ExchangeConfig {
-    let testnet = env::var("OKX_TESTNET")
-        .map(|v| v.to_lowercase() == "true")
-        .unwrap_or(false);
+    let testnet = env::var("OKX_TESTNET").is_ok_and(|v| v.to_lowercase() == "true");
 
     // Create config with credentials if available, otherwise use defaults
     let api_key = env::var("OKX_API_KEY").unwrap_or_else(|_| "your_api_key".to_string());