diff --git a/data-machine.php b/data-machine.php
index bd1faf68..a88f0845 100644
--- a/data-machine.php
+++ b/data-machine.php
@@ -345,9 +345,11 @@ function datamachine_activate_plugin( $network_wide = false ) {
 function datamachine_activate_for_site() {
 	$db_pipelines = new \DataMachine\Core\Database\Pipelines\Pipelines();
 	$db_pipelines->create_table();
+	$db_pipelines->migrate_columns();
 
 	$db_flows = new \DataMachine\Core\Database\Flows\Flows();
 	$db_flows->create_table();
+	$db_flows->migrate_columns();
 
 	$db_jobs = new \DataMachine\Core\Database\Jobs\Jobs();
 	$db_jobs->create_table();
diff --git a/inc/Core/Database/Flows/Flows.php b/inc/Core/Database/Flows/Flows.php
index 1ffc2596..d4c07159 100644
--- a/inc/Core/Database/Flows/Flows.php
+++ b/inc/Core/Database/Flows/Flows.php
@@ -26,11 +26,13 @@ public static function create_table(): void {
 		$sql = "CREATE TABLE $table_name (
             flow_id bigint(20) unsigned NOT NULL AUTO_INCREMENT,
             pipeline_id bigint(20) unsigned NOT NULL,
+            user_id bigint(20) unsigned NOT NULL DEFAULT 0,
             flow_name varchar(255) NOT NULL,
             flow_config longtext NOT NULL,
             scheduling_config longtext NOT NULL,
             PRIMARY KEY (flow_id),
-            KEY pipeline_id (pipeline_id)
+            KEY pipeline_id (pipeline_id),
+            KEY user_id (user_id)
         ) $charset_collate;";
 
 		require_once ABSPATH . 'wp-admin/includes/upgrade.php';
@@ -48,6 +50,57 @@ public static function create_table(): void {
 		);
 	}
 
+	/**
+	 * Migrate existing table columns to current schema.
+	 *
+	 * Handles:
+	 * - user_id column: added for multi-agent support
+	 *
+	 * Safe to run multiple times - only executes if columns need updating.
+	 */
+	public function migrate_columns(): void {
+		// Check if user_id column already exists.
+		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery
+		$column = $this->wpdb->get_var(
+			$this->wpdb->prepare(
+				"SELECT COLUMN_NAME
+				 FROM information_schema.COLUMNS
+				 WHERE TABLE_SCHEMA = %s AND TABLE_NAME = %s AND COLUMN_NAME = 'user_id'",
+				DB_NAME,
+				$this->table_name
+			)
+		);
+
+		if ( null === $column ) {
+			// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.SchemaChange
+			$result = $this->wpdb->query(
+				"ALTER TABLE {$this->table_name}
+				 ADD COLUMN user_id bigint(20) unsigned NOT NULL DEFAULT 0 AFTER pipeline_id,
+				 ADD KEY user_id (user_id)"
+			);
+
+			if ( false === $result ) {
+				do_action(
+					'datamachine_log',
+					'error',
+					'Failed to add user_id column to flows table',
+					array(
+						'table_name' => $this->table_name,
+						'db_error'   => $this->wpdb->last_error,
+					)
+				);
+				return;
+			}
+
+			do_action(
+				'datamachine_log',
+				'info',
+				'Added user_id column to flows table for multi-agent support',
+				array( 'table_name' => $this->table_name )
+			);
+		}
+	}
+
 	public function create_flow( array $flow_data ) {
 
 		// Validate required fields
@@ -70,8 +123,11 @@ public function create_flow( array $flow_data ) {
 		$flow_config       = wp_json_encode( $flow_data['flow_config'] );
 		$scheduling_config = wp_json_encode( $flow_data['scheduling_config'] );
 
