Add runtime error repair PR example

Author: igorcosta

examples/RuntimeErrorToPullRequest.java

@@ -0,0 +1,106 @@
+import ai.autohand.sdk.sdk.Agent;
+import ai.autohand.sdk.sdk.AgentOptions;
+import ai.autohand.sdk.sdk.RunResult;
+import ai.autohand.sdk.types.Events;
+
+/**
+ * Runtime error to pull request.
+ *
+ * This example shows how an application can capture a runtime error and ask
+ * Autohand to fix it instead of only logging it. Point AUTOHAND_TARGET_REPO at
+ * the application repository that should receive the branch, commit, push, and
+ * pull request.
+ *
+ * Run with:
+ *   AUTOHAND_TARGET_REPO=/path/to/app mvn compile exec:java -Dexec.mainClass="RuntimeErrorToPullRequest"
+ */
+public class RuntimeErrorToPullRequest {
+    record Cart(double subtotal, Customer customer) {}
+    record Customer(String loyaltyTier) {}
+
+    public static void main(String[] args) throws Exception {
+        String targetRepo = getenvOrDefault("AUTOHAND_TARGET_REPO", ".");
+        String cliPath = System.getenv("AUTOHAND_CLI_PATH");
+        String model = System.getenv("AUTOHAND_MODEL");
+        String capturedError = captureRuntimeError();
+
+        Agent agent = Agent.create(AgentOptions.builder()
+            .cwd(targetRepo)
+            .cliPath(cliPath)
+            .model(model)
+            .instructions(String.join("\n",
+                "You are a QA engineering agent that turns production error reports into small repair pull requests.",
+                "Reproduce the failure when the repository makes that possible.",
+                "Fix the root cause, add or update a focused regression test, run the relevant validation command, commit the fix, push a branch, and create a pull request.",
+                "Keep the pull request description concise and include the error signature, the fix summary, and the validation result."))
+            .build());
+
+        try {
+            var run = agent.send(String.join("\n",
+                "A runtime error was captured by the application error boundary.",
+                "Use this error report to repair the application automatically.",
+                "",
+                "Captured error:",
+                "```text",
+                capturedError,
+                "```",
+                "",
+                "Expected user impact:",
+                "A checkout session should still calculate a safe default discount when the customer object is missing.",
+                "",
+                "Please create a pull request with the fix."));
+
+            run.stream(event -> {
+                switch (event) {
+                    case Events.MessageUpdateEvent message -> System.out.print(message.delta());
+                    case Events.ToolStartEvent tool -> System.out.println("\n[tool] " + tool.toolName());
+                    case Events.PermissionRequestEvent permission -> System.out.println("\n[permission] " + permission.tool() + ": " + permission.description());
+                    case Events.ErrorEvent error -> System.err.println("\n[error] " + error.message());
+                    default -> {}
+                }
+            });
+
+            RunResult result = run.waitForResult();
+            System.out.println("\n\nRun " + result.id() + " " + result.status() + ".");
+        } finally {
+            agent.close();
+        }
+    }
+
+    static double checkoutDiscount(Cart cart) {
+        try {
+            if (cart.customer().loyaltyTier().equals("gold")) {
+                return cart.subtotal() * 0.15;
+            }
+            return cart.subtotal() * 0.05;
+        } catch (RuntimeException error) {
+            throw new IllegalStateException("checkout discount failed: " + error.getMessage(), error);
+        }
+    }
+
+    static String captureRuntimeError() {
+        try {
+            checkoutDiscount(new Cart(129, null));
+        } catch (Exception error) {
+            return error + "\n" + stackTrace(error);
+        }
+
+        return String.join("\n",
+            "IllegalStateException: checkout discount failed: Cannot invoke Customer.loyaltyTier() because customer is null",
+            "    at checkout.Discounts.checkoutDiscount(Discounts.java:42)",
+            "    at checkout.Session.createCheckoutSession(Session.java:88)",
+            "Request: POST /checkout",
+            "Payload: {\"subtotal\":129,\"customer\":null}");
+    }
+
+    static String stackTrace(Exception error) {
+        java.io.StringWriter writer = new java.io.StringWriter();
+        error.printStackTrace(new java.io.PrintWriter(writer));
+        return writer.toString();
+    }
+
+    static String getenvOrDefault(String name, String fallback) {
+        String value = System.getenv(name);
+        return value == null || value.isBlank() ? fallback : value;
+    }
+}

src/test/java/ai/autohand/sdk/ExampleCompileTest.java

@@ -27,7 +27,7 @@ void allExamplesCompileAgainstPublishedApi() throws Exception {
                     .toList();
         }
 
-        assertEquals(27, examples.size(), "Keep this aligned with the TypeScript example set.");
+        assertEquals(28, examples.size(), "Keep this aligned with the TypeScript example set.");
 
         var compiler = ToolProvider.getSystemJavaCompiler();
         assertNotNull(compiler, "Run tests with a JDK, not a JRE.");