feat(agent): make model presets session-scoped (#4866)

webui/src/components/thread/ThreadShell.tsx

@@ -170,8 +170,14 @@ interface ModelBadgeInfo {
   needsSetup: boolean;
 }
 
-function activeModelPreset(settings: SettingsPayload | null): SettingsPayload["model_presets"][number] | null {
+function modelPresetForBadge(
+  settings: SettingsPayload | null,
+  scopedPreset: string | null,
+): SettingsPayload["model_presets"][number] | null {
   if (!settings) return null;
+  if (scopedPreset) {
+    return settings.model_presets.find((preset) => preset.name === scopedPreset) ?? null;
+  }
   const configured = settings.agent.model_preset || "default";
   return (
     settings.model_presets.find((preset) => preset.name === configured)
@@ -180,19 +186,25 @@ function activeModelPreset(settings: SettingsPayload | null): SettingsPayload["m
   );
 }
 
-function resolvedModelProvider(settings: SettingsPayload | null, modelName: string | null): string | null {
-  const preset = activeModelPreset(settings);
-  const rawProvider = preset?.provider || settings?.agent.provider || null;
-  if (rawProvider === "auto") {
-    return settings?.agent.resolved_provider || inferProviderFromModelName(modelName) || null;
-  }
-  return rawProvider || inferProviderFromModelName(modelName);
-}
-
-function toModelBadgeInfo(modelName: string | null, settings: SettingsPayload | null): ModelBadgeInfo {
-  const model = modelName || settings?.agent.model || null;
+function toModelBadgeInfo(
+  modelName: string | null,
+  settings: SettingsPayload | null,
+  modelPreset: string | null = null,
+): ModelBadgeInfo {
+  const scopedPreset = modelPreset?.trim() || null;
+  const preset = modelPresetForBadge(settings, scopedPreset);
+  const model = scopedPreset
+    ? preset?.model || null
+    : modelName || settings?.agent.model || null;
   const label = toModelBadgeLabel(model);
-  const provider = resolvedModelProvider(settings, model);
+  const rawProvider = preset?.provider
+    || (!scopedPreset ? settings?.agent.provider : null)
+    || null;
+  const provider = rawProvider === "auto"
+    ? preset?.resolved_provider
+      || (!scopedPreset ? settings?.agent.resolved_provider : null)
+      || null
+    : rawProvider || inferProviderFromModelName(model);
   const providerRow = provider
     ? settings?.providers.find((item) => item.name === provider)
     : null;
@@ -459,9 +471,10 @@ export function ThreadShell({
 
   const showHeroComposer = messages.length === 0 && !loading;
   const wasShowingHeroComposerRef = useRef(showHeroComposer);
+  const sessionModelPreset = session?.modelPreset?.trim() || null;
   const modelBadge = useMemo(
-    () => toModelBadgeInfo(modelName, settings),
-    [modelName, settings],
+    () => toModelBadgeInfo(modelName, settings, sessionModelPreset),
+    [modelName, sessionModelPreset, settings],
   );
   const modelBadgeLabel = modelBadge.needsSetup
     ? t("thread.composer.modelNotConfigured", { defaultValue: "Model not configured" })

webui/src/lib/api.ts

@@ -132,6 +132,7 @@ export async function listSessions(
     updated_at: string | null;
     title?: string;
     preview?: string;
+    model_preset?: string | null;
     run_started_at?: number | null;
     workspace_scope?: WorkspaceScopePayload | null;
   };
@@ -148,6 +149,7 @@ export async function listSessions(
     updatedAt: s.updated_at,
     title: s.title ?? "",
     preview: s.preview ?? "",
+    modelPreset: s.model_preset ?? null,
     runStartedAt: s.run_started_at ?? null,
     workspaceScope: s.workspace_scope ?? null,
   }));

webui/src/lib/types.ts

@@ -245,6 +245,8 @@ export interface ChatSummary {
   updatedAt: string | null;
   title?: string;
   preview: string;
+  /** Model preset persisted for this session; null means it still follows the global default. */
+  modelPreset?: string | null;
   /** Unix epoch seconds when this session currently has a turn in flight. */
   runStartedAt?: number | null;
   workspaceScope?: WorkspaceScopePayload | null;
@@ -406,6 +408,7 @@ export interface SettingsPayload {
     is_default: boolean;
     model: string;
     provider: string;
+    resolved_provider?: string | null;
     max_tokens: number;
     context_window_tokens: number;
     temperature: number;

