Better fallback for the event localTimestamp calculation.

spec/unit/matrixrtc/CallMembership.spec.ts

@@ -85,7 +85,7 @@ describe("CallMembership", () => {
 
     it("considers memberships expired when local age large", () => {
         const fakeEvent = makeMockEvent(1000);
-        fakeEvent.getLocalAge = jest.fn().mockReturnValue(6000);
+        fakeEvent.localTimestamp = Date.now() - 6000;
         const membership = new CallMembership(fakeEvent, membershipTemplate);
         expect(membership.isExpired()).toEqual(true);
     });

spec/unit/matrixrtc/mocks.ts

@@ -60,8 +60,7 @@ export function mockRTCEvent(
         }),
         getSender: jest.fn().mockReturnValue("@mock:user.example"),
         getTs: jest.fn().mockReturnValue(1000),
-        getLocalAge: getLocalAgeFn,
-        localTimestamp: Date.now(),
+        localTimestamp: Date.now() - getLocalAgeFn(),
         getRoomId: jest.fn().mockReturnValue(roomId),
         sender: {
             userId: "@mock:user.example",

src/matrixrtc/CallMembership.ts

@@ -91,7 +91,7 @@ export class CallMembership {
     }
 
     public isExpired(): boolean {
-        return this.getAbsoluteExpiry() < this.parentEvent.getTs() + this.parentEvent.getLocalAge();
+        return this.getMsUntilExpiry() <= 0;
     }
 
     public getActiveFoci(): Focus[] {

src/models/event.ts

@@ -404,7 +404,8 @@ export class MatrixEvent extends TypedEventEmitter<MatrixEventEmittedEvents, Mat
         });
 
         this.txnId = event.txn_id;
-        this.localTimestamp = Date.now() - (this.getAge() ?? 0);
+        const age = this.getAge();
+        this.localTimestamp = age ? Date.now() - age : this.getTs() ?? 0;
         this.reEmitter = new TypedReEmitter(this);
     }