oauth2

Cargo.toml

@@ -46,6 +46,9 @@ unic-langid = { version = "0.9" }
 axum-extra = { version = "0.10", features = ["form"] }
 bytes = { version = "1" }
 axum-casbin = "1.3.0"
+loco-oauth2 = "0.5.0"
+passwords = "3.1.16"
+tower-sessions = "0.14"
 
 [[bin]]
 name = "kompress-eshop-cli"

assets/i18n/en/main.ftl

@@ -66,6 +66,8 @@ login-email = Email
 login-password = Password
 login-no-account = Don't have an account?
 login-have-account = Already have an account?
+auth-or = or
+auth-google = Continue with Google
 nav-login = Sign in
 nav-register = Register
 register-title = Create account

assets/i18n/sk/main.ftl

@@ -66,6 +66,8 @@ login-email = E-mail
 login-password = Heslo
 login-no-account = Nemáte účet?
 login-have-account = Už máte účet?
+auth-or = alebo
+auth-google = Pokračovať cez Google
 nav-login = Prihlásiť sa
 nav-register = Registrácia
 register-title = Vytvoriť účet

assets/views/auth/login.html

@@ -46,6 +46,13 @@
         {{ ui::button(label=t(key="login-auth", lang=lang | default(value='sk')), type="submit", extra="mt-1 w-full") }}
       </form>
 
+      <div class="mt-5 flex items-center gap-3 text-xs text-on-surface/50 dark:text-on-surface-dark/50">
+        <span class="h-px flex-1 bg-outline dark:bg-outline-dark"></span>
+        {{ t(key="auth-or", lang=lang | default(value='sk')) }}
+        <span class="h-px flex-1 bg-outline dark:bg-outline-dark"></span>
+      </div>
+      {{ ui::button(label=t(key="auth-google", lang=lang | default(value='sk')), href="/api/oauth2/google", variant="outline-secondary", attrs='hx-boost="false"', extra="mt-4 w-full", icon='<svg class="size-4" viewBox="0 0 48 48" xmlns="http://www.w3.org/2000/svg" aria-hidden="true"><path fill="#FFC107" d="M43.611 20.083H42V20H24v8h11.303c-1.649 4.657-6.08 8-11.303 8-6.627 0-12-5.373-12-12s5.373-12 12-12c3.059 0 5.842 1.154 7.961 3.039l5.657-5.657C34.046 6.053 29.268 4 24 4 12.955 4 4 12.955 4 24s8.955 20 20 20 20-8.955 20-20c0-1.341-.138-2.65-.389-3.917z"/><path fill="#FF3D00" d="m6.306 14.691 6.571 4.819C14.655 15.108 18.961 12 24 12c3.059 0 5.842 1.154 7.961 3.039l5.657-5.657C34.046 6.053 29.268 4 24 4 16.318 4 9.656 8.337 6.306 14.691z"/><path fill="#4CAF50" d="M24 44c5.166 0 9.86-1.977 13.409-5.192l-6.19-5.238A11.91 11.91 0 0 1 24 36c-5.202 0-9.619-3.317-11.283-7.946l-6.522 5.025C9.505 39.556 16.227 44 24 44z"/><path fill="#1976D2" d="M43.611 20.083H42V20H24v8h11.303a12.04 12.04 0 0 1-4.087 5.571l.003-.002 6.19 5.238C36.971 39.205 44 34 44 24c0-1.341-.138-2.65-.389-3.917z"/></svg>') }}
+
       <p class="mt-4 text-sm text-on-surface dark:text-on-surface-dark">
         {{ t(key="login-no-account", lang=lang | default(value='sk')) }}
         <a href="/register"

assets/views/auth/register.html

@@ -54,6 +54,13 @@
         {{ ui::button(label=t(key="register-submit", lang=lang | default(value='sk')), type="submit", extra="mt-1 w-full") }}
       </form>
 
