diff --git a/assets/hanyuu.css/main.css b/assets/oauth2.css/main.css
similarity index 100%
rename from assets/hanyuu.css/main.css
rename to assets/oauth2.css/main.css
diff --git a/assets/hanyuu.js/main.js b/assets/oauth2.js/main.js
similarity index 100%
rename from assets/hanyuu.js/main.js
rename to assets/oauth2.js/main.js
diff --git a/build.js b/build.js
index c2467b7..3142bac 100644
--- a/build.js
+++ b/build.js
@@ -17,11 +17,11 @@ const fs = require('fs');
 
     const tasks = {
         js: [
-            { source: 'hanyuu.js', target: '/assets', name: 'hanyuu.{hash}.js', },
+            { source: 'oauth2.js', target: '/assets', name: 'oauth2.{hash}.js', },
         ],
         css: [
             { source: 'errors.css', target: '/', name: 'errors.css', },
-            { source: 'hanyuu.css', target: '/assets', name: 'hanyuu.{hash}.css', },
+            { source: 'oauth2.css', target: '/assets', name: 'oauth2.{hash}.css', },
         ],
         twig: [
             { source: 'errors/400', target: '/', name: 'error-400.html', },
diff --git a/package-lock.json b/package-lock.json
index 6bc5688..6e8cefa 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -703,9 +703,9 @@
       }
     },
     "node_modules/electron-to-chromium": {
-      "version": "1.4.827",
-      "resolved": "https://registry.npmjs.org/electron-to-chromium/-/electron-to-chromium-1.4.827.tgz",
-      "integrity": "sha512-VY+J0e4SFcNfQy19MEoMdaIcZLmDCprqvBtkii1WTCTQHpRvf5N8+3kTYCgL/PcntvwQvmMJWTuDPsq+IlhWKQ==",
+      "version": "1.4.829",
+      "resolved": "https://registry.npmjs.org/electron-to-chromium/-/electron-to-chromium-1.4.829.tgz",
+      "integrity": "sha512-5qp1N2POAfW0u1qGAxXEtz6P7bO1m6gpZr5hdf5ve6lxpLM7MpiM4jIPz7xcrNlClQMafbyUDDWjlIQZ1Mw0Rw==",
       "license": "ISC"
     },
     "node_modules/entities": {
@@ -831,9 +831,9 @@
       }
     },
     "node_modules/node-releases": {
-      "version": "2.0.14",
-      "resolved": "https://registry.npmjs.org/node-releases/-/node-releases-2.0.14.tgz",
-      "integrity": "sha512-y10wOWt8yZpqXmOgRo77WaHEmhYQYGNA6y421PKsKYWEK8aW+cqAphborZDhqfyKrbZEN92CN1X2KbafY2s7Yw==",
+      "version": "2.0.17",
+      "resolved": "https://registry.npmjs.org/node-releases/-/node-releases-2.0.17.tgz",
+      "integrity": "sha512-Ww6ZlOiEQfPfXM45v17oabk77Z7mg5bOt7AjDyzy7RjK9OrLrLC8dyZQoAPEOtFX9SaNf1Tdvr5gRJWdTJj7GA==",
       "license": "MIT"
     },
     "node_modules/normalize-range": {
@@ -1429,9 +1429,9 @@
       }
     },
     "node_modules/terser": {
-      "version": "5.31.2",
-      "resolved": "https://registry.npmjs.org/terser/-/terser-5.31.2.tgz",
-      "integrity": "sha512-LGyRZVFm/QElZHy/CPr/O4eNZOZIzsrQ92y4v9UJe/pFJjypje2yI3C2FmPtvUEnhadlSbmG2nXtdcjHOjCfxw==",
+      "version": "5.31.3",
+      "resolved": "https://registry.npmjs.org/terser/-/terser-5.31.3.tgz",
+      "integrity": "sha512-pAfYn3NIZLyZpa83ZKigvj6Rn9c/vd5KfYGX7cN1mnzqgDcxWvrU5ZtAfIKhEXz9nRecw4z3LXkjaq96/qZqAA==",
       "license": "BSD-2-Clause",
       "dependencies": {
         "@jridgewell/source-map": "^0.3.3",
diff --git a/src/Apps/AppInfo.php b/src/Apps/AppInfo.php
new file mode 100644
index 0000000..24ec250
--- /dev/null
+++ b/src/Apps/AppInfo.php
@@ -0,0 +1,95 @@
+<?php
+namespace Hanyuu\Apps;
+
+use Index\Data\IDbResult;
+
+class AppInfo {
+    public function __construct(
+        private string $id,
+        private string $name,
+        private string $summary,
+        private string $website,
+        private bool $trusted,
+        private string $type,
+        private string $clientId,
+        private string $clientSecret, // should this be stored hashed?
+        private int $created,
+        private int $updated,
+        private ?int $deleted
+    ) {}
+
+    public static function fromResult(IDbResult $result): AppInfo {
+        return new AppInfo(
+            id: $result->getString(0),
+            name: $result->getString(1),
+            summary: $result->getString(2),
+            website: $result->getString(3),
+            trusted: $result->getBoolean(4),
+            type: $result->getString(5),
+            clientId: $result->getString(6),
+            clientSecret: $result->getString(7),
+            created: $result->getInteger(8),
+            updated: $result->getInteger(9),
+            deleted: $result->getIntegerOrNull(10),
+        );
+    }
+
+    public function getId(): string {
+        return $this->id;
+    }
+
+    public function getName(): string {
+        return $this->name;
+    }
+
+    public function getSummary(): string {
+        return $this->summary;
+    }
+
+    public function getWebsite(): string {
+        return $this->website;
+    }
+
+    public function isTrusted(): bool {
+        return $this->trusted;
+    }
+
+    public function getType(): string {
+        return $this->type;
+    }
+    public function isPublic(): bool {
+        return strcasecmp($this->type, 'public') === 0;
+    }
+    public function isConfidential(): bool {
+        return strcasecmp($this->type, 'confidential') === 0;
+    }
+
+    public function getClientId(): string {
+        return $this->clientId;
+    }
+
+    public function getClientSecret(): string {
+        return $this->clientSecret;
+    }
+    public function verifyClientSecret(string $input): bool {
+        return password_verify($input, $this->clientSecret);
+    }
+
+    public function getCreatedTime(): int {
+        return $this->created;
+    }
+
+    public function getUpdatedTime(): int {
+        return $this->updated;
+    }
+    public function isUpdated(): bool {
+        return $this->updated > $this->created;
+    }
+
+    public function getDeletedTime(): ?int {
+        return $this->deleted;
+    }
+    public function isDeleted(): bool {
+        return $this->deleted !== null;
+    }
+}
diff --git a/src/Apps/AppUriInfo.php b/src/Apps/AppUriInfo.php
new file mode 100644
index 0000000..4336626
--- /dev/null
+++ b/src/Apps/AppUriInfo.php
@@ -0,0 +1,41 @@
+<?php
+namespace Hanyuu\Apps;
+
+use Index\Data\IDbResult;
+
+class AppUriInfo {
+    public function __construct(
+        private string $id,
+        private string $appId,
+        private string $string,
+        private int $created
+    ) {}
+
+    public static function fromResult(IDbResult $result): AppUriInfo {
+        return new AppUriInfo(
+            id: $result->getString(0),
+            appId: $result->getString(1),
+            string: $result->getString(2),
+            created: $result->getInteger(3)
+        );
+    }
+
+    public function getId(): string {
+        return $this->id;
+    }
+
+    public function getAppId(): string {
+        return $this->appId;
+    }
+
+    public function getString(): string {
+        return $this->string;
+    }
+    public function compareString(string $other): int {
+        return strcmp($this->string, $other);
+    }
+
+    public function getCreatedTime(): int {
+        return $this->created;
+    }
+}
diff --git a/src/Apps/AppsContext.php b/src/Apps/AppsContext.php
new file mode 100644
index 0000000..5e0803a
--- /dev/null
+++ b/src/Apps/AppsContext.php
@@ -0,0 +1,16 @@
+<?php
+namespace Hanyuu\Apps;
+
+use Index\Data\IDbConnection;
+
+class AppsContext {
+    private AppsData $data;
+
+    public function __construct(IDbConnection $dbConn) {
+        $this->data = new AppsData($dbConn);
+    }
+
+    public function getData(): AppsData {
+        return $this->data;
+    }
+}
diff --git a/src/Apps/AppsData.php b/src/Apps/AppsData.php
new file mode 100644
index 0000000..abeedb3
--- /dev/null
+++ b/src/Apps/AppsData.php
@@ -0,0 +1,90 @@
+<?php
+namespace Hanyuu\Apps;
+
+use InvalidArgumentException;
+use RuntimeException;
+use Index\Data\DbStatementCache;
+use Index\Data\IDbConnection;
+
+class AppsData {
+    private IDbConnection $dbConn;
+    private DbStatementCache $cache;
+
+    public function __construct(IDbConnection $dbConn) {
+        $this->dbConn = $dbConn;
+        $this->cache = new DbStatementCache($dbConn);
+    }
+
+    public function getApp(
+        ?string $appId = null,
+        ?string $clientId = null,
+        ?bool $deleted = null
+    ): AppInfo {
+        $hasAppId = $appId !== null;
+        $hasClientId = $clientId !== null;
+        $hasDeleted = $deleted !== null;
+
+        if($hasAppId === $hasClientId)
+            throw new InvalidArgumentException('you must specify either $appId or $clientId');
+
+        $values = [];
+        $query = 'SELECT app_id, app_name, app_summary, app_website, app_trusted, app_type, app_client_id, app_client_secret, UNIX_TIMESTAMP(app_created), UNIX_TIMESTAMP(app_updated), UNIX_TIMESTAMP(app_deleted) FROM hau_apps';
+        $query .= sprintf(' WHERE %s = ?', $hasAppId ? 'app_id' : 'app_client_id');
+        if($hasDeleted)
+            $query .= sprintf(' AND app_deleted %s NULL', $deleted ? 'IS NOT' : 'IS');
+
+        $stmt = $this->cache->get($query);
+        $stmt->addParameter(1, $hasAppId ? $appId : $clientId);
+        $stmt->execute();
+
+        $result = $stmt->getResult();
+        if(!$result->next())
+            throw new RuntimeException('Application not found.');
+
+        return AppInfo::fromResult($result);
+    }
+
+    public function countAppUris(AppInfo|string $appInfo): int {
+        $stmt = $this->cache->get('SELECT COUNT(*) FROM hau_apps_uris WHERE app_id = ?');
+        $stmt->addParameter(1, $appInfo instanceof AppInfo ? $appInfo->getId() : $appInfo);
+        $stmt->execute();
+
+        $result = $stmt->getResult();
+        return $result->next() ? $result->getInteger(0) : 0;
+    }
+
+    public function getAppUris(AppInfo|string $appInfo): array {
+        $stmt = $this->cache->get('SELECT uri_id, app_id, uri_string, UNIX_TIMESTAMP(uri_created) FROM hau_apps_uris WHERE app_id = ?');
+        $stmt->addParameter(1, $appInfo instanceof AppInfo ? $appInfo->getId() : $appInfo);
+        $stmt->execute();
+
+        $infos = [];
+        $result = $stmt->getResult();
+        while($result->next())
+            $infos[] = AppUriInfo::fromResult($result);
+
+        return $infos;
+    }
+
+    public function getAppUri(string $uriId): AppUriInfo {
+        $stmt = $this->cache->get('SELECT uri_id, app_id, uri_string, UNIX_TIMESTAMP(uri_created) FROM hau_apps_uris WHERE uri_id = ?');
+        $stmt->addParameter(1, $uriId);
+        $stmt->execute();
+
+        $result = $stmt->getResult();
+        if(!$result->next())
+            throw new RuntimeException('URI not found.');
+
+        return AppUriInfo::fromResult($result);
+    }
+
+    public function getAppUriId(AppInfo|string $appInfo, string $uriString): ?string {
+        $stmt = $this->cache->get('SELECT uri_id FROM hau_apps_uris WHERE app_id = ? AND uri_string = ?');
+        $stmt->addParameter(1, $appInfo instanceof AppInfo ? $appInfo->getId() : $appInfo);
+        $stmt->addParameter(2, $uriString);
+        $stmt->execute();
+
+        $result = $stmt->getResult();
+        return $result->next() ? $result->getStringOrNull(0) : null;
+    }
+}
diff --git a/src/HanyuuContext.php b/src/HanyuuContext.php
index 90874fb..d62f8bb 100644
--- a/src/HanyuuContext.php
+++ b/src/HanyuuContext.php
@@ -2,6 +2,7 @@
 namespace Hanyuu;
 
