Which end of a Matrix call offers now has a test where the rule lives, and nobilis carries the test review: every test read, the ones that could not fail made to, and the faults they were hiding fixed

The offering rule was only ever tested through a copy of it compiled for the daemon's tests; the window's own is checked here, including that two devices of one person tell each other apart and that nobody offers to themselves.

nobilis: ddd4503

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>

src/renderer/src/lib/matrixcall.test.ts

@@ -0,0 +1,21 @@
+import { describe, expect, it } from 'vitest'
+import { shouldOffer } from './matrixcall'
+
+describe('which end of a Matrix call offers', () => {
+  it('is exactly one end of every pair, whichever way round they ask', () => {
+    // Both ends compute this about each other and must not agree, or the call
+    // collides with itself.
+    expect(shouldOffer('@a:example.org|AAA', '@b:example.org|BBB')).toBe(true)
+    expect(shouldOffer('@b:example.org|BBB', '@a:example.org|AAA')).toBe(false)
+  })
+
+  it('tells two devices of the same person apart', () => {
+    // The case that makes a user-id comparison alone wrong.
+    expect(shouldOffer('@a:example.org|AAA', '@a:example.org|ZZZ')).toBe(true)
+    expect(shouldOffer('@a:example.org|ZZZ', '@a:example.org|AAA')).toBe(false)
+  })
+
+  it('never has an end offer to itself', () => {
+    expect(shouldOffer('@a:example.org|AAA', '@a:example.org|AAA')).toBe(false)
+  })
+})