Q142: a conversation is read only up to the message the reader actually saw

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/unit/chat-read-state.test.ts

@@ -0,0 +1,47 @@
+import { randomUUID } from "node:crypto";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { describe, expect, test } from "vitest";
+import { DatabaseConnection } from "../../src/main/database/connection";
+import { OrganizationService } from "../../src/main/services/organization-service";
+import { ChatService } from "../../src/main/services/chat-service";
+
+describe("read state", () => {
+  test("marks read up to the message the reader saw, never past it and never backwards", () => {
+    const connection = new DatabaseConnection(join(tmpdir(), `ac-read-state-${randomUUID()}.db`));
+    const chat = new ChatService(connection.db);
+    let orgId = "";
+    connection.transaction(() => {
+      orgId = new OrganizationService(connection.db).createOrganization({ organizationName: "Acme", employeeName: "Yang", mission: "m", goal: "g" });
+    });
+    const employeeId = (connection.db.prepare("select id from employees where org_id = ?").get(orgId) as { id: string }).id;
+    const space = (name: string) => (connection.db.prepare("select id from chat_spaces where org_id = ? and name = ?").get(orgId, name) as { id: string }).id;
+    const general = space("general");
+    const send = (spaceId: string, bodyMd: string) => connection.transaction(() => chat.sendMessage({
+      orgId, spaceId, threadId: null, senderType: "employee", senderId: employeeId, bodyMd, attachmentFileIds: [],
+    }));
+    const createdAt = (id: string) => (connection.db.prepare("select created_at from chat_messages where id = ?").get(id) as { created_at: string }).created_at;
+    const readState = () => connection.db.prepare("select last_read_message_id as id, last_read_at as at from chat_read_state where space_id = ?").get(general);
+    const seen = send(general, "Seen");
+    const later = send(general, "Arrived while scrolled up");
+    connection.db.prepare("update chat_messages set created_at = ? where id = ?").run("2099-01-01T00:00:00.000Z", later);
+
+    chat.markSpaceRead({ orgId, employeeId, spaceId: general, upToMessageId: seen });
+    expect(readState()).toEqual({ id: seen, at: createdAt(seen) });
+    chat.markSpaceRead({ orgId, employeeId, spaceId: general, upToMessageId: later });
+    chat.markSpaceRead({ orgId, employeeId, spaceId: general, upToMessageId: seen });
+    expect(readState()).toEqual({ id: later, at: "2099-01-01T00:00:00.000Z" });
+    // Two messages in the same millisecond still order by insertion, so reading the second advances.
+    const first = send(general, "Same instant one");
+    const second = send(general, "Same instant two");
+    connection.db.prepare("update chat_messages set created_at = '2099-06-01T00:00:00.000Z' where id in (?, ?)").run(first, second);
+    chat.markSpaceRead({ orgId, employeeId, spaceId: general, upToMessageId: first });
+    chat.markSpaceRead({ orgId, employeeId, spaceId: general, upToMessageId: second });
+    expect(readState()).toEqual({ id: second, at: "2099-06-01T00:00:00.000Z" });
+    chat.markSpaceRead({ orgId, employeeId, spaceId: general, upToMessageId: first });
+    expect(readState()).toEqual({ id: second, at: "2099-06-01T00:00:00.000Z" });
+    expect(() => chat.markSpaceRead({ orgId, employeeId, spaceId: general, upToMessageId: send(space("engineering"), "Elsewhere") }))
+      .toThrow("The message read is not in this conversation.");
+    connection.close();
+  });
+});

tests/unit/conversation-pinning.test.ts

@@ -4,6 +4,7 @@ import type {
   AgentRecord,
   ChatMembershipRecord,
   ChatMessageRecord,
+  ChatReadStateRecord,
   ChatSpaceRecord,
   EmployeeRecord,
 } from "../../src/shared/domain";
@@ -103,3 +104,18 @@ describe("conversation pinning", () => {
     expect(conversations[0].preview).toContain("CEO:");
   });
 });
+
+describe("unread counts", () => {
+  test("count by position after the last read message, so a same-millisecond arrival is still unread", () => {
+    const { spaces, memberships } = fixtures();
+    const at = "2026-02-01T00:00:00.000Z";
+    const messages = [message("m_read", "spc_general", CEO, at), message("m_same_ms", "spc_general", ENGINEER, at)];
+    const unread = (readStates: ChatReadStateRecord[]) => buildConversations({ spaces, memberships, messages, readStates, employees, agents, currentEmployeeId: FOUNDER, ceoAgentId: CEO })
+      .find((item) => item.space.id === "spc_general")!.unread;
+    const state = (lastReadMessageId: string | null): ChatReadStateRecord => ({ orgId: ORG, employeeId: FOUNDER, spaceId: "spc_general", lastReadMessageId, lastReadAt: at });
+    expect(unread([state("m_read")])).toBe(1);
+    expect(unread([state("m_same_ms")])).toBe(0);
+    // A read message older than the loaded window means every loaded message came after it.
+    expect(unread([state("m_older_than_window")])).toBe(2);
+  });
+});