TheGreatAxios · Sep 17, 2026 · Sep 17, 2026
@@ -37,7 +37,7 @@
     "@corbits/inbox": "workspace:*",
     "@corbits/inference-catalog": "workspace:*",
     "@corbits/last-30-days-research-workflow": "workspace:*",
-    "@corbits/mailbox": "github:corbitsdev/corbits-mailbox#fea6211e42fddfc87e8e1755c219c437e45a7d62",
+    "@corbits/mailbox": "github:corbitsdev/corbits-mailbox#bc964040fa42ffe4e5d5004f87edaab6486e5d60",
     "@corbits/mcp-tools": "workspace:*",
     "@corbits/memory": "github:corbitsdev/corbits-memory#9e6f213fa2c002b531d3f6af1aa0abd737b8afe3",
     "@corbits/memory-hub": "workspace:*",

@@ -34,6 +34,7 @@
     "@tanstack/react-query": "catalog:",
     "@corbits/connections": "workspace:*",
     "@corbits/jimmy-agent": "workspace:*",
+    "@corbits/mailbox": "github:corbitsdev/corbits-mailbox#bc964040fa42ffe4e5d5004f87edaab6486e5d60",
     "arktype": "catalog:",
     "@corbits/icons": "workspace:*",
     "react": "^19.2.0",

@@ -37,6 +37,9 @@ export type {
   CorbitAvatarSize,
 } from "./avatar";
 
+export { threadMessagesToTimeline, roomRefFor } from "./mailbox-timeline";
+export type { TimelineItem } from "./mailbox-timeline";
+
 export { PinnedStrip } from "./pinned-strip";
 export type { PinsStatus } from "./use-workbench-feed";
 export {