+		$user_id = isset( $flow_data['user_id'] ) ? absint( $flow_data['user_id'] ) : 0;
+
 		$insert_data = array(
 			'pipeline_id'       => intval( $flow_data['pipeline_id'] ),
+			'user_id'           => $user_id,
 			'flow_name'         => sanitize_text_field( $flow_data['flow_name'] ),
 			'flow_config'       => $flow_config,
 			'scheduling_config' => $scheduling_config,
@@ -79,6 +135,7 @@ public function create_flow( array $flow_data ) {
 
 		$insert_format = array(
 			'%d', // pipeline_id
+			'%d', // user_id
 			'%s', // flow_name
 			'%s', // flow_config
 			'%s',  // scheduling_config
@@ -197,14 +254,23 @@ public function get_flows_for_pipeline( int $pipeline_id ): array {
 	 *
 	 * Used for global operations like handler-based filtering across the entire system.
 	 *
+	 * @param int|null $user_id Optional user ID to filter by.
 	 * @return array All flows with decoded configs.
 	 */
-	public function get_all_flows(): array {
-		// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared
-		$flows = $this->wpdb->get_results(
-			$this->wpdb->prepare( 'SELECT * FROM %i ORDER BY pipeline_id ASC, flow_id ASC', $this->table_name ),
-			ARRAY_A
-		);
+	public function get_all_flows( ?int $user_id = null ): array {
+		if ( null !== $user_id ) {
+			// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared
+			$flows = $this->wpdb->get_results(
+				$this->wpdb->prepare( 'SELECT * FROM %i WHERE user_id = %d ORDER BY pipeline_id ASC, flow_id ASC', $this->table_name, $user_id ),
+				ARRAY_A
+			);
+		} else {
+			// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared
+			$flows = $this->wpdb->get_results(
+				$this->wpdb->prepare( 'SELECT * FROM %i ORDER BY pipeline_id ASC, flow_id ASC', $this->table_name ),
+				ARRAY_A
+			);
+		}
 
 		if ( null === $flows ) {
 			return array();
@@ -522,6 +588,9 @@ public function get_flow_scheduling( int $flow_id ): ?array {
 	 * Get flows ready for execution based on scheduling.
 	 *
 	 * Uses jobs table to determine last run time (single source of truth).
+	 *
+	 * Note: No user_id filter here — the scheduler must run ALL users' flows.
+	 * User-scoping happens at the pipeline/flow management level, not execution.
 	 */
 	public function get_flows_ready_for_execution(): array {
 
diff --git a/inc/Core/Database/Jobs/Jobs.php b/inc/Core/Database/Jobs/Jobs.php
index 3f458074..6fd075cb 100644
--- a/inc/Core/Database/Jobs/Jobs.php
+++ b/inc/Core/Database/Jobs/Jobs.php
@@ -127,6 +127,7 @@ public static function create_table() {
 		// status is VARCHAR(255) to support compound statuses with reasons
 		$sql = "CREATE TABLE $table_name (
             job_id bigint(20) unsigned NOT NULL AUTO_INCREMENT,
+            user_id bigint(20) unsigned NOT NULL DEFAULT 0,
             pipeline_id varchar(20) NOT NULL,
             flow_id varchar(20) NOT NULL,
             source varchar(50) NOT NULL DEFAULT 'pipeline',
@@ -141,7 +142,8 @@ public static function create_table() {
             KEY pipeline_id (pipeline_id),
             KEY flow_id (flow_id),
             KEY source (source),
-            KEY parent_job_id (parent_job_id)
+            KEY parent_job_id (parent_job_id),
+            KEY user_id (user_id)
         ) $charset_collate;";
 
