Add per-staff metrics: StaffAction event log + /stats command

Event-sourced tracking of staff/ticket lifecycle actions, plus a /stats
command. Foundation for a future tickets-website analytics dashboard.

Data:
- StaffAction model (event log) + Ticket.game / Ticket.closedAt
- STATS_ADMIN_IDS config (who may view others' stats)

Recording (fire-and-forget, idempotent on real state transitions):
- claim, response (channel reply + /response send), escalate, de-escalate,
  transfer, close (4 sites), reopen — each denormalizes ticketType, tier,
  priority, game, requester (senderEmail / creatorId), guildId
- close events carry closerType / resolverId (claimer credit) / wasClaimed;
  transfer carries fromId / toId; reopen stamps resolverId
- conditional close transition helper (atomic open->closed + closedAt) shared
  by all four close paths

Query + command:
- pure period parser (presets + free-text) and stats shaper (per-metric keys)
- command-aware autocomplete dispatch
- /stats: period (autocomplete) + member (admin-gated) + source (all/email/
  discord), ManageMessages + staff-role gated, ephemeral, tier-labeled embed

288+ unit tests; timing/busiest-times data is collected but displayed later.

tests/transferEvents.test.js

@@ -0,0 +1,166 @@
+/**
+ * Phase 5b — transfer event recording tests.
+ *
+ * Follows the same injectable-parameter pattern as claimEvents.test.js:
+ *   _TicketModel  — controls the DB layer (updateOne)
+ *   _recordAction — captures recording calls without any module mocking
+ *
+ * No vi.mock needed; all dependencies injected directly.
+ *
+ * Tests applyTransfer directly (same pattern as testing applyClaim directly).
+ *
+ * Covers:
+ *   (a) transfer to different member — one 'transfer' event with fromId/toId
+ *   (b) transfer to current claimer  — fromId === toId → no event
+ *   (c) fromId/toId/staffId/guildId correctness
+ */
+import { describe, it, expect, vi } from 'vitest';
+
+import { applyTransfer } from '../handlers/commands/index.js';
+
+// ---------------------------------------------------------------------------
+// Shared factories
+// ---------------------------------------------------------------------------
+
+function makeTicket(overrides = {}) {
+  return {
+    gmailThreadId:  'discord-test-001',
+    escalationTier: 0,
+    escalated:      false,
+    claimerId:      'prev-claimer-001',
+    claimedBy:      'PrevClaimerName',
+    priority:       'normal',
+    game:           'TestGame',
+    senderEmail:    'user@example.com',
+    creatorId:      'creator-001',
+    ticketNumber:   42,
+    ...overrides
+  };
+}
+
+function makeGuildMember(userId = 'new-claimer-002') {
+  return {
+    id:          userId,
+    displayName: 'New Claimer',
+    user: {
+      id:       userId,
+      username: 'newclaimer',
+      tag:      'newclaimer#0002',
+      toString: () => `<@${userId}>`
+    }
+  };
+}
+
+function makeInteraction(userId = 'staff-001') {
+  return {
+    user: {
+      id:       userId,
+      username: 'staffuser',
+      tag:      'staffuser#0001',
+      toString: () => `<@${userId}>`
+    },
+    member: { displayName: 'Staff Member' },
+    guild: {
+      id: 'guild-001',
+      members: {
+        fetch: vi.fn().mockRejectedValue(new Error('no member in test env'))
+      }
+    },
+    channel: {
+      id:       'chan-001',
+      name:     'ticket-chan-001',
+      isThread: vi.fn().mockReturnValue(true),
+      send:     vi.fn().mockResolvedValue({ id: 'sent-msg-001' })
+    },
+    editReply:  vi.fn().mockResolvedValue(undefined),
+    client: {
+      channels: { fetch: vi.fn().mockResolvedValue(null) }
+    }
+  };
+}
+
+// ---------------------------------------------------------------------------
+// (a) Transfer to a different member — one event
+// ---------------------------------------------------------------------------
+