 use Index\Environment;
+use Index\Colour\Colour;
 use Index\Data\IDbConnection;
 use Index\Data\Migration\{IDbMigrationRepo,DbMigrationManager,FsDbMigrationRepo};
 use Sasae\SasaeEnvironment;
@@ -10,13 +11,40 @@ use Syokuhou\IConfig;
 class HanyuuContext {
     private IConfig $config;
     private IDbConnection $dbConn;
-    private ?SasaeEnvironment $templating = null;
+    private SasaeEnvironment $templating;
     private SiteInfo $siteInfo;
 
+    private MisuzuInterop $misuzuInterop;
+    private object $authInfo;
+
+    private Apps\AppsContext $appsCtx;
+    private OAuth2\OAuth2Context $oauth2Ctx;
+
     public function __construct(IConfig $config, IDbConnection $dbConn) {
         $this->config = $config;
         $this->dbConn = $dbConn;
         $this->siteInfo = new SiteInfo($config->scopeTo('site'));
+        $this->misuzuInterop = new MisuzuInterop($config->scopeTo('misuzu'));
+
+        $this->appsCtx = new Apps\AppsContext($dbConn);
+        $this->oauth2Ctx = new OAuth2\OAuth2Context($dbConn);
+
+        $isDebug = Environment::isDebug();
+
+        $this->templating = new SasaeEnvironment(
+            HAU_DIR_TEMPLATES,
+            cache: null,//$isDebug ? null : ['Hanyuu', GitInfo::hash(true)],
+            debug: $isDebug,
+        );
+        $this->templating->addExtension(new HanyuuSasaeExtension($this));
+
+        $this->templating->addGlobal('globals', [
+            'siteInfo' => $this->siteInfo,
+        ]);
+    }
+
+    public function getMisuzu(): MisuzuInterop {
+        return $this->misuzuInterop;
     }
 
     public function getDatabase(): IDbConnection {
@@ -36,42 +64,36 @@ class HanyuuContext {
         return new FsDbMigrationRepo(HAU_DIR_MIGRATIONS);
     }
 
