diff --git a/src/Plug/Contract/Authenticable.php b/src/Plug/Contract/Authenticable.php
new file mode 100644
index 0000000..4389077
--- /dev/null
+++ b/src/Plug/Contract/Authenticable.php
@@ -0,0 +1,45 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Core\Plug\Contract;
+
+use Core\Plug\Response;
+
+/**
+ * Contract for authentication operations.
+ *
+ * Covers OAuth2, API key, webhook, and credential-based auth flows.
+ */
+interface Authenticable
+{
+    /**
+     * Get provider identifier (e.g., 'twitter', 'bluesky').
+     */
+    public static function identifier(): string;
+
+    /**
+     * Get display name (e.g., 'X', 'Bluesky').
+     */
+    public static function name(): string;
+
+    /**
+     * Get OAuth authorisation URL.
+     *
+     * Returns empty string if not OAuth-based.
+     */
+    public function getAuthUrl(): string;
+
+    /**
+     * Exchange credentials/callback params for access token.
+     *
+     * @param  array  $params  OAuth callback params or credentials
+     * @return array Token data or error
+     */
+    public function requestAccessToken(array $params): array;
+
+    /**
+     * Get authenticated account information.
+     */
+    public function getAccount(): Response;
+}
diff --git a/src/Plug/Contract/Commentable.php b/src/Plug/Contract/Commentable.php
new file mode 100644
index 0000000..26916df
--- /dev/null
+++ b/src/Plug/Contract/Commentable.php
@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Core\Plug\Contract;
+
+use Core\Plug\Response;
+
+/**
+ * Contract for comment/reply operations.
+ */
+interface Commentable
+{
+    /**
+     * Post a comment or reply to existing content.
+     *
+     * @param  string  $text  Comment content
+     * @param  string  $postId  ID of the post to comment on
+     * @param  array  $params  Platform-specific options
+     */
+    public function comment(string $text, string $postId, array $params = []): Response;
+}
diff --git a/src/Plug/Contract/Deletable.php b/src/Plug/Contract/Deletable.php
new file mode 100644
index 0000000..22e5565
--- /dev/null
+++ b/src/Plug/Contract/Deletable.php
@@ -0,0 +1,18 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Core\Plug\Contract;
+
+use Core\Plug\Response;
+
+/**
+ * Contract for content deletion operations.
+ */
+interface Deletable
+{
+    /**
+     * Delete a post by its external ID.
+     */
+    public function delete(string $id): Response;
+}
diff --git a/src/Plug/Contract/Listable.php b/src/Plug/Contract/Listable.php
new file mode 100644
index 0000000..5e25281
--- /dev/null
+++ b/src/Plug/Contract/Listable.php
@@ -0,0 +1,21 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Core\Plug\Contract;
+
+use Core\Plug\Response;
+
+/**
+ * Contract for listing entities (pages, boards, publications, etc.).
+ *
+ * Used by providers that require selecting a target entity before posting.
+ * Examples: Meta pages, Pinterest boards, Medium publications.
+ */
+interface Listable
+{
+    /**
+     * List available entities for the authenticated user.
+     */
+    public function listEntities(): Response;
+}
diff --git a/src/Plug/Contract/MediaUploadable.php b/src/Plug/Contract/MediaUploadable.php
new file mode 100644
index 0000000..1018e41
--- /dev/null
+++ b/src/Plug/Contract/MediaUploadable.php
@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Core\Plug\Contract;
+
+use Core\Plug\Response;
+
+/**
+ * Contract for media upload operations.
+ */
+interface MediaUploadable
+{
+    /**
+     * Upload media to the platform.
+     *
+     * @param  array  $item  Media item with 'path', 'mime_type', 'name', etc.
+     */
+    public function upload(array $item): Response;
+}
diff --git a/src/Plug/Contract/Postable.php b/src/Plug/Contract/Postable.php
new file mode 100644
index 0000000..7a51d29
--- /dev/null
+++ b/src/Plug/Contract/Postable.php
@@ -0,0 +1,23 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Core\Plug\Contract;
+
+use Core\Plug\Response;
+use Illuminate\Support\Collection;
+
+/**
+ * Contract for content publishing operations.
+ */
+interface Postable
+{
+    /**
+     * Publish content to the platform.
+     *
+     * @param  string  $text  Post content
+     * @param  Collection  $media  Media items (may be empty)
+     * @param  array  $params  Platform-specific options
+     */
+    public function publish(string $text, Collection $media, array $params = []): Response;
+}
diff --git a/src/Plug/Contract/Readable.php b/src/Plug/Contract/Readable.php
new file mode 100644
index 0000000..6289071
--- /dev/null
+++ b/src/Plug/Contract/Readable.php
@@ -0,0 +1,25 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Core\Plug\Contract;
+
+use Core\Plug\Response;
+
+/**
+ * Contract for reading posts and content.
+ */
+interface Readable
+{
+    /**
+     * Get a single post by ID.
+     */
+    public function get(string $id): Response;
+
+    /**
+     * Get multiple posts (timeline/feed).
+     *
+     * @param  array  $params  Pagination and filter options
+     */
+    public function list(array $params = []): Response;
+}
diff --git a/src/Plug/Contract/Refreshable.php b/src/Plug/Contract/Refreshable.php
new file mode 100644
index 0000000..326f2ee
--- /dev/null
+++ b/src/Plug/Contract/Refreshable.php
@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Core\Plug\Contract;
+
+use Core\Plug\Response;
+
+/**
+ * Contract for token refresh operations.
+ */
+interface Refreshable
+{
+    /**
+     * Refresh an expired access token.
+     *
+     * @return Response Contains new token data on success
+     */
+    public function refresh(): Response;
+}
diff --git a/src/Plug/Registry.php b/src/Plug/Registry.php
index 67ba112..0561496 100644
--- a/src/Plug/Registry.php
+++ b/src/Plug/Registry.php
@@ -67,6 +67,21 @@ class Registry
         $this->discovered = true;
     }
 
+    /**
+     * Register a provider programmatically.
+     *
+     * Used by plug packages to self-register without filesystem scanning.
+     */
+    public function register(string $identifier, string $category, string $name, string $namespace): void
+    {
+        $this->providers[$identifier] = [
+            'category' => $category,
+            'name' => $name,
+            'namespace' => $namespace,
+            'path' => null,
+        ];
+    }
+
     /**
      * Get all registered provider identifiers.
      *