 		dbDelta( $sql );
@@ -179,7 +181,7 @@ private static function migrate_columns( string $table_name ): void {
 				"SELECT COLUMN_NAME, DATA_TYPE, CHARACTER_MAXIMUM_LENGTH 
                  FROM information_schema.COLUMNS 
                  WHERE TABLE_SCHEMA = %s AND TABLE_NAME = %s 
-                 AND COLUMN_NAME IN ('status', 'pipeline_id', 'flow_id', 'source', 'parent_job_id')",
+                 AND COLUMN_NAME IN ('status', 'pipeline_id', 'flow_id', 'source', 'parent_job_id', 'user_id')",
 				DB_NAME,
 				$table_name
 			),
@@ -286,5 +288,24 @@ private static function migrate_columns( string $table_name ): void {
 				);
 			}
 		}
+
+		// Add user_id column for multi-agent support.
+		if ( ! isset( $columns['user_id'] ) ) {
+			// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.SchemaChange
+			$result = $wpdb->query(
+				"ALTER TABLE {$table_name}
+				 ADD COLUMN user_id bigint(20) unsigned NOT NULL DEFAULT 0 AFTER job_id,
+				 ADD KEY user_id (user_id)"
+			);
+
+			if ( false !== $result ) {
+				do_action(
+					'datamachine_log',
+					'info',
+					'Added user_id column to jobs table for multi-agent support',
+					array( 'table_name' => $table_name )
+				);
+			}
+		}
 	}
 }
diff --git a/inc/Core/Database/Jobs/JobsOperations.php b/inc/Core/Database/Jobs/JobsOperations.php
index 99121467..d3767540 100644
--- a/inc/Core/Database/Jobs/JobsOperations.php
+++ b/inc/Core/Database/Jobs/JobsOperations.php
@@ -62,16 +62,18 @@ public function create_job( array $job_data ): int|false {
 		$label = isset( $job_data['label'] ) ? sanitize_text_field( $job_data['label'] ) : null;
 
 		$parent_job_id = isset( $job_data['parent_job_id'] ) ? absint( $job_data['parent_job_id'] ) : 0;
+		$user_id       = isset( $job_data['user_id'] ) ? absint( $job_data['user_id'] ) : 0;
 
 		$data = array(
 			'pipeline_id' => $pipeline_id,
 			'flow_id'     => $flow_id,
+			'user_id'     => $user_id,
 			'source'      => $source,
 			'label'       => $label,
 			'status'      => 'pending',
 		);
 
-		$format = array( '%s', '%s', '%s', '%s', '%s' );
+		$format = array( '%s', '%s', '%d', '%s', '%s', '%s' );
 
 		if ( $parent_job_id > 0 ) {
 			$data['parent_job_id'] = $parent_job_id;
@@ -153,6 +155,11 @@ public function get_jobs_count( array $args = array() ): int {
 			$where_values[]  = sanitize_text_field( $args['source'] );
 		}
 
+		if ( isset( $args['user_id'] ) ) {
+			$where_clauses[] = 'user_id = %d';
+			$where_values[]  = absint( $args['user_id'] );
+		}
+
 		if ( ! empty( $args['since'] ) ) {
 			$where_clauses[] = 'created_at >= %s';
 			$where_values[]  = sanitize_text_field( $args['since'] );
@@ -244,6 +251,11 @@ public function get_jobs_for_list_table( array $args ): array {
 			$where_values[]  = sanitize_text_field( $args['source'] );
 		}
 
+		if ( isset( $args['user_id'] ) ) {
+			$where_clauses[] = 'j.user_id = %d';
+			$where_values[]  = absint( $args['user_id'] );
+		}
+
 		if ( ! empty( $args['since'] ) ) {
 			$where_clauses[] = 'j.created_at >= %s';
 			$where_values[]  = sanitize_text_field( $args['since'] );
diff --git a/inc/Core/Database/Pipelines/Pipelines.php b/inc/Core/Database/Pipelines/Pipelines.php
index 9d59bdee..29a52278 100644
--- a/inc/Core/Database/Pipelines/Pipelines.php
+++ b/inc/Core/Database/Pipelines/Pipelines.php
@@ -39,15 +39,17 @@ public function create_pipeline( array $pipeline_data ): int|false {
 		$pipeline_name        = sanitize_text_field( $pipeline_data['pipeline_name'] );
 		$pipeline_config      = $pipeline_data['pipeline_config'] ?? array();
 		$pipeline_config_json = wp_json_encode( $pipeline_config );
+		$user_id              = isset( $pipeline_data['user_id'] ) ? absint( $pipeline_data['user_id'] ) : 0;
 
