juliusmarminge · Sep 25, 2026 · Sep 25, 2026 · Sep 25, 2026
diff --git a/apps/server/scripts/record-codex-app-server-replay-fixture.ts b/apps/server/scripts/record-codex-app-server-replay-fixture.ts
@@ -1,5 +1,6 @@
 import * as NodeOS from "node:os";
 
+import { CODEX_THREAD_CONFIG } from "../src/orchestration-v2/Adapters/CodexAdapterV2.ts";
 import { revertCodexThread } from "../src/provider/CodexThreadRevert.ts";
 import * as NodeRuntime from "@effect/platform-node/NodeRuntime";
 import * as NodeServices from "@effect/platform-node/NodeServices";
@@ -119,8 +120,11 @@ interface ReplayRun {
   readonly steps: ReadonlyArray<ReplayStep>;
   readonly turnDefaults?: Omit<TurnStartParams, "input" | "threadId">;
   readonly interactionMode?: "plan";
-  /** Config overrides for `thread/start`; replay ignores them when matching frames. */
-  readonly threadConfig?: CodexSchema.V2ThreadStartParams["config"];
+  /**
+   * Recorder-only `thread/start` config merged over the adapter's. Its keys go in the
+   * transcript header as `recorderThreadConfigKeys`, which replay leaves out of matching.
+   */
+  readonly threadConfig?: Readonly<Record<string, boolean | number | string>>;
 }
 
 type ReplayStep =
@@ -585,8 +589,6 @@ function scenarios(): ReadonlyArray<ReplayScenario> {
           name: "todo-list",
           description: "Default-mode turn that should surface turn/plan/updated notifications.",
           prompt: TODO_LIST_PROMPT,
-          // Codex 0.156 only registers update_plan when this is enabled.
-          threadConfig: { "tools.update_plan.enabled": true },
           turnDefaults: {
             approvalPolicy: "never",
             sandboxPolicy: readOnlyFullAccessSandbox(),
@@ -947,6 +949,11 @@ function scenarios(): ReadonlyArray<ReplayScenario> {
   ];
 }
 
+function recorderThreadConfigMetadata(scenario: ReplayScenario) {
+  const keys = [...new Set(scenario.runs.flatMap((run) => Object.keys(run.threadConfig ?? {})))];
+  return keys.length === 0 ? {} : { recorderThreadConfigKeys: keys };
+}
+
 function makeRecorder({
   outPath,
   scenario,
@@ -992,6 +999,7 @@ function makeRecorder({
               fileName: scenario.fileName,
               description: scenario.description,
               model: scenarioModel(scenario),
+              ...recorderThreadConfigMetadata(scenario),
             },
           },
           ...outputRecords,
@@ -1209,7 +1217,7 @@ function runReplaySession({
       approvalGate ? Deferred.await(approvalGate) : Effect.void;
     const model = scenarioModel(scenario);
     // Same runtime params the adapter sends on thread/start, thread/resume and thread/fork.
-    const threadRuntimeParams = { cwd: process.cwd(), model };
+    const threadRuntimeParams = { cwd: process.cwd(), model, config: CODEX_THREAD_CONFIG };
     const lastTurnIdByThread = new Map<string, string>();
     const runningCommandProcessIds = new Map<string, Map<string, string>>();
 
@@ -1358,7 +1366,7 @@ function runReplaySession({
       const client = yield* initializeClient;
       const thread = yield* client.request("thread/start", {
         ...threadRuntimeParams,
-        ...(run.threadConfig === undefined ? {} : { config: run.threadConfig }),
+        config: { ...threadRuntimeParams.config, ...run.threadConfig },
       });
       let activeThreadId = thread.thread.id;
       const threadIds = new Map<string, string>([["source", thread.thread.id]]);

