fix: maintain reasoning selections for multiple providers

apps/web/src/components/chat/ChatComposer.tsx

@@ -727,9 +727,16 @@ export const ChatComposer = memo(function ChatComposer(props: ChatComposerProps)
         model: selectedModel,
         models: selectedProviderModels,
         prompt,
-        modelOptions: composerModelOptions?.[selectedProvider],
+        modelOptions: composerModelOptions?.[selectedInstanceId],
       }),
-    [composerModelOptions, prompt, selectedModel, selectedProvider, selectedProviderModels],
+    [
+      composerModelOptions,
+      prompt,
+      selectedInstanceId,
+      selectedModel,
+      selectedProvider,
+      selectedProviderModels,
+    ],
   );
 
   const selectedPromptEffort = composerProviderState.promptEffort;
@@ -1018,21 +1025,23 @@ export const ChatComposer = memo(function ChatComposer(props: ChatComposerProps)
 
   const providerTraitsMenuContent = renderProviderTraitsMenuContent({
     provider: selectedProvider,
+    instanceId: selectedInstanceId,
     ...(routeKind === "server" ? { threadRef: routeThreadRef } : {}),
     ...(routeKind === "draft" && draftId ? { draftId } : {}),
     model: selectedModel,
     models: selectedProviderModels,
-    modelOptions: composerModelOptions?.[selectedProvider],
+    modelOptions: composerModelOptions?.[selectedInstanceId],
     prompt,
     onPromptChange: setPromptFromTraits,
   });
   const providerTraitsPicker = renderProviderTraitsPicker({
     provider: selectedProvider,
+    instanceId: selectedInstanceId,
     ...(routeKind === "server" ? { threadRef: routeThreadRef } : {}),
     ...(routeKind === "draft" && draftId ? { draftId } : {}),
     model: selectedModel,
     models: selectedProviderModels,
-    modelOptions: composerModelOptions?.[selectedProvider],
+    modelOptions: composerModelOptions?.[selectedInstanceId],
     prompt,
     onPromptChange: setPromptFromTraits,
   });

apps/web/src/components/chat/TraitsPicker.tsx

@@ -1,5 +1,6 @@
 import {
   type ProviderDriverKind,
+  type ProviderInstanceId,
   type ProviderOptionDescriptor,
   type ProviderOptionSelection,
   type ScopedThreadRef,
@@ -196,6 +197,7 @@ export function shouldRenderTraitsControls(input: {
 
 export interface TraitsMenuContentProps {
   provider: ProviderDriverKind;
+  instanceId?: ProviderInstanceId;
   models: ReadonlyArray<ServerProviderModel>;
   model: string | null | undefined;
   prompt: string;
@@ -208,6 +210,7 @@ export interface TraitsMenuContentProps {
 
 export const TraitsMenuContent = memo(function TraitsMenuContentImpl({
   provider,
+  instanceId,
   models,
   model,
   prompt,
@@ -228,11 +231,12 @@ export const TraitsMenuContent = memo(function TraitsMenuContentImpl({
         return;
       }
       setProviderModelOptions(threadTarget, provider, nextOptions, {
+        ...(instanceId ? { instanceId } : {}),
         model,
         persistSticky: true,
       });
     },
-    [model, persistence, provider, setProviderModelOptions],
+    [instanceId, model, persistence, provider, setProviderModelOptions],
   );
   const {
     descriptors,
@@ -343,6 +347,7 @@ export const TraitsMenuContent = memo(function TraitsMenuContentImpl({
 
 export const TraitsPicker = memo(function TraitsPicker({
   provider,
+  instanceId,
   models,
   model,
   prompt,
@@ -431,6 +436,7 @@ export const TraitsPicker = memo(function TraitsPicker({
       <MenuPopup align="start">
         <TraitsMenuContent
           provider={provider}
+          {...(instanceId ? { instanceId } : {})}
           models={models}
           model={model}
           prompt={prompt}

apps/web/src/components/chat/composerProviderState.tsx

@@ -1,5 +1,6 @@
 import {
   type ProviderDriverKind,
+  type ProviderInstanceId,
   type ProviderOptionSelection,
   type ScopedThreadRef,
   type ServerProviderModel,
@@ -35,6 +36,7 @@ export type ComposerProviderState = {
 
 type TraitsRenderInput = {
   provider: ProviderDriverKind;
+  instanceId?: ProviderInstanceId;
   threadRef?: ScopedThreadRef;
   draftId?: DraftId;
   model: string;
@@ -76,8 +78,17 @@ function renderTraitsControl(
   Component: typeof TraitsMenuContent | typeof TraitsPicker,
   input: TraitsRenderInput,
 ): ReactNode {
-  const { provider, threadRef, draftId, model, models, modelOptions, prompt, onPromptChange } =
-    input;
+  const {
+    provider,
+    instanceId,
+    threadRef,
+    draftId,
+    model,
+    models,
+    modelOptions,
+    prompt,
+    onPromptChange,
+  } = input;
   const hasTarget = threadRef !== undefined || draftId !== undefined;
   if (
     !hasTarget ||
@@ -88,6 +99,7 @@ function renderTraitsControl(
   return (
     <Component
       provider={provider}
+      {...(instanceId ? { instanceId } : {})}
       models={models}
       {...(threadRef ? { threadRef } : {})}
       {...(draftId ? { draftId } : {})}