 		$data = array(
+			'user_id'         => $user_id,
 			'pipeline_name'   => $pipeline_name,
 			'pipeline_config' => $pipeline_config_json,
 			'created_at'      => current_time( 'mysql', true ),
 			'updated_at'      => current_time( 'mysql', true ),
 		);
 
-		$format = array( '%s', '%s', '%s', '%s' );
+		$format = array( '%d', '%s', '%s', '%s', '%s' );
 
 		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
 		$inserted = $this->wpdb->insert( $this->table_name, $data, $format );
@@ -104,11 +106,17 @@ public function get_pipeline( int $pipeline_id ): ?array {
 	/**
 	 * Get all pipelines from the database.
 	 *
+	 * @param int|null $user_id Optional user ID to filter by.
 	 * @return array Array of all pipeline records
 	 */
-	public function get_all_pipelines(): array {
-		// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared
-		$results = $this->wpdb->get_results( $this->wpdb->prepare( 'SELECT * FROM %i ORDER BY updated_at DESC', $this->table_name ), ARRAY_A );
+	public function get_all_pipelines( ?int $user_id = null ): array {
+		if ( null !== $user_id ) {
+			// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared
+			$results = $this->wpdb->get_results( $this->wpdb->prepare( 'SELECT * FROM %i WHERE user_id = %d ORDER BY updated_at DESC', $this->table_name, $user_id ), ARRAY_A );
+		} else {
+			// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared
+			$results = $this->wpdb->get_results( $this->wpdb->prepare( 'SELECT * FROM %i ORDER BY updated_at DESC', $this->table_name ), ARRAY_A );
+		}
 
 		foreach ( $results as &$pipeline ) {
 			if ( ! empty( $pipeline['pipeline_config'] ) ) {
@@ -121,10 +129,17 @@ public function get_all_pipelines(): array {
 
 	/**
 	 * Get lightweight pipelines list for UI dropdowns.
+	 *
+	 * @param int|null $user_id Optional user ID to filter by.
 	 */
-	public function get_pipelines_list(): array {
-		// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared
-		$results = $this->wpdb->get_results( $this->wpdb->prepare( 'SELECT pipeline_id, pipeline_name FROM %i ORDER BY pipeline_name ASC', $this->table_name ), ARRAY_A );
+	public function get_pipelines_list( ?int $user_id = null ): array {
+		if ( null !== $user_id ) {
+			// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared
+			$results = $this->wpdb->get_results( $this->wpdb->prepare( 'SELECT pipeline_id, pipeline_name FROM %i WHERE user_id = %d ORDER BY pipeline_name ASC', $this->table_name, $user_id ), ARRAY_A );
+		} else {
+			// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared
+			$results = $this->wpdb->get_results( $this->wpdb->prepare( 'SELECT pipeline_id, pipeline_name FROM %i ORDER BY pipeline_name ASC', $this->table_name ), ARRAY_A );
+		}
 
 		return $results ? $results : array();
 	}
@@ -324,10 +339,17 @@ public function get_pipeline_config( int $pipeline_id ): array {
 