+    public function getAuthInfo(): object {
+        return $this->authInfo;
+    }
+
     public function getWebAssetInfo(): ?object {
         $path = HAU_DIR_ASSETS . '/current.json';
         return is_file($path) ? json_decode(file_get_contents($path)) : null;
     }
 
     public function getTemplating(): SasaeEnvironment {
-        if($this->templating === null) {
-            $isDebug = Environment::isDebug();
-
-            $this->templating = new SasaeEnvironment(
-                HAU_DIR_TEMPLATES,
-                cache: null,//$isDebug ? null : ['Hanyuu', GitInfo::hash(true)],
-                debug: $isDebug,
-            );
-            $this->templating->addExtension(new HanyuuSasaeExtension($this));
-
-            $this->templating->addGlobal('globals', [
-                'siteInfo' => $this->siteInfo,
-            ]);
-        }
-
         return $this->templating;
     }
 
-    public function renderTemplate(...$args): string {
-        return $this->getTemplating()->render(...$args);
-    }
-
     public function createRouting(): RoutingContext {
         $routingCtx = new RoutingContext($this->getTemplating());
 
+        $routingCtx->getRouter()->use('/', function($response, $request) {
+            $this->authInfo = $this->misuzuInterop->authCheck('Misuzu', (string)$request->getCookie('msz_auth'), $_SERVER['REMOTE_ADDR']);
+        });
+
         $routingCtx->getRouter()->get('/', function($response, $request) {
             return 503;
         });
 
-        $routingCtx->register(new OAuth2\OAuth2Routes);
+        $routingCtx->register(new OAuth2\OAuth2Routes(
+            $this->oauth2Ctx,
+            $this->appsCtx,
+            $this->templating,
+            $this->getAuthInfo(...)
+        ));
 
