refactor(codex): keep the receipt-timed notification methods with the event they stamp

src/main/codex/codex-structured-session-acquire.ts

@@ -38,6 +38,7 @@ import {
 } from './codex-structured-fast-mode'
 import {
   assertCodexConnectionOpen,
+  CODEX_RECEIPT_TIMED_METHODS,
   codexSessionLifecycle,
   mintCodexAcquisitionGeneration,
   type CodexAcquisitionRegistry,
@@ -49,15 +50,6 @@ import type { CodexStructuredSessionTeardown } from './codex-structured-session-
 import type { CodexStructuredNotificationRetry } from './codex-structured-notification-retry'
 import type { deliverCodexServerRequest } from './codex-structured-provider-events'
 
-// Turn and item boundaries are timed by when the host received them, never by when a buffered or
-// retried delivery got round to them.
-const RECEIPT_TIMED_METHODS: ReadonlySet<string> = new Set([
-  'turn/started',
-  'turn/completed',
-  'item/started',
-  'item/completed'
-])
-
 export async function acquireCodexStructuredSession(input: {
   input: StructuredAgentSessionAcquireInput
   deps: CodexStructuredSessionAdapterDeps
@@ -151,7 +143,7 @@ export async function acquireCodexStructuredSession(input: {
       {
         onNotification: (method, params) => {
           // Stamped at receipt, ahead of any pre-publication buffering or retry.
-          const observedAt = RECEIPT_TIMED_METHODS.has(method)
+          const observedAt = CODEX_RECEIPT_TIMED_METHODS.has(method)
             ? (deps.now?.() ?? Date.now())
             : undefined
           const dispatchSequenceAtReceipt =

src/main/codex/codex-structured-session-state.ts

@@ -44,6 +44,15 @@ export type CodexStructuredLaunch = {
   env?: Record<string, string>
 }
 
+/** Turn and item boundaries, timed by when the host received them, never by when a buffered or
+ *  retried delivery got round to them. */
+export const CODEX_RECEIPT_TIMED_METHODS: ReadonlySet<string> = new Set([
+  'turn/started',
+  'turn/completed',
+  'item/started',
+  'item/completed'
+])
+
 export type CodexStructuredSessionEvent =
   | {
       type: 'notification'
@@ -51,7 +60,8 @@ export type CodexStructuredSessionEvent =
       threadId: string
       method: string
       params: unknown
-      /** Host receipt time of a turn boundary; survives retry and deferral so a replay is not re-stamped. */
+      /** Host receipt time of a `CODEX_RECEIPT_TIMED_METHODS` boundary; survives retry and
+       *  deferral so a replay is not re-stamped. */
       observedAt?: number
       /** Highest dispatch sequence armed when this turn-start was first received. */
       dispatchSequenceAtReceipt?: number