feat: harden trading SDK examples

examples/nonce_cache/README.md

@@ -0,0 +1,17 @@
+# Durable Nonce
+
+[中文](README_CN.md)
+
+Shows how to fetch a durable nonce and attach it to a PumpFun transaction triggered by a `sol-parser-sdk` gRPC event.
+
+> This is a live-transaction template. Set `PRIVATE_KEY`, replace `use_your_nonce_account_here`, and configure RPC and gRPC before running. The nonce authority must match the signer.
+
+```bash
+export GRPC_ENDPOINT=https://your-yellowstone.example
+export GRPC_AUTH_TOKEN=optional-token
+cargo run --package nonce_cache
+```
+
+Do not set both a recent blockhash and a durable nonce in new code; use `SimpleBuyParams::with_durable_nonce`. Refresh nonce state immediately before construction, and never reuse consumed nonce state. A nonce extends transaction validity but does not preserve quote freshness.
+
+See [Nonce Cache](../../docs/NONCE_CACHE.md).

examples/nonce_cache/README_CN.md

@@ -0,0 +1,17 @@
+# Durable Nonce
+
+[English](README.md)
+
+展示如何获取 durable nonce，并附加到由 `sol-parser-sdk` gRPC 事件触发的 PumpFun 交易。
+
+> 这是会发送真实交易的模板。运行前设置 `PRIVATE_KEY`，替换 `use_your_nonce_account_here`，并配置 RPC 和 gRPC；nonce authority 必须与签名者匹配。
+
+```bash
+export GRPC_ENDPOINT=https://your-yellowstone.example
+export GRPC_AUTH_TOKEN=optional-token
+cargo run --package nonce_cache
+```
+
+新代码不要同时设置 recent blockhash 和 durable nonce，应使用 `SimpleBuyParams::with_durable_nonce`。构建前刷新 nonce，已消费状态不可复用。Nonce 只延长交易有效期，不会保持报价新鲜。
+
+参见[Nonce Cache 说明](../../docs/NONCE_CACHE_CN.md)。

examples/nonce_cache/src/main.rs

@@ -23,7 +23,7 @@ use sol_trade_sdk::{
     SolanaTrade,
 };
 use solana_commitment_config::CommitmentConfig;
-use solana_sdk::{pubkey::Pubkey, signature::Keypair};
+use solana_sdk::pubkey::Pubkey;
 
 static ALREADY_EXECUTED: AtomicBool = AtomicBool::new(false);
 
@@ -104,7 +104,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
 
 async fn create_solana_trade_client() -> AnyResult<SolanaTrade> {
     println!("🚀 Initializing SolanaTrade client...");
-    let payer = Keypair::from_base58_string("use_your_payer_keypair_here");
+    let payer = sol_trade_sdk::common::keypair::load_keypair_from_env("PRIVATE_KEY")?;
     let rpc_url = "https://api.mainnet-beta.solana.com".to_string();
     let commitment = CommitmentConfig::confirmed();
     let swqos_configs: Vec<SwqosConfig> = vec![SwqosConfig::Default(rpc_url.clone())];