diff --git a/README.md b/README.md
index 2e66018..3e28d09 100644
--- a/README.md
+++ b/README.md
@@ -49,6 +49,7 @@ Pre-release packages are published on matching npm dist-tags instead of `latest`
 2. Use the picker buttons, or pass a filter like `/codex_resume release-fix` or `/codex_resume --projects`.
 3. Send normal chat messages once the thread is bound.
 4. Use control commands such as `/codex_status`, `/codex_plan`, `/codex_review`, `/codex_model`, and `/codex_stop` as needed.
+5. If you leave plan mode through the normal `Implement this plan` button, you do not need `/codex_plan off`; use `/codex_plan off` only when you want to exit planning manually instead.
 
 ## Command Reference
 
@@ -65,7 +66,7 @@ Pre-release packages are published on matching npm dist-tags instead of `latest`
 | `/codex_stop` | Interrupt the active Codex run. | Only applies when a turn is currently in progress. |
 | `/codex_steer <message>` | Send follow-up steer text to an active run. | Example: `/codex_steer focus on the failing tests first` |
 | `/codex_plan <goal>` | Ask Codex to plan instead of execute. | The plugin relays plan questions and the final plan back into chat. |
-| `/codex_plan off` | Exit plan mode for this conversation. | Interrupts a lingering plan run so future turns go back to default coding mode. |
+| `/codex_plan off` | Exit plan mode for this conversation. | Use this when you want to leave planning manually instead of through the normal `Implement this plan` button. |
 | `/codex_review` | Review the current uncommitted changes in the bound workspace. | Requires an existing binding. |
 | `/codex_review <focus>` | Review with custom instructions. | Example: `/codex_review focus on thread selection regressions` |
 | `/codex_compact` | Compact the bound Codex thread. | The plugin posts progress and final context usage. |
diff --git a/src/client.test.ts b/src/client.test.ts
index 2151348..185a2cc 100644
--- a/src/client.test.ts
+++ b/src/client.test.ts
@@ -64,6 +64,49 @@ describe("buildTurnStartPayloads", () => {
       },
     ]);
   });
+
+  it("uses the fallback model to send an explicit default collaboration mode", () => {
+    expect(
+      __testing.buildTurnStartPayloads({
+        threadId: "thread-123",
+        prompt: "run it",
+        collaborationMode: {
+          mode: "default",
+          settings: {
+            developerInstructions: null,
+          },
+        },
+        collaborationFallbackModel: "gpt-5.4",
+      }),
+    ).toEqual([
+      {
+        threadId: "thread-123",
+        input: [{ type: "text", text: "run it" }],
+        collaborationMode: {
+          mode: "default",
+          settings: {
+            model: "gpt-5.4",
+            developerInstructions: null,
+          },
+        },
+      },
+      {
+        threadId: "thread-123",
+        input: [{ type: "text", text: "run it" }],
+        collaboration_mode: {
+          mode: "default",
+          settings: {
+            model: "gpt-5.4",
+            developer_instructions: null,
+          },
+        },
+      },
+      {
+        threadId: "thread-123",
+        input: [{ type: "text", text: "run it" }],
+      },
+    ]);
+  });
 });
 
 describe("buildTurnSteerPayloads", () => {
diff --git a/src/client.ts b/src/client.ts
index eedd2b6..c191a52 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -1072,6 +1072,7 @@ function buildTurnStartPayloads(params: {
   prompt: string;
   model?: string;
   collaborationMode?: CollaborationMode;
+  collaborationFallbackModel?: string;
 }): unknown[] {
   const base: Record<string, unknown> = {
     threadId: params.threadId,
@@ -1085,7 +1086,7 @@ function buildTurnStartPayloads(params: {
   }
   const collaborationPayloads = buildCollaborationModePayloads(
     params.collaborationMode,
-    params.model,
+    params.collaborationFallbackModel ?? params.model,
   ).flatMap((variant) => [
     {
       ...base,
@@ -1099,6 +1100,34 @@ function buildTurnStartPayloads(params: {
   return [...collaborationPayloads, base];
 }
 