+      <div class="mt-5 flex items-center gap-3 text-xs text-on-surface/50 dark:text-on-surface-dark/50">
+        <span class="h-px flex-1 bg-outline dark:bg-outline-dark"></span>
+        {{ t(key="auth-or", lang=lang | default(value='sk')) }}
+        <span class="h-px flex-1 bg-outline dark:bg-outline-dark"></span>
+      </div>
+      {{ ui::button(label=t(key="auth-google", lang=lang | default(value='sk')), href="/api/oauth2/google", variant="outline-secondary", attrs='hx-boost="false"', extra="mt-4 w-full", icon='<svg class="size-4" viewBox="0 0 48 48" xmlns="http://www.w3.org/2000/svg" aria-hidden="true"><path fill="#FFC107" d="M43.611 20.083H42V20H24v8h11.303c-1.649 4.657-6.08 8-11.303 8-6.627 0-12-5.373-12-12s5.373-12 12-12c3.059 0 5.842 1.154 7.961 3.039l5.657-5.657C34.046 6.053 29.268 4 24 4 12.955 4 4 12.955 4 24s8.955 20 20 20 20-8.955 20-20c0-1.341-.138-2.65-.389-3.917z"/><path fill="#FF3D00" d="m6.306 14.691 6.571 4.819C14.655 15.108 18.961 12 24 12c3.059 0 5.842 1.154 7.961 3.039l5.657-5.657C34.046 6.053 29.268 4 24 4 16.318 4 9.656 8.337 6.306 14.691z"/><path fill="#4CAF50" d="M24 44c5.166 0 9.86-1.977 13.409-5.192l-6.19-5.238A11.91 11.91 0 0 1 24 36c-5.202 0-9.619-3.317-11.283-7.946l-6.522 5.025C9.505 39.556 16.227 44 24 44z"/><path fill="#1976D2" d="M43.611 20.083H42V20H24v8h11.303a12.04 12.04 0 0 1-4.087 5.571l.003-.002 6.19 5.238C36.971 39.205 44 34 44 24c0-1.341-.138-2.65-.389-3.917z"/></svg>') }}
+
       <p class="mt-4 text-sm text-on-surface dark:text-on-surface-dark">
         {{ t(key="login-have-account", lang=lang | default(value='sk')) }}
         <a href="/login"

config/development.yaml

@@ -125,3 +125,30 @@ settings:
   # Bank-transfer payment details shown on the order confirmation.
   bank_iban: {{ get_env(name="BANK_IBAN", default="SK00 0000 0000 0000 0000 0000") }}
   bank_account_name: {{ get_env(name="BANK_ACCOUNT_NAME", default="Kompress s.r.o.") }}
+
+# loco-oauth2: social login. Credentials come from .env (create them in the
+# Google Cloud console and register the redirect_url below as an authorized
+# redirect URI). Until OAUTH_CLIENT_ID/SECRET are set, the "Continue with
+# Google" button will fail at the consent screen — the rest of auth is unaffected.
+initializers:
+  oauth2:
+    # Key for the loco-oauth2 private cookie jar (>= 64 bytes). Override in prod.
+    secret_key: {{ get_env(name="OAUTH_PRIVATE_KEY", default="144, 76, 183, 1, 15, 184, 233, 174, 214, 251, 190, 186, 122, 61, 74, 84, 225, 110, 189, 115, 10, 251, 133, 128, 52, 46, 15, 66, 85, 1, 245, 73, 27, 113, 189, 15, 209, 205, 61, 100, 73, 31, 18, 58, 235, 105, 141, 36, 70, 92, 231, 151, 27, 32, 243, 117, 30, 244, 110, 89, 233, 196, 137, 130") }}
+    authorization_code:
+      - client_identifier: google
+        client_credentials:
+          client_id: {{ get_env(name="OAUTH_CLIENT_ID", default="oauth_client_id") }}
+          client_secret: {{ get_env(name="OAUTH_CLIENT_SECRET", default="oauth_client_secret") }}
+        url_config:
+          auth_url: {{ get_env(name="OAUTH_AUTH_URL", default="https://accounts.google.com/o/oauth2/auth") }}
+          token_url: {{ get_env(name="OAUTH_TOKEN_URL", default="https://www.googleapis.com/oauth2/v3/token") }}
+          redirect_url: {{ get_env(name="OAUTH_REDIRECT_URL", default="http://localhost:5150/api/oauth2/google/callback/cookie") }}
+          profile_url: {{ get_env(name="OAUTH_PROFILE_URL", default="https://openidconnect.googleapis.com/v1/userinfo") }}
+          scopes:
+            - "https://www.googleapis.com/auth/userinfo.email"
+            - "https://www.googleapis.com/auth/userinfo.profile"
+        cookie_config:
+          # After loco-oauth2 sets its session cookie it redirects here, where we
+          # mint our own auth_token cookie (see controllers/oauth2.rs::complete).
+          protected_url: {{ get_env(name="OAUTH_PROTECTED_URL", default="http://localhost:5150/api/oauth2/protected") }}
+        timeout_seconds: 600

