diff --git a/src/bridge/server.ts b/src/bridge/server.ts
index 148e2a1..f1507c9 100644
--- a/src/bridge/server.ts
+++ b/src/bridge/server.ts
@@ -1338,14 +1338,21 @@ export function startCoreServer(opts: CoreServerOptions, port: number = 9876): v
       }
     });
     if (tls.httpRedirect) {
-      if (tls.redirectHost == null && (host === '0.0.0.0' || host === '::')) {
-        logger.warn(
-          `[server] HTTP->HTTPS redirect host falls back to the wildcard bind address (${host}); browsers cannot follow it. ` +
-            `Set server.tls.redirect_host to the externally reachable hostname.`,
+      const isWildcardBind = host === '0.0.0.0' || host === '::';
+      // With a wildcard bind and no explicit redirect_host there is no single
+      // correct host to pin (the bind address itself, 0.0.0.0, is not browser-
+      // reachable). Derive the redirect target from the client's own Host header
+      // instead — a scheme upgrade to the host they already used. 'localhost' is
+      // only the last-resort pin for a request with no usable Host header.
+      const preferRequestHost = tls.redirectHost == null && isWildcardBind;
+      if (preferRequestHost) {
+        logger.info(
+          `[server] HTTP->HTTPS redirect derives its host from the request Host header ` +
+            `(wildcard bind ${host}, no server.tls.redirect_host set). Set redirect_host to pin it explicitly.`,
         );
       }
-      const pinnedHost = tls.redirectHost ?? (isLoopbackBind ? 'localhost' : host);
-      const redirector = createHttpRedirectServer({ httpsPort: port, pinnedHost });
+      const pinnedHost = tls.redirectHost ?? (isWildcardBind || isLoopbackBind ? 'localhost' : host);
+      const redirector = createHttpRedirectServer({ httpsPort: port, pinnedHost, preferRequestHost });
       redirector.on('error', (e) => logger.warn(`[server] HTTP redirect listener error: ${(e as Error).message}`));
       redirector.listen(tls.httpRedirectPort, host, () =>
         logger.info(`HTTP->HTTPS redirect listening on http://${host}:${tls.httpRedirectPort}`),
diff --git a/src/net/http-redirect.test.ts b/src/net/http-redirect.test.ts
index be5556a..a5e15d5 100644
--- a/src/net/http-redirect.test.ts
+++ b/src/net/http-redirect.test.ts
@@ -1,7 +1,7 @@
 import { describe, it, expect, afterEach } from 'vitest';
 import type { Server } from 'http';
 import * as http from 'http';
-import { buildRedirectLocation, createHttpRedirectServer } from './http-redirect.js';
+import { buildRedirectLocation, createHttpRedirectServer, safeHostFromHeader } from './http-redirect.js';
 
