diff --git a/includes/Models/Contact.php b/includes/Models/Contact.php
new file mode 100644
index 0000000..994b767
--- /dev/null
+++ b/includes/Models/Contact.php
@@ -0,0 +1,191 @@
+<?php
+
+namespace Escalated\Models;
+
+use Escalated\Escalated;
+
+/**
+ * First-class identity for guest requesters (Pattern B).
+ *
+ * Deduped by email (unique index, case-insensitively normalized
+ * before write). Links to a WordPress user via `user_id` once the
+ * guest accepts a signup invite.
+ *
+ * Coexists with the inline `guest_name` / `guest_email` /
+ * `guest_token` columns on Ticket for backwards compatibility —
+ * a follow-up pass backfills `contact_id` from `guest_email`.
+ * New code should resolve contacts via
+ * {@see Contact::find_or_create_by_email}.
+ *
+ * @see https://github.com/escalated-dev/escalated-nestjs/pull/17 reference impl
+ */
+class Contact
+{
+    /**
+     * @return string
+     */
+    public static function table()
+    {
+        return Escalated::table('contacts');
+    }
+
+    /**
+     * Canonical email normalization: trim + lowercase. Always call
+     * on any caller-supplied email before inserting or looking up.
+     *
+     * @param  string|null  $email
+     * @return string
+     */
+    public static function normalize_email($email)
+    {
+        if (! is_string($email)) {
+            return '';
+        }
+
+        return strtolower(trim($email));
+    }
+
+    /**
+     * Decide what {@see find_or_create_by_email} should do given the
+     * lookup result and incoming name. Pure function — testable
+     * without touching the database.
+     *
+     * @param  object|null  $existing  Row from wpdb->get_row or null
+     * @param  string|null  $incoming_name
+     * @return string One of 'create', 'update-name', 'return-existing'
+     */
+    public static function decide_action($existing, $incoming_name)
+    {
+        if ($existing === null) {
+            return 'create';
+        }
+        $existing_name = isset($existing->name) ? $existing->name : null;
+        if ((is_null($existing_name) || $existing_name === '') && ! empty($incoming_name)) {
+            return 'update-name';
+        }
+
+        return 'return-existing';
+    }
+
+    /**
+     * @param  int  $id
+     * @return object|null
+     */
+    public static function find($id)
+    {
+        global $wpdb;
+        $table = static::table();
+
+        return $wpdb->get_row(
+            $wpdb->prepare("SELECT * FROM {$table} WHERE id = %d", $id)
+        );
+    }
+
+    /**
+     * @param  string  $email
+     * @return object|null
+     */
+    public static function find_by_email($email)
+    {
+        global $wpdb;
+        $table = static::table();
+        $normalized = static::normalize_email($email);
+        if ($normalized === '') {
+            return null;
+        }
+
+        return $wpdb->get_row(
+            $wpdb->prepare("SELECT * FROM {$table} WHERE email = %s", $normalized)
+        );
+    }
+
+    /**
+     * Dedupe-on-write: returns the existing Contact row for a
+     * previously-seen email, or creates a new one. If the existing
+     * row has a blank name and a non-blank name is supplied,
+     * the existing row is updated in place.
+     *
+     * @param  string  $email
+     * @param  string|null  $name
+     * @return object Row from wpdb->get_row
+     */
+    public static function find_or_create_by_email($email, $name = null)
+    {
+        global $wpdb;
+        $table = static::table();
+        $normalized = static::normalize_email($email);
+
+        $existing = static::find_by_email($normalized);
+        $action = static::decide_action($existing, $name);
+
+        if ($action === 'return-existing') {
+            return $existing;
+        }
+
+        $now = current_time('mysql');
+
+        if ($action === 'update-name') {
+            $wpdb->update(
+                $table,
+                ['name' => $name, 'updated_at' => $now],
+                ['id' => $existing->id]
+            );
+
+            return static::find($existing->id);
+        }
+
+        // action === 'create'
+        $wpdb->insert($table, [
+            'email' => $normalized,
+            'name' => $name ?: null,
+            'user_id' => null,
+            'metadata' => wp_json_encode(new \stdClass),
+            'created_at' => $now,
+            'updated_at' => $now,
+        ]);
+
+        return static::find((int) $wpdb->insert_id);
+    }
+
+    /**
+     * Link a Contact to a WP user id.
