fix(runtime): deliver fire-and-forget notify() when the script throws

runScript drained un-awaited async verbs only after fn(scope) returned, so a
script that threw skipped the drain entirely. The CLI catches that throw and
calls process.exit(1), which kills the in-flight POST — dropping exactly the
notification the operator most wants:

  notify("build failed"); nope();

printed the "notify() -> build failed" line but never delivered it.

Drain in a finally block instead. Promise.allSettled never rejects, so the
script's own error still propagates unchanged.

Author: clawedassistant26

src/runtime.mjs

@@ -144,9 +144,18 @@ export async function runScript(source, opts = {}) {
   const scope = makeScope(registry, ctx, control, pending);
   const body = `with (__scope__) {\n${stripShebang(source)}\n}`;
   const fn = new AsyncFunction("__scope__", body);
-  await fn(scope);
-  // Let any un-awaited async verbs (fire-and-forget notify) finish delivering.
-  if (pending.length) await Promise.allSettled(pending);
+  try {
+    await fn(scope);
+  } finally {
+    // Let any un-awaited async verbs (fire-and-forget notify) finish delivering.
+    //
+    // Drained in `finally`, not after the call: a script that throws has already
+    // queued its notify(), and the CLI's catch calls process.exit(1) — which kills
+    // the in-flight POST. Draining only on the success path silently dropped the
+    // failure ping, i.e. exactly the notification the operator most wants.
+    // allSettled never rejects, so this cannot mask the script's own error.
+    if (pending.length) await Promise.allSettled(pending);
+  }
 
   return { iterations: control.ticks, stopped: control.stopped };
 }

test/runtime-drain-on-throw.test.mjs

@@ -0,0 +1,122 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import { runScript } from "../src/runtime.mjs";
+import { createRegistry } from "../src/registry.mjs";
+
+// A vocabulary whose async verb only records once it has actually settled, the
+// way notify()'s POST only counts once it reaches the app. `delivered` therefore
+// distinguishes "queued" from "really delivered" — the whole point of the drain.
+//
+// The verb resolves on a macrotask (setTimeout), not a microtask: an un-drained
+// promise chained purely off microtasks can still finish by accident before the
+// caller observes anything, which would make these tests pass for the wrong
+// reason. A timer cannot.
+function slowVocab() {
+  const delivered = [];
+  const registry = createRegistry([
+    {
+      name: "notify",
+      summary: "fire-and-forget async verb",
+      run: (_ctx, msg) =>
+        new Promise((resolve) => setTimeout(() => { delivered.push(msg); resolve({ ok: true }); }, 5)),
+    },
+    {
+      name: "reject",
+      summary: "fire-and-forget async verb that fails",
+      run: () => new Promise((_res, rej) => setTimeout(() => rej(new Error("delivery refused")), 5)),
+    },
+    { name: "sync", summary: "blocking verb", run: () => "done" },
+  ]);
+  return { delivered, registry };
+}
+
+test("a fire-and-forget notify still delivers when the script throws", async () => {
+  const { delivered, registry } = slowVocab();
+  await assert.rejects(
+    async () => runScript(`notify("build failed"); nope();`, { commands: registry }),
+    /nope is not defined/
+  );
+  // The failure ping is the one the operator most wants; it must not be dropped.
+  assert.deepEqual(delivered, ["build failed"]);
+});
+
+test("a fire-and-forget notify still delivers when a verb throws", async () => {
+  const { delivered, registry } = slowVocab();
+  registry.register({ name: "explode", run: () => { throw new Error("verb blew up"); } });
+  await assert.rejects(
+    async () => runScript(`notify("half way"); explode();`, { commands: registry }),
+    /verb blew up/
+  );
+  assert.deepEqual(delivered, ["half way"]);
+});
+
+test("every queued notify delivers when the script throws, not just the first", async () => {
+  const { delivered, registry } = slowVocab();
+  await assert.rejects(
+    async () => runScript(`notify("one"); notify("two"); notify("three"); nope();`, { commands: registry }),
+    /nope is not defined/
+  );
+  assert.deepEqual(delivered.sort(), ["one", "three", "two"]);
+});
+
+test("notifies queued inside a while (alive) loop deliver when the script throws", async () => {
+  const { delivered, registry } = slowVocab();
+  await assert.rejects(
+    async () => runScript(`while (alive) { notify("tick"); } nope();`, { commands: registry, max: 3 }),
+    /nope is not defined/
+  );
+  assert.deepEqual(delivered, ["tick", "tick", "tick"]);
+});
+
+test("the script's own error survives the drain unchanged", async () => {
+  const { registry } = slowVocab();
+  // allSettled never rejects, so draining cannot replace or mask the real cause.
+  await assert.rejects(
+    async () => runScript(`notify("x"); throw new Error("the original cause");`, { commands: registry }),
+    /the original cause/
+  );
+});
+
+test("a REJECTING fire-and-forget verb does not mask the script's error", async () => {
+  const { registry } = slowVocab();
+  await assert.rejects(
+    async () => runScript(`reject(); nope();`, { commands: registry }),
+    /nope is not defined/
+  );
+});
+
+// ---- controls: the pre-existing contract must be unchanged both ways ----
+
+test("control: notify still delivers on the success path", async () => {
+  const { delivered, registry } = slowVocab();
+  const r = await runScript(`notify("all good");`, { commands: registry });
+  assert.deepEqual(delivered, ["all good"]);
+  assert.equal(r.stopped, false);
+});
+
+test("control: runScript still resolves { iterations, stopped } after draining", async () => {
+  const { delivered, registry } = slowVocab();
+  registry.register({ name: "halt", summary: "stop the loop", run: (ctx) => ctx.stop() });
+  const r = await runScript(`while (alive) { notify("x"); halt(); }`, { commands: registry, max: 5 });
+  assert.equal(r.iterations, 1);
+  assert.equal(r.stopped, true);
+  assert.deepEqual(delivered, ["x"]);
+});
+
+test("control: a throwing script with nothing queued still rejects", async () => {
+  const { delivered, registry } = slowVocab();
+  await assert.rejects(
+    async () => runScript(`sync(); nope();`, { commands: registry }),
+    /nope is not defined/
+  );
+  assert.deepEqual(delivered, []);
+});
+
+test("control: an awaited notify is unaffected and still returns its value", async () => {
+  const { delivered, registry } = slowVocab();
+  await runScript(`const r = await notify("awaited"); if (!r.ok) throw new Error("lost the return value");`, {
+    commands: registry,
+  });
+  assert.deepEqual(delivered, ["awaited"]);
+});