From fe40ff94f40a142b8e7713e747c36262460b162f Mon Sep 17 00:00:00 2001
From: Gourav Kumar Dhiman <gkrdhiman@gmail.com>
Date: Fri, 30 Oct 2026 14:20:08 +0530
Subject: [PATCH] fix(web): the fallback model has its own reasoning selector

Settings > New threads showed a reasoning control for the default model but
not for the fallback model, so fallback threads always started at the
provider's default effort. The fallback row now offers the same control and
saves the choice with the fallback selection.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
---
 .../settings/ProjectDefaultsSettings.tsx      | 79 ++++++++++++-------
 1 file changed, 51 insertions(+), 28 deletions(-)

diff --git a/apps/web/src/components/settings/ProjectDefaultsSettings.tsx b/apps/web/src/components/settings/ProjectDefaultsSettings.tsx
index 43c4419962a02..cdd107b150da1 100644
--- a/apps/web/src/components/settings/ProjectDefaultsSettings.tsx
+++ b/apps/web/src/components/settings/ProjectDefaultsSettings.tsx
@@ -79,6 +79,7 @@ export function ProjectDefaultsSettings({ category }: { category: ProjectSetting
   const mixedModel = useScopedSettingsMixed(["defaultModelSelection"]);
   const mixedFallback = useScopedSettingsMixed(["fallbackModelSelection"]);
   const fallbackSelection = settings.fallbackModelSelection ?? selection;
+  const fallbackEntry = entries.find((entry) => entry.instanceId === fallbackSelection?.instanceId);
   const fallbackModelOptions = getCustomModelOptionsByInstance(
     settings,
     providers,
@@ -242,34 +243,56 @@ export function ProjectDefaultsSettings({ category }: { category: ProjectSetting
       }
       control={
         fallbackSelection ? (
-          <ProviderModelPicker
-            environmentId={representative?.environmentId ?? null}
-            activeInstanceId={fallbackSelection.instanceId}
-            model={fallbackSelection.model}
-            lockedProvider={null}
-            instanceEntries={entries}
-            modelOptionsByInstance={fallbackModelOptions}
-            triggerClassName={SETTINGS_PICKER_TRIGGER_CLASSNAME}
-            triggerAriaLabel="Fallback model"
-            {...(mixedFallback
-              ? { triggerLabel: "Mixed" }
-              : settings.fallbackModelSelection === null
-                ? { triggerLabel: "None" }
-                : {})}
-            getModelDisabledReason={modelDisabledReason}
-            onInstanceModelChange={(instanceId, model) => {
-              const reason = modelDisabledReason(instanceId, model);
-              if (reason) {
-                toastManager.add({
-                  type: "error",
-                  title: "Fallback model not saved",
-                  description: reason,
-                });
-                return;
-              }
-              updateSettings({ fallbackModelSelection: createModelSelection(instanceId, model) });
-            }}
-          />
+          <div className="flex min-w-0 flex-wrap items-center justify-end gap-1.5">
+            <ProviderModelPicker
+              environmentId={representative?.environmentId ?? null}
+              activeInstanceId={fallbackSelection.instanceId}
+              model={fallbackSelection.model}
+              lockedProvider={null}
+              instanceEntries={entries}
+              modelOptionsByInstance={fallbackModelOptions}
+              triggerClassName={SETTINGS_PICKER_TRIGGER_CLASSNAME}
+              triggerAriaLabel="Fallback model"
+              {...(mixedFallback
+                ? { triggerLabel: "Mixed" }
+                : settings.fallbackModelSelection === null
+                  ? { triggerLabel: "None" }
+                  : {})}
+              getModelDisabledReason={modelDisabledReason}
+              onInstanceModelChange={(instanceId, model) => {
+                const reason = modelDisabledReason(instanceId, model);
+                if (reason) {
+                  toastManager.add({
+                    type: "error",
+                    title: "Fallback model not saved",
+                    description: reason,
+                  });
+                  return;
+                }
+                updateSettings({ fallbackModelSelection: createModelSelection(instanceId, model) });
+              }}
+            />
+            {fallbackEntry && !mixedFallback && settings.fallbackModelSelection !== null ? (
+              <TraitsPicker
+                provider={fallbackEntry.driverKind}
+                models={fallbackEntry.models}
+                model={fallbackSelection.model}
+                modelOptions={fallbackSelection.options ?? []}
+                allowPromptInjectedEffort={false}
+                planModeEnabled={settings.planModeEnabled}
+                triggerClassName={SETTINGS_PICKER_TRIGGER_CLASSNAME}
+                onModelOptionsChange={(options) =>
+                  updateSettings({
+                    fallbackModelSelection: createModelSelection(
+                      fallbackSelection.instanceId,
+                      fallbackSelection.model,
+                      options,
+                    ),
+                  })
+                }
+              />
+            ) : null}
+          </div>
         ) : (
           <span className="text-sm text-muted-foreground">No providers available</span>
         )