 	/**
 	 * Get pipeline count.
+	 *
+	 * @param int|null $user_id Optional user ID to filter by.
 	 */
-	public function get_pipelines_count(): int {
-		// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared
-		$count = $this->wpdb->get_var( $this->wpdb->prepare( 'SELECT COUNT(pipeline_id) FROM %i', $this->table_name ) );
+	public function get_pipelines_count( ?int $user_id = null ): int {
+		if ( null !== $user_id ) {
+			// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared
+			$count = $this->wpdb->get_var( $this->wpdb->prepare( 'SELECT COUNT(pipeline_id) FROM %i WHERE user_id = %d', $this->table_name, $user_id ) );
+		} else {
+			// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared
+			$count = $this->wpdb->get_var( $this->wpdb->prepare( 'SELECT COUNT(pipeline_id) FROM %i', $this->table_name ) );
+		}
 
 		return (int) $count;
 	}
@@ -341,22 +363,28 @@ public function get_pipelines_for_list_table( array $args ): array {
 		$order    = strtoupper( $args['order'] ?? 'DESC' );
 		$per_page = (int) ( $args['per_page'] ?? 20 );
 		$offset   = (int) ( $args['offset'] ?? 0 );
+		$user_id  = isset( $args['user_id'] ) ? absint( $args['user_id'] ) : null;
 		$is_asc   = ( 'ASC' === $order );
 
+		$where = '';
+		if ( null !== $user_id ) {
+			$where = $this->wpdb->prepare( ' WHERE user_id = %d', $user_id );
+		}
+
 		// phpcs:disable WordPress.DB.DirectDatabaseQuery,WordPress.DB.PreparedSQL
 		$results = match ( $orderby ) {
 			'pipeline_name' => $is_asc
-				? $this->wpdb->get_results( $this->wpdb->prepare( 'SELECT * FROM %i ORDER BY pipeline_name ASC LIMIT %d OFFSET %d', $this->table_name, $per_page, $offset ), ARRAY_A )
-				: $this->wpdb->get_results( $this->wpdb->prepare( 'SELECT * FROM %i ORDER BY pipeline_name DESC LIMIT %d OFFSET %d', $this->table_name, $per_page, $offset ), ARRAY_A ),
+				? $this->wpdb->get_results( $this->wpdb->prepare( "SELECT * FROM %i{$where} ORDER BY pipeline_name ASC LIMIT %d OFFSET %d", $this->table_name, $per_page, $offset ), ARRAY_A )
+				: $this->wpdb->get_results( $this->wpdb->prepare( "SELECT * FROM %i{$where} ORDER BY pipeline_name DESC LIMIT %d OFFSET %d", $this->table_name, $per_page, $offset ), ARRAY_A ),
 			'created_at' => $is_asc
-				? $this->wpdb->get_results( $this->wpdb->prepare( 'SELECT * FROM %i ORDER BY created_at ASC LIMIT %d OFFSET %d', $this->table_name, $per_page, $offset ), ARRAY_A )
-				: $this->wpdb->get_results( $this->wpdb->prepare( 'SELECT * FROM %i ORDER BY created_at DESC LIMIT %d OFFSET %d', $this->table_name, $per_page, $offset ), ARRAY_A ),
+				? $this->wpdb->get_results( $this->wpdb->prepare( "SELECT * FROM %i{$where} ORDER BY created_at ASC LIMIT %d OFFSET %d", $this->table_name, $per_page, $offset ), ARRAY_A )
+				: $this->wpdb->get_results( $this->wpdb->prepare( "SELECT * FROM %i{$where} ORDER BY created_at DESC LIMIT %d OFFSET %d", $this->table_name, $per_page, $offset ), ARRAY_A ),
 			'updated_at' => $is_asc
-				? $this->wpdb->get_results( $this->wpdb->prepare( 'SELECT * FROM %i ORDER BY updated_at ASC LIMIT %d OFFSET %d', $this->table_name, $per_page, $offset ), ARRAY_A )
-				: $this->wpdb->get_results( $this->wpdb->prepare( 'SELECT * FROM %i ORDER BY updated_at DESC LIMIT %d OFFSET %d', $this->table_name, $per_page, $offset ), ARRAY_A ),
+				? $this->wpdb->get_results( $this->wpdb->prepare( "SELECT * FROM %i{$where} ORDER BY updated_at ASC LIMIT %d OFFSET %d", $this->table_name, $per_page, $offset ), ARRAY_A )
+				: $this->wpdb->get_results( $this->wpdb->prepare( "SELECT * FROM %i{$where} ORDER BY updated_at DESC LIMIT %d OFFSET %d", $this->table_name, $per_page, $offset ), ARRAY_A ),
 			default => $is_asc
-				? $this->wpdb->get_results( $this->wpdb->prepare( 'SELECT * FROM %i ORDER BY pipeline_id ASC LIMIT %d OFFSET %d', $this->table_name, $per_page, $offset ), ARRAY_A )
-				: $this->wpdb->get_results( $this->wpdb->prepare( 'SELECT * FROM %i ORDER BY pipeline_id DESC LIMIT %d OFFSET %d', $this->table_name, $per_page, $offset ), ARRAY_A ),
+				? $this->wpdb->get_results( $this->wpdb->prepare( "SELECT * FROM %i{$where} ORDER BY pipeline_id ASC LIMIT %d OFFSET %d", $this->table_name, $per_page, $offset ), ARRAY_A )
+				: $this->wpdb->get_results( $this->wpdb->prepare( "SELECT * FROM %i{$where} ORDER BY pipeline_id DESC LIMIT %d OFFSET %d", $this->table_name, $per_page, $offset ), ARRAY_A ),
 		};
 		// phpcs:enable WordPress.DB.DirectDatabaseQuery,WordPress.DB.PreparedSQL
 