config/production.yaml

@@ -55,3 +55,25 @@ auth:
 settings:
   admin_email: "{{ get_env(name="ADMIN_EMAIL", default="") }}"
   uploads_root: "{{ get_env(name="UPLOADS_ROOT", default="data/uploads") }}"
+
+# loco-oauth2 social login. All values must come from the environment in prod;
+# OAUTH_REDIRECT_URL / OAUTH_PROTECTED_URL must use the real public origin.
+initializers:
+  oauth2:
+    secret_key: "{{ get_env(name="OAUTH_PRIVATE_KEY") }}"
+    authorization_code:
+      - client_identifier: google
+        client_credentials:
+          client_id: "{{ get_env(name="OAUTH_CLIENT_ID") }}"
+          client_secret: "{{ get_env(name="OAUTH_CLIENT_SECRET") }}"
+        url_config:
+          auth_url: "{{ get_env(name="OAUTH_AUTH_URL", default="https://accounts.google.com/o/oauth2/auth") }}"
+          token_url: "{{ get_env(name="OAUTH_TOKEN_URL", default="https://www.googleapis.com/oauth2/v3/token") }}"
+          redirect_url: "{{ get_env(name="OAUTH_REDIRECT_URL") }}"
+          profile_url: "{{ get_env(name="OAUTH_PROFILE_URL", default="https://openidconnect.googleapis.com/v1/userinfo") }}"
+          scopes:
+            - "https://www.googleapis.com/auth/userinfo.email"
+            - "https://www.googleapis.com/auth/userinfo.profile"
+        cookie_config:
+          protected_url: "{{ get_env(name="OAUTH_PROTECTED_URL") }}"
+        timeout_seconds: 600

