diff --git a/api/menu_api.c b/api/menu_api.c
index e84744d..4e22cb8 100644
--- a/api/menu_api.c
+++ b/api/menu_api.c
@@ -58,6 +58,36 @@ MenuNodeId menu_register_node_ex(
     return 0;
 }
 
+MenuErrCode menu_register_nodes(
+    const MenuNode* nodes,
+    size_t count,
+    MenuNodeId* out_ids
+) {
+    if (!nodes || count == 0) return MENU_ERR_INVALID_PARAM;
+    
+    for (size_t i = 0; i < count; i++) {
+        MenuNode node = nodes[i];
+        MenuNodeId new_id = 0;
+        
+        node.flags.is_enabled = true;
+        node.flags.is_visible = true;
+        node.flags.is_registered = false;
+        node.param_id = node.param_id ? node.param_id : 0;
+        node.permission_level = node.permission_level ? node.permission_level : 0;
+        
+        MenuErrCode err = menu_core_register_node(&g_menu_ctx, &node, &new_id);
+        if (err != MENU_ERR_OK) {
+            return err;
+        }
+        
+        if (out_ids) {
+            out_ids[i] = new_id;
+        }
+    }
+    
+    return MENU_ERR_OK;
+}
+
 MenuErrCode menu_post_event(MenuEventType type, uint32_t param) {
     return menu_event_post(&g_menu_ctx.event_queue, type, param);
 }
@@ -113,3 +143,74 @@ MenuErrCode menu_node_bind_param(MenuNodeId node_id, uint16_t param_id) {
     node->param_id = param_id;
     return MENU_ERR_OK;
 }
+
+// Permission management functions
+MenuErrCode menu_permission_register_role(uint8_t role_id, const char* name, MenuPermissionLevel level) {
+    if (!name) return MENU_ERR_INVALID_PARAM;
+    if (g_menu_ctx.permission.role_count >= 8) return MENU_ERR_NO_MEM;
+    
+    for (uint8_t i = 0; i < g_menu_ctx.permission.role_count; i++) {
+        if (g_menu_ctx.permission.roles[i].id == role_id) {
+            return MENU_ERR_FAIL;
+        }
+    }
+    
+    MenuRole* role = &g_menu_ctx.permission.roles[g_menu_ctx.permission.role_count];
+    role->id = role_id;
+    role->name = name;
+    role->level = level;
+    g_menu_ctx.permission.role_count++;
+    
+    return MENU_ERR_OK;
+}
+
+MenuErrCode menu_permission_set_current_role(uint8_t role_id) {
+    g_menu_ctx.permission.current_role_id = role_id;
+    return MENU_ERR_OK;
+}
+
+MenuErrCode menu_permission_update_node_level(MenuNodeId node_id, MenuPermissionLevel level) {
+    MenuNode* node = menu_core_get_node(&g_menu_ctx, node_id);
+    if (!node) return MENU_ERR_NOT_FOUND;
+    
+    node->permission_level = level;
+    return MENU_ERR_OK;
+}
+
+bool menu_permission_check_node_access(MenuNodeId node_id) {
+    MenuNode* node = menu_core_get_node(&g_menu_ctx, node_id);
+    if (!node) return false;
+    
+    #if MENU_CONFIG_ENABLE_PERMISSION
+    MenuRole* role_node = NULL;
+    for (uint8_t i = 0; i < g_menu_ctx.permission.role_count; i++) {
+        if (g_menu_ctx.permission.roles[i].id == g_menu_ctx.permission.current_role_id) {
+            role_node = &g_menu_ctx.permission.roles[i];
+            break;
+        }
+    }
+    
+    if (!role_node || role_node->level < node->permission_level) {
+        return false;
+    }
+    #endif
+    
+    return true;
+}
+
+// Persistence functions
+MenuErrCode menu_persistence_save(void) {
+    return menu_core_save_state(&g_menu_ctx);
+}
+
+MenuErrCode menu_persistence_load(void) {
+    return menu_core_load_state(&g_menu_ctx);
+}
+
+MenuErrCode menu_refresh(void) {
+    MenuErrCode err = menu_post_event(MENU_EVENT_RENDER, 0);
+    if (err != MENU_ERR_OK) {
+        return err;
+    }
+    return MENU_ERR_OK;
+}
diff --git a/api/menu_api.h b/api/menu_api.h
index d88c31b..514c90e 100644
--- a/api/menu_api.h
+++ b/api/menu_api.h
@@ -34,6 +34,13 @@ MenuNodeId menu_register_node_ex(
     void* user_data
 );
 
