fix(auth): make the Secure cookie flag fail-safe (default on)

secureCookies() keyed off NODE_ENV === "production", so an appliance deployed
without that var silently sent the auth + CSRF cookies WITHOUT the Secure flag —
the review's one Medium finding.

Now Secure is the DEFAULT and you only ever opt OUT: a misconfigured/forgotten env
can only make cookies more restrictive, never drop the flag. Dropped only on a
deliberate COOKIE_SECURE=0/false/no/off (or an explicit NODE_ENV=development as a
dev fallback). The LAN appliance that serves the SPA over plain http sets
COOKIE_SECURE=0 on purpose (a Secure cookie would never be sent over its http origin
and would lock operators out); a TLS deploy leaves it unset and gets Secure.

- auth.test.ts (5): pins the matrix — default Secure, production Secure, dev opt-out,
  COOKIE_SECURE falsey opts out, any other value opts in.
- .env.example documents COOKIE_SECURE (replaces the stale NODE_ENV cookie note).
- dev .env sets COOKIE_SECURE=0 (local http://localhost login keeps working).

server 80/80; build+lint green.

Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V

apps/server/.env.example

@@ -20,7 +20,13 @@ EVENT_SIGNING_KEY=
 # HOST=0.0.0.0                 # interface to bind. 127.0.0.1 = loopback only.
 # LOG_LEVEL=info
 # DATABASE_URL=./parking.sqlite
-# NODE_ENV=production          # set in prod: makes auth cookies Secure (HTTPS-only)
+#
+# Auth-cookie Secure flag. FAIL-SAFE: cookies are Secure (HTTPS-only) BY DEFAULT —
+# you only ever opt OUT, never in. Set COOKIE_SECURE=0 for a plain-HTTP deployment
+# (e.g. the LAN appliance serving the SPA same-origin over http, where a Secure
+# cookie would never be sent and would lock operators out). Local dev over
+# http://localhost MUST set this (the dev .env does). Leave unset in any TLS deploy.
+# COOKIE_SECURE=0
 
 # First admin (seed once): pnpm --filter @parking/server seed-admin
 # ADMIN_USER=admin

apps/server/src/auth.test.ts

@@ -0,0 +1,56 @@
+import { afterEach, beforeEach, describe, expect, it } from "vitest";
+import { secureCookies } from "./auth.js";
+
+// The auth/CSRF cookies' Secure flag must be FAIL-SAFE: Secure by default, dropped only
+// on a deliberate opt-out. The old behaviour (Secure iff NODE_ENV==="production") leaked
+// cookies over plain HTTP on an appliance that forgot to set NODE_ENV — this pins the
+// corrected matrix.
+
+let savedCookieSecure: string | undefined;
+let savedNodeEnv: string | undefined;
+
+beforeEach(() => {
+  savedCookieSecure = process.env.COOKIE_SECURE;
+  savedNodeEnv = process.env.NODE_ENV;
+  delete process.env.COOKIE_SECURE;
+  delete process.env.NODE_ENV;
+});
+afterEach(() => {
+  restore("COOKIE_SECURE", savedCookieSecure);
+  restore("NODE_ENV", savedNodeEnv);
+});
+function restore(key: string, val: string | undefined) {
+  if (val === undefined) delete process.env[key];
+  else process.env[key] = val;
+}
+
+describe("secureCookies — fail-safe Secure flag", () => {
+  it("defaults to Secure when nothing is set (the appliance-forgot-NODE_ENV case)", () => {
+    expect(secureCookies()).toBe(true);
+  });
+
+  it("stays Secure in production", () => {
+    process.env.NODE_ENV = "production";
+    expect(secureCookies()).toBe(true);
+  });
+
+  it("drops Secure only for an explicit local-dev NODE_ENV", () => {
+    process.env.NODE_ENV = "development";
+    expect(secureCookies()).toBe(false);
+  });
+
+  it("COOKIE_SECURE override wins: falsey values opt OUT", () => {
+    for (const v of ["0", "false", "no", "off", "FALSE", " Off "]) {
+      process.env.COOKIE_SECURE = v;
+      expect(secureCookies(), `COOKIE_SECURE=${JSON.stringify(v)}`).toBe(false);
+    }
+  });
+
+  it("COOKIE_SECURE override wins: any other value opts IN (even in dev)", () => {
+    process.env.NODE_ENV = "development";
+    for (const v of ["1", "true", "yes", "on", ""]) {
+      process.env.COOKIE_SECURE = v;
+      expect(secureCookies(), `COOKIE_SECURE=${JSON.stringify(v)}`).toBe(true);
+    }
+  });
+});

apps/server/src/auth.ts

@@ -50,9 +50,28 @@ export function requireJwtSecret(): string {
   return secret;
 }
 
-/** Cookies are secure in production; relaxed for local http dev. */
-function secureCookies(): boolean {
-  return process.env.NODE_ENV === "production";
+/**
+ * Whether to set the `Secure` flag on the auth/CSRF cookies. FAIL-SAFE: default is
+ * `true` (Secure) — a misconfigured/forgotten env can only ever make cookies MORE
+ * restrictive, never silently drop the flag.
+ *
+ * The previous gate keyed off `NODE_ENV === "production"`, which meant an appliance
+ * deployed without that var leaked cookies over plain HTTP. Now `Secure` is the
+ * default and is dropped ONLY for an explicit, deliberate opt-out — `COOKIE_SECURE`
+ * set to a falsey value (`0/false/no/off`), or the legacy `NODE_ENV !== production`
+ * signal kept as a fallback so existing dev setups still work over http://localhost.
+ *
+ * The parking appliance often serves the SPA same-origin over the LAN with no TLS;
+ * THAT box sets `COOKIE_SECURE=0` on purpose (a Secure cookie would never be sent
+ * over its http origin and would lock operators out). Everything else stays secure.
+ */
+export function secureCookies(): boolean {
+  const override = process.env.COOKIE_SECURE;
+  if (override !== undefined) {
+    return !/^(0|false|no|off)$/i.test(override.trim());
+  }
+  // No explicit override: secure unless this is an obvious local-dev run.
+  return process.env.NODE_ENV !== "development";
 }
 
 export function newCsrfToken(): string {