docs/integrations/google-oauth.md

@@ -0,0 +1,104 @@
+# Google OAuth2 sign-in
+
+"Continue with Google" on `/login` and `/register` is wired through
+[`loco-oauth2`](https://github.com/yinho999/loco-oauth2). The code is complete
+and compiles; this doc is the checklist to make the live flow work. Until the
+credentials below are set, the button reaches Google and fails at the consent
+screen — the rest of auth (password login, registration, verification) is
+unaffected.
+
+## How the flow works (for context)
+
+1. User clicks **Continue with Google** → `GET /api/oauth2/google` redirects to
+   Google's consent screen.
+2. Google redirects back to `GET /api/oauth2/google/callback/cookie`.
+   loco-oauth2 exchanges the code, fetches the profile, upserts the user
+   (`OAuth2UserTrait::upsert_with_oauth`), stores an `o_auth2_sessions` row, sets
+   its own private session cookie, and redirects to `protected_url`.
+3. `protected_url` = `GET /api/oauth2/protected` (our bridge,
+   `controllers/oauth2.rs::complete`). It mints **our** `auth_token` JWT cookie
+   and redirects: admins (email == `ADMIN_EMAIL`) → `/admin/dashboard`,
+   everyone else → `/`.
+
+From there the user is a normal logged-in user (same JWT cookie as a password
+login; the Casbin layer and guards treat them identically).
+
+## 1. Create Google OAuth credentials
+
+1. Go to <https://console.cloud.google.com/> → create/select a project.
+2. **APIs & Services → OAuth consent screen**: configure it (External), add the
+   `.../auth/userinfo.email` and `.../auth/userinfo.profile` scopes, and add
+   your Google account as a **test user** while the app is in "Testing".
+3. **APIs & Services → Credentials → Create Credentials → OAuth client ID**:
+   - Application type: **Web application**.
+   - **Authorized redirect URIs** — add exactly (must match the config's
+     `redirect_url`, no trailing slash):
+     - dev: `http://localhost:5150/api/oauth2/google/callback/cookie`
+     - prod: `https://YOUR_DOMAIN/api/oauth2/google/callback/cookie`
+4. Copy the generated **Client ID** and **Client secret**.
+
+## 2. Set environment variables (`.env`)
+
+Read by `config/development.yaml` → `initializers.oauth2` (and the prod
+equivalent). dotenvy loads `.env` on boot.
+
+```bash
+# Required
+OAUTH_CLIENT_ID=xxxxxxxx.apps.googleusercontent.com
+OAUTH_CLIENT_SECRET=xxxxxxxx
+
+# Required in PRODUCTION (dev has working defaults)
+OAUTH_PRIVATE_KEY="comma,separated,bytes >= 64 long"   # key for loco-oauth2's private cookie jar
+OAUTH_REDIRECT_URL=https://YOUR_DOMAIN/api/oauth2/google/callback/cookie
+OAUTH_PROTECTED_URL=https://YOUR_DOMAIN/api/oauth2/protected
+```
+
+Notes:
+- **dev** ships defaults for everything except `OAUTH_CLIENT_ID` /
+  `OAUTH_CLIENT_SECRET`, so locally you only need those two.
+- `OAUTH_PRIVATE_KEY` must be ≥ 64 bytes (the dev default is a sample key — do
+  **not** reuse it in production). Generate a fresh one, e.g.
+  `python3 -c "import os;print(','.join(str(b) for b in os.urandom(64)))"`.
+- `OAUTH_REDIRECT_URL` here and the Authorized redirect URI in the Google
+  console must be byte-for-byte identical.
+
+## 3. Run / test
+
+```bash
+nix develop -c cargo loco start   # MUST be inside nix develop (OpenSSL link, see memory)
+```
+
+- `auto_migrate: true` (dev) creates the `o_auth2_sessions` table on boot.
+- Open `http://localhost:5150/login` → **Continue with Google** → consent →
+  you should land back on `/` logged in (cart/nav reflect the session).
+
+## 4. Production checklist
+
+- [ ] Separate OAuth client (or at least the prod redirect URI) in Google.
+- [ ] OAuth consent screen **published** (not just "Testing"), or real users
+      get blocked.
+- [ ] `OAUTH_PRIVATE_KEY` set to a fresh ≥64-byte key (not the dev sample).
+- [ ] `OAUTH_REDIRECT_URL` / `OAUTH_PROTECTED_URL` use the real `https://` origin.
+- [ ] `server.host` / public origin correct so cookies + redirects resolve.
+
+## Troubleshooting
+
+| Symptom | Cause / fix |
+|---|---|
+| `redirect_uri_mismatch` at Google | Authorized redirect URI ≠ `OAUTH_REDIRECT_URL`. Make them identical (scheme, host, port, path, no trailing slash). |
+| 403 / "access blocked: app not verified" | Add your account as a test user, or publish the consent screen. |
+| `openssl-sys ... Could not find directory` at build | You ran `cargo` outside the dev shell. Use `nix develop -c cargo ...`. |
+| Callback 500 / "could not create oauth2 store" | `initializers.oauth2` missing/invalid, or `OAUTH_PRIVATE_KEY` < 64 bytes. |
+| Logged into Google but not into the app | The bridge (`/api/oauth2/protected`) didn't run — check `protected_url` (`OAUTH_PROTECTED_URL`) points at it. |
+
+## Where things live
+
+- Config: `config/development.yaml` / `config/production.yaml` →
+  `initializers.oauth2`
+- Client store + session initializers: `src/initializers/oauth2.rs`,
+  `src/initializers/oauth2_session.rs`
+- Routes + bridge handler: `src/controllers/oauth2.rs`
+- User upsert (random password per advisory LOC-2025-04): `src/models/users.rs`
+  (`OAuth2UserTrait`)
+- Session table: `src/models/o_auth2_sessions.rs` +
+  `migration/.../m20260618_000001_o_auth2_sessions.rs`

flake.nix

@@ -86,7 +86,10 @@
             buildInputs = [
               rust
               pkgs.pkg-config
+              # OpenSSL for crypto dependencies (loco-oauth2 -> oauth2/reqwest
+              # use native-tls); .dev provides headers + pkg-config metadata.
               pkgs.openssl
+              pkgs.openssl.dev
               pkgs.cmake
               pkgs.llvmPackages.clang
               pkgs.llvmPackages.libclang.lib

migration/src/lib.rs

@@ -30,6 +30,7 @@ mod m20260616_160000_add_parent_to_categories;
 mod m20260617_000001_add_carrier_to_shipping_methods;
 mod m20260617_000002_add_shipment_to_orders;
 mod m20260617_000003_add_phone_to_orders;
+mod m20260618_000001_o_auth2_sessions;
 pub struct Migrator;
 