         return $routingCtx;
     }
diff --git a/src/MisuzuInterop.php b/src/MisuzuInterop.php
new file mode 100644
index 0000000..fe961c0
--- /dev/null
+++ b/src/MisuzuInterop.php
@@ -0,0 +1,103 @@
+<?php
+namespace Hanyuu;
+
+use stdClass;
+use RuntimeException;
+use Syokuhou\IConfig;
+use Index\Serialisation\UriBase64;
+
+class MisuzuInterop {
+    public function __construct(
+        private IConfig $config
+    ) {}
+
+    public function authCheck(string $method, string $token, string $remoteAddr, array $avatars = []): object {
+        $result = $this->callRpc('auth-check', body: [
+            'method' => $method,
+            'token' => $token,
+            'remote_addr' => $remoteAddr,
+            'avatars' => implode(',', $avatars),
+        ]);
+
+        if(!str_starts_with($result->name, 'auth:check:'))
+            return new stdClass;
+
+        return $result->attrs;
+    }
+
+    private function callRpc(string $action, array $params = [], array $body = []): object {
+        $time = time();
+
+        $url = sprintf('%s/_hanyuu/%s', $this->config->getString('endpoint'), $action);
+        if(empty($params))
+            $params = '';
+        else {
+            $params = http_build_query($params, '', '&', PHP_QUERY_RFC3986);
+            $url .= sprintf('?%s', $params);
+        }
+
+        $hasBody = !empty($body);
+        $body = $hasBody ? http_build_query($body, '', '&', PHP_QUERY_RFC3986) : '';
+
+        $signature = UriBase64::encode(hash_hmac(
+            'sha256',
+            sprintf('[%s|%s|%s]', $time, $url, $body),
+            $this->config->getString('secret'),
+            true
+        ));
+        $headers = [
+            sprintf('X-Hanyuu-Timestamp: %s', $time),
+            sprintf('X-Hanyuu-Signature: %s', $signature),
+        ];
+
+        if($hasBody)
+            $headers[] = 'Content-Type: application/x-www-form-urlencoded';
+
+        $req = curl_init($url);
+        try {
+            curl_setopt_array($req, [
+                CURLOPT_AUTOREFERER => false,
+                CURLOPT_FAILONERROR => false,
+                CURLOPT_FOLLOWLOCATION => false,
+                CURLOPT_HEADER => false,
+                CURLOPT_RETURNTRANSFER => true,
+                CURLOPT_TCP_FASTOPEN => true,
+                CURLOPT_CONNECTTIMEOUT => 2,
+                CURLOPT_MAXREDIRS => 2,
+                CURLOPT_PROTOCOLS => CURLPROTO_HTTPS,
+                CURLOPT_TIMEOUT => 5,
+                CURLOPT_USERAGENT => 'Hanyuu',
+                CURLOPT_HTTPHEADER => $headers,
+            ]);
+
+            if($hasBody)
+                curl_setopt_array($req, [
+                    CURLOPT_POST => true,
+                    CURLOPT_POSTFIELDS => $body,
+                ]);
+
+            $response = curl_exec($req);
+            if($response === false)
+                throw new RuntimeException(curl_error($req));
+        } finally {
+            curl_close($req);
+        }
+
+        $decoded = json_decode($response);
+        if($decoded === null)
+            throw new RuntimeException($response);
+
+        if(empty($decoded->name) || !isset($decoded->attrs))
+            throw new RuntimeException('Missing name or attrs attribute in response body.');
+
+        if($decoded->name === 'error') {
+            $line = $decoded->attrs->code ?? 'unknown';
+            if(!empty($decoded->attrs->text))
+                $line = sprintf('[%s] %s', $line, $decoded->attrs->text);
+
+            throw new RuntimeException($line);
+        }
+
+        return $decoded;
+    }
+}
diff --git a/src/OAuth2/OAuth2AccessInfo.php b/src/OAuth2/OAuth2AccessInfo.php
new file mode 100644
index 0000000..f305a80
--- /dev/null
+++ b/src/OAuth2/OAuth2AccessInfo.php
@@ -0,0 +1,67 @@
+<?php
+namespace Hanyuu\OAuth2;
+
+use Index\Data\IDbResult;
+
+class OAuth2AccessInfo {
+    public function __construct(
+        private string $id,
+        private string $appId,
+        private string $userId,
+        private string $token,
+        private string $scope,
+        private int $created,
+        private int $expires
+    ) {}
+
+    public static function fromResult(IDbResult $result): OAuth2AccessInfo {
+        return new OAuth2AccessInfo(
+            id: $result->getString(0),
+            appId: $result->getString(1),
+            userId: $result->getString(2),
+            token: $result->getString(3),
+            scope: $result->getString(4),
+            created: $result->getInteger(5),
+            expires: $result->getInteger(6),
+        );
+    }
+
+    public function getId(): string {
+        return $this->id;
+    }
+
+    public function getAppId(): string {
+        return $this->appId;
+    }
+
+    public function getUserId(): string {
+        return $this->userId;
+    }
+
+    public function getToken(): string {
+        return $this->token;
+    }
+
+    public function getScope(): string {
+        return $this->scope;
+    }
+    public function getScopes(): array {
+        return explode(' ', $this->scope);
+    }
+
+    public function getCreatedTime(): int {
+        return $this->created;
+    }
+
+    public function getExpiresTime(): int {
+        return $this->expires;
+    }
+
+    public function getRemainingLifetime(): int {
+        return max(0, $this->expires - time());
+    }
+
+    public function hasExpired(): bool {
+        return time() > $this->expires;
+    }
+}
diff --git a/src/OAuth2/OAuth2Context.php b/src/OAuth2/OAuth2Context.php
new file mode 100644
index 0000000..4d931f8
--- /dev/null
+++ b/src/OAuth2/OAuth2Context.php
@@ -0,0 +1,31 @@
+<?php
+namespace Hanyuu\OAuth2;
+
+use Index\Data\IDbConnection;
+use Hanyuu\Apps\AppInfo;
+
+class OAuth2Context {
+    private OAuth2RequestsData $requests;
+    private OAuth2TokensData $tokens;
+
+    public function __construct(IDbConnection $dbConn) {
+        $this->requests = new OAuth2RequestsData($dbConn);
+        $this->tokens = new OAuth2TokensData($dbConn);
+    }
+
+    public function getRequestsData(): OAuth2RequestsData {
+        return $this->requests;
+    }
+
+    public function getTokensData(): OAuth2TokensData {
+        return $this->tokens;
+    }
+
+    public function validateScopes(AppInfo $appInfo, array $scopes): bool {
+        foreach($scopes as $scope)
+            if(strlen($scope) > 128) // rather than this, actually check if they are defined/supported or smth
+                return false;
+
+        return true;
+    }
+}
diff --git a/src/OAuth2/OAuth2RefreshInfo.php b/src/OAuth2/OAuth2RefreshInfo.php
new file mode 100644
index 0000000..5482509
--- /dev/null
+++ b/src/OAuth2/OAuth2RefreshInfo.php
@@ -0,0 +1,76 @@
+<?php
+namespace Hanyuu\OAuth2;
+
+use Index\Data\IDbResult;
+
+class OAuth2RefreshInfo {
+    public function __construct(
+        private string $id,
+        private string $appId,
+        private string $userId,
+        private ?string $accId,
+        private string $token,
+        private string $scope,
+        private int $created,
+        private int $expires
+    ) {}
+
+    public static function fromResult(IDbResult $result): OAuth2RefreshInfo {
+        return new OAuth2RefreshInfo(
+            id: $result->getString(0),
+            appId: $result->getString(1),
+            userId: $result->getString(2),
+            accId: $result->getStringOrNull(3),
+            token: $result->getString(4),
+            scope: $result->getString(5),
+            created: $result->getInteger(6),
+            expires: $result->getInteger(7),
+        );
+    }
+
+    public function getId(): string {
+        return $this->id;
+    }
+
+    public function getAppId(): string {
+        return $this->appId;
+    }
+
+    public function getUserId(): string {
+        return $this->userId;
+    }
+
+    public function hasAccessId(): bool {
+        return $this->accId !== null;
+    }
+    public function getAccessId(): ?string {
+        return $this->accId;
+    }
+
+    public function getToken(): string {
+        return $this->token;
+    }
+
+    public function getScope(): string {
+        return $this->scope;
+    }
+    public function getScopes(): array {
+        return explode(' ', $this->scope);
+    }
+
+    public function getCreatedTime(): int {
+        return $this->created;
+    }
+
+    public function getExpiresTime(): int {
+        return $this->expires;
+    }
+
+    public function getRemainingLifetime(): int {
+        return max(0, $this->expires - time());
+    }
+
+    public function hasExpired(): bool {
+        return time() > $this->expires;
+    }
+}
diff --git a/src/OAuth2/OAuth2RequestInfo.php b/src/OAuth2/OAuth2RequestInfo.php
new file mode 100644
index 0000000..eb34ff1
--- /dev/null
+++ b/src/OAuth2/OAuth2RequestInfo.php
@@ -0,0 +1,115 @@
+<?php
+namespace Hanyuu\OAuth2;
+
+use Index\Data\IDbResult;
+use Index\Serialisation\UriBase64;
+
+class OAuth2RequestInfo {
+    private const EXPIRES_TIME = 10 * 60;
+
+    public function __construct(
+        private string $id,
+        private string $appId,
+        private string $userId,
+        private string $uriId,
+        private string $state,
+        private string $challengeCode,
+        private string $challengeMethod,
+        private string $scope,
+        private string $code,
+        private string $approval,
+        private int $created
+    ) {}
+
+    public static function fromResult(IDbResult $result): OAuth2RequestInfo {
+        return new OAuth2RequestInfo(
+            id: $result->getString(0),
+            appId: $result->getString(1),
+            userId: $result->getString(2),
+            uriId: $result->getString(3),
+            state: $result->getString(4),
+            challengeCode: $result->getString(5),
+            challengeMethod: $result->getString(6),
+            scope: $result->getString(7),
+            code: $result->getString(8),
+            approval: $result->getString(9),
+            created: $result->getInteger(10),
+        );
+    }
+
+    public function getId(): string {
+        return $this->id;
+    }
+
+    public function getAppId(): string {
+        return $this->appId;
+    }
+
+    public function getUriId(): string {
+        return $this->uriId;
+    }
+
+    public function getUserId(): string {
+        return $this->userId;
+    }
+
+    public function getState(): string {
+        return $this->state;
+    }
+
+    public function hasCodeChallenge(): bool {
+        return $this->challengeCode !== '';
+    }
+
+    public function getChallengeCode(): string {
+        return $this->challengeCode;
+    }
+
+    public function getChallengeMethod(): string {
+        return $this->challengeMethod;
+    }
+
+    public function verifyCodeChallenge(string $codeVerifier): bool {
+        if($this->challengeMethod === 'plain')
+            return hash_equals($this->challengeCode, $codeVerifier);
+
+        if($this->challengeMethod === 'S256') {
+            $knownHash = UriBase64::decode($this->challengeCode);
+            $userHash = hash('sha256', $codeVerifier, true);
+            return hash_equals($knownHash, $userHash);
+        }
+
+        return false;
+    }
+
+    public function getScope(): string {
+        return $this->scope;
+    }
+    public function getScopes(): array {
+        return explode(' ', $this->scope);
+    }
+
+    public function getCode(): string {
+        return $this->code;
+    }
+
+    public function getApproval(): string {
+        return $this->approval;
+    }
+    public function isPending(): bool {
+        return strcasecmp($this->approval, 'pending') === 0;
+    }
+    public function isApproved(): bool {
+        return strcasecmp($this->approval, 'approved') === 0;
+    }
+    public function isDenied(): bool {
+        return strcasecmp($this->approval, 'denied') === 0;
+    }
+
+    public function getCreatedTime(): int {
+        return $this->created;
+    }
+    public function hasExpired(): bool {
+        return time() > ($this->created + self::EXPIRES_TIME);
+    }
+}
diff --git a/src/OAuth2/OAuth2RequestsData.php b/src/OAuth2/OAuth2RequestsData.php
new file mode 100644
index 0000000..397b097
--- /dev/null
+++ b/src/OAuth2/OAuth2RequestsData.php
@@ -0,0 +1,159 @@
+<?php
+namespace Hanyuu\OAuth2;
+
+use InvalidArgumentException;
+use RuntimeException;
+use Index\XString;
+use Index\Data\DbStatementCache;
+use Index\Data\IDbConnection;
+use Hanyuu\Apps\AppInfo;
+use Hanyuu\Apps\AppUriInfo;
+
+class OAuth2RequestsData {
+    private IDbConnection $dbConn;
+    private DbStatementCache $cache;
+
+    public function __construct(IDbConnection $dbConn) {
+        $this->dbConn = $dbConn;
+        $this->cache = new DbStatementCache($dbConn);
+    }
+
+    public function getRequest(
+        ?string $requestId = null,
+        AppInfo|string|null $appInfo = null,
+        ?string $userId = null,
+        AppUriInfo|string|null $appUriInfo = null,
+        ?string $state = null,
+        ?string $challengeCode = null,
+        ?string $challengeMethod = null,
+        ?string $scope = null,
+        ?string $code = null
+    ): OAuth2RequestInfo {
+        $selectors = [];
+        $values = [];
+        if($requestId !== null) {
+            $selectors[] = 'req_id = ?';
+            $values[] = $requestId;
+        }
+        if($appInfo !== null) {
+            $selectors[] = 'app_id = ?';
+            $values[] = $appInfo instanceof AppInfo ? $appInfo->getId() : $appInfo;
+        }
+        if($userId !== null) {
+            $selectors[] = 'user_id = ?';
+            $values[] = $userId;
+        }
+        if($appUriInfo !== null) {
+            $selectors[] = 'uri_id = ?';
+            $values[] = $appUriInfo instanceof AppUriInfo ? $appUriInfo->getId() : $appUriInfo;
+        }
+        if($state !== null) {
+            $selectors[] = 'req_state = ?';
+            $values[] = $state;
+        }
+        if($challengeCode !== null) {
+            $selectors[] = 'req_challenge_code = ?';
+            $values[] = $challengeCode;
+        }
+        if($challengeMethod !== null) {
+            $selectors[] = 'req_challenge_method = ?';
+            $values[] = $challengeMethod;
+        }
+        if($scope !== null) {
+            $selectors[] = 'req_scope = ?';
+            $values[] = $scope;
+        }
+        if($code !== null) {
+            $selectors[] = 'req_code = ?';
+            $values[] = $code;
+        }
+
+        if(empty($selectors))
+            throw new RuntimeException('Insufficient data to do request lookup.');
+
+        $args = 0;
+        $stmt = $this->cache->get('SELECT req_id, app_id, user_id, uri_id, req_state, req_challenge_code, req_challenge_method, req_scope, req_code, req_approval, UNIX_TIMESTAMP(req_created) FROM hau_oauth2_requests WHERE ' . implode(' AND ', $selectors));
+        foreach($values as $value)
+            $stmt->addParameter(++$args, $value);
+        $stmt->execute();
+
+        $result = $stmt->getResult();
+        if(!$result->next())
+            throw new RuntimeException('Request not found.');
+
+        return OAuth2RequestInfo::fromResult($result);
+    }
+
+    public function createRequest(
+        AppInfo|string $appInfo,
+        string $userId,
+        AppUriInfo|string $appUriInfo,
+        string $state,
+        string $challengeCode,
+        string $challengeMethod,
+        string $scope
+    ): OAuth2RequestInfo {
+        $stmt = $this->cache->get('INSERT INTO hau_oauth2_requests (app_id, user_id, uri_id, req_state, req_challenge_code, req_challenge_method, req_scope, req_code) VALUES (?, ?, ?, ?, ?, ?, ?, ?)');
+        $stmt->addParameter(1, $appInfo instanceof AppInfo ? $appInfo->getId() : $appInfo);
+        $stmt->addParameter(2, $userId);
+        $stmt->addParameter(3, $appUriInfo instanceof AppUriInfo ? $appUriInfo->getId() : $appUriInfo);
+        $stmt->addParameter(4, $state);
+        $stmt->addParameter(5, $challengeCode);
+        $stmt->addParameter(6, $challengeMethod);
+        $stmt->addParameter(7, $scope);
+        $stmt->addParameter(8, XString::random(100));
+        $stmt->execute();
+
+        return $this->getRequest(requestId: (string)$this->dbConn->getLastInsertId());
+    }
+
+    public function deleteRequests(
+        OAuth2RequestInfo|string|null $requestInfo = null,
+        AppInfo|string|null $appInfo = null,
+        ?string $userId = null,
+        ?string $code = null
+    ): void {
+        $selectors = [];
+        $values = [];
+        if($requestInfo !== null) {
+            $selectors[] = 'req_id = ?';
+            $values[] = $requestInfo instanceof OAuth2RequestInfo ? $requestInfo->getId() : $requestInfo;
+        }
+        if($appInfo !== null) {
+            $selectors[] = 'app_id = ?';
+            $values[] = $appInfo instanceof AppInfo ? $appInfo->getId() : $appInfo;
+        }
+        if($userId !== null) {
+            $selectors[] = 'user_id = ?';
+            $values[] = $userId;
+        }
+        if($code !== null) {
+            $selectors[] = 'req_code = ?';
+            $values[] = $code;
+        }
+
+        $query = 'DELETE FROM hau_oauth2_requests';
+        if(!empty($selectors))
+            $query .= sprintf(' WHERE %s', implode(' AND ', $selectors));
+
+        $args = 0;
+        $stmt = $this->cache->get($query);
+        foreach($values as $value)
+            $stmt->addParameter(++$args, $value);
+        $stmt->execute();
+    }
+
+    public function setRequestApproval(OAuth2RequestInfo|string $requestInfo, bool $approval): void {
+        if($requestInfo instanceof OAuth2RequestInfo) {
+            if(!$requestInfo->isPending())
+                return;
+
+            $requestInfo = $requestInfo->getId();
+        }
+
+        $stmt = $this->cache->get('UPDATE hau_oauth2_requests SET req_approval = ? WHERE req_id = ? AND req_approval = "pending"');
+        $stmt->addParameter(1, $approval ? 'approved' : 'denied');
+        $stmt->addParameter(2, $requestInfo);
+        $stmt->execute();
+    }
+}
diff --git a/src/OAuth2/OAuth2Routes.php b/src/OAuth2/OAuth2Routes.php
index 4a1c300..393a48c 100644
--- a/src/OAuth2/OAuth2Routes.php
+++ b/src/OAuth2/OAuth2Routes.php
@@ -1,48 +1,262 @@
 <?php
 namespace Hanyuu\OAuth2;
 
