From 551aebc6046f23eabcf0ea6dddab73619b83b2da Mon Sep 17 00:00:00 2001
From: Julius Marminge <julius0216@outlook.com>
Date: Thu, 5 Mar 2026 22:43:16 -0800
Subject: [PATCH] Add default collaboration mode preset for Codex turn starts

- Send `collaborationMode` for both `default` and `plan` interactions
- Add default-mode developer instructions and preserve plan-mode behavior
- Update server/web tests for default collaboration mode and model constant usage
---
 apps/server/src/codexAppServerManager.test.ts | 31 +++++++++++++++++++
 apps/server/src/codexAppServerManager.ts      | 26 +++++++++++++---
 apps/web/src/store.test.ts                    | 10 ++++--
 3 files changed, 60 insertions(+), 7 deletions(-)

diff --git a/apps/server/src/codexAppServerManager.test.ts b/apps/server/src/codexAppServerManager.test.ts
index 58c34020294c8552e62d609679b19e1e3b7847ea..f2e11ca292e39b1a00e3917620d29d7666c2d66b 100644
--- a/apps/server/src/codexAppServerManager.test.ts
+++ b/apps/server/src/codexAppServerManager.test.ts
@@ -7,6 +7,7 @@ import { ApprovalRequestId, ThreadId } from "@t3tools/contracts";
 
 import {
   buildCodexInitializeParams,
+  CODEX_DEFAULT_MODE_DEVELOPER_INSTRUCTIONS,
   CODEX_PLAN_MODE_DEVELOPER_INSTRUCTIONS,
   CodexAppServerManager,
   classifyCodexStderrLine,
@@ -346,6 +347,36 @@ describe("sendTurn", () => {
     });
   });
 
+  it("passes Codex default mode as a collaboration preset on turn/start", async () => {
+    const { manager, context, sendRequest } = createSendTurnHarness();
+
+    await manager.sendTurn({
+      threadId: asThreadId("thread_1"),
+      input: "PLEASE IMPLEMENT THIS PLAN:\n- step 1",
+      interactionMode: "default",
+    });
+
+    expect(sendRequest).toHaveBeenCalledWith(context, "turn/start", {
+      threadId: "thread_1",
+      input: [
+        {
+          type: "text",
+          text: "PLEASE IMPLEMENT THIS PLAN:\n- step 1",
+          text_elements: [],
+        },
+      ],
+      model: "gpt-5.3-codex",
+      collaborationMode: {
+        mode: "default",
+        settings: {
+          model: "gpt-5.3-codex",
+          reasoning_effort: "medium",
+          developer_instructions: CODEX_DEFAULT_MODE_DEVELOPER_INSTRUCTIONS,
+        },
+      },
+    });
+  });
+
   it("rejects empty turn input", async () => {
     const { manager } = createSendTurnHarness();
 
diff --git a/apps/server/src/codexAppServerManager.ts b/apps/server/src/codexAppServerManager.ts
index 185851ae16cb1c6ffc0e053459f5047383269963..6e83d211ad91e9bbcb13c2b76346bbc47b1d08a8 100644
--- a/apps/server/src/codexAppServerManager.ts
+++ b/apps/server/src/codexAppServerManager.ts
@@ -257,6 +257,19 @@ Do not ask "should I proceed?" in the final output. The user can easily switch o
 Only produce at most one \`<proposed_plan>\` block per turn, and only when you are presenting a complete spec.
 </collaboration_mode>`;
 
+export const CODEX_DEFAULT_MODE_DEVELOPER_INSTRUCTIONS = `<collaboration_mode># Collaboration Mode: Default
+
+You are now in Default mode. Any previous instructions for other modes (e.g. Plan mode) are no longer active.
+
+Your active mode changes only when new developer instructions with a different \`<collaboration_mode>...</collaboration_mode>\` change it; user requests or tool descriptions do not change mode by themselves. Known mode names are Default and Plan.
+
+## request_user_input availability
+
+The \`request_user_input\` tool is unavailable in Default mode. If you call it while in Default mode, it will return an error.
+
+In Default mode, strongly prefer making reasonable assumptions and executing the user's request rather than stopping to ask questions. If you absolutely must ask a question because the answer cannot be discovered from local context and a reasonable assumption would be risky, ask the user directly with a concise plain-text question. Never write a multiple choice question as a textual assistant message.
+</collaboration_mode>`;
+
 function mapCodexRuntimeMode(runtimeMode: RuntimeMode): {
   readonly approvalPolicy: "on-request" | "never";
   readonly sandbox: "workspace-write" | "danger-full-access";
@@ -326,7 +339,7 @@ function buildCodexCollaborationMode(input: {
   readonly effort?: string;
 }):
   | {
-      mode: "plan";
+      mode: "default" | "plan";
       settings: {
         model: string;
         reasoning_effort: string;
@@ -334,16 +347,19 @@ function buildCodexCollaborationMode(input: {
       };
     }
   | undefined {
-  if (input.interactionMode !== "plan") {
+  if (input.interactionMode === undefined) {
     return undefined;
   }
   const model = normalizeCodexModelSlug(input.model) ?? "gpt-5.3-codex";
   return {
-    mode: "plan",
+    mode: input.interactionMode,
     settings: {
       model,
       reasoning_effort: input.effort ?? "medium",
-      developer_instructions: CODEX_PLAN_MODE_DEVELOPER_INSTRUCTIONS,
+      developer_instructions:
+        input.interactionMode === "plan"
+          ? CODEX_PLAN_MODE_DEVELOPER_INSTRUCTIONS
+          : CODEX_DEFAULT_MODE_DEVELOPER_INSTRUCTIONS,
     },
   };
 }
@@ -644,7 +660,7 @@ export class CodexAppServerManager extends EventEmitter<CodexAppServerManagerEve
       effort?: string;
       serviceTier?: string;
       collaborationMode?: {
-        mode: "plan";
+        mode: "default" | "plan";
         settings: {
           model: string;
           reasoning_effort: string;
diff --git a/apps/web/src/store.test.ts b/apps/web/src/store.test.ts
index 77b913c3d32ceca2c99bd7dd79aaa4b69f32f508..145d8301ee233fb7a81d730cc17bf5228ae5e1ad 100644
--- a/apps/web/src/store.test.ts
+++ b/apps/web/src/store.test.ts
@@ -1,4 +1,10 @@
-import { ProjectId, ThreadId, TurnId, type OrchestrationReadModel } from "@t3tools/contracts";
+import {
+  DEFAULT_MODEL_BY_PROVIDER,
+  ProjectId,
+  ThreadId,
+  TurnId,
+  type OrchestrationReadModel,
+} from "@t3tools/contracts";
 import { describe, expect, it } from "vitest";
 
 import { markThreadUnread, syncServerReadModel, type AppState } from "./store";
@@ -139,6 +145,6 @@ describe("store read model sync", () => {
 
     const next = syncServerReadModel(initialState, readModel);
 
-    expect(next.threads[0]?.model).toBe("gpt-5.3-codex");
+    expect(next.threads[0]?.model).toBe(DEFAULT_MODEL_BY_PROVIDER.codex);
   });
 });
-- 
2.54.0