 #[async_trait::async_trait]
@@ -64,6 +65,7 @@ impl MigratorTrait for Migrator {
             Box::new(m20260617_000001_add_carrier_to_shipping_methods::Migration),
             Box::new(m20260617_000002_add_shipment_to_orders::Migration),
             Box::new(m20260617_000003_add_phone_to_orders::Migration),
+            Box::new(m20260618_000001_o_auth2_sessions::Migration),
             // inject-above (do not remove this comment)
         ]
     }

migration/src/m20260618_000001_o_auth2_sessions.rs

@@ -0,0 +1,29 @@
+use loco_rs::schema::*;
+use sea_orm_migration::prelude::*;
+
+#[derive(DeriveMigrationName)]
+pub struct Migration;
+
+#[async_trait::async_trait]
+impl MigrationTrait for Migration {
+    async fn up(&self, m: &SchemaManager) -> Result<(), DbErr> {
+        // OAuth2 session store used by loco-oauth2 to correlate the provider's
+        // access token with a local user during the callback flow. `user` adds
+        // a user_id FK to the users table.
+        create_table(
+            m,
+            "o_auth2_sessions",
+            &[
+                ("id", ColType::PkAuto),
+                ("session_id", ColType::StringUniq),
+                ("expires_at", ColType::TimestampWithTimeZone),
+            ],
+            &[("user", "")],
+        )
+        .await
+    }
+
+    async fn down(&self, m: &SchemaManager) -> Result<(), DbErr> {
+        drop_table(m, "o_auth2_sessions").await
+    }
+}

src/app.rs

@@ -18,7 +18,8 @@ use std::{path::Path, sync::Arc};
 use crate::{
     controllers::{
         admin_categories, admin_dashboard, admin_form, admin_orders,
-        admin_products, admin_shipping, auth, auth_pages, cart, checkout, home, i18n, media, shop,
+        admin_products, admin_shipping, auth, auth_pages, cart, checkout, home, i18n, media, oauth2,
+        shop,
     },
     initializers,
     models::_entities::users,
@@ -75,6 +76,8 @@ impl Hooks for App {
             Box::new(initializers::view_engine::ViewEngineInitializer),
             Box::new(initializers::admin_seeder::AdminSeeder),
             Box::new(initializers::shipping_seeder::ShippingSeeder),
+            Box::new(initializers::oauth2::OAuth2StoreInitializer),
+            Box::new(initializers::oauth2_session::OAuth2SessionInitializer),
         ])
     }
 
@@ -88,6 +91,7 @@ impl Hooks for App {
             // cross-cutting
             .add_route(auth::routes())
             .add_route(auth_pages::routes())
+            .add_route(oauth2::routes())
             .add_route(i18n::routes())
             .add_route(media::routes())
             // admin

src/controllers/mod.rs

@@ -1,5 +1,6 @@
 pub mod auth;
 pub mod auth_pages;
+pub mod oauth2;
 pub mod admin_categories;
 pub mod admin_dashboard;
 pub mod admin_form;

src/controllers/oauth2.rs

@@ -0,0 +1,56 @@
+//! HTML OAuth2 (Google) sign-in.
+//!
+//! The provider round-trip is handled by loco-oauth2's built-in authorize +
+//! cookie-callback handlers. The callback upserts the user, stores an OAuth2
+//! session, sets loco-oauth2's *private* session cookie, and redirects to the
+//! configured `protected_url` — which is our [`complete`] handler. There we
+//! trade the OAuth2 session for OUR Loco `auth_token` JWT cookie, so the rest of
+//! the app (the Casbin layer, `guard`, the unified `/login`) treats a Google
+//! user exactly like a password login. Admins (matching `ADMIN_EMAIL`) land on
+//! the dashboard, everyone else on the storefront.
+
+use loco_oauth2::controllers::{
+    middleware::OAuth2CookieUser,
+    oauth2::{google_authorization_url, google_callback_cookie},
+};
+use loco_rs::prelude::*;
+
+use crate::{
+    controllers::auth as auth_controller,
+    models::{o_auth2_sessions, users, users::OAuth2UserProfile},
+    shared::guard,
+};
+
+type GoogleCookieUser = OAuth2CookieUser<OAuth2UserProfile, users::Model, o_auth2_sessions::Model>;
+
+/// Bridge from loco-oauth2's session cookie to our own auth cookie.
+#[debug_handler]
+async fn complete(State(ctx): State<AppContext>, user: GoogleCookieUser) -> Result<Response> {
+    let user: &users::Model = user.as_ref();
+    let jwt_secret = ctx.config.get_jwt_config()?;
+    let token = user
+        .generate_jwt(&jwt_secret.secret, jwt_secret.expiration)
+        .or_else(|_| unauthorized("unauthorized!"))?;
+    let dest = if guard::is_admin(&ctx, user) {
+        "/admin/dashboard"
+    } else {
+        "/"
+    };
+    format::render()
+        .cookies(&[auth_controller::auth_cookie(&token, jwt_secret.expiration)])?
+        .redirect(dest)
+}
+
+pub fn routes() -> Routes {
+    Routes::new()
+        .prefix("api/oauth2")
+        // Redirects the browser to Google's consent screen.
+        .add("/google", get(google_authorization_url))
+        // Google redirects back here; loco-oauth2 exchanges the code, upserts
+        // the user, and redirects to `protected_url` (/api/oauth2/protected).
+        .add(
+            "/google/callback/cookie",
+            get(google_callback_cookie::<OAuth2UserProfile, users::Model, o_auth2_sessions::Model>),
+        )
+        .add("/protected", get(complete))
+}

