refactor(codex): keep native effort config at owner

extensions/codex/src/app-server/thread-requests.ts

@@ -164,7 +164,6 @@ export function buildThreadStartParams(
     environmentSelection?: CodexTurnEnvironmentParams[];
     model?: string | null;
     modelProvider?: string | null;
-    reasoningEffort?: string | null;
     hostSystemAgentActive?: boolean;
     restrictedToolSurfaceInheritedMcpServerNames?: readonly string[];
     shellEnvironment?: Readonly<Record<string, string>>;
@@ -217,7 +216,6 @@ export function buildThreadStartParams(
         options.restrictedToolSurfaceInheritedMcpServerNames,
       shellEnvironment: options.shellEnvironment,
       disableLoginShell: options.disableLoginShell,
-      reasoningEffort: options.reasoningEffort,
     }),
     ...resolveCodexThreadEnvironmentSelection(options),
     developerInstructions:
@@ -253,7 +251,6 @@ export function buildThreadResumeParams(
     restrictedToolSurfaceInheritedMcpServerNames?: readonly string[];
     shellEnvironment?: Readonly<Record<string, string>>;
     disableLoginShell?: boolean;
-    reasoningEffort?: string | null;
     preserveNativeModel?: boolean;
   },
 ): CodexThreadResumeParams {
@@ -424,7 +421,6 @@ export function buildCodexRuntimeThreadConfigForRun(
     restrictedToolSurfaceInheritedMcpServerNames?: readonly string[];
     shellEnvironment?: Readonly<Record<string, string>>;
     disableLoginShell?: boolean;
-    reasoningEffort?: string | null;
   } = {},
 ): JsonObject {
   const ringZeroActive =
@@ -486,7 +482,6 @@ export function buildCodexRuntimeThreadConfigForRun(
       params.authoredContextTokenCap === undefined
         ? undefined
         : { model_context_window: params.authoredContextTokenCap },
-      options.reasoningEffort ? { model_reasoning_effort: options.reasoningEffort } : undefined,
     ) ?? baseConfig;
   const contextConfig = {
     ...runtimeConfig,

extensions/codex/src/app-server/thread-supervision.ts

@@ -13,6 +13,7 @@ import {
 import { CodexAppServerRpcError, type CodexAppServerClient } from "./client.js";
 import type { CodexAppServerRuntimeOptions } from "./config.js";
 import { buildCodexAppServerConnectionFingerprint } from "./plugin-app-cache-key.js";
+import { mergeCodexThreadConfigs } from "./plugin-thread-config.js";
 import {
   attestCodexPluginThreadApps,
   discardUnattestedCodexPluginThread,
@@ -176,7 +177,12 @@ export async function materializePendingSupervisionBranch(
       dynamicTools: params.dynamicTools,
       appServer: params.appServer,
       developerInstructions: params.developerInstructions,
-      config: params.config,
+      config: mergeCodexThreadConfigs(
+        params.config,
+        probeResponse.reasoningEffort
+          ? { model_reasoning_effort: probeResponse.reasoningEffort }
+          : undefined,
+      ),
       nativeCodeModeEnabled: params.nativeCodeModeEnabled,
       nativeProviderWebSearchSupport: params.nativeProviderWebSearchSupport,
       nativeCodeModeOnlyEnabled: params.nativeCodeModeOnlyEnabled,
@@ -184,7 +190,6 @@ export async function materializePendingSupervisionBranch(
       environmentSelection: params.environmentSelection,
       model: nativeModel,
       modelProvider: nativeModelProvider,
-      reasoningEffort: probeResponse.reasoningEffort,
       hostSystemAgentActive: params.hostSystemAgentActive,
       restrictedToolSurfaceInheritedMcpServerNames:
         params.restrictedToolSurfaceInheritedMcpServerNames,