fix(auth): use public URL for magic-link redirects

apps/web/src/app/auth/discord/route.ts

@@ -3,6 +3,7 @@ import { createAuthRepository, ipObservations, recordEvent } from "@minecraft-ac
 import { getClientIp } from "@minecraft-account-manager/network";
 import type { NextRequest } from "next/server";
 import { NextResponse } from "next/server";
+import { applicationUrl } from "@/lib/application-url";
 import { db } from "@/lib/database";
 import { getIpIntelligence, toAuditIpData } from "@/lib/ip-intelligence";
 
@@ -38,7 +39,7 @@ export async function GET(request: NextRequest) {
     ]);
 
     const destination = result.user.firstName ? "/account" : "/welcome";
-    const response = NextResponse.redirect(new URL(destination, request.url));
+    const response = NextResponse.redirect(applicationUrl(destination));
     response.cookies.set(SESSION_COOKIE_NAME, result.sessionToken, {
       httpOnly: true,
       secure: process.env.NODE_ENV === "production",
@@ -49,7 +50,7 @@ export async function GET(request: NextRequest) {
     return response;
   } catch (error) {
     if (error instanceof InvalidLoginCodeError) {
-      return NextResponse.redirect(new URL("/auth/error", request.url));
+      return NextResponse.redirect(applicationUrl("/auth/error"));
     }
     throw error;
   }

apps/web/src/lib/application-url.test.ts

@@ -0,0 +1,9 @@
+import { describe, expect, it } from "vitest";
+import { applicationUrl } from "./application-url";
+
+describe("applicationUrl", () => {
+  it("builds browser redirects from the configured public application URL", () => {
+    expect(applicationUrl("/welcome", "https://portal.somc.club"))
+      .toEqual(new URL("https://portal.somc.club/welcome"));
+  });
+});

apps/web/src/lib/application-url.ts

@@ -0,0 +1,4 @@
+export function applicationUrl(path: string, baseUrl = process.env.APP_URL) {
+  if (!baseUrl) throw new Error("APP_URL is required to build public application URLs");
+  return new URL(path, baseUrl);
+}

design/log.md

@@ -2,6 +2,7 @@
 
 ## 2026-08-01
 
+* **Fix**: Build magic-link redirects from the configured public portal URL instead of the reverse proxy's internal request origin.
 * **Verify**: Confirmed `v1.1.1` left all pre-existing `latest` digests unchanged while publishing versioned artifacts.
 * **Refine**: Removed mutable `latest` publication so all deployable artifacts use explicit semantic versions.
 * **Verify**: Confirmed the `v1.1.0` Discord bot image and matching web, migration, and Velocity artifacts.

design/us-002-discord-magic-link.md

@@ -3,7 +3,7 @@ type: User Story
 title: Authenticate with a Discord magic link
 description: Discord users receive private single-use links that establish secure portal sessions.
 tags: [player, discord, authentication, security]
-timestamp: 2026-08-01T18:43:58Z
+timestamp: 2026-08-01T20:43:46Z
 story_id: US-002
 status: verified
 ---
@@ -19,6 +19,7 @@ As a Discord community member, I want `/register` and `/account` to issue a priv
 - [x] Given a login token, then it expires after ten minutes and can be consumed only once.
 - [x] Given repeated link requests, then requests are rate limited per Discord user and older active links are invalidated.
 - [x] Given a valid link, when it is consumed, then the Discord user is created or refreshed and a secure seven-day session is established.
+- [x] Given a magic-link result behind a reverse proxy, then the browser is redirected through the configured public application URL rather than an internal container address.
 - [x] Given an invalid, expired, or consumed link, then the user sees a safe recovery page instructing them to request another link.
 
 # Implementation
@@ -27,10 +28,12 @@ As a Discord community member, I want `/register` and `/account` to issue a priv
 - [`packages/auth/src/index.ts`](../packages/auth/src/index.ts)
 - [`packages/database/src/auth-repository.ts`](../packages/database/src/auth-repository.ts)
 - [`apps/web/src/app/auth/discord/route.ts`](../apps/web/src/app/auth/discord/route.ts)
+- [`apps/web/src/lib/application-url.ts`](../apps/web/src/lib/application-url.ts)
 
 # Validation
 
 - [`packages/auth/test/magic-link.test.ts`](../packages/auth/test/magic-link.test.ts)
+- [`apps/web/src/lib/application-url.test.ts`](../apps/web/src/lib/application-url.test.ts)
 - Discord command and authentication workspaces pass TypeScript validation.
 
 # Related Stories