fix(hub): mail an attached file under a US-ASCII name

apps/hub/src/artifacts/materials.test.ts

@@ -0,0 +1,15 @@
+import { expect, test } from "bun:test";
+import { mailAttachmentName } from "./materials.ts";
+
+test("a mailed attachment's name is the person's, made US-ASCII", () => {
+  // macOS names a screenshot with a narrow no-break space before AM.
+  expect(
+    mailAttachmentName("Screenshot 2026-11-03 at 8.51.17\u202fAM.png"),
+  ).toBe("Screenshot 2026-11-03 at 8.51.17 AM.png");
+  expect(mailAttachmentName("r\u00e9sum\u00e9 \u2014 final.pdf")).toBe(
+    "resume  final.pdf",
+  );
+  expect(mailAttachmentName('say "hi".txt')).toBe("say 'hi'.txt");
+  expect(mailAttachmentName("plain-name.png")).toBe("plain-name.png");
+  expect(mailAttachmentName("\u5831\u544a.pdf")).toBe(".pdf");
+});

apps/hub/src/artifacts/materials.ts

@@ -44,6 +44,22 @@ export function materialMimeType(file: { name: string; type: string }): string {
   return declared;
 }
 
+// A mailed attachment's name sits in a signed MIME header with no encoding, so the assembler takes
+// US-ASCII only; the validator the hub runs first does not check that. The material keeps the
+// person's name; the mailed copy carries this one, which the coordinator still reads as the file.
+const ASCII_SPACE_LIKE = /[\u00a0\u2000-\u200b\u202f\u205f\u3000]/g;
+
+/** The name a file is mailed under: the person's, with every non-ASCII character made plain. */
+export function mailAttachmentName(name: string): string {
+  const plain = name
+    .replace(ASCII_SPACE_LIKE, " ")
+    .normalize("NFKD")
+    .replace(/[^\x20-\x7e]/g, "")
+    .replace(/"/g, "'")
+    .trim();
+  return plain === "" ? "attachment" : plain;
+}
+
 function utf8(bytes: Uint8Array): string | undefined {
   try {
     return new TextDecoder("utf-8", { fatal: true }).decode(bytes);

apps/hub/src/artifacts/service.ts

@@ -148,6 +148,7 @@ import { materialsNote } from "../config/materials.ts";
 import { servingOffering } from "../workflows/install-for-tenant.ts";
 import {
   acceptedMaterials,
+  mailAttachmentName,
   materialContent,
   materialMimeType,
 } from "./materials.ts";
@@ -1238,7 +1239,11 @@ export function createArtifactService(
       await mailRun(
         coordinator.runId,
         message.trim() || materialsNote(inputs.map((input) => input.name)),
-        inputs.map((input) => ({ ...input, data: base64Encode(input.data) })),
+        inputs.map((input) => ({
+          name: mailAttachmentName(input.name),
+          mimeType: input.mimeType,
+          data: base64Encode(input.data),
+        })),
       );
       return { materials };
     },