webui/src/tests/api.test.ts

@@ -797,6 +797,7 @@ describe("webui API helpers", () => {
             created_at: "2026-05-01T10:00:00",
             updated_at: "2026-05-01T10:01:00",
             title: "优化 WebUI 标题",
+            model_preset: "fast",
             run_started_at: 1_700_000_000,
           },
         ],
@@ -808,6 +809,7 @@ describe("webui API helpers", () => {
         key: "websocket:chat-1",
         title: "优化 WebUI 标题",
         preview: "",
+        modelPreset: "fast",
         runStartedAt: 1_700_000_000,
       },
     ]);

webui/src/tests/thread-shell.test.tsx

@@ -94,7 +94,7 @@ function expectSendMessageWithTurn(
   );
 }
 
-function session(chatId: string) {
+function session(chatId: string, modelPreset?: string | null) {
   return {
     key: `websocket:${chatId}`,
     channel: "websocket" as const,
@@ -102,6 +102,7 @@ function session(chatId: string) {
     createdAt: null,
     updatedAt: null,
     preview: "",
+    modelPreset,
   };
 }
 
@@ -220,6 +221,20 @@ function modelSettings(model: string, provider: string): SettingsPayload {
   };
 }
 
+function settingsWithFastPreset(): SettingsPayload {
+  const settings = modelSettings("deepseek-v4-pro", "deepseek");
+  settings.model_presets.push({
+    ...settings.model_presets[0]!,
+    name: "fast",
+    label: "Fast",
+    active: false,
+    is_default: false,
+    model: "openai-codex/gpt-5.5",
+    provider: "openai_codex",
+  });
+  return settings;
+}
+
 describe("ThreadShell", () => {
   beforeEach(() => {
     vi.stubGlobal(
@@ -341,6 +356,61 @@ describe("ThreadShell", () => {
     expect(await screen.findByTestId("composer-model-logo-openai_codex")).toBeInTheDocument();
   });
 
+  it("resolves the composer model from the active session preset", async () => {
+    const client = makeClient();
+    render(
+      wrap(
+        client,
+        <ThreadShell
+          session={session("chat-fast", "fast")}
+          title="Fast session"
+          onToggleSidebar={() => {}}
+          settingsSnapshot={settingsWithFastPreset()}
+        />,
+        "deepseek-v4-pro",
+      ),
+    );
+
+    expect(await screen.findByTitle("gpt-5.5 · OpenAI Codex")).toBeInTheDocument();
+    expect(screen.queryByTitle("deepseek-v4-pro · DeepSeek")).not.toBeInTheDocument();
+  });
+
+  it("uses the backend-resolved provider for an auto session preset", async () => {
+    const client = makeClient();
+    const settings = modelSettings("deepseek-v4-pro", "deepseek");
+    settings.providers.push({
+      name: "companyproxy",
+      label: "Company Proxy",
+      configured: true,
+    });
+    settings.model_presets.push({
+      ...settings.model_presets[0]!,
+      name: "fast",
+      label: "Fast",
+      active: false,
+      is_default: false,
+      model: "companyproxy/gpt-4",
+      provider: "auto",
+      resolved_provider: "companyproxy",
+    });
+
+    render(
+      wrap(
+        client,
+        <ThreadShell
+          session={session("chat-auto", "fast")}
+          title="Auto provider session"
+          onToggleSidebar={() => {}}
+          settingsSnapshot={settings}
+        />,
+        "deepseek-v4-pro",
+      ),
+    );
+
+    expect(await screen.findByTitle("gpt-4 · Company Proxy")).toBeInTheDocument();
+    expect(screen.queryByRole("button", { name: "Model not configured" })).not.toBeInTheDocument();
+  });
+
   it("opens model settings from the unconfigured model badge", async () => {
     const client = makeClient();
     const settings = modelSettings("openai-codex/gpt-5.1-codex", "openai_codex");