diff --git a/bin/aas.mjs b/bin/aas.mjs
index 134e608..079fc36 100644
--- a/bin/aas.mjs
+++ b/bin/aas.mjs
@@ -112,22 +112,25 @@ export function parseJsonOutput(text, label) {
   if (!trimmed) {
     throw new Error(`${label} produced empty output.`);
   }
+  let parseError;
+  try {
+    return JSON.parse(trimmed);
+  } catch (error) {
+    parseError = error;
+  }
   const lines = trimmed.split(/\r?\n/).filter((line) => line.trim().length > 0);
-  for (let index = lines.length - 1; index >= 0; index -= 1) {
-    const line = lines[index].trim();
-    if (line.startsWith("{") || line.startsWith("[")) {
+  for (let end = lines.length; end > 0; end -= 1) {
+    if (!/[}\]]$/.test(lines[end - 1].trim())) continue;
+    for (let start = 0; start < end; start += 1) {
+      if (!/^[\[{]/.test(lines[start].trim())) continue;
       try {
-        return JSON.parse(line);
+        return JSON.parse(lines.slice(start, end).join("\n"));
       } catch {
-        // Continue until the complete output is tried.
+        // Keep looking for the last complete JSON range.
       }
     }
   }
-  try {
-    return JSON.parse(trimmed);
-  } catch (error) {
-    throw new Error(`${label} did not return JSON: ${error.message}`);
-  }
+  throw new Error(`${label} did not return JSON: ${parseError.message}`);
 }
 
 function pythonCandidates() {
diff --git a/test/stack.test.mjs b/test/stack.test.mjs
index e577805..f327413 100644
--- a/test/stack.test.mjs
+++ b/test/stack.test.mjs
@@ -6,6 +6,7 @@ import test from "node:test";
 import { fileURLToPath } from "node:url";
 import { loadComponentLock, inspectDependencyDirectory, npmInvocation } from "../scripts/bootstrap.mjs";
 import {
+  parseJsonOutput,
   persistRunBundle,
   resolveComponentProvenance,
   runAct,
@@ -139,6 +140,20 @@ test("act rejects a zero-exit payload without a valid outcome", () => {
   );
 });
 
+test("child output parser accepts logged pretty-printed JSON", () => {
+  assert.deepEqual(
+    parseJsonOutput('starting child\n{\n  "ok": true,\n  "result": { "count": 2 }\n}\n', "fixture"),
+    { ok: true, result: { count: 2 } },
+  );
+});
+
+test("child output parser accepts JSON before a trailing log", () => {
+  assert.deepEqual(
+    parseJsonOutput('{"ok":true}\nchild complete\n', "fixture"),
+    { ok: true },
+  );
+});
+
 test("pass bundle contains stage status, provenance, and only current artifacts", async () => {
   const outputRoot = tempRoot();
   const result = await runDemo(["--response", "pass"], stubOptions(outputRoot, { runId: "pass-run" }));