fix(web,mobile): thread-bound scheduled tasks no longer offer a model their runs ignore

apps/mobile/src/features/settings/SettingsScheduledTasksRouteScreen.tsx

@@ -858,7 +858,10 @@ function TaskForm({
           {promptField}
         </SettingsSection>
 
-        <SettingsSection title="Context">
+        <SettingsSection
+          title="Context"
+          footer={draft.threadId !== null ? "Runs use this thread's current model." : undefined}
+        >
           <SelectRow
             label="Project"
             value={
@@ -904,7 +907,9 @@ function TaskForm({
               (modelOptions.length ? "Choose model" : "No models available")
             }
             onPress={() => navigation.navigate("SettingsScheduledTaskModel")}
-            disabled={saving || dictationPending || environmentUnavailable}
+            disabled={
+              saving || dictationPending || environmentUnavailable || draft.threadId !== null
+            }
           />
         </SettingsSection>
 

apps/web/src/components/settings/ScheduledTasksSettings.browser.test.tsx

@@ -215,4 +215,20 @@ describe("ScheduledTasksSettings", () => {
     await expect.element(dialog.getByRole("heading", { name: "New task" })).toBeInTheDocument();
     await expect.element(name).toHaveValue("My draft");
   });
+
+  it("locks the model while the task is bound to a thread", async () => {
+    setup();
+    await using _screen = await render(<ScheduledTasksSettings taskId={task.id} />);
+    const dialog = page.getByRole("dialog");
+    const model = dialog.getByRole("button", { name: "Choose model" });
+    const note = dialog.getByText("Runs use this thread's current model.");
+    await expect.element(model).toBeDisabled();
+    await expect.element(note).toBeVisible();
+
+    await userEvent.click(dialog.getByRole("combobox", { name: "Destination" }));
+    await userEvent.click(page.getByRole("option", { name: "New thread each run" }));
+
+    await expect.element(model).toBeEnabled();
+    await expect.element(note).not.toBeInTheDocument();
+  });
 });

apps/web/src/components/settings/ScheduledTasksSettings.tsx

@@ -1786,7 +1786,7 @@ function ScheduledTaskEditorForm({
             <div>
               <ProviderModelPicker
                 environmentId={environmentId}
-                disabled={saving || !connected}
+                disabled={saving || !connected || draft.threadId !== ""}
                 activeInstanceId={activeInstanceId}
                 model={activeModel}
                 lockedProvider={null}
@@ -1799,6 +1799,9 @@ function ScheduledTaskEditorForm({
                 }
               />
             </div>
+            {draft.threadId !== "" ? (
+              <p className="text-sm text-muted-foreground">Runs use this thread's current model.</p>
+            ) : null}
           </Field>
 
           <div className="space-y-3">