+use InvalidArgumentException;
+use RuntimeException;
+use Index\XString;
 use Index\Http\Routing\{HttpGet,HttpOptions,HttpPost,RouteHandler};
+use Sasae\SasaeEnvironment;
+use Hanyuu\Apps\AppsContext;
 
 final class OAuth2Routes extends RouteHandler {
-    #[HttpGet('/oauth2/authorise')]
-    public function getAuthorise($response, $request) {
-        $type = (string)$request->getParam('response_type');
-        if($type !== 'code')
-            return 400; // TODO: descriptive/better looking error notice
+    public function __construct(
+        private OAuth2Context $oauth2Ctx,
+        private AppsContext $appsCtx,
+        private SasaeEnvironment $templating,
+        private $getAuthInfo
+    ) {
+        if(!is_callable($getAuthInfo))
+            throw new InvalidArgumentException('$getAuthInfo must be callable');
+    }
 
-        $state = (string)$request->getParam('state');
-        if($state === '') // technically state is not required by the spec but its probably best to enforce it
-            return 400; // TODO: ^
+    private static function buildCallbackUri(string $target, array $params): string {
+        if($target === '')
+            $target = '/oauth2/error';
 
-        $clientId = (string)$request->getParam('client_id');
-        if($clientId === 'wrong')
-            return 404; // TODO: is this the correct error code for this situation?
+        $target .= strpos($target, '?') === false ? '?' : '&';
+        $target .= http_build_query($params, '', '&', PHP_QUERY_RFC3986);
+        return $target;
+    }
 
-        $scope = explode(' ', (string)$request->getParam('scope'));
-        if(in_array('invalid', $scope))
-            return 403; // TODO: ensure the set of scopes we have is valid for this application
+    private static function filterScopes(string $source): array {
+        $scopes = [];
 