src/initializers/mod.rs

@@ -1,3 +1,5 @@
 pub mod admin_seeder;
+pub mod oauth2;
+pub mod oauth2_session;
 pub mod shipping_seeder;
 pub mod view_engine;

src/initializers/oauth2.rs

@@ -0,0 +1,36 @@
+//! Builds the loco-oauth2 client store from `initializers.oauth2` config and
+//! injects it as an Axum extension so the oauth2 controllers can reach it.
+
+use axum::{Extension, Router as AxumRouter};
+use loco_oauth2::{config::Config as OAuth2Config, OAuth2ClientStore};
+use loco_rs::prelude::*;
+
+pub struct OAuth2StoreInitializer;
+
+#[async_trait]
+impl Initializer for OAuth2StoreInitializer {
+    fn name(&self) -> String {
+        "oauth2-store".to_string()
+    }
+
+    async fn after_routes(&self, router: AxumRouter, ctx: &AppContext) -> Result<AxumRouter> {
+        let settings = ctx.config.initializers.clone().ok_or_else(|| {
+            Error::Message("Initializers config not configured for OAuth2".to_string())
+        })?;
+        let oauth2_config_value = settings
+            .get("oauth2")
+            .ok_or_else(|| {
+                Error::Message("oauth2 config not found in initializers configuration".to_string())
+            })?
+            .clone();
+        let oauth2_config: OAuth2Config = oauth2_config_value.try_into().map_err(|e| {
+            tracing::error!(error = ?e, "could not convert oauth2 config from yaml");
+            Error::Message("could not convert oauth2 config from yaml".to_string())
+        })?;
+        let oauth2_store = OAuth2ClientStore::new(oauth2_config).map_err(|e| {
+            tracing::error!(error = ?e, "could not create oauth2 store from config");
+            Error::Message("could not create oauth2 store from config".to_string())
+        })?;
+        Ok(router.layer(Extension(oauth2_store)))
+    }
+}

src/initializers/oauth2_session.rs

@@ -0,0 +1,25 @@
+//! tower-sessions layer that loco-oauth2 uses to hold the short-lived CSRF /
+//! PKCE state between the authorize redirect and the provider callback. An
+//! in-memory store is sufficient since the state only needs to survive the
+//! round-trip to the provider.
+
+use axum::Router as AxumRouter;
+use loco_rs::prelude::*;
+use tower_sessions::{cookie::time::Duration, Expiry, MemoryStore, SessionManagerLayer};
+
+pub struct OAuth2SessionInitializer;
+
+#[async_trait]
+impl Initializer for OAuth2SessionInitializer {
+    fn name(&self) -> String {
+        "oauth2-session".to_string()
+    }
+
+    async fn after_routes(&self, router: AxumRouter, _ctx: &AppContext) -> Result<AxumRouter> {
+        let session_store = MemoryStore::default();
+        let session_layer = SessionManagerLayer::new(session_store)
+            .with_secure(false)
+            .with_expiry(Expiry::OnInactivity(Duration::minutes(10)));
+        Ok(router.layer(session_layer))
+    }
+}

src/models/_entities/mod.rs

@@ -4,6 +4,7 @@ pub mod prelude;
 
 pub mod audit_logs;
 pub mod categories;
+pub mod o_auth2_sessions;
 pub mod order_items;
 pub mod orders;
 pub mod product_images;

