Treat nonzero child JSON as failed stages

bin/aas.mjs

@@ -141,6 +141,15 @@ function booleanField(payload, field, label) {
   return payload[field];
 }
 
+function parseStageJson(label, result) {
+  try {
+    return parseJsonOutput(result.stdout, label);
+  } catch (error) {
+    if (result.status !== 0) throw childProcessError(label, result);
+    throw error;
+  }
+}
+
 function pythonCandidates() {
   if (process.platform === "win32") {
     return [["py", ["-3"]], ["python", []], ["python3", []]];
@@ -195,14 +204,10 @@ export function runDecide(
       lastError = result.error;
       continue;
     }
+    const evaluation = parseStageJson("decide", result);
     if (result.status !== 0) {
-      const payload = (result.stdout || "").trim();
-      if (payload.startsWith("{")) {
-        return { ok: false, raw: parseJsonOutput(payload, "decide"), status: result.status };
-      }
-      throw childProcessError("decide", result);
+      return { ok: false, raw: evaluation, status: result.status };
     }
-    const evaluation = parseJsonOutput(result.stdout, "decide");
     return { ok: booleanField(evaluation, "passed", "decide"), raw: evaluation, status: 0 };
   }
   throw new Error(`Python not found for decide stage${lastError ? ` (${lastError.code ?? "spawn-error"})` : ""}`);
@@ -237,8 +242,9 @@ export function runProve(
     [cli, "simulate", "--scenario", scenario],
     { cwd: join(depsDir, "mandatebound") },
   );
-  if (result.status !== 0) throw childProcessError("prove", result);
-  const payload = parseJsonOutput(result.stdout, "prove");
+  if (result.error) throw childProcessError("prove", result);
+  const payload = parseStageJson("prove", result);
+  if (result.status !== 0) return { ok: false, raw: payload, status: result.status };
   return { ok: booleanField(payload, "ok", "prove"), raw: payload, status: 0 };
 }
 

test/stack.test.mjs

@@ -153,6 +153,56 @@ test("decide and prove reject non-boolean success fields", () => {
   assert.throws(() => runProve("unused", { runner }), /boolean ok field/);
 });
 
+test("decide reads logged JSON on a nonzero exit", () => {
+  const result = runDecide("unused", {
+    runner: () => ({
+      status: 1,
+      stdout: 'evaluating policy\n{\n  "passed": false,\n  "policy_id": "refund-v1"\n}\n',
+      stderr: "",
+      error: null,
+    }),
+  });
+  assert.equal(result.ok, false);
+  assert.equal(result.status, 1);
+  assert.equal(result.raw.policy_id, "refund-v1");
+});
+
+test("prove treats nonzero JSON as an unsuccessful proof", () => {
+  const result = runProve("unused", {
+    runner: () => ({
+      status: 2,
+      stdout: '{"ok":false,"error":{"code":"ALB_CLI_USAGE","message":"Simulate accepts one scenario."}}\n',
+      stderr: '{"level":"error","code":"ALB_CLI_USAGE"}\n',
+      error: null,
+    }),
+  });
+  assert.equal(result.ok, false);
+  assert.equal(result.status, 2);
+  assert.equal(result.raw.error.code, "ALB_CLI_USAGE");
+});
+
+test("prove fail-closes a nonzero payload that claims success", () => {
+  const result = runProve("unused", {
+    runner: () => ({
+      status: 5,
+      stdout: '{"ok":true,"result":{}}\n',
+      stderr: "",
+      error: null,
+    }),
+  });
+  assert.equal(result.ok, false);
+  assert.equal(result.status, 5);
+});
+
+test("prove still throws when a nonzero child has no JSON", () => {
+  assert.throws(
+    () => runProve("unused", {
+      runner: () => ({ status: 2, stdout: "simulate failed\n", stderr: "", error: null }),
+    }),
+    /exited with status 2/,
+  );
+});
+
 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"),
@@ -233,6 +283,26 @@ test("an unsuccessful proof fails the run", async () => {
   assert.equal(result.manifest.stages.prove.status, "failed");
 });
 
+test("nonzero prove JSON is recorded as a failed proof, not a child-process error", async () => {
+  const outputRoot = tempRoot();
+  const options = stubOptions(outputRoot, { runId: "prove-json-fail-run" });
+  delete options.runProveFn;
+  options.runner = () => ({
+    status: 2,
+    stdout: '{"ok":false,"error":{"code":"ALB_CLI_USAGE","message":"Simulate accepts one scenario."}}\n',
+    stderr: "",
+    error: null,
+  });
+  const result = await runDemo(["--response", "pass", "--dispute"], options);
+  assert.equal(result.exitCode, 1);
+  assert.equal(result.manifest.stages.prove.status, "failed");
+  assert.equal(result.report.stages.prove.ok, false);
+  assert.deepEqual(
+    JSON.parse(readFileSync(join(result.bundleDir, "stages", "prove.json"), "utf8")).error,
+    { code: "ALB_CLI_USAGE", message: "Simulate accepts one scenario." },
+  );
+});
+
 test("child-process errors are visible as safe stage errors and downstream skips", async () => {
   const outputRoot = tempRoot();
   const result = await runDemo(["--response", "pass"], stubOptions(outputRoot, {