-        $codeChallengeMethod = (string)$request->getParam('code_challenge_method');
-        if($codeChallengeMethod === '')
-            $codeChallengeMethod = 'plain';
-        elseif(!in_array($codeChallengeMethod, ['plain', 'S256']))
-            return 400; // TODO: see $type check
-
-        $codeChallenge = (string)$request->getParam('code_challenge');
-        if($codeChallengeMethod !== 'plain' && $codeChallenge === '')
-            return 400; // TODO: see $type check, not technically part of the spec but if you're bothering to specify a method then like ???
-        elseif($codeChallengeMethod === 'S256' && strlen($codeChallenge) !== 32)
-            return 400; // TODO: see $type check, code_challenge should always be 32 chars long if S256
-
-        // optional, yoink default from database
-        $redirectUri = (string)$request->getParam('redirect_uri');
-        if($redirectUri !== '') {
-            if($redirectUri === 'bad')
-                return 403; // TODO: if specified, ensure the redirect_uri is allowed, make sure to do this again in the token request
+        $source = explode(' ', $source);
+        foreach($source as $scope) {
+            $scope = trim($scope);
+            if($scope !== '' && !in_array($scope, $scopes))
+                $scopes[] = $scope;
         }
 
-        // display confirm diag
-        // upon yes, redir to whatever with the code and the state
+        sort($scopes);
+
+        return $scopes;
+    }
+
+    #[HttpGet('/oauth2/error')]
+    public function getError($response, $request) {
+        //
+    }
+
+    #[HttpGet('/oauth2/test')]
+    public function getTest($response) {
+        $response->redirect(self::buildCallbackUri('/oauth2/authorise', [
+            'response_type' => 'code',
+            'client_id' => 'rGKPeDeWQfOVhhHi2qFz',
+            'redirect_uri' => 'https://edgii.net/auth/return',
+            'state' => 'beanz',
+            'scope' => 'windows:xp microsoft:vista windows:forworkgroups',
+        ]));
+    }
+
+    #[HttpGet('/oauth2/authorise')]
+    public function getAuthorise($response, $request) {
+        $redirectUri = (string)$request->getParam('redirect_uri');
+        if($redirectUri !== '' && filter_var($redirectUri, FILTER_VALIDATE_URL) === false)
+            return $response->redirect(self::buildCallbackUri('', [
+                'error' => 'invalid_request',
+                'error_description' => 'Request URI must be a correctly formatted absolute URI.',
+            ]));
+
+        $clientId = (string)$request->getParam('client_id');
+        $appsData = $this->appsCtx->getData();
+        try {
+            $appInfo = $appsData->getApp(clientId: $clientId, deleted: false);
+        } catch(RuntimeException $ex) {
+            return $response->redirect(self::buildCallbackUri($redirectUri, [
+                'error' => 'invalid_request',
+                'error_description' => 'Client ID is missing or is not associated with an existing application.',
+            ]));
+        }
+
+        $state = (string)$request->getParam('state');
+        if(strlen($state) > 255)
+            return $response->redirect(self::buildCallbackUri($redirectUri, [
+                'error' => 'invalid_request',
+                'error_description' => 'State parameter may not be longer than 255 characters.',
+            ]));
+
+        if($redirectUri === '') {
+            $uriInfos = $appsData->countAppUris($appInfo);
+            if($uriInfos !== 1)
+                return $response->redirect(self::buildCallbackUri($redirectUri, [
+                    'error' => 'invalid_request',
+                    'error_description' => 'A registered redirect URI must be specified.',
+                    'state' => $state,
+                ]));
+
+            $uriInfos = $appsData->getAppUris($appInfo);
+            if(count($uriInfos) !== 1)
+                return $response->redirect(self::buildCallbackUri($redirectUri, [
+                    'error' => 'invalid_request',
+                    'error_description' => 'A registered redirect URI must be specified (congrats, you hit an edge case!).',
+                    'state' => $state,
+                ]));
+
+            $uriInfo = array_pop($uriInfos);
+            $redirectUriId = $uriInfo->getId();
+            $redirectUri = $uriInfo->getString();
+        } else {
+            $redirectUriId = $appsData->getAppUriId($appInfo, $redirectUri);
+            if($redirectUriId === null)
+                return $response->redirect(self::buildCallbackUri($redirectUri, [
+                    'error' => 'invalid_request',
+                    'error_description' => 'Specified redirect URI is not registered with the application.',
+                    'state' => $state,
+                ]));
+        }
+
+        $type = (string)$request->getParam('response_type');
+        if($type !== 'code')
+            return $response->redirect(self::buildCallbackUri($redirectUri, [
+                'error' => 'unsupported_response_type',
+                'state' => $state,
+            ]));
+
+        $codeChallengeMethod = (string)$request->getParam('code_challenge_method');
+        if($codeChallengeMethod === '') $codeChallengeMethod = 'plain';
+
+        $codeChallenge = (string)$request->getParam('code_challenge');
+        $codeChallengeLength = strlen($codeChallenge);
+
+        if($codeChallengeMethod === 'plain') {
+            if($codeChallengeLength === 0) {
+                if($appInfo->isPublic())
+                    return $response->redirect(self::buildCallbackUri($redirectUri, [
+                        'error' => 'invalid_request',
+                        'error_description' => 'Public clients are required to specify a code challenge.',
+                        'state' => $state,
+                    ]));
+            } elseif($codeChallengeLength < 43)
+                return $response->redirect(self::buildCallbackUri($redirectUri, [
+                    'error' => 'invalid_request',
+                    'error_description' => 'Code challenge must be at least 43 characters long.',
+                    'state' => $state,
+                ]));
+            elseif($codeChallengeLength > 128)
+                return $response->redirect(self::buildCallbackUri($redirectUri, [
+                    'error' => 'invalid_request',
+                    'error_description' => 'Code challenge may not be longer than 128 characters.',
+                    'state' => $state,
+                ]));
+        } elseif($codeChallengeMethod === 'S256') {
+            if($codeChallengeLength !== 43)
+                return $response->redirect(self::buildCallbackUri($redirectUri, [
+                    'error' => 'invalid_request',
+                    'error_description' => 'Specified code challenge is not a valid SHA-256 hash.',
+                    'state' => $state,
+                ]));
+        } else {
+            return $response->redirect(self::buildCallbackUri($redirectUri, [
+                'error' => 'invalid_request',
+                'error_description' => 'Request code challenge method is not supported.',
+                'state' => $state,
+            ]));
+        }
+
+        $scopes = self::filterScopes((string)$request->getParam('scope'));
+        if(!$this->oauth2Ctx->validateScopes($appInfo, $scopes))
+            return $response->redirect(self::buildCallbackUri($redirectUri, [
+                'error' => 'invalid_scope',
+                'state' => $state,
+            ]));
+        $scope = implode(' ', $scopes);
+
+        $authInfo = ($this->getAuthInfo)();
+        if(!isset($authInfo->user))
+            return $this->templating->render('oauth2/login', [
+                'app' => $appInfo,
+                'auth' => $authInfo,
+            ]);
+
+        $reqsData = $this->oauth2Ctx->getRequestsData();
+        try {
+            $requestInfo = $reqsData->createRequest(
+                $appInfo,
+                $authInfo->user->id,
+                $redirectUriId,
+                $state,
+                $codeChallenge,
+                $codeChallengeMethod,
+                $scope
+            );
+        } catch(RuntimeException $ex) {
+            return $response->redirect(self::buildCallbackUri($redirectUri, [
+                'error' => 'server_error',
+                'state' => $state,
+            ]));
+        }
+
+        return $this->templating->render('oauth2/authorise', [
+            'app' => $appInfo,
+            'req' => $requestInfo,
+            'auth' => $authInfo,
+        ]);
+    }
+
+
+    #[HttpPost('/oauth2/authorise')]
+    public function postAuthorise($response, $request) {
+        if(!$request->isFormContent())
+            return 400;
+
+        $authInfo = ($this->getAuthInfo)();
+        if(!isset($authInfo->user))
+            return 401;
+
+        // TODO: CSRFP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+        $content = $request->getContent();
+        $approve = (string)$content->getParam('approve');
+        if(!in_array($approve, ['yes', 'no']))
+            return 400;
+
+        $code = (string)$content->getParam('code');
+        if(strlen($code) !== 100)
+            return 400;
+
+        $reqsData = $this->oauth2Ctx->getRequestsData();
+        try {
+            $requestInfo = $reqsData->getRequest(
+                userId: $authInfo->user->id,
+                code: $code,
+            );
+        } catch(RuntimeException $ex) {
+            return 404;
+        }
+
+        if(!$requestInfo->isPending())
+            return 410;
+
+        $appsData = $this->appsCtx->getData();
+        try {
+            $uriInfo = $appsData->getAppUri($requestInfo->getUriId());
+        } catch(RuntimeException $ex) {
+            return 400;
+        }
+
+        $approved = $approve === 'yes';
+        $reqsData->setRequestApproval($requestInfo, $approved);
+
+        if($approved)
+            $response->redirect(self::buildCallbackUri($uriInfo->getString(), [
+                'code' => $requestInfo->getCode(),
+                'state' => $requestInfo->getState(),
+            ]));
+        else
+            $response->redirect(self::buildCallbackUri($uriInfo->getString(), [
+                'error' => 'access_denied',
+                'state' => $requestInfo->getState(),
+            ]));
     }
 