+     *
+     * @param  int  $contact_id
+     * @param  int  $user_id
+     * @return object|null
+     */
+    public static function link_to_user($contact_id, $user_id)
+    {
+        global $wpdb;
+        $table = static::table();
+        $wpdb->update(
+            $table,
+            ['user_id' => $user_id, 'updated_at' => current_time('mysql')],
+            ['id' => $contact_id]
+        );
+
+        return static::find($contact_id);
+    }
+
+    /**
+     * Link + back-stamp requester_id on all prior tickets owned
+     * by this contact. Called when a guest accepts the signup invite.
+     *
+     * @param  int  $contact_id
+     * @param  int  $user_id
+     * @return object|null
+     */
+    public static function promote_to_user($contact_id, $user_id)
+    {
+        global $wpdb;
+        $contact = static::link_to_user($contact_id, $user_id);
+        $tickets_table = Ticket::table();
+        $wpdb->update(
+            $tickets_table,
+            ['requester_id' => $user_id, 'updated_at' => current_time('mysql')],
+            ['contact_id' => $contact_id]
+        );
+
+        return $contact;
+    }
+}
diff --git a/includes/Services/TicketService.php b/includes/Services/TicketService.php
index 37a625b..8a67de6 100644
--- a/includes/Services/TicketService.php
+++ b/includes/Services/TicketService.php
@@ -70,6 +70,22 @@ public function create_guest(array $data): object
         $priority = $data['priority'] ?? \Escalated\Models\Setting::get('default_priority', 'medium');
         $valid_priorities = array_keys(\Escalated\Helpers\Enums::ticket_priorities());
 
+        $guest_email = sanitize_email($data['guest_email'] ?? '');
+        $guest_name = sanitize_text_field($data['guest_name'] ?? '');
+
+        // Dedupe repeat guests by email (Pattern B). Inline guest_* fields
+        // remain populated for the backwards-compat dual-read period.
+        $contact_id = null;
+        if (! empty($guest_email)) {
+            $contact = \Escalated\Models\Contact::find_or_create_by_email(
+                $guest_email,
+                $guest_name ?: null
+            );
+            if ($contact && isset($contact->id)) {
+                $contact_id = (int) $contact->id;
+            }
+        }
+
         $ticket_data = [
             'reference' => $reference,
             'requester_id' => null,
@@ -80,9 +96,10 @@ public function create_guest(array $data): object
             'ticket_type' => in_array($data['ticket_type'] ?? '', ['question', 'problem', 'incident', 'task'], true) ? $data['ticket_type'] : 'question',
             'channel' => sanitize_text_field($data['channel'] ?? 'web'),
             'department_id' => ! empty($data['department_id']) ? absint($data['department_id']) : null,
-            'guest_name' => sanitize_text_field($data['guest_name'] ?? ''),
-            'guest_email' => sanitize_email($data['guest_email'] ?? ''),
+            'guest_name' => $guest_name,
+            'guest_email' => $guest_email,
             'guest_token' => wp_generate_password(64, false),
+            'contact_id' => $contact_id,
             'created_at' => $now,
             'updated_at' => $now,
         ];
diff --git a/includes/class-activator.php b/includes/class-activator.php
index c7ffa64..c308380 100644
--- a/includes/class-activator.php
+++ b/includes/class-activator.php
@@ -98,12 +98,30 @@ private static function create_tables(): void
             guest_name VARCHAR(255) NULL,
             guest_email VARCHAR(255) NULL,
             guest_token VARCHAR(64) NULL,
+            contact_id BIGINT UNSIGNED NULL,
             created_at DATETIME,
             updated_at DATETIME,
             deleted_at DATETIME NULL,
             PRIMARY KEY  (id),
             UNIQUE KEY reference (reference),
-            UNIQUE KEY guest_token (guest_token)
+            UNIQUE KEY guest_token (guest_token),
+            KEY contact_id (contact_id)
+        ) $charset_collate;";
+        dbDelta($sql);
+
+        // 4b. escalated_contacts (Pattern B convergence — first-class
+        // identity for guest requesters, deduped by email).