+// Batch node registration
+MenuErrCode menu_register_nodes(
+    const MenuNode* nodes,
+    size_t count,
+    MenuNodeId* out_ids
+);
+
 // Event Handling
 MenuErrCode menu_post_event(MenuEventType type, uint32_t param);
 
@@ -44,6 +51,19 @@ MenuErrCode menu_back(void);
 // Parameter Binding
 MenuErrCode menu_node_bind_param(MenuNodeId node_id, uint16_t param_id);
 
+// Permission Management
+MenuErrCode menu_permission_register_role(uint8_t role_id, const char* name, MenuPermissionLevel level);
+MenuErrCode menu_permission_set_current_role(uint8_t role_id);
+MenuErrCode menu_permission_update_node_level(MenuNodeId node_id, MenuPermissionLevel level);
+bool menu_permission_check_node_access(MenuNodeId node_id);
+
+// Persistence Management
+MenuErrCode menu_persistence_save(void);
+MenuErrCode menu_persistence_load(void);
+
+// Dynamic menu updates
+MenuErrCode menu_refresh(void);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/examples/demo.c b/examples/demo.c
index 1855fbf..12d9896 100644
--- a/examples/demo.c
+++ b/examples/demo.c
@@ -8,7 +8,7 @@
 // Globals
 int32_t g_volume = 50;
 int32_t g_brightness = 80;
-uint8_t g_language = 0; // 0=EN, 1=CN
+uint8_t g_language = 1; // 0=EN, 1=CN
 
 // Callbacks
 MenuErrCode on_enter_main(MenuNodeId id, struct MenuCoreCtx* ctx) {
diff --git a/src/core/menu_core.c b/src/core/menu_core.c
index 86b83dd..a0e7096 100644
--- a/src/core/menu_core.c
+++ b/src/core/menu_core.c
@@ -8,14 +8,7 @@
 // Internal helper to get node pointer from ID
 MenuNode* menu_core_get_node(MenuCoreCtx* ctx, MenuNodeId id) {
     if (!ctx || id == 0) return NULL;
-    // Simple linear scan for now. 
-    // Optimization: Could use hash table if implemented to return index/pointer
-    for (int i = 0; i < MENU_CONFIG_MAX_NODES; i++) {
-        if (ctx->nodes[i].flags.is_registered && ctx->nodes[i].id == id) {
-            return &ctx->nodes[i];
-        }
-    }
-    return NULL;
+    return menu_hash_find(ctx, id);
 }
 
 MenuErrCode menu_core_init(MenuCoreCtx* ctx) {
@@ -86,15 +79,91 @@ MenuErrCode menu_core_register_node(MenuCoreCtx* ctx, const MenuNode* node, Menu
             }
         }
     }
-    
+
     // Add to hash
-    menu_hash_insert(ctx, new_node->id);
+    menu_hash_insert(ctx, new_node->id, slot);
     
     if (out_id) *out_id = new_node->id;
     
     return MENU_ERR_OK;
 }
 
+MenuErrCode menu_core_unregister_node(MenuCoreCtx* ctx, MenuNodeId id) {
+    if (!ctx || id == 0) return MENU_ERR_INVALID_PARAM;
+    
+    MenuNode* node = menu_core_get_node(ctx, id);
+    if (!node) return MENU_ERR_NOT_FOUND;
+    
+    // Find slot index
+    int slot = -1;
+    for (int i = 0; i < MENU_CONFIG_MAX_NODES; i++) {
+        if (ctx->nodes[i].flags.is_registered && ctx->nodes[i].id == id) {
+            slot = i;
+            break;
+        }
+    }
+    
+    if (slot == -1) return MENU_ERR_NOT_FOUND;
+    
+    // Update parent-child relationship
+    if (node->parent_id != 0) {
+        MenuNode* parent = menu_core_get_node(ctx, node->parent_id);
+        if (parent) {
+            // Check if this is the first child
+            if (parent->first_child_id == id) {
+                parent->first_child_id = node->next_sibling_id;
+            } else {
+                // Find previous sibling to update links
+                MenuNode* prev_sibling = menu_core_get_node(ctx, node->prev_sibling_id);
+                if (prev_sibling) {
+                    prev_sibling->next_sibling_id = node->next_sibling_id;
+                }
+            }
+        }
+    }
+    
+    // Update next sibling's prev_sibling_id
+    if (node->next_sibling_id != 0) {
+        MenuNode* next_sibling = menu_core_get_node(ctx, node->next_sibling_id);
+        if (next_sibling) {
+            next_sibling->prev_sibling_id = node->prev_sibling_id;
+        }
+    }
+    
+    // Clear node data
+    ctx->nodes[slot].flags.is_registered = false;
+    ctx->nodes[slot].id = 0;
+    ctx->nodes[slot].parent_id = 0;
+    ctx->nodes[slot].first_child_id = 0;
+    ctx->nodes[slot].next_sibling_id = 0;
+    ctx->nodes[slot].prev_sibling_id = 0;
+    ctx->nodes[slot].hash_next_id = 0;
+    ctx->nodes[slot].flags.is_selected = false;
+    ctx->nodes[slot].flags.is_visible = false;
+    ctx->nodes[slot].flags.is_enabled = false;
+    ctx->nodes[slot].permission_level = 0;
+    ctx->nodes[slot].param_id = 0;
+    ctx->nodes[slot].user_data = NULL;
+    ctx->nodes[slot].name = NULL;
+    ctx->nodes[slot].enter_cb = NULL;
+    ctx->nodes[slot].exit_cb = NULL;
+    ctx->nodes[slot].render_cb = NULL;
+    
+    // Update counts
+    ctx->node_count--;
+    ctx->free_node_count++;
+    
+    // Rebuild hash table since we can't easily remove from it
+    menu_hash_init(ctx);
+    for (int i = 0; i < MENU_CONFIG_MAX_NODES; i++) {
+        if (ctx->nodes[i].flags.is_registered) {
+            menu_hash_insert(ctx, ctx->nodes[i].id, i);
+        }
+    }
+    
+    return MENU_ERR_OK;
+}
+
 MenuErrCode menu_core_enter_node(MenuCoreCtx* ctx, MenuNodeId node_id) {
     if (!ctx) return MENU_ERR_INVALID_PARAM;
     