     private static function error(string $code, string $message = '', string $url = ''): array {
@@ -70,7 +284,7 @@ final class OAuth2Routes extends RouteHandler {
             return self::error('invalid_client', 'No application has been registered with this client id.');
         }
 
-        $scope = explode(' ', (string)$content->getParam('scope'));
+        $scope = self::filterScopes((string)$content->getParam('scope'));
         if(in_array('invalid', $scope)) {
             $response->setStatusCode(400);
             return self::error('invalid_scope', 'An invalid scope was requested.');
@@ -93,6 +307,8 @@ final class OAuth2Routes extends RouteHandler {
     #[HttpOptions('/oauth2/token')]
     #[HttpPost('/oauth2/token')]
     public function postToken($response, $request) {
+        $response->setHeader('Cache-Control', 'no-store');
+
         $originHeaders = ['Origin', 'X-Origin', 'Referer'];
         $origins = [];
         foreach($originHeaders as $originHeader) {
@@ -123,6 +339,7 @@ final class OAuth2Routes extends RouteHandler {
 
         $content = $request->getContent();
 
+        // authz header should be the preferred method
         $authzHeader = explode(' ', (string)$request->getHeaderLine('Authorization'));
         if($authzHeader[0] === 'Basic') {
             $authzHeader = explode(':', base64_decode($authzHeader[1] ?? ''));
@@ -138,42 +355,97 @@ final class OAuth2Routes extends RouteHandler {
             $clientSecret = (string)$content->getParam('client_secret');
         }
 
-        if($clientId === 'wrong') { // verify and look up
+        $appsData = $this->appsCtx->getData();
+        $reqsData = $this->oauth2Ctx->getRequestsData();
+
+        try {
+            $appInfo = $appsData->getApp(clientId: $clientId, deleted: false);
+        } catch(RuntimeException $ex) {
             $response->setStatusCode(400);
             return self::error('invalid_client', 'No application has been registered with this client id.');
         }
 
         $type = (string)$content->getParam('grant_type');
         if($type === 'authorization_code') {
-            $code = (string)$content->getParam('code');
-
             // require a code verifier be used if client_secret is not supplied or if the field for it is populated
             // error code for this is: invalid_request
             $codeVerifier = (string)$content->getParam('code_verifier');
+            $hasCodeVerifier = $codeVerifier !== '';
+            if($clientSecret === '') {
+                if(!$hasCodeVerifier) {
+                    $response->setStatusCode(400);
+                    return self::error('invalid_request', 'Application authentication through client secret is required if no code verifier is specified.');
+                }
+            } elseif(!$appInfo->verifyClientSecret($clientSecret)) {
+                $response->setStatusCode(400);
+                return self::error('invalid_client', 'Provided client secret is not correct for this application.');
+            }
+
+            try {
+                $requestInfo = $reqsData->getRequest(code: (string)$content->getParam('code'));
+            } catch(RuntimeException $ex) {
+                $response->setStatusCode(400);
+                return self::error('invalid_grant', 'No authorisation request with this code exists.');
+            }
+
+            if($requestInfo->hasExpired()) {
+                $response->setStatusCode(400);
+                return self::error('invalid_grant', 'Authorisation request has expired.');
+            }
+
+            if($requestInfo->hasCodeChallenge()) {
+                if(!$hasCodeVerifier) {
+                    $response->setStatusCode(400);
+                    return self::error('invalid_request', 'Authorisation required included a code challenge, but no code verifier is supplied.');
+                }
+
+                if(!$requestInfo->verifyCodeChallenge($codeVerifier)) {
+                    $response->setStatusCode(400);
+                    return self::error('invalid_request', 'Code challenge verification failed.');
+                }
+            }
 
-            // required if it was specified in the authorise req, check!
-            // error code for this is also likely: invalid_request
             $redirectUri = (string)$content->getParam('redirect_uri');
+            if($redirectUri === '') {
+                if(!$hasCodeVerifier && $appInfo->isPublic()) {
+                    $response->setStatusCode(400);
+                    return self::error('invalid_request', 'You must specified the redirect URI if no code verifier is specified.');
+                }
+            } elseif($appsData->getAppUriId($appInfo, $redirectUri) !== $requestInfo->getUriId()) {
+                $response->setStatusCode(400);
+                return self::error('invalid_request', 'Provided redirect URI does not match up with the one used during the authorisation request.');
+            }
+
+            if(!$requestInfo->isApproved()) {
+                $response->setStatusCode(400);
+                return self::error('invalid_grant', 'Authorisation request has not been approved.');
+            }
+
+            $scopes = $requestInfo->getScopes();
+            if(!$this->oauth2Ctx->validateScopes($appInfo, $scopes)) {
+                $response->setStatusCode(400);
+                return self::error('invalid_scope', 'One or more requested scopes are no longer valid for this application, please restart authorisation.');
+            }
         } elseif($type === 'refresh_token') {
             $refreshToken = (string)$content->getParam('refresh_token');
 
-            // should not contain more than the original access_token, prolly just omit
-            $scope = explode(' ', (string)$content->getParam('scope'));
+            // should not contain more than the original access_token, refresh info contains the stuff we need!
+            $newScopes = self::filterScopes((string)$content->getParam('scope'));
+            $oldScopes = [];
 