diff --git a/apps/server/src/orchestration-v2/Adapters/CodexAdapterV2.test.ts b/apps/server/src/orchestration-v2/Adapters/CodexAdapterV2.test.ts
@@ -73,6 +73,7 @@ import {
   canReuseCodexContextUsage,
   CODEX_DEFAULT_INSTANCE_ID,
   CODEX_DRIVER_KIND,
+  CODEX_THREAD_CONFIG,
   codexBackgroundCommandDetail,
   codexFileChangeApprovalPrompt,
   codexProviderTurnTokenUsage,
@@ -639,6 +640,7 @@ describe("CodexAdapterV2 process spawning", () => {
           cwd: "/workspace/thread-codex-mcp",
           model: "gpt-5.4",
           config: {
+            "tools.update_plan.enabled": true,
             mcp_servers: {
               "t3-code": {
                 url: "http://127.0.0.1:43123/mcp",
@@ -1492,7 +1494,7 @@ function codexReplayPreamble(input: {
     {
       type: "expect_outbound",
       label: "thread/start",
-      frame: { id: 2, method: "thread/start", params: {} },
+      frame: { id: 2, method: "thread/start", params: { config: CODEX_THREAD_CONFIG } },
     },
     {
       type: "emit_inbound",
@@ -2348,7 +2350,11 @@ describe("CodexAdapterV2 post-settle continuation", () => {
               frame: {
                 id: 3,
                 method: "thread/resume",
-                params: { threadId: nativeThreadId, excludeTurns: true },
+                params: {
+                  threadId: nativeThreadId,
+                  excludeTurns: true,
+                  config: CODEX_THREAD_CONFIG,
+                },
               },
             },
             {
@@ -2393,7 +2399,11 @@ describe("CodexAdapterV2 post-settle continuation", () => {
               frame: {
                 id: 3,
                 method: "thread/resume",
-                params: { threadId: nativeThreadId, excludeTurns: true },
+                params: {
+                  threadId: nativeThreadId,
+                  excludeTurns: true,
+                  config: CODEX_THREAD_CONFIG,
+                },
               },
             },
             {
@@ -6485,7 +6495,11 @@ describe("CodexAdapterV2 post-settle continuation", () => {
             {
               type: "expect_outbound",
               label: "thread/fork",
-              frame: { id: 3, method: "thread/fork", params: { threadId: nativeThreadId } },
+              frame: {
+                id: 3,
+                method: "thread/fork",
+                params: { threadId: nativeThreadId, config: CODEX_THREAD_CONFIG },
+              },
             },
             {
               type: "emit_inbound",
@@ -6620,7 +6634,11 @@ describe("CodexAdapterV2 post-settle continuation", () => {
             {
               type: "expect_outbound",
               label: "thread/fork",
-              frame: { id: 3, method: "thread/fork", params: { threadId: nativeThreadId } },
+              frame: {
+                id: 3,
+                method: "thread/fork",
+                params: { threadId: nativeThreadId, config: CODEX_THREAD_CONFIG },
+              },
             },
             {
               type: "emit_inbound",
@@ -6718,7 +6736,11 @@ describe("CodexAdapterV2 post-settle continuation", () => {
             frame: {
               id: 3,
               method: "thread/fork",
-              params: { threadId: nativeThreadId, lastTurnId: "native-turn-first" },
+              params: {
+                threadId: nativeThreadId,
+                lastTurnId: "native-turn-first",
+                config: CODEX_THREAD_CONFIG,
+              },
             },
           },
           {

diff --git a/apps/server/src/orchestration-v2/Adapters/CodexAdapterV2.ts b/apps/server/src/orchestration-v2/Adapters/CodexAdapterV2.ts
@@ -1141,24 +1141,32 @@ export class CodexAppServerClientFactory extends Context.Service<
   CodexAppServerClientFactoryShape
 >()("t3/orchestration-v2/Adapters/CodexAdapterV2/CodexAppServerClientFactory") {}
 
