diff --git a/bin/aas.mjs b/bin/aas.mjs
index b6ddc43..7f80208 100644
--- a/bin/aas.mjs
+++ b/bin/aas.mjs
@@ -451,6 +451,7 @@ export async function runDemo(args = [], options = {}) {
     proveStarted = true;
     const prove = await (options.runProveFn ?? runProve)(scenario, { depsDir: paths.deps, runner: options.runner });
     stages.prove = stageRecord(prove.ok ? "passed" : "failed", { raw: prove.raw });
+    if (!prove.ok) exitCode = 1;
     report.stages.prove = {
       status: stages.prove.status,
       scenario,
diff --git a/test/stack.test.mjs b/test/stack.test.mjs
index 25d274f..ebbb419 100644
--- a/test/stack.test.mjs
+++ b/test/stack.test.mjs
@@ -183,6 +183,17 @@ test("an unresolved act outcome is sent to proof", async () => {
   assert.equal(result.report.stages.prove.triggered_by, "act_outcome=null");
 });
 
+test("an unsuccessful proof fails the run", async () => {
+  const outputRoot = tempRoot();
+  const result = await runDemo(["--response", "pass", "--dispute"], stubOptions(outputRoot, {
+    runId: "failed-proof-run",
+    runProveFn: async () => ({ ok: false, raw: { ok: false, result: {} }, status: 0 }),
+  }));
+  assert.equal(result.exitCode, 1);
+  assert.equal(result.manifest.exit_code, 1);
+  assert.equal(result.manifest.stages.prove.status, "failed");
+});
+
 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, {