src/models/_entities/o_auth2_sessions.rs

@@ -0,0 +1,36 @@
+//! `SeaORM` Entity for loco-oauth2 sessions. Hand-written to match the
+//! `o_auth2_sessions` migration (the rest of `_entities/` is codegen; this table
+//! is owned by the loco-oauth2 integration).
+
+use sea_orm::entity::prelude::*;
+use serde::{Deserialize, Serialize};
+
+#[derive(Clone, Debug, PartialEq, DeriveEntityModel, Eq, Serialize, Deserialize)]
+#[sea_orm(table_name = "o_auth2_sessions")]
+pub struct Model {
+    pub created_at: DateTimeUtc,
+    pub updated_at: DateTimeUtc,
+    #[sea_orm(primary_key)]
+    pub id: i32,
+    pub session_id: String,
+    pub expires_at: DateTimeUtc,
+    pub user_id: i32,
+}
+
+#[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]
+pub enum Relation {
+    #[sea_orm(
+        belongs_to = "super::users::Entity",
+        from = "Column::UserId",
+        to = "super::users::Column::Id",
+        on_update = "Cascade",
+        on_delete = "Cascade"
+    )]
+    Users,
+}
+
+impl Related<super::users::Entity> for Entity {
+    fn to() -> RelationDef {
+        Relation::Users.def()
+    }
+}

src/models/_entities/prelude.rs

@@ -2,6 +2,7 @@
 
 pub use super::audit_logs::Entity as AuditLogs;
 pub use super::categories::Entity as Categories;
+pub use super::o_auth2_sessions::Entity as OAuth2Sessions;
 pub use super::order_items::Entity as OrderItems;
 pub use super::orders::Entity as Orders;
 pub use super::product_images::Entity as ProductImages;

src/models/mod.rs

@@ -8,6 +8,7 @@ pub mod _entities;
 
 pub mod audit_logs;
 pub mod categories;
+pub mod o_auth2_sessions;
 pub mod order_items;
 pub mod orders;
 pub mod product_images;

src/models/o_auth2_sessions.rs

@@ -0,0 +1,79 @@
+pub use super::_entities::o_auth2_sessions::{ActiveModel, Column, Entity, Model};
+use crate::models::{o_auth2_sessions, users};
+use async_trait::async_trait;
+use chrono::Utc;
+use loco_oauth2::base_oauth2::{basic::BasicTokenResponse, TokenResponse};
+use loco_oauth2::models::oauth2_sessions::OAuth2SessionsTrait;
+use loco_rs::prelude::*;
+use sea_orm::entity::prelude::*;
+
+pub type OAuth2Sessions = Entity;
+
+#[async_trait::async_trait]
+impl ActiveModelBehavior for ActiveModel {
+    async fn before_save<C>(self, _db: &C, insert: bool) -> std::result::Result<Self, DbErr>
+    where
+        C: ConnectionTrait,
+    {
+        if !insert && self.updated_at.is_unchanged() {
+            let mut this = self;
+            this.updated_at = sea_orm::ActiveValue::Set(Utc::now());
+            Ok(this)
+        } else {
+            Ok(self)
+        }
+    }
+}
+
+#[async_trait]
+impl OAuth2SessionsTrait<users::Model> for Model {
+    /// Whether the session identified by `session_id` has expired.
+    async fn is_expired(db: &DatabaseConnection, session_id: &str) -> ModelResult<bool> {
+        let session = o_auth2_sessions::Entity::find()
+            .filter(o_auth2_sessions::Column::SessionId.eq(session_id))
+            .one(db)
+            .await?
+            .ok_or_else(|| ModelError::EntityNotFound)?;
+        Ok(session.expires_at < Utc::now())
+    }
+
+    /// Create or refresh the session row for `user` from the provider token.
+    async fn upsert_with_oauth2(
+        db: &DatabaseConnection,
+        token: &BasicTokenResponse,
+        user: &users::Model,
+    ) -> ModelResult<Self> {
+        let txn = db.begin().await?;
+        let session_id = token.access_token().secret().clone();
+        let expires_at = Utc::now()
+            + token
+                .expires_in()
+                .unwrap_or(std::time::Duration::from_secs(3600));
+
+        let session = match o_auth2_sessions::Entity::find()
+            .filter(o_auth2_sessions::Column::UserId.eq(user.id))
+            .one(&txn)
+            .await?
+        {
+            Some(session) => {
+                let mut session: o_auth2_sessions::ActiveModel = session.into();
+                session.session_id = ActiveValue::set(session_id);
+                session.expires_at = ActiveValue::set(expires_at);
+                session.updated_at = ActiveValue::set(Utc::now());
+                session.update(&txn).await?
+            }
+            None => {
+                o_auth2_sessions::ActiveModel {
+                    session_id: ActiveValue::set(session_id),
+                    expires_at: ActiveValue::set(expires_at),
+                    user_id: ActiveValue::set(user.id),
+                    ..Default::default()
+                }
+                .insert(&txn)
+                .await?
+            }
+        };
+        txn.commit().await?;
+        Ok(session)
+    }
+}

src/models/users.rs

@@ -1,10 +1,13 @@
 use async_trait::async_trait;
 use chrono::{offset::Local, Duration};
+use loco_oauth2::models::users::OAuth2UserTrait;
 use loco_rs::{auth::jwt, hash, prelude::*};
+use passwords::PasswordGenerator;
 use serde::{Deserialize, Serialize};
 use serde_json::Map;
 use uuid::Uuid;
 