-            // i'm honestly not sure if this is the proper place for it but
-            if(in_array('invalid', $scope)) {
+            if($this->oauth2Ctx->validateScopes($appInfo, $newScopes)) {
                 $response->setStatusCode(400);
-                return self::error('invalid_scope', 'An invalid scope was requested.');
+                return self::error('invalid_scope', 'One or more requested scopes are no longer valid for this application, please restart authorisation.');
             }
         } elseif($type === 'client_credentials') {
             // uses client_secret
         } elseif($type === 'password') {
-            if($clientId !== 'flashii') {
+            // still really not sure if i should bother with implementing this, especially since its omitted from OAuth 2.1 entirely
+            if(!$appInfo->isTrusted()) {
                 $response->setStatusCode(400);
-                return self::error('unauthorized_client', 'This application is not allowed t ouse this grant type.');
+                return self::error('unauthorized_client', 'This application is not allowed to use this grant type.');
             }
 
-            // this should only be allowed for certain applications
             $userName = (string)$content->getParam('username');
             $password = (string)$content->getParam('password');
         } elseif($type === 'device_code' || $type === 'urn:ietf:params:oauth:grant-type:device_code') {
@@ -203,7 +475,7 @@ final class OAuth2Routes extends RouteHandler {
             return self::error('unsupported_grant_type', 'Requested grant type is not supported by this server.');
         }
 
-        if($clientId === 'invalid_grant') {
+        if(empty($accessInfo)) {
             $response->setStatusCode(400);
 
             if($type === 'refresh_token')
@@ -218,21 +490,17 @@ final class OAuth2Routes extends RouteHandler {
             return self::error('invalid_grant', $message);
         }
 
-        // TODO: ensure the set of requested scopes is still valid for this application
-        $scope ??= [];
-        if(in_array('invalid', $scope)) {
-            $response->setStatusCode(400);
-            return self::error('invalid_scope', 'One or more requested scopes are no longer valid for this application, please restart authorisation.');
-        }
-
         $result = [
-            'access_token' => 'abcdef',
+            'access_token' => $accessInfo->getToken(),
             'token_type' => 'Bearer',
-            'expires_in' => 3600, // should be bigger on the server side to offer leeway
+            'expires_in' => $accessInfo->getRemainingLifetime(),
         ];
 
-        // only if refreshable
-        $result['refresh_token'] = 'ghijkl';
+        if(isset($scopes))
+            $result['scope'] = implode(' ', $scopes);
+
+        if(empty($refreshInfo))
+            $result['refresh_token'] = $refreshInfo->getToken();
 
         return $result;
     }
diff --git a/src/OAuth2/OAuth2TokensData.php b/src/OAuth2/OAuth2TokensData.php
new file mode 100644
index 0000000..512a8ac
--- /dev/null
+++ b/src/OAuth2/OAuth2TokensData.php
@@ -0,0 +1,19 @@
+<?php
+namespace Hanyuu\OAuth2;
+
+use InvalidArgumentException;
+use RuntimeException;
+use Index\XString;
+use Index\Data\DbStatementCache;
+use Index\Data\IDbConnection;
+
+class OAuth2TokensData {
+    private IDbConnection $dbConn;
+    private DbStatementCache $cache;
+
+    public function __construct(IDbConnection $dbConn) {
+        $this->dbConn = $dbConn;
+        $this->cache = new DbStatementCache($dbConn);
+    }
+
+}
diff --git a/templates/errors/master.twig b/templates/errors/master.twig
index 7641d1d..9747280 100644
--- a/templates/errors/master.twig
+++ b/templates/errors/master.twig
@@ -4,7 +4,7 @@
         <meta charset="utf-8">
         <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no">
         <title>{{ http_error_title }} :: {{ globals.siteInfo.name }}</title>
-        <link href="/errors.css" type="text/css" rel="stylesheet">
+        <link href="/errors.css" rel="stylesheet">
     </head>
     <body>
         <div class="http-err">
diff --git a/templates/master.twig b/templates/master.twig
index ae91556..e0cf1bc 100644
--- a/templates/master.twig
+++ b/templates/master.twig
@@ -4,10 +4,8 @@
         <meta charset="utf-8">
         <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no">
         <title>{% if title is defined %}{{ title }} :: {% endif %}{{ globals.siteInfo.name }}</title>
-        <link href="/assets/hanyuu.css" type="text/css" rel="stylesheet">
     </head>
     <body>
         {% block body %}{% endblock %}
-        <script src="/assets/hanyuu.js" type="text/javascript"></script>
     </body>
 </html>
diff --git a/templates/oauth2/authorise.twig b/templates/oauth2/authorise.twig
new file mode 100644
index 0000000..0e5cfe1
--- /dev/null
+++ b/templates/oauth2/authorise.twig
@@ -0,0 +1,23 @@
+{% extends 'oauth2/master.twig' %}
+
+{% block body %}
+    <h1><a href="{{ app.website }}" target="_blank">{{ app.name }}</a></h1>
+    <p>{{ app.summary }}</p>
+    <p>{% if app.isTrusted %}This is an official application. Things should probably just implicitly authorise if we hit this.{% else %}This is a third-party application.{% endif %}</p>
+
+    <p>You are logged in as <a href="{{ auth.user.profile_url }}" target="_blank" style="color: {{ auth.user.colour }}">{{ auth.user.name }}</a>.</p>
+    {% if auth.guise is defined %}
+        <p>Are you <a href="{{ auth.guise.profile_url }}" target="_blank" style="color: {{ auth.guise.colour }}">{{ auth.guise.name }}</a> and did you mean to use your own account? <a href="{{ auth.guise.revert_url }}" target="_blank">Click here</a> and reload this page.</p>
+    {% endif %}
+
+    <form method="post" action="/oauth2/authorise">
+        <input type="hidden" name="code" value="{{ req.code }}">
+        <input type="hidden" name="approve" value="yes">
+        <button>Authorise</button>
+    </form>
+    <form method="post" action="/oauth2/authorise">
+        <input type="hidden" name="code" value="{{ req.code }}">
+        <input type="hidden" name="approve" value="no">
+        <button>Cancel</button>
+    </form>
+{% endblock %}
diff --git a/templates/oauth2/login.twig b/templates/oauth2/login.twig
new file mode 100644
index 0000000..2f8478b
--- /dev/null
+++ b/templates/oauth2/login.twig
@@ -0,0 +1,9 @@
+{% extends 'oauth2/master.twig' %}
+
+{% block body %}
+    <h1><a href="{{ app.website }}" target="_blank">{{ app.name }}</a></h1>
+    <p>{{ app.summary }}</p>
+    <p>{% if app.isTrusted %}This is an official application. Things should probably just implicitly authorise if we hit this.{% else %}This is a third-party application.{% endif %}</p>
+
+    <p>You must be logged in to authorise applications. <a href="{{ auth.login_url }}" target="_blank">Log in</a> or <a href="{{ auth.register_url }}" target="_blank">create an account</a> and reload this page to try again.</p>
+{% endblock %}
diff --git a/templates/oauth2/master.twig b/templates/oauth2/master.twig
new file mode 100644
index 0000000..d412fa4
--- /dev/null
+++ b/templates/oauth2/master.twig
@@ -0,0 +1,13 @@
+<!doctype html>
+<html>
+    <head>
+        <meta charset="utf-8">
+        <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no">
+        <title>{% if title is defined %}{{ title }} :: {% endif %}{{ globals.siteInfo.name }}</title>
+        <link href="{{ asset('oauth2.css') }}" rel="stylesheet">
+    </head>
+    <body>
+        {% block body %}{% endblock %}
+        <script src="{{ asset('oauth2.js') }}"></script>
+    </body>
+</html>