@@ -470,6 +498,57 @@ public function get_pipeline_step_config( string $pipeline_step_id ): array {
 		return $step_config;
 	}
 
+	/**
+	 * Migrate existing table columns to current schema.
+	 *
+	 * Handles:
+	 * - user_id column: added for multi-agent support
+	 *
+	 * Safe to run multiple times - only executes if columns need updating.
+	 */
+	public function migrate_columns(): void {
+		// Check if user_id column already exists.
+		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery
+		$column = $this->wpdb->get_var(
+			$this->wpdb->prepare(
+				"SELECT COLUMN_NAME
+				 FROM information_schema.COLUMNS
+				 WHERE TABLE_SCHEMA = %s AND TABLE_NAME = %s AND COLUMN_NAME = 'user_id'",
+				DB_NAME,
+				$this->table_name
+			)
+		);
+
+		if ( null === $column ) {
+			// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.SchemaChange
+			$result = $this->wpdb->query(
+				"ALTER TABLE {$this->table_name}
+				 ADD COLUMN user_id bigint(20) unsigned NOT NULL DEFAULT 0 AFTER pipeline_id,
+				 ADD KEY user_id (user_id)"
+			);
+
+			if ( false === $result ) {
+				do_action(
+					'datamachine_log',
+					'error',
+					'Failed to add user_id column to pipelines table',
+					array(
+						'table_name' => $this->table_name,
+						'db_error'   => $this->wpdb->last_error,
+					)
+				);
+				return;
+			}
+
+			do_action(
+				'datamachine_log',
+				'info',
+				'Added user_id column to pipelines table for multi-agent support',
+				array( 'table_name' => $this->table_name )
+			);
+		}
+	}
+
 	public static function create_table() {
 		global $wpdb;
 		$table_name      = $wpdb->prefix . 'datamachine_pipelines';
@@ -480,11 +559,13 @@ public static function create_table() {
 