+use crate::models::_entities::o_auth2_sessions;
 pub use crate::models::_entities::users::{self, ActiveModel, Entity, Model};
 
 pub const MAGIC_LINK_LENGTH: i8 = 32;
@@ -367,3 +370,93 @@ impl ActiveModel {
         self.update(db).await.map_err(ModelError::from)
     }
 }
+
+/// Google OpenID Connect user profile (the fields our scopes request).
+/// <https://developers.google.com/identity/openid-connect/openid-connect#obtainuserinfo>
+#[derive(Serialize, Deserialize, Clone, Debug)]
+pub struct OAuth2UserProfile {
+    pub email: String,
+    pub name: String,
+    pub sub: String,
+    pub email_verified: bool,
+    pub given_name: Option<String>,
+    pub family_name: Option<String>,
+    pub picture: Option<String>,
+    pub locale: Option<String>,
+}
+
+#[async_trait]
+impl OAuth2UserTrait<OAuth2UserProfile> for Model {
+    /// Resolve the user behind an active OAuth2 session id.
+    async fn find_by_oauth2_session_id(
+        db: &DatabaseConnection,
+        session_id: &str,
+    ) -> ModelResult<Self> {
+        let session = o_auth2_sessions::Entity::find()
+            .filter(o_auth2_sessions::Column::SessionId.eq(session_id))
+            .one(db)
+            .await?
+            .ok_or_else(|| ModelError::EntityNotFound)?;
+        users::Entity::find_by_id(session.user_id)
+            .one(db)
+            .await?
+            .ok_or_else(|| ModelError::EntityNotFound)
+    }
+
+    /// Find-or-create the local user for a verified OAuth2 profile.
+    ///
+    /// Per security advisory LOC-2025-04, OAuth2-created accounts get a strong
+    /// RANDOM password (never the provider `sub`) — they sign in via the
+    /// provider, and the random secret just satisfies the NOT NULL column.
+    /// Google has already verified the email, so we mark it verified.
+    async fn upsert_with_oauth(
+        db: &DatabaseConnection,
+        profile: &OAuth2UserProfile,
+    ) -> ModelResult<Self> {
+        let txn = db.begin().await?;
+        let user = match users::Entity::find()
+            .filter(users::Column::Email.eq(&profile.email))
+            .one(&txn)
+            .await?
+        {
+            Some(user) => user,
+            None => {
+                let password = PasswordGenerator::new()
+                    .length(16)
+                    .numbers(true)
+                    .lowercase_letters(true)
+                    .uppercase_letters(true)
+                    .symbols(true)
+                    .exclude_similar_characters(true)
+                    .strict(true)
+                    .generate_one()
+                    .map_err(|e| ModelError::Any(e.into()))?;
+                let password_hash =
+                    hash::hash_password(&password).map_err(|e| ModelError::Any(e.into()))?;
+                users::ActiveModel {
+                    email: ActiveValue::set(profile.email.to_string()),
+                    name: ActiveValue::set(profile.name.to_string()),
+                    email_verified_at: ActiveValue::set(Some(Local::now().into())),
+                    password: ActiveValue::set(password_hash),
+                    ..Default::default()
+                }
+                .insert(&txn)
+                .await
+                .map_err(|e| {
+                    tracing::error!(error = %e, "failed to create OAuth2 user");
+                    ModelError::Any(e.into())
+                })?
+            }
+        };
+        txn.commit().await?;
+        Ok(user)
+    }
+
+    /// Required by the trait; mirrors the inherent [`Model::generate_jwt`]
+    /// (inlined to avoid the inherent/trait name clash).
+    fn generate_jwt(&self, secret: &str, expiration: &u64) -> ModelResult<String> {
+        jwt::JWT::new(secret)
+            .generate_token(*expiration, self.pid.to_string(), Map::new())
+            .map_err(ModelError::from)
+    }
+}