Fix missing exit code check for streaming prepare command

The streaming version of run_stream() did not return exit code
information, so the prepare command in DefaultProvider would proceed
even if the command failed with non-zero exit code.

Changes:
- Add ExitCode(i32) variant to OutputLine enum
- Modify ShellConnector::run_stream() to yield exit code after
  stdout/stderr complete
- Check exit code in DefaultProvider::from_config() and return
  ProviderError::ExecFailed if prepare command fails
- Handle new ExitCode variant in output callbacks

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: jacobkirmayer-imbue

src/connector.rs

@@ -420,7 +420,16 @@ impl Connector for ShellConnector {
 
         let combined = futures::stream::select(stdout_stream, stderr_stream);
 
-        Ok(Box::pin(combined))
+        // After stdout/stderr close, wait for child and yield exit code
+        let exit_stream = futures::stream::once(async move {
+            let exit_code = match child.wait().await {
+                Ok(status) => status.code().unwrap_or(-1),
+                Err(_) => -1,
+            };
+            OutputLine::ExitCode(exit_code)
+        });
+
+        Ok(Box::pin(combined.chain(exit_stream)))
     }
 }
 

src/orchestrator.rs

@@ -424,6 +424,7 @@ where
                         let callback: OutputCallback = Arc::new(|test_id, line| match line {
                             OutputLine::Stdout(s) => println!("[{}] {}", test_id, s),
                             OutputLine::Stderr(s) => eprintln!("[{}] {}", test_id, s),
+                            OutputLine::ExitCode(_) => {}
                         });
                         runner = runner.with_output_callback(callback);
                     }

src/orchestrator/runner.rs

@@ -228,6 +228,7 @@ impl<'a, S: Sandbox, D: TestFramework> TestRunner<'a, S, D> {
                                         stderr.push_str(s);
                                         stderr.push('\n');
                                     }
+                                    OutputLine::ExitCode(_) => {}
                                 }
                             }
                             None => break, // Stream ended
@@ -253,6 +254,7 @@ impl<'a, S: Sandbox, D: TestFramework> TestRunner<'a, S, D> {
                         stderr.push_str(s);
                         stderr.push('\n');
                     }
+                    OutputLine::ExitCode(_) => {}
                 }
             }
         }

src/provider.rs

@@ -397,13 +397,16 @@ impl ExecResult {
 /// A single line of output from a streaming command.
 ///
 /// Used with [`Sandbox::exec_stream`] to process output in real-time.
-/// Each line is tagged with its source (stdout or stderr).
+/// Each line is tagged with its source (stdout or stderr), or indicates
+/// the final exit code of the command.
 #[derive(Debug, Clone)]
 pub enum OutputLine {
     /// A line from standard output.
     Stdout(String),
     /// A line from standard error.
     Stderr(String),
+    /// The exit code of the command (yielded last, after all output).
+    ExitCode(i32),
 }
 
 /// A stream of output lines from a command.

src/provider/default.rs

@@ -119,6 +119,7 @@ impl DefaultProvider {
 
             let mut stream = connector.run_stream(&full_prepare_cmd).await?;
             let mut last_stdout_line = String::new();
+            let mut exit_code = 0;
 
             while let Some(line) = stream.next().await {
                 match line {
@@ -129,9 +130,19 @@ impl DefaultProvider {
                     OutputLine::Stderr(s) => {
                         eprintln!("  {}", s);
                     }
+                    OutputLine::ExitCode(code) => {
+                        exit_code = code;
+                    }
                 }
             }
 
+            if exit_code != 0 {
+                return Err(ProviderError::ExecFailed(format!(
+                    "Prepare command failed with exit code {}",
+                    exit_code
+                )));
+            }
+
             // Image id is the last line of stdout
             let image_id = last_stdout_line.trim().to_string();