+/**
+ * Config overrides sent with every `thread/start`, `thread/resume` and `thread/fork`.
+ * Codex 0.152 made the `update_plan` checklist tool opt-in; T3 renders it as the
+ * todo list. Codex layers these above the user's and project's `config.toml`.
+ */
+export const CODEX_THREAD_CONFIG = { "tools.update_plan.enabled": true } as const;
+
 export function codexThreadRuntimeParams(input: {
   readonly threadId: ThreadId | null;
   readonly modelSelection?: { readonly model: string };
   readonly runtimePolicy?: ProviderAdapterV2RuntimePolicy;
 }): {
   readonly cwd?: string;
   readonly model?: string;
-  readonly config?: Readonly<Record<string, Schema.Json>>;
+  readonly config: Readonly<Record<string, Schema.Json>>;
 } {
   const mcpSession =
     input.threadId === null ? undefined : McpProviderSession.readMcpProviderSession(input.threadId);
   return {
     ...(input.runtimePolicy?.cwd == null ? {} : { cwd: input.runtimePolicy.cwd }),
     ...(input.modelSelection === undefined ? {} : { model: input.modelSelection.model }),
-    ...(mcpSession === undefined
-      ? {}
-      : {
-          config: {
+    config: {
+      ...CODEX_THREAD_CONFIG,
+      ...(mcpSession === undefined
+        ? {}
+        : {
             mcp_servers: {
               "t3-code": {
                 url: mcpSession.endpoint,
@@ -1167,8 +1175,8 @@ export function codexThreadRuntimeParams(input: {
                 },
               },
             },
-          },
-        }),
+          }),
+    },
   };
 }
 

