docs: replace vague provenance prose with recorded facts

packages/core/session/tests/surface.spec.ts

@@ -78,8 +78,8 @@ function toolResultEvent(
   }
 }
 
-describe('foldSurface provenance', () => {
-  it('accepts absent or valid provenance and complete replacement coverage', () => {
+describe('foldSurface source-event references', () => {
+  it('accepts absent or valid source-event references and complete replacement coverage', () => {
     const events = [
       provenanceEvent(0, undefined),
       provenanceEvent(1, undefined),
@@ -91,7 +91,7 @@ describe('foldSurface provenance', () => {
     expect(() => foldSurface(events)).not.toThrow()
   })
 
-  it('rejects provenance on a non-surface event', () => {
+  it('rejects source-event references on a non-surface event', () => {
     const event = {
       type: 'turn/start',
       seq: 0,
@@ -102,7 +102,7 @@ describe('foldSurface provenance', () => {
     expect(() => foldSurface([event])).toThrow(/cannot carry sourceEventSeqs/)
   })
 
-  it('accepts explicit empty provenance on an assistant message', () => {
+  it('accepts an explicit empty source-event list on an assistant message', () => {
     const event = {
       type: 'assistant/message',
       seq: 0,