feat(FN-4554): complete Step 6 — docs and changeset

Fusion-Task-Id: FN-4554
Fusion-Task-Lineage: 12d517c5-1954-4b27-8c63-c7f0dde93d3f

.changeset/fn-4554-github-copilot-device-code.md

@@ -0,0 +1,5 @@
+---
+"@runfusion/fusion": patch
+---
+
+Fix GitHub Copilot OAuth login hanging in Settings and Onboarding. The dashboard now auto-answers the enterprise-domain prompt (defaulting to github.com) and surfaces the device user code + verification URL so users can complete the device-code flow end to end.

docs/settings-reference.md

@@ -411,6 +411,19 @@ Recovery entrypoints in the dashboard:
 
 ### Authentication troubleshooting (mobile OAuth fallback)
 
+#### `/api/auth/login` response shape for device-code providers
+
+`POST /api/auth/login` returns:
+
+- `url: string`
+- `instructions?: string`
+- `manualCode?: { prompt: string; placeholder?: string; helpText?: string }`
+- `deviceCode?: { userCode: string; verificationUri: string }`
+
+For `github-copilot`, Fusion auto-resolves the upstream enterprise-domain prompt to blank (`github.com` default), then returns `deviceCode` so Settings/Onboarding can render a dedicated “Enter this code on GitHub” panel.
+
+Request body remains `{ provider: string, origin?: string }`. `enterpriseDomain` is reserved for future UX expansion and is not required for this flow.
+
 When an OAuth provider returns a localhost callback that this dashboard host cannot open directly, use the **manual code** fallback in Settings/Onboarding:
 - Tap **Login** for the provider, complete sign-in in the browser, then paste either the final redirect URL or the authorization code into the fallback textbox. Fusion now shows a pre-login warning first so you know to copy the browser address bar URL before the redirect tab appears to fail.
 - On mobile/coarse-pointer layouts, the fallback textbox now auto-scrolls into view on focus (and after keyboard viewport shifts) so the paste/submit path remains usable.

packages/dashboard/src/routes/register-auth-routes.ts

@@ -803,17 +803,20 @@ export const registerAuthRoutes: ApiRouteRegistrar = (ctx) => {
       // Start login flow in background — don't await the full login
       const loginPromise = storage.login(provider, {
         onAuth: (info) => {
-          const deviceCode =
+          const parsedUserCode =
             provider === "github-copilot" && info.instructions
-              ? {
+              ? parseGitHubCopilotDeviceCode(info.instructions)
-                  userCode: parseGitHubCopilotDeviceCode(info.instructions),
-                  verificationUri: info.url,
-                }
               : undefined;
+          const deviceCode = parsedUserCode
+            ? {
+                userCode: parsedUserCode,
+                verificationUri: info.url,
+              }
+            : undefined;
           authResolve({
             url: info.url,
             instructions: appendManualCodeHint(info.instructions, provider, origin),
-            deviceCode: deviceCode?.userCode ? deviceCode : undefined,
+            deviceCode,
           });
         },
         onPrompt: async (_prompt) => {