feat: add typed engine run exits

crates/agen/examples/engine_cancel_demo.rs

@@ -4,7 +4,7 @@
 
 use agen::llm_client::scheme::{Scheme, anthropic::AnthropicScheme};
 use agen::llm_client::transport::{HttpTransport, ResolvedAuth};
-use agen::{Engine, EngineResult};
+use agen::{Engine, EngineRunExit, StopReason};
 use std::time::Duration;
 
 #[tokio::main]
@@ -45,16 +45,15 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
 
     println!("📡 Sending request to LLM...");
 
-    match engine.run("Tell me a very long story about a brave knight. Make it as detailed as possible with many paragraphs.").await {
-        Ok(out) => match out.result {
-            EngineResult::Finished => println!("✅ Task completed normally"),
-            EngineResult::Paused => println!("⏸️  Task paused"),
-            EngineResult::LimitReached => println!("🔒 Turn limit reached"),
-            EngineResult::Yielded => println!("↩️  Task yielded"),
-        },
-        Err(e) => {
-            println!("❌ Task error: {}", e);
+    let output = engine.run("Tell me a very long story about a brave knight. Make it as detailed as possible with many paragraphs.").await;
+    match output.result {
+        EngineRunExit::Finished => println!("✅ Task completed normally"),
+        EngineRunExit::Paused => println!("⏸️  Task paused"),
+        EngineRunExit::Yielded => println!("↩️  Task yielded"),
+        EngineRunExit::Interrupted(StopReason::LimitReached) => {
+            println!("🔒 Turn limit reached")
         }
+        EngineRunExit::Interrupted(reason) => println!("❌ Task interrupted: {reason:?}"),
     }
 
     println!("\n✨ Demo complete!");

crates/agen/examples/engine_cli.rs

@@ -39,7 +39,7 @@ use tracing::info;
 use tracing_subscriber::EnvFilter;
 
 use agen::{
-    Engine,
+    Engine, EngineRunExit, StopReason,
     interceptor::{Interceptor, PostToolAction, ToolResultInfo},
     llm_client::{
         LlmClient,
@@ -476,12 +476,9 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
 
     // One-shot mode
     if let Some(prompt) = args.prompt {
-        match engine.run(&prompt).await {
-            Ok(_) => {}
-            Err(e) => {
-                eprintln!("\n❌ Error: {}", e);
-                std::process::exit(1);
-            }
+        let output = engine.run(&prompt).await;
+        if let EngineRunExit::Interrupted(StopReason::Unexpected(error)) = output.result {
+            eprintln!("\n❌ Error: {error}");
         }
 
         return Ok(());
@@ -500,13 +497,8 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
         return Ok(());
     }
 
-    let mut locked = match engine.run(first_input).await {
-        Ok(out) => out.engine,
-        Err(e) => {
-            eprintln!("\n❌ Error: {}", e);
-            return Ok(());
-        }
-    };
+    let output = engine.run(first_input).await;
+    let mut locked = output.engine;
 
     loop {
         print!("\n👤 You: ");
@@ -525,11 +517,8 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
             break;
         }
 
-        match locked.run(input).await {
-            Ok(_) => {}
-            Err(e) => {
-                eprintln!("\n❌ Error: {}", e);
-            }
+        if let EngineRunExit::Interrupted(StopReason::Unexpected(error)) = locked.run(input).await {
+            eprintln!("\n❌ Error: {error}");
         }
     }