 		$sql = "CREATE TABLE $table_name (
 			pipeline_id bigint(20) unsigned NOT NULL AUTO_INCREMENT,
+			user_id bigint(20) unsigned NOT NULL DEFAULT 0,
 			pipeline_name varchar(255) NOT NULL,
 			pipeline_config longtext NULL,
 			created_at datetime NOT NULL DEFAULT CURRENT_TIMESTAMP,
 			updated_at datetime NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
 			PRIMARY KEY  (pipeline_id),
+			KEY user_id (user_id),
 			KEY pipeline_name (pipeline_name),
 			KEY created_at (created_at),
 			KEY updated_at (updated_at)
diff --git a/inc/Core/FilesRepository/AgentMemory.php b/inc/Core/FilesRepository/AgentMemory.php
index 29fe5bf4..e2584efe 100644
--- a/inc/Core/FilesRepository/AgentMemory.php
+++ b/inc/Core/FilesRepository/AgentMemory.php
@@ -35,9 +35,23 @@ class AgentMemory {
 	 */
 	private string $file_path;
 
-	public function __construct() {
+	/**
+	 * WordPress user ID for per-agent partitioning. 0 = legacy shared directory.
+	 *
+	 * @since 0.37.0
+	 * @var int
+	 */
+	private int $user_id;
+
+	/**
+	 * @since 0.37.0 Added $user_id parameter for multi-agent partitioning.
+	 *
+	 * @param int $user_id WordPress user ID. 0 = legacy shared directory.
+	 */
+	public function __construct( int $user_id = 0 ) {
+		$this->user_id           = $user_id;
 		$this->directory_manager = new DirectoryManager();
-		$agent_dir               = $this->directory_manager->get_agent_directory();
+		$agent_dir               = $this->directory_manager->get_agent_directory( $user_id );
 		$this->file_path         = "{$agent_dir}/MEMORY.md";
 
 		// Self-heal: ensure agent files exist on first use.
@@ -375,7 +389,7 @@ private function replace_section_content( string $file_content, array $position,
 	 * so a recreated MEMORY.md includes the standard sections.
 	 */
 	private function ensure_file_exists(): void {
-		$this->directory_manager->ensure_agent_directory_writable();
+		$this->directory_manager->ensure_agent_directory_writable( $this->user_id );
 
 		if ( ! file_exists( $this->file_path ) ) {
 			$content = "# Agent Memory\n";
diff --git a/inc/Core/FilesRepository/DailyMemory.php b/inc/Core/FilesRepository/DailyMemory.php
index 031b313f..aef96e22 100644
--- a/inc/Core/FilesRepository/DailyMemory.php
+++ b/inc/Core/FilesRepository/DailyMemory.php
@@ -31,9 +31,14 @@ class DailyMemory {
 	 */
 	private string $base_path;
 
-	public function __construct() {
+	/**
+	 * @since 0.37.0 Added $user_id parameter for multi-agent partitioning.
+	 *
+	 * @param int $user_id WordPress user ID. 0 = legacy shared directory.
+	 */
+	public function __construct( int $user_id = 0 ) {
 		$this->directory_manager = new DirectoryManager();
-		$agent_dir               = $this->directory_manager->get_agent_directory();
+		$agent_dir               = $this->directory_manager->get_agent_directory( $user_id );
 		$this->base_path         = "{$agent_dir}/daily";
 	}
 
diff --git a/inc/Core/FilesRepository/DirectoryManager.php b/inc/Core/FilesRepository/DirectoryManager.php
index ae6fc717..a23ae824 100644
--- a/inc/Core/FilesRepository/DirectoryManager.php
+++ b/inc/Core/FilesRepository/DirectoryManager.php
@@ -128,16 +128,60 @@ public function get_pipeline_context_directory( int|string $pipeline_id, string
 	}
 