+function buildDefaultCollaborationMode(settings: {
+  model?: string;
+  reasoningEffort?: string;
+}): CollaborationMode | undefined {
+  const model = settings.model?.trim();
+  if (!model) {
+    return undefined;
+  }
+  return {
+    mode: "default",
+    settings: {
+      model,
+      ...(settings.reasoningEffort?.trim()
+        ? { reasoningEffort: settings.reasoningEffort.trim() }
+        : {}),
+      developerInstructions: null,
+    },
+  };
+}
+
+function payloadHasCollaborationMode(payload: unknown): boolean {
+  const record = asRecord(payload);
+  return Boolean(
+    record &&
+      (Object.hasOwn(record, "collaborationMode") || Object.hasOwn(record, "collaboration_mode")),
+  );
+}
+
 function buildTurnSteerPayloads(params: {
   threadId: string;
   turnId: string;
@@ -3104,6 +3133,8 @@ export class CodexAppServerClient {
   }): ActiveCodexRun {
     let threadId = params.existingThreadId?.trim() || "";
     let turnId = "";
+    let threadModel = "";
+    let threadReasoningEffort = "";
     let assistantText = "";
     let sawAssistantOutput = false;
     let assistantItemId = "";
@@ -3352,29 +3383,58 @@ export class CodexAppServerClient {
             ],
             timeoutMs: this.settings.requestTimeoutMs,
           });
+          const createdState = extractThreadState(created);
           threadId = extractIds(created).threadId ?? "";
+          threadModel = createdState.model?.trim() || threadModel;
+          threadReasoningEffort = createdState.reasoningEffort?.trim() || threadReasoningEffort;
           if (!threadId) {
             throw new Error("Codex App Server did not return a thread id.");
           }
-          this.logger.debug(`codex turn thread created run=${params.runId} thread=${threadId}`);
+          this.logger.debug(
+            `codex turn thread created run=${params.runId} thread=${threadId} model=${threadModel || "<none>"} reasoningEffort=${threadReasoningEffort || "<none>"}`,
+          );
         } else {
-          await requestWithFallbacks({
+          const resumed = await requestWithFallbacks({
             client,
             methods: ["thread/resume"],
             payloads: [{ threadId }],
             timeoutMs: this.settings.requestTimeoutMs,
           }).catch(() => undefined);
-          this.logger.debug(`codex turn thread resumed run=${params.runId} thread=${threadId}`);
+          const resumedState = resumed ? extractThreadState(resumed) : undefined;
+          threadModel = resumedState?.model?.trim() || threadModel;
+          threadReasoningEffort =
+            resumedState?.reasoningEffort?.trim() || threadReasoningEffort;
+          this.logger.debug(
+            `codex turn thread resumed run=${params.runId} thread=${threadId} model=${threadModel || "<none>"} reasoningEffort=${threadReasoningEffort || "<none>"}`,
+          );
+        }
+        const synthesizedDefaultMode = buildDefaultCollaborationMode({
+          model: params.model?.trim() || threadModel,
+          reasoningEffort: threadReasoningEffort,
+        });
+        const collaborationMode = params.collaborationMode ?? synthesizedDefaultMode;
+        const turnStartPayloads = buildTurnStartPayloads({
+          threadId,
+          prompt: params.prompt,
+          model: params.model,
+          collaborationMode,
+          collaborationFallbackModel: params.model?.trim() || threadModel,
+        });
+        const collaborationPayload = turnStartPayloads.some((payload) =>
+          payloadHasCollaborationMode(payload),
+        );
+        this.logger.debug(
+          `codex turn start payload run=${params.runId} thread=${threadId} requestedMode=${params.collaborationMode?.mode ?? "default"} modeSource=${params.collaborationMode ? "explicit" : "synthesized"} requestedModel=${params.model?.trim() || "<none>"} threadModel=${threadModel || "<none>"} collaborationPayload=${collaborationPayload ? "yes" : "no"}`,
+        );
+        if (collaborationMode && !collaborationPayload) {
+          this.logger.warn(
+            `codex turn start omitted collaboration mode payload run=${params.runId} thread=${threadId} requestedMode=${collaborationMode.mode} requestedModel=${params.model?.trim() || "<none>"} threadModel=${threadModel || "<none>"}`,
+          );
         }
         const started = await requestWithFallbacks({
           client,
           methods: ["turn/start"],
-          payloads: buildTurnStartPayloads({
-            threadId,
-            prompt: params.prompt,
-            model: params.model,
-            collaborationMode: params.collaborationMode,
-          }),
+          payloads: turnStartPayloads,
           timeoutMs: this.settings.requestTimeoutMs,
         });
         const startedIds = extractIds(started);
diff --git a/src/controller.ts b/src/controller.ts
index 295c160..1b02b79 100644
--- a/src/controller.ts
+++ b/src/controller.ts
@@ -1156,6 +1156,9 @@ export class CodexPluginController {
     if (parsed.mode === "off") {
       const key = buildConversationKey(conversation);
       const active = this.activeRuns.get(key);
+      this.api.logger.debug?.(
+        `codex plan off requested ${this.formatConversationForLog(conversation)} active=${active?.mode ?? "none"} boundThread=${binding?.threadId ?? "<none>"}`,
+      );
       if (active?.mode === "plan") {
         this.activeRuns.delete(key);
         await active.handle.interrupt().catch(() => undefined);
@@ -3239,6 +3242,9 @@ export class CodexPluginController {
       }).catch(() => []),
       this.resolveProjectFolder(binding?.workspaceDir || workspaceDir),
     ]);
+    this.api.logger.debug?.(
+      `codex status snapshot bindingActive=${bindingActive ? "yes" : "no"} activeRun=${activeRun?.mode ?? "none"} boundThread=${binding?.threadId ?? "<none>"} threadModel=${threadState?.model?.trim() || "<none>"} threadCwd=${threadState?.cwd?.trim() || "<none>"}`,
+    );
 
     return formatCodexStatusText({
       threadState,