@@ -0,0 +1,57 @@
+import { describe, expect, test } from "bun:test";
+import type { MailboxThreadMessage } from "@corbits/mailbox";
+
+import { roomRefFor, threadMessagesToTimeline } from "./mailbox-timeline";
+
+function message(
+  overrides: Partial<MailboxThreadMessage> & Pick<MailboxThreadMessage, "id" | "messageId">,
+): MailboxThreadMessage {
+  return {
+    references: [],
+    fromAddress: "sender@dana.localhost",
+    createdAt: "2026-09-17T00:00:00.000000Z",
+    read: true,
+    archived: false,
+    parentId: null,
+    body: "hello",
+    ...overrides,
+  };
+}
+
+describe("threadMessagesToTimeline", () => {
+  test("links a reply's threadId to its parent's own id via inReplyTo", () => {
+    const parent = message({ id: "id-1", messageId: "msg-1@mail" });
+    const child = message({
+      id: "id-2",
+      messageId: "msg-2@mail",
+      inReplyTo: "msg-1@mail",
+      body: "reply",
+    });
+
+    const items = threadMessagesToTimeline([parent, child]);
+
+    expect(items[0]?.threadId).toBeUndefined();
+    expect(items[1]?.threadId).toBe("id-1");
+  });
+
+  test("leaves threadId absent when the parent isn't in this batch", () => {
+    const orphan = message({
+      id: "id-3",
+      messageId: "msg-3@mail",
+      inReplyTo: "msg-missing@mail",
+    });
+
+    const [item] = threadMessagesToTimeline([orphan]);
+
+    expect(item?.threadId).toBeUndefined();
+  });
+});
+
+describe("roomRefFor", () => {
+  test("stamps the same { kind: 'workbench', id } ref the mailbox writers use", () => {
+    expect(roomRefFor("tenant-1", "room-1")).toEqual({
+      kind: "workbench",
+      id: "room-1",
+    });
+  });
+});
@@ -0,0 +1,69 @@
+// Pure adapter from a mailbox thread read (`@corbits/mailbox`'s
+// `MailboxThreadMessage`) onto the timeline item shape `use-workbench-feed.ts`
+// already produces (CL-8174 slice 2a). No new wire shape: a mail message
+// becomes exactly the `MessageItem` the rest of chat-ui already knows how to
+// render, so the timeline never has to branch on where a message came from.
+
+import type { MailboxRef, MailboxThreadMessage } from "@corbits/mailbox";
+import type { MessageItem } from "./api";
+
+/** The timeline item shape — an alias, not a new type, so a mail-derived
+ * row and a chat-native row are interchangeable everywhere the timeline
+ * already consumes `MessageItem`. */
+export type TimelineItem = MessageItem;
+
+/**
+ * Maps one mailbox thread's messages onto timeline items.
+ *
+ * `subject`, when present, prefixes the body as its own line — mail is the
+ * only source that carries a subject, so it is folded into the one text
+ * part a `MessageItem` has room for rather than inventing a field the rest
+ * of chat-ui would have to learn about.
+ *
+ * `threadId` links a reply to its parent's own `id` (not its `messageId`,
+ * which is the RFC-2822-style id the `inReplyTo`/`references` headers
+ * carry) by resolving `inReplyTo` against every message's `messageId` in
+ * this same batch. A message whose parent isn't in this batch — the root,
+ * or a reply to a message this read didn't page in — keeps `threadId`
+ * absent rather than guessing.
+ */
+export function threadMessagesToTimeline(
+  messages: readonly MailboxThreadMessage[],
+): TimelineItem[] {
+  const idByMessageId = new Map<string, string>();
+  for (const message of messages) {
+    idByMessageId.set(message.messageId, message.id);
+  }
+
+  return messages.map((message) => {
+    const parentId =
+      message.inReplyTo !== undefined
+        ? idByMessageId.get(message.inReplyTo)
+        : undefined;
+    const text =
+      message.subject !== undefined && message.subject.length > 0
+        ? `${message.subject}\n${message.body}`
+        : message.body;
+    return {
+      id: message.id,
+      createdAt: message.createdAt,
+      parts: [{ kind: "text", text }],
+      sender: { name: null, address: message.fromAddress },
+      ...(parentId !== undefined ? { threadId: parentId } : {}),
+    };
+  });
+}
+
+/**
+ * The same `{ kind: "workbench", id }` ref every mailbox writer stamps
+ * (`apps/hub/src/mailbox-persist.ts`'s `hubMailboxResolveRefs`,
+ * `packages/chat/src/mailbox-fanout.ts`'s `writeChatMailboxFanout`) — a
+ * workbench is a plain tenant now (CL-8083), so the room a thread hangs
+ * off is the same id a chat room is scoped to, and `tenantId` is carried
+ * here only so a caller with just a tenant in hand has a matching call
+ * shape; the stamped ref itself never varies by which of the two identical
+ * ids produced it.
+ */
+export function roomRefFor(_tenantId: string, roomId: string): MailboxRef {
+  return { kind: "workbench", id: roomId };
+}
@@ -44,7 +44,7 @@
     "@corbits/commands": "workspace:*",
     "@corbits/error-sink": "workspace:*",
     "@corbits/hub-api-client": "workspace:*",
-    "@corbits/mailbox": "github:corbitsdev/corbits-mailbox#fea6211e42fddfc87e8e1755c219c437e45a7d62",
+    "@corbits/mailbox": "github:corbitsdev/corbits-mailbox#bc964040fa42ffe4e5d5004f87edaab6486e5d60",
     "@corbits/memory": "github:corbitsdev/corbits-memory#9e6f213fa2c002b531d3f6af1aa0abd737b8afe3",
     "@corbits/turn-artifacts": "workspace:*",
     "@corbits/workflows": "workspace:*",

@@ -16,7 +16,7 @@
   },
   "dependencies": {
     "@corbits/error-sink": "workspace:*",
-    "@corbits/mailbox": "github:corbitsdev/corbits-mailbox#fea6211e42fddfc87e8e1755c219c437e45a7d62",
+    "@corbits/mailbox": "github:corbitsdev/corbits-mailbox#bc964040fa42ffe4e5d5004f87edaab6486e5d60",
     "@corbits/notify": "workspace:*",
     "@intx/hub-api": "workspace:*",
     "@intx/log": "0.3.0",