+        $sql = "CREATE TABLE {$prefix}contacts (
+            id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
+            email VARCHAR(320) NOT NULL,
+            name VARCHAR(255) NULL,
+            user_id BIGINT UNSIGNED NULL,
+            metadata TEXT NULL,
+            created_at DATETIME NOT NULL,
+            updated_at DATETIME NOT NULL,
+            PRIMARY KEY  (id),
+            UNIQUE KEY email (email),
+            KEY user_id (user_id)
         ) $charset_collate;";
         dbDelta($sql);
 
diff --git a/tests/Test_Contact_Model.php b/tests/Test_Contact_Model.php
new file mode 100644
index 0000000..c7fe596
--- /dev/null
+++ b/tests/Test_Contact_Model.php
@@ -0,0 +1,99 @@
+<?php
+
+/**
+ * Tests for the Contact model (Pattern B public-ticket dedupe).
+ *
+ * Pure-function tests for normalize_email / decide_action; the
+ * find_or_create_by_email flow is exercised via a live wpdb
+ * (the test suite's SQLite/mysql harness).
+ */
+
+use Escalated\Models\Contact;
+
+class Test_Contact_Model extends WP_UnitTestCase
+{
+    // ---------------------------------------------------------------------
+    // normalize_email
+    // ---------------------------------------------------------------------
+
+    public function test_normalize_email_lowercases()
+    {
+        $this->assertEquals('alice@example.com', Contact::normalize_email('ALICE@Example.COM'));
+    }
+
+    public function test_normalize_email_trims_whitespace()
+    {
+        $this->assertEquals('alice@example.com', Contact::normalize_email('  alice@example.com  '));
+    }
+
+    public function test_normalize_email_handles_null_and_non_string()
+    {
+        $this->assertEquals('', Contact::normalize_email(null));
+        $this->assertEquals('', Contact::normalize_email(123));
+    }
+
+    // ---------------------------------------------------------------------
+    // decide_action
+    // ---------------------------------------------------------------------
+
+    public function test_decide_action_create_when_no_existing()
+    {
+        $this->assertEquals('create', Contact::decide_action(null, 'Alice'));
+    }
+
+    public function test_decide_action_return_existing_when_existing_has_name()
+    {
+        $existing = (object) ['name' => 'Alice'];
+        $this->assertEquals('return-existing', Contact::decide_action($existing, 'Different'));
+    }
+
+    public function test_decide_action_update_name_when_existing_name_is_blank()
+    {
+        $existing = (object) ['name' => null];
+        $this->assertEquals('update-name', Contact::decide_action($existing, 'Alice'));
+
+        $existing->name = '';
+        $this->assertEquals('update-name', Contact::decide_action($existing, 'Alice'));
+    }
+
+    public function test_decide_action_return_existing_when_no_incoming_name()
+    {
+        $existing = (object) ['name' => null];
+        $this->assertEquals('return-existing', Contact::decide_action($existing, null));
+        $this->assertEquals('return-existing', Contact::decide_action($existing, ''));
+    }
+
+    // -----------------------------------------------------------------
+    // Wire-up: TicketService::create_guest sets contact_id
+    // -----------------------------------------------------------------
+
+    public function test_create_guest_dedupes_contacts_by_email()
+    {
+        $service = new \Escalated\Services\TicketService;
+
+        $t1 = $service->create_guest([
+            'subject' => 'First',
+            'description' => 'body',
+            'guest_name' => 'Alice',
+            'guest_email' => 'alice@example.com',
+            'channel' => 'web',
+        ]);
+        $t2 = $service->create_guest([
+            'subject' => 'Second',
+            'description' => 'body',
+            'guest_name' => 'Alice',
+            'guest_email' => 'ALICE@Example.COM', // casing variant
+            'channel' => 'web',
+        ]);
+
+        global $wpdb;
+        $contacts_table = Contact::table();
+        $count = (int) $wpdb->get_var(
+            $wpdb->prepare("SELECT COUNT(*) FROM {$contacts_table} WHERE email = %s", 'alice@example.com')
+        );
+        $this->assertEquals(1, $count, 'repeat submissions should dedupe to one Contact row');
+        $this->assertNotNull($t1->contact_id);
+        $this->assertNotNull($t2->contact_id);
+        $this->assertEquals((int) $t1->contact_id, (int) $t2->contact_id);
+    }
+}