diff --git a/...erver/src/orchestration-v2/testkit/fixtures/delegated_task_status/codex_transcript.ndjson b/...erver/src/orchestration-v2/testkit/fixtures/delegated_task_status/codex_transcript.ndjson
@@ -2,14 +2,14 @@
 {"type":"expect_outbound","label":"initialize","frame":{"id":1,"method":"initialize","params":{"capabilities":{"experimentalApi":true,"optOutNotificationMethods":["turn/diff/updated"]},"clientInfo":{"name":"t3code_desktop","title":"T3 Code Desktop","version":"0.1.0"}}}}
 {"type":"emit_inbound","label":"initialize","frame":{"id":1,"result":{"userAgent":"t3code_desktop/0.120.0 (Mac OS 26.4.1; arm64) dumb (t3code_desktop; 0.1.0)","codexHome":"/home/replay-user/.codex","platformFamily":"unix","platformOs":"macos"}}}
 {"type":"expect_outbound","label":"initialized","frame":{"method":"initialized"}}
-{"type":"expect_outbound","label":"parent.thread/start","frame":{"id":2,"method":"thread/start","params":{}}}
+{"type":"expect_outbound","label":"parent.thread/start","frame":{"id":2,"method":"thread/start","params":{"config":{"tools.update_plan.enabled":true}}}}
 {"type":"emit_inbound","label":"parent.thread/start","frame":{"id":2,"result":{"thread":{"id":"019f1000-0000-7000-8000-000000000001","forkedFromId":null,"preview":"","ephemeral":false,"modelProvider":"openai","createdAt":1776739467,"updatedAt":1776739467,"status":{"type":"idle"},"path":"/home/replay-user/.codex/sessions/delegated-task-status-parent.jsonl","cwd":"/home/replay-user/t3code","cliVersion":"0.120.0","source":"vscode","agentNickname":null,"agentRole":null,"gitInfo":null,"name":null,"turns":[]},"model":"gpt-5.4","modelProvider":"openai","serviceTier":"fast","cwd":"/home/replay-user/t3code","approvalPolicy":"on-request","approvalsReviewer":"user","sandbox":{"type":"workspaceWrite","writableRoots":[],"readOnlyAccess":{"type":"fullAccess"},"networkAccess":false,"excludeTmpdirEnvVar":false,"excludeSlashTmp":false},"reasoningEffort":"xhigh"}}}
 {"type":"expect_outbound","label":"parent.turn/start","frame":{"id":3,"method":"turn/start","params":{"approvalPolicy":"never","cwd":"<workspace>","input":[{"text":"Keep this parent turn active while orchestration tools are tested.","type":"text"}],"model":"gpt-5.4","sandboxPolicy":{"type":"dangerFullAccess"},"threadId":"019f1000-0000-7000-8000-000000000001","approvalsReviewer":"user","summary":"detailed"}}}
 {"type":"emit_inbound","label":"parent.thread/started","frame":{"method":"thread/started","params":{"thread":{"id":"019f1000-0000-7000-8000-000000000001","forkedFromId":null,"preview":"","ephemeral":false,"modelProvider":"openai","createdAt":1776739467,"updatedAt":1776739467,"status":{"type":"idle"},"path":"/home/replay-user/.codex/sessions/delegated-task-status-parent.jsonl","cwd":"/home/replay-user/t3code","cliVersion":"0.120.0","source":"vscode","agentNickname":null,"agentRole":null,"gitInfo":null,"name":null,"turns":[]}}}}
 {"type":"emit_inbound","label":"parent.turn/start","frame":{"id":3,"result":{"turn":{"id":"019f1000-0000-7000-8000-000000000002","items":[],"status":"inProgress","error":null,"startedAt":null,"completedAt":null,"durationMs":null}}}}
 {"type":"emit_inbound","label":"parent.thread/status/changed","frame":{"method":"thread/status/changed","params":{"threadId":"019f1000-0000-7000-8000-000000000001","status":{"type":"active","activeFlags":[]}}}}
 {"type":"emit_inbound","label":"parent.turn/started","frame":{"method":"turn/started","params":{"threadId":"019f1000-0000-7000-8000-000000000001","turn":{"id":"019f1000-0000-7000-8000-000000000002","items":[],"status":"inProgress","error":null,"startedAt":1776739467,"completedAt":null,"durationMs":null}}}}
-{"type":"expect_outbound","label":"child.thread/start","frame":{"id":4,"method":"thread/start","params":{}}}
+{"type":"expect_outbound","label":"child.thread/start","frame":{"id":4,"method":"thread/start","params":{"config":{"tools.update_plan.enabled":true}}}}
 {"type":"emit_inbound","label":"child.thread/start","frame":{"id":4,"result":{"thread":{"id":"019f1000-0000-7000-8000-000000000003","forkedFromId":null,"preview":"","ephemeral":false,"modelProvider":"openai","createdAt":1776739468,"updatedAt":1776739468,"status":{"type":"idle"},"path":"/home/replay-user/.codex/sessions/delegated-task-status-child.jsonl","cwd":"/home/replay-user/t3code","cliVersion":"0.120.0","source":"vscode","agentNickname":null,"agentRole":null,"gitInfo":null,"name":null,"turns":[]},"model":"gpt-5.4","modelProvider":"openai","serviceTier":"fast","cwd":"/home/replay-user/t3code","approvalPolicy":"on-request","approvalsReviewer":"user","sandbox":{"type":"workspaceWrite","writableRoots":[],"readOnlyAccess":{"type":"fullAccess"},"networkAccess":false,"excludeTmpdirEnvVar":false,"excludeSlashTmp":false},"reasoningEffort":"xhigh"}}}
 {"type":"expect_outbound","label":"child.original.turn/start","frame":{"id":5,"method":"turn/start","params":{"approvalPolicy":"never","cwd":"<workspace>","input":[{"text":"Inspect the delegated API boundary and return the result.","type":"text"}],"model":"gpt-5.4","sandboxPolicy":{"type":"dangerFullAccess"},"threadId":"019f1000-0000-7000-8000-000000000003","approvalsReviewer":"user","summary":"detailed"}}}
 {"type":"emit_inbound","label":"child.thread/started","frame":{"method":"thread/started","params":{"thread":{"id":"019f1000-0000-7000-8000-000000000003","forkedFromId":null,"preview":"","ephemeral":false,"modelProvider":"openai","createdAt":1776739468,"updatedAt":1776739468,"status":{"type":"idle"},"path":"/home/replay-user/.codex/sessions/delegated-task-status-child.jsonl","cwd":"/home/replay-user/t3code","cliVersion":"0.120.0","source":"vscode","agentNickname":null,"agentRole":null,"gitInfo":null,"name":null,"turns":[]}}}}