+describe('applyTransfer — different member emits one event', () => {
+  it('emits exactly one "transfer" event', async () => {
+    const ticket       = makeTicket({ claimerId: 'prev-claimer-001' });
+    const guildMember  = makeGuildMember('new-claimer-002');
+    const mockUpdateOne = vi.fn().mockResolvedValue({ modifiedCount: 1 });
+    const mockRecord   = vi.fn();
+    const interaction  = makeInteraction('staff-001');
+
+    await applyTransfer(interaction, ticket, guildMember, 'reason', { updateOne: mockUpdateOne }, mockRecord);
+
+    expect(mockRecord).toHaveBeenCalledTimes(1);
+    const [staffId, type] = mockRecord.mock.calls[0];
+    expect(staffId).toBe('staff-001');
+    expect(type).toBe('transfer');
+  });
+
+  it('passes correct fromId, toId, guildId, and ticket', async () => {
+    const ticket       = makeTicket({ claimerId: 'prev-claimer-001' });
+    const guildMember  = makeGuildMember('new-claimer-002');
+    const mockUpdateOne = vi.fn().mockResolvedValue({ modifiedCount: 1 });
+    const mockRecord   = vi.fn();
+    const interaction  = makeInteraction('staff-001');
+
+    await applyTransfer(interaction, ticket, guildMember, 'reason', { updateOne: mockUpdateOne }, mockRecord);
+
+    const [, , payload] = mockRecord.mock.calls[0];
+    expect(payload.fromId).toBe('prev-claimer-001');
+    expect(payload.toId).toBe('new-claimer-002');
+    expect(payload.guildId).toBe('guild-001');
+    expect(payload.ticket).toBe(ticket);
+  });
+
+  it('fromId is the pre-write claimerId (captured before the DB write)', async () => {
+    const ticket       = makeTicket({ claimerId: 'original-claimer' });
+    const guildMember  = makeGuildMember('new-staff-003');
+    const mockUpdateOne = vi.fn().mockResolvedValue({ modifiedCount: 1 });
+    const mockRecord   = vi.fn();
+    const interaction  = makeInteraction('staff-001');
+
+    await applyTransfer(interaction, ticket, guildMember, 'reason', { updateOne: mockUpdateOne }, mockRecord);
+
+    const [, , payload] = mockRecord.mock.calls[0];
+    expect(payload.fromId).toBe('original-claimer');
+    expect(payload.toId).toBe('new-staff-003');
+  });
+});
+
+// ---------------------------------------------------------------------------
+// (b) Transfer to the current claimer — no event
+// ---------------------------------------------------------------------------
+
+describe('applyTransfer — transfer to current claimer emits no event', () => {
+  it('emits no event when fromId === toId (transferring to existing claimer)', async () => {
+    const ticket       = makeTicket({ claimerId: 'same-claimer-001' });
+    const guildMember  = makeGuildMember('same-claimer-001');
+    const mockUpdateOne = vi.fn().mockResolvedValue({ modifiedCount: 1 });
+    const mockRecord   = vi.fn();
+    const interaction  = makeInteraction('staff-001');
+
+    await applyTransfer(interaction, ticket, guildMember, 'reason', { updateOne: mockUpdateOne }, mockRecord);
+
+    expect(mockRecord).not.toHaveBeenCalled();
+  });
+
+  it('emits one event when the ticket is unclaimed (fromId null) and toId is non-null — null !== toId satisfies the fromId !== toId gate', async () => {
+    // null !== 'new-claimer' so this IS a real transfer — event IS emitted
+    const ticket       = makeTicket({ claimerId: null });
+    const guildMember  = makeGuildMember('new-claimer-002');
+    const mockUpdateOne = vi.fn().mockResolvedValue({ modifiedCount: 1 });
+    const mockRecord   = vi.fn();
+    const interaction  = makeInteraction('staff-001');
+
+    await applyTransfer(interaction, ticket, guildMember, 'reason', { updateOne: mockUpdateOne }, mockRecord);
+
+    // null !== 'new-claimer-002' → event IS emitted
+    expect(mockRecord).toHaveBeenCalledTimes(1);
+    const [, , payload] = mockRecord.mock.calls[0];
+    expect(payload.fromId).toBeNull();
+    expect(payload.toId).toBe('new-claimer-002');
+  });
+});