 	/**
-	 * Get agent directory path
+	 * Get agent directory path.
 	 *
-	 * @return string Full path to agent directory
+	 * When a user_id is provided, returns the per-agent subdirectory
+	 * ({base}/agent/{user_id}). When user_id is 0, returns the legacy
+	 * shared directory ({base}/agent) for backward compatibility.
+	 *
+	 * @since 0.37.0 Added $user_id parameter for multi-agent partitioning.
+	 *
+	 * @param int $user_id WordPress user ID. 0 = legacy shared directory.
+	 * @return string Full path to agent directory.
 	 */
-	public function get_agent_directory(): string {
+	public function get_agent_directory( int $user_id = 0 ): string {
 		$upload_dir = wp_upload_dir();
 		$base       = trailingslashit( $upload_dir['basedir'] ) . self::REPOSITORY_DIR;
+
+		if ( 0 < $user_id ) {
+			return "{$base}/agent/{$user_id}";
+		}
+
 		return "{$base}/agent";
 	}
 
+	/**
+	 * Get the default agent user ID.
+	 *
+	 * For single-agent installs, returns the configured default or the first admin user.
+	 *
+	 * @since 0.37.0
+	 * @return int Default agent user ID.
+	 */
+	public static function get_default_agent_user_id(): int {
+		if ( defined( 'DATAMACHINE_DEFAULT_AGENT_USER' ) ) {
+			return absint( DATAMACHINE_DEFAULT_AGENT_USER );
+		}
+
+		// Cache in a static to avoid repeated DB queries.
+		static $default_id = null;
+		if ( null !== $default_id ) {
+			return $default_id;
+		}
+
+		// First admin user.
+		$admins = get_users( array(
+			'role'    => 'administrator',
+			'number'  => 1,
+			'orderby' => 'ID',
+			'order'   => 'ASC',
+			'fields'  => 'ID',
+		) );
+
+		$default_id = ! empty( $admins ) ? absint( $admins[0] ) : 1;
+		return $default_id;
+	}
+
 	/**
 	 * Get workspace directory path.
 	 *
@@ -214,10 +258,13 @@ public function ensure_directory_exists( string $directory ): bool {
 	 * directory and its parent (datamachine-files/).
 	 *
 	 * @since 0.32.0
+	 * @since 0.37.0 Added $user_id parameter for multi-agent partitioning.
+	 *
+	 * @param int $user_id WordPress user ID. 0 = legacy shared directory.
 	 * @return bool True if directory exists and permissions were set.
 	 */
-	public function ensure_agent_directory_writable(): bool {
-		$agent_dir = $this->get_agent_directory();
+	public function ensure_agent_directory_writable( int $user_id = 0 ): bool {
+		$agent_dir = $this->get_agent_directory( $user_id );
 
 		if ( ! $this->ensure_directory_exists( $agent_dir ) ) {
 			return false;
diff --git a/inc/Engine/AI/Directives/CoreMemoryFilesDirective.php b/inc/Engine/AI/Directives/CoreMemoryFilesDirective.php
index 9e1de329..7e9fd15e 100644
--- a/inc/Engine/AI/Directives/CoreMemoryFilesDirective.php
+++ b/inc/Engine/AI/Directives/CoreMemoryFilesDirective.php
@@ -49,6 +49,7 @@ public static function get_outputs( string $provider_name, array $tools, ?string
 		DirectoryManager::ensure_agent_files();
 
 		$directory_manager = new DirectoryManager();
+		// TODO: Multi-agent Phase 2 — resolve user_id from execution context (#565).
 		$agent_dir         = $directory_manager->get_agent_directory();
 		$outputs           = array();
 
diff --git a/inc/Engine/AI/Directives/MemoryFilesReader.php b/inc/Engine/AI/Directives/MemoryFilesReader.php
index 47dc4eda..665aab7d 100644
--- a/inc/Engine/AI/Directives/MemoryFilesReader.php
+++ b/inc/Engine/AI/Directives/MemoryFilesReader.php
@@ -31,6 +31,7 @@ public static function read( array $memory_files, string $scope_label, int $scop
 		}
 
 		$directory_manager = new DirectoryManager();
+		// TODO: Multi-agent Phase 2 — resolve user_id from execution context (#565).
 		$agent_dir         = $directory_manager->get_agent_directory();
 		$outputs           = array();