From 941e743f8e142986216f2eb000b2d3e79c688f3f Mon Sep 17 00:00:00 2001
From: Sawyer Cutler <sawyer@dirtroad.dev>
Date: Wed, 7 Oct 2026 16:53:59 -0700
Subject: [PATCH] fix: await router calls so unroutable trigger mail is not
 dropped

---
 src/deliver.test.ts | 37 ++++++++++++++++++++++++++++++++++++-
 src/deliver.ts      | 31 ++++++++++++++++---------------
 2 files changed, 52 insertions(+), 16 deletions(-)

diff --git a/src/deliver.test.ts b/src/deliver.test.ts
index abaf70c..d97ebe6 100644
--- a/src/deliver.test.ts
+++ b/src/deliver.test.ts
@@ -47,7 +47,7 @@ function recordingRouter() {
   return {
     grants,
     mail,
-    router: {
+    router: <HookMailRouter>{
       routeMail: (
         _address: string,
         rawMessage: string,
@@ -203,6 +203,41 @@ describe("createRunTriggerDeliverer", () => {
     expect(recorded.grants).toHaveLength(1);
   });
 
+  test("an async router answering false for grants is unroutable", async () => {
+    const sender = await durableSystemSender();
+    const recorded = recordingRouter();
+    recorded.router.sendRunGrants = async () => false;
+    const error = await deliverer(recorded.router, sender.sender)
+      .to(ADDRESS, "tick", "tnt_1", undefined)
+      .then(
+        () => {
+          throw new Error("the dead run delivered");
+        },
+        (e: unknown) => e,
+      );
+
+    expect(isRunTriggerUnroutable(error)).toBe(true);
+    expect((error as { code: string }).code).toBe(RUN_GRANTS_NOT_ROUTABLE);
+    expect(recorded.mail).toEqual([]);
+  });
+
+  test("an async router answering false for mail is unroutable", async () => {
+    const sender = await durableSystemSender();
+    const recorded = recordingRouter();
+    recorded.router.routeMail = async () => false;
+    const error = await deliverer(recorded.router, sender.sender)
+      .to(ADDRESS, "tick", "tnt_1", undefined)
+      .then(
+        () => {
+          throw new Error("the dead run delivered");
+        },
+        (e: unknown) => e,
+      );
+
+    expect(isRunTriggerUnroutable(error)).toBe(true);
+    expect((error as { code: string }).code).toBe(RUN_MAIL_NOT_ROUTABLE);
+  });
+
   test("rejected grants deliver nothing", async () => {
     const sender = await durableSystemSender();
     const recorded = recordingRouter();
diff --git a/src/deliver.ts b/src/deliver.ts
index 3c5a3f4..d811914 100644
--- a/src/deliver.ts
+++ b/src/deliver.ts
@@ -20,13 +20,13 @@ export type HookMailRouter = {
     rawMessage: string,
     authenticatedSender: string,
     messageId?: string,
-  ) => boolean;
+  ) => boolean | Promise<boolean>;
   sendRunGrants: (
     address: string,
     runId: string,
     stepGrants: RunGrantsFrame["stepGrants"],
     senderIdentities: RunGrantsFrame["senderIdentities"],
-  ) => boolean;
+  ) => boolean | Promise<boolean>;
 };
 
 export type RunTriggerMaterialize = ReturnType<
@@ -130,11 +130,13 @@ export function createRunTriggerDeliverer(
       // Co-deliver the system sender's durable key on the grants barrier so
       // the recipient can verify the trigger mail against the key the hub
       // vouches for, exactly as a person-originated trigger does.
-      if (
-        !opts.router.sendRunGrants(address, runId, grants.stepGrants, [
-          { address: sender.address, publicKey: sender.publicKey },
-        ])
-      ) {
+      const grantsRouted = await opts.router.sendRunGrants(
+        address,
+        runId,
+        grants.stepGrants,
+        [{ address: sender.address, publicKey: sender.publicKey }],
+      );
+      if (!grantsRouted) {
         throw new RunTriggerUnroutableError(
           RUN_GRANTS_NOT_ROUTABLE,
           address,
@@ -150,14 +152,13 @@ export function createRunTriggerDeliverer(
         subject,
         sender,
       });
-      if (
-        !opts.router.routeMail(
-          address,
-          raw.base64,
-          sender.address,
-          raw.messageId,
-        )
-      ) {
+      const mailRouted = await opts.router.routeMail(
+        address,
+        raw.base64,
+        sender.address,
+        raw.messageId,
+      );
+      if (!mailRouted) {
         throw new RunTriggerUnroutableError(
           RUN_MAIL_NOT_ROUTABLE,
           address,