test(desktop): add regression test for Photon messaging source (#46761)

Assert isMessagingSource('photon') is true and that Photon/iMessage search aliases resolve, so a silent removal of the photon entry from MESSAGING_SESSION_SOURCE_IDS fails CI instead of regressing the sidebar section added in #47395.

apps/desktop/src/lib/session-source.test.ts

@@ -0,0 +1,39 @@
+import { describe, expect, it } from 'vitest'
+
+import {
+  MESSAGING_SESSION_SOURCE_IDS,
+  isMessagingSource,
+  sessionSourceSearchTerms
+} from './session-source'
+
+// Regression guard for #46761 / PR #47395: Photon (iMessage) must keep its own
+// sidebar section. refreshMessagingSessions() filters rows through
+// isMessagingSource(), so this entry is the sole condition that keeps Photon
+// sessions out of generic recents. A silent removal would regress the feature
+// with no test failure — these asserts pin the contract.
+describe('photon messaging source registration', () => {
+  it('treats photon as a messaging source (own sidebar section)', () => {
+    expect(isMessagingSource('photon')).toBe(true)
+  })
+
+  it('is case/space insensitive on the source id', () => {
+    expect(isMessagingSource('PHOTON')).toBe(true)
+    expect(isMessagingSource('  photon ')).toBe(true)
+  })
+
+  it('exposes the iMessage/messages search aliases so Photon sessions are findable', () => {
+    const terms = sessionSourceSearchTerms('photon')
+    expect(terms).toContain('imessage')
+    expect(terms).toContain('messages')
+  })
+
+  it('is registered in the messaging source id list', () => {
+    expect(MESSAGING_SESSION_SOURCE_IDS).toContain('photon')
+  })
+
+  it('does not flag local/CLI-ish sources as messaging (guard sanity)', () => {
+    expect(isMessagingSource('cli')).toBe(false)
+    expect(isMessagingSource(null)).toBe(false)
+    expect(isMessagingSource(undefined)).toBe(false)
+  })
+})