diff --git a/apps/server/src/orchestration-v2/testkit/fixtures/message_steering/codex_transcript.ndjson b/apps/server/src/orchestration-v2/testkit/fixtures/message_steering/codex_transcript.ndjson
@@ -2,7 +2,7 @@
 {"type":"expect_outbound","label":"initialize","frame":{"id":1,"method":"initialize","params":{"capabilities":{"experimentalApi":true,"optOutNotificationMethods":["turn/diff/updated"]},"clientInfo":{"name":"t3code_desktop","title":"T3 Code Desktop","version":"0.1.0"}}}}
 {"type":"emit_inbound","label":"initialize","frame":{"id":1,"result":{"userAgent":"t3code_desktop/0.156.1 (Debian 13.0.0; x86_64) unknown (t3code_desktop; 0.1.0)","codexHome":"/home/replay-user/.codex","platformFamily":"unix","platformOs":"linux"}}}
 {"type":"expect_outbound","label":"initialized","frame":{"method":"initialized"}}
-{"type":"expect_outbound","label":"thread/start","frame":{"id":2,"method":"thread/start","params":{"cwd":"<workspace>","model":"gpt-6-luna"}}}
+{"type":"expect_outbound","label":"thread/start","frame":{"id":2,"method":"thread/start","params":{"config":{"tools.update_plan.enabled":true},"cwd":"<workspace>","model":"gpt-6-luna"}}}
 {"type":"emit_inbound","label":"configWarning","frame":{"method":"configWarning","params":{"summary":"Codex could not find bubblewrap on PATH. Install bubblewrap with your OS package manager. See the sandbox prerequisites: https://developers.openai.com/codex/concepts/sandboxing#prerequisites. Codex will use the bundled bubblewrap in the meantime.","details":null},"emittedAtMs":1790295500250}}
 {"type":"emit_inbound","label":"remoteControl/status/changed","frame":{"method":"remoteControl/status/changed","params":{"status":"disabled","serverName":"replay-host","installationId":"00000000-0000-4000-8000-000000000000","environmentId":null},"emittedAtMs":1790295500250}}
 {"type":"emit_inbound","label":"thread/start","frame":{"id":2,"result":{"thread":{"id":"01a0d5ed-65ea-7d42-b8e9-d06f045cfa86","environments":[{"environmentId":"local","cwd":"/home/replay-user/t3code/packages/effect-codex-app-server","runtimeWorkspaceRoots":["/home/replay-user/t3code/packages/effect-codex-app-server"]}],"extra":null,"sessionId":"01a0d5ed-65ea-7d42-b8e9-d06f045cfa86","forkedFromId":null,"parentThreadId":null,"preview":"","ephemeral":false,"section":null,"sectionEnteredAt":null,"projectId":null,"historyMode":"paginated","modelProvider":"openai","model":"gpt-6-luna","reasoningEffort":null,"createdAt":1790295500,"updatedAt":1790295500,"recencyAt":1790295500,"status":{"type":"idle"},"path":"/home/replay-user/.codex/sessions/2026/09/24/rollout-2026-09-24T17-18-20-01a0d5ed-65ea-7d42-b8e9-d06f045cfa86.jsonl","cwd":"/home/replay-user/t3code/packages/effect-codex-app-server","cliVersion":"0.156.1","originator":"t3code_desktop","source":"vscode","canAcceptDirectInput":true,"threadSource":null,"agentNickname":null,"agentRole":null,"gitInfo":null,"name":null,"daybreakEnabled":null,"turns":[]},"model":"gpt-6-luna","modelProvider":"openai","serviceTier":null,"disabledPluginIds":[],"cwd":"/home/replay-user/t3code/packages/effect-codex-app-server","runtimeWorkspaceRoots":["/home/replay-user/t3code/packages/effect-codex-app-server"],"instructionSources":["/home/replay-user/.codex/AGENTS.md","/home/replay-user/t3code/AGENTS.md"],"approvalPolicy":"on-request","approvalsReviewer":"user","sandbox":{"type":"workspaceWrite","writableRoots":[],"networkAccess":false,"excludeTmpdirEnvVar":false,"excludeSlashTmp":false},"activePermissionProfile":{"id":":workspace","extends":null},"reasoningEffort":null,"multiAgentMode":"explicitRequestOnly"}}}