chore(pocket-pi): hello acceptance example

README.md

@@ -209,6 +209,9 @@ extensions), TLS `rustls`+`ring` (~0.6 MB), `regex` (~0.5 MB), and QuickJS (~0.5
 ## Build & test
 
 ```sh
+# Acceptance: a self-contained ~8.9 MB binary carrying the whole pi says hello.
+OPENAI_API_KEY=…  cargo run --release --example hello    # → "Hello! Nice to meet you."
+
 # The full pi bundle is committed + embedded, so the whole suite runs with only
 # Rust — no Node, no build step. This includes the offline pi tests: it loads,
 # an extension binds to a session, sessions persist to disk.

crates/pocket-pi/examples/hello.rs

@@ -0,0 +1,56 @@
+//! Dead-simple acceptance: boot the full, embedded pi on a real model and say
+//! hello. This binary carries the WHOLE unmodified pi-coding-agent inside it.
+//!
+//!   OPENAI_API_KEY=…  cargo run --release --example hello
+//!   OPENAI_API_KEY=…  OPENAI_MODEL=gpt-5.6  cargo run --release --example hello
+use pocket_pi::{HostEvent, PiRuntime};
+use std::cell::RefCell;
+use std::io::Write;
+use std::rc::Rc;
+
+fn main() {
+    let key = std::env::var("OPENAI_API_KEY").expect("set OPENAI_API_KEY");
+    let model = std::env::var("OPENAI_MODEL").unwrap_or_else(|_| "gpt-5.6".into());
+
+    // The whole pi is embedded — new() stands it up with no external files.
+    let mut rt = PiRuntime::new().expect("runtime");
+
+    let reply = Rc::new(RefCell::new(String::new()));
+    let r = reply.clone();
+    rt.on_event(move |ev: &HostEvent| match ev.kind.as_str() {
+        "text" => {
+            if let Some(d) = ev.value.get("delta").and_then(|v| v.as_str()) {
+                r.borrow_mut().push_str(d);
+                print!("{d}");
+                std::io::stdout().flush().ok();
+            }
+        }
+        "assistant_text" if r.borrow().is_empty() => {
+            if let Some(t) = ev.value.get("text").and_then(|v| v.as_str()) {
+                *r.borrow_mut() = t.to_string();
+                print!("{t}");
+            }
+        }
+        "error" => eprintln!("\n[error] {}", ev.raw),
+        _ => {}
+    });
+
+    let cfg = serde_json::json!({
+        "provider": "openai", "model": model, "apiKey": key,
+        "maxTokens": 2048,
+        "systemPrompt": "You are a friendly assistant. Be very brief."
+    });
+    eprintln!("booting full pi on {model} …");
+    rt.boot(&cfg.to_string()).expect("boot");
+    eprint!("pi > ");
+    rt.prompt("Say hello in a few words.").expect("prompt");
+    while !rt.is_idle() {
+        rt.pump().expect("pump");
+        std::thread::sleep(std::time::Duration::from_millis(50));
+    }
+    println!();
+    if reply.borrow().trim().is_empty() {
+        eprintln!("(no reply — check OPENAI_API_KEY / proxy)");
+        std::process::exit(1);
+    }
+}