diff --git a/packages/desktop/src/main/ipc.ts b/packages/desktop/src/main/ipc.ts
index 8dbca8ee..45ed1b4e 100644
--- a/packages/desktop/src/main/ipc.ts
+++ b/packages/desktop/src/main/ipc.ts
@@ -11,7 +11,7 @@ import type {
   WslConfig,
 } from "../preload/types"
 import { getStore } from "./store"
-import { setTitlebar } from "./windows"
+import { setTitlebar, setNativeThemeSource } from "./windows"
 
 const pickerFilters = (ext?: string[]) => {
   if (!ext || ext.length === 0) return undefined
@@ -38,6 +38,7 @@ type Deps = {
   checkUpdate: () => Promise<{ updateAvailable: boolean; version?: string }>
   installUpdate: () => Promise<void> | void
   setBackgroundColor: (color: string) => void
+  setNativeTheme: (mode: "light" | "dark") => void
 }
 
 export function registerIpcHandlers(deps: Deps) {
@@ -69,6 +70,7 @@ export function registerIpcHandlers(deps: Deps) {
   ipcMain.handle("check-update", () => deps.checkUpdate())
   ipcMain.handle("install-update", () => deps.installUpdate())
   ipcMain.handle("set-background-color", (_event: IpcMainInvokeEvent, color: string) => deps.setBackgroundColor(color))
+  ipcMain.handle("set-native-theme", (_event: IpcMainInvokeEvent, mode: "light" | "dark") => setNativeThemeSource(mode))
   ipcMain.handle("store-get", (_event: IpcMainInvokeEvent, name: string, key: string) => {
     const store = getStore(name)
     const value = store.get(key)
diff --git a/packages/desktop/src/main/windows.ts b/packages/desktop/src/main/windows.ts
index 337e1ca0..ae1b45f1 100644
--- a/packages/desktop/src/main/windows.ts
+++ b/packages/desktop/src/main/windows.ts
@@ -52,6 +52,10 @@ function overlay(theme: Partial<TitlebarTheme> = {}) {
   }
 }
 
+export function setNativeThemeSource(mode: "light" | "dark") {
+  nativeTheme.themeSource = mode
+}
+
 export function setTitlebar(win: BrowserWindow, theme: Partial<TitlebarTheme> = {}) {
   if (process.platform !== "win32") return
   win.setTitleBarOverlay(overlay(theme))
diff --git a/packages/desktop/src/preload/index.ts b/packages/desktop/src/preload/index.ts
index 6261419c..4b33f0ed 100644
--- a/packages/desktop/src/preload/index.ts
+++ b/packages/desktop/src/preload/index.ts
@@ -66,6 +66,7 @@ const api: ElectronAPI = {
   checkUpdate: () => ipcRenderer.invoke("check-update"),
   installUpdate: () => ipcRenderer.invoke("install-update"),
   setBackgroundColor: (color: string) => ipcRenderer.invoke("set-background-color", color),
+  setNativeTheme: (mode: "light" | "dark") => ipcRenderer.invoke("set-native-theme", mode),
 }
 
 contextBridge.exposeInMainWorld("api", api)
diff --git a/packages/desktop/src/preload/types.ts b/packages/desktop/src/preload/types.ts
index 6e22954d..74beeee9 100644
--- a/packages/desktop/src/preload/types.ts
+++ b/packages/desktop/src/preload/types.ts
@@ -76,4 +76,5 @@ export type ElectronAPI = {
   checkUpdate: () => Promise<{ updateAvailable: boolean; version?: string }>
   installUpdate: () => Promise<void>
   setBackgroundColor: (color: string) => Promise<void>
+  setNativeTheme: (mode: "light" | "dark") => Promise<void>
 }
diff --git a/packages/desktop/src/renderer/index.tsx b/packages/desktop/src/renderer/index.tsx
index f7df9d4d..83e9fb6a 100644
--- a/packages/desktop/src/renderer/index.tsx
+++ b/packages/desktop/src/renderer/index.tsx
@@ -310,11 +310,12 @@ render(() => {
 
     createEffect(() => {
       theme.themeId()
-      theme.mode()
+      const mode = theme.mode()
       const bg = getComputedStyle(document.documentElement).getPropertyValue("--background-base").trim()
       if (bg) {
         void window.api.setBackgroundColor(bg)
       }
+      void window.api.setNativeTheme(mode)
     })
 
     return null
diff --git a/packages/opencode/src/cli/cmd/tui/component/dialog-provider.tsx b/packages/opencode/src/cli/cmd/tui/component/dialog-provider.tsx
index c9c94a45..a2f73152 100644
--- a/packages/opencode/src/cli/cmd/tui/component/dialog-provider.tsx
+++ b/packages/opencode/src/cli/cmd/tui/component/dialog-provider.tsx
@@ -188,10 +188,9 @@ export async function runCustomProviderWizard(opts: {
   const baseURL = baseURLRaw.trim()
   if (!baseURL) return
 
-  const apiKeyRaw = await step(4, 6, "API key", "sk-...")
+  const apiKeyRaw = await step(4, 6, "API key (optional, Enter to skip)", "sk-...")
   if (apiKeyRaw === null) return
   const apiKey = apiKeyRaw.trim()
-  if (!apiKey) return
 
   const modelIDRaw = await step(5, 6, "First model id", "e.g. claude-sonnet-4-6")
   if (modelIDRaw === null) return
@@ -208,7 +207,7 @@ export async function runCustomProviderWizard(opts: {
       [providerID]: {
         name,
         npm: "@ai-sdk/openai-compatible",
-        env: [envKey],
+        ...(apiKey ? { env: [envKey] } : {}),
         options: {
           baseURL,
           setCacheKey: true,
@@ -228,13 +227,15 @@ export async function runCustomProviderWizard(opts: {
     return
   }
 
-  const authRes = await sdk.client.auth.set({
-    providerID,
-    auth: { type: "api", key: apiKey },
-  })
-  if (authRes.error) {
-    toast.show({ variant: "error", message: JSON.stringify(authRes.error) })
-    return
+  if (apiKey) {
+    const authRes = await sdk.client.auth.set({
+      providerID,
+      auth: { type: "api", key: apiKey },
+    })
+    if (authRes.error) {
+      toast.show({ variant: "error", message: JSON.stringify(authRes.error) })
+      return
+    }
   }
 
   await sdk.client.instance.dispose()