 describe('buildRedirectLocation', () => {
   it('pins the host and preserves path + query', () => {
@@ -67,4 +67,51 @@ describe('createHttpRedirectServer', () => {
       await new Promise<void>((r) => srv.close(() => r()));
     }
   });
+
+  it('preferRequestHost: scheme-upgrades to the request Host (port stripped, https port reapplied)', async () => {
+    const srv = createHttpRedirectServer({ httpsPort: 443, pinnedHost: 'localhost', preferRequestHost: true });
+    await new Promise<void>((r) => srv.listen(0, '127.0.0.1', r));
+    try {
+      const addr = srv.address();
+      const port = typeof addr === 'object' && addr ? addr.port : 0;
+      const loc = await new Promise<string>((resolve, reject) => {
+        const req = http.request(
+          { hostname: '127.0.0.1', port, path: '/tasks?id=5', method: 'GET', headers: { Host: '10.0.0.10:9080' } },
+          (res) => resolve(res.headers['location'] ?? ''),
+        );
+        req.on('error', reject);
+        req.end();
+      });
+      expect(loc).toBe('https://10.0.0.10/tasks?id=5');
+    } finally {
+      await new Promise<void>((r) => srv.close(() => r()));
+    }
+  });
+});
+
+describe('safeHostFromHeader', () => {
+  it('strips the port from a host:port header', () => {
+    expect(safeHostFromHeader('app.lan:9876')).toBe('app.lan');
+    expect(safeHostFromHeader('10.0.0.10:9080')).toBe('10.0.0.10');
+  });
+
+  it('keeps a bare hostname', () => {
+    expect(safeHostFromHeader('app.lan')).toBe('app.lan');
+  });
+
+  it('keeps an IPv6 literal in brackets and drops its port', () => {
+    expect(safeHostFromHeader('[::1]:8443')).toBe('[::1]');
+    expect(safeHostFromHeader('[2001:db8::1]')).toBe('[2001:db8::1]');
+  });
+
+  it('returns null for missing/empty headers', () => {
+    expect(safeHostFromHeader(undefined)).toBeNull();
+    expect(safeHostFromHeader('')).toBeNull();
+    expect(safeHostFromHeader('   ')).toBeNull();
+  });
+
+  it('never lets CR/LF through (no header injection)', () => {
+    const out = safeHostFromHeader('evil.com\r\nSet-Cookie: x=1');
+    expect(out == null || !/[\r\n]/.test(out)).toBe(true);
+  });
 });
diff --git a/src/net/http-redirect.ts b/src/net/http-redirect.ts
index be45563..9bbc426 100644
--- a/src/net/http-redirect.ts
+++ b/src/net/http-redirect.ts
@@ -7,14 +7,57 @@ export function buildRedirectLocation(pinnedHost: string, httpsPort: number, req
   return `https://${hostPort}${safePath.startsWith('/') ? safePath : `/${safePath}`}`;
 }
 
+/**
+ * Extract a safe host from a request `Host` header for a scheme-upgrade redirect:
+ * strip whitespace/CRLF, drop the port, and accept only a plausible
+ * hostname / IPv4 / [IPv6] token. Returns null if the header is missing or does
+ * not look like a valid host (caller then falls back to the pinned host).
+ *
+ * Used only in `preferRequestHost` mode (see createHttpRedirectServer).
+ */
+export function safeHostFromHeader(hostHeader: string | undefined): string | null {
+  if (!hostHeader) return null;
+  const cleaned = hostHeader.replace(/[\r\n\t ]/g, '');
+  if (!cleaned) return null;
+  let host = cleaned;
+  if (host.startsWith('[')) {
+    // IPv6 literal: [addr] or [addr]:port — keep the brackets, drop any port.
+    const end = host.indexOf(']');
+    if (end === -1) return null;
+    host = host.slice(0, end + 1);
+    if (!/^\[[0-9A-Fa-f:]+\]$/.test(host)) return null;
+    return host;
+  }
+  const colon = host.indexOf(':');
+  if (colon !== -1) host = host.slice(0, colon);
+  if (!host) return null;
+  // Hostname or IPv4: letters, digits, dot, hyphen only.
+  if (!/^[A-Za-z0-9.-]+$/.test(host)) return null;
+  return host;
+}
+
 export interface RedirectServerOpts {
   httpsPort: number;
   pinnedHost: string;
+  /**
+   * When true AND the request carries a usable Host header, redirect to that
+   * host (a scheme upgrade to the same host the client already used) instead of
+   * the pinned host. Enabled ONLY when no redirect_host is configured and the
+   * bind host is a wildcard (0.0.0.0 / ::), where there is no single correct
+   * host to pin. Defaults to false, preserving the strict pinned-host behavior
+   * (the open-redirect guard) for every other deployment.
+   */
+  preferRequestHost?: boolean;
 }
 
 export function createHttpRedirectServer(opts: RedirectServerOpts): Server {
   return createServer((req, res) => {
-    const location = buildRedirectLocation(opts.pinnedHost, opts.httpsPort, req.url ?? '/');
+    let host = opts.pinnedHost;
+    if (opts.preferRequestHost) {
+      const fromHeader = safeHostFromHeader(req.headers.host);
+      if (fromHeader) host = fromHeader;
+    }
+    const location = buildRedirectLocation(host, opts.httpsPort, req.url ?? '/');
     res.writeHead(301, { Location: location });
     res.end();
   });