apps/web/src/composerDraftStore.test.ts

@@ -21,6 +21,7 @@ import { createModelSelection } from "@t3tools/shared/model";
 // `stickyModelSelectionByProvider` maps are keyed by `ProviderInstanceId`
 // in production; these aliases keep the legacy-key migration tests concise.
 const CODEX_INSTANCE = ProviderInstanceId.make("codex");
+const CODEX_SECONDARY_INSTANCE = ProviderInstanceId.make("codex_secondary");
 const CLAUDE_AGENT_INSTANCE = ProviderInstanceId.make("claudeAgent");
 const CURSOR_INSTANCE = ProviderInstanceId.make("cursor");
 const CODEX_DRIVER = ProviderDriverKind.make("codex");
@@ -1201,6 +1202,43 @@ describe("composerDraftStore modelSelection", () => {
     );
   });
 
+  it("stores provider option changes on a selected custom instance", () => {
+    const store = useComposerDraftStore.getState();
+
+    store.setProviderModelOptions(
+      threadRef,
+      CODEX_DRIVER,
+      toSelections({ reasoningEffort: "low" }),
+      {
+        instanceId: CODEX_SECONDARY_INSTANCE,
+        model: "gpt-5-codex",
+        persistSticky: true,
+      },
+    );
+
+    expect(
+      draftFor(threadId, TEST_ENVIRONMENT_ID)?.modelSelectionByProvider[CODEX_SECONDARY_INSTANCE],
+    ).toEqual(
+      expect.objectContaining({
+        instanceId: CODEX_SECONDARY_INSTANCE,
+        options: [{ id: "reasoningEffort", value: "low" }],
+      }),
+    );
+    expect(draftFor(threadId, TEST_ENVIRONMENT_ID)?.activeProvider).toBe(CODEX_SECONDARY_INSTANCE);
+    expect(useComposerDraftStore.getState().stickyActiveProvider).toBe(CODEX_SECONDARY_INSTANCE);
+    expect(useComposerDraftStore.getState().stickyModelSelectionByProvider[CODEX_INSTANCE]).toBe(
+      undefined,
+    );
+    expect(
+      useComposerDraftStore.getState().stickyModelSelectionByProvider[CODEX_SECONDARY_INSTANCE],
+    ).toEqual(
+      expect.objectContaining({
+        instanceId: CODEX_SECONDARY_INSTANCE,
+        options: [{ id: "reasoningEffort", value: "low" }],
+      }),
+    );
+  });
+
   it("updates only the draft when sticky persistence is disabled", () => {
     const store = useComposerDraftStore.getState();
 

apps/web/src/composerDraftStore.ts

@@ -371,6 +371,7 @@ interface ComposerDraftStoreState {
     provider: ProviderDriverKind,
     nextProviderOptions: ReadonlyArray<ProviderOptionSelection> | null | undefined,
     options?: {
+      instanceId?: ProviderInstanceId | null | undefined;
       model?: string | null | undefined;
       persistSticky?: boolean;
     },
@@ -2456,7 +2457,7 @@ const composerDraftStore = create<ComposerDraftStoreState>()(
           if (normalizedProvider === null) {
             return;
           }
-          const instanceKey = defaultInstanceIdForDriver(normalizedProvider);
+          const instanceKey = options?.instanceId ?? defaultInstanceIdForDriver(normalizedProvider);
           const fallbackModel =
             normalizeModelSlug(options?.model, normalizedProvider) ??
             DEFAULT_MODEL_BY_PROVIDER[normalizedProvider] ??
@@ -2501,7 +2502,9 @@ const composerDraftStore = create<ComposerDraftStoreState>()(
                 const { options: _, ...rest } = stickyBase;
                 nextStickyMap[instanceKey] = rest as ModelSelection;
               }
-              nextStickyActiveProvider = base.activeProvider ?? instanceKey;
+              nextStickyActiveProvider = options.instanceId
+                ? instanceKey
+                : (base.activeProvider ?? instanceKey);
             }
 
             if (
@@ -2514,6 +2517,7 @@ const composerDraftStore = create<ComposerDraftStoreState>()(
 
             const nextDraft: ComposerThreadDraftState = {
               ...base,
+              ...(options?.instanceId ? { activeProvider: instanceKey } : {}),
               modelSelectionByProvider: nextMap,
             };
             const nextDraftsByThreadKey = { ...state.draftsByThreadKey };