@@ -103,7 +172,16 @@ MenuErrCode menu_core_enter_node(MenuCoreCtx* ctx, MenuNodeId node_id) {
     
     // Permission check
     #if MENU_CONFIG_ENABLE_PERMISSION
-    // TODO: Check permission
+    MenuRole* role_node = NULL;
+    for (uint8_t i = 0; i < ctx->permission.role_count; i++) {
+        if (ctx->permission.roles[i].id == ctx->permission.current_role_id) {
+            role_node = &ctx->permission.roles[i];
+            break;
+        }
+    }
+    if (!role_node || role_node->level < node->permission_level) {
+        return MENU_ERR_PERMISSION_DENIED;
+    }
     #endif
     
     // Call enter callback
@@ -295,6 +373,46 @@ MenuErrCode menu_core_handle_event(MenuCoreCtx* ctx, const MenuEvent* event) {
     return MENU_ERR_OK;
 }
 
+static uint8_t calculate_checksum(const MenuPersistenceData* data) {
+    uint8_t checksum = 0;
+    const uint8_t* bytes = (const uint8_t*)data;
+    size_t len = sizeof(MenuPersistenceData) - sizeof(data->checksum);
+    for (size_t i = 0; i < len; i++) {
+        checksum ^= bytes[i];
+    }
+    return checksum;
+}
+
+MenuErrCode menu_core_save_state(MenuCoreCtx* ctx) {
+    if (!ctx) return MENU_ERR_INVALID_PARAM;
+    
+    MenuPersistenceData data = {
+        .current_node_id = ctx->current_node_id,
+        .current_state = ctx->current_state,
+        .nav_path = ctx->nav_path,
+        .stack = ctx->stack,
+        .timestamp = 0,
+        .checksum = 0
+    };
+    
+    data.checksum = calculate_checksum(&data);
+    
+    // TODO: Implement actual storage write logic here
+    // This would typically write to EEPROM, Flash, or other non-volatile storage
+    // For now, we'll just mark as not dirty
+    ctx->persistence.dirty = false;
+    return MENU_ERR_OK;
+}
+
+MenuErrCode menu_core_load_state(MenuCoreCtx* ctx) {
+    if (!ctx) return MENU_ERR_INVALID_PARAM;
+    
+    // TODO: Implement actual storage read logic here
+    // This would typically read from EEPROM, Flash, or other non-volatile storage
+    // For now, we'll just return OK
+    return MENU_ERR_OK;
+}
+
 void menu_core_loop(MenuCoreCtx* ctx, uint32_t tick) {
     if (!ctx || !ctx->is_initialized) return;
     
@@ -303,14 +421,20 @@ void menu_core_loop(MenuCoreCtx* ctx, uint32_t tick) {
         MenuEvent evt;
         if (menu_event_get(&ctx->event_queue, &evt) == MENU_ERR_OK) {
             menu_core_handle_event(ctx, &evt);
+            ctx->persistence.dirty = true;
         }
     }
     
     // Render
-    // Optimization: Add a render callback to the context or port
-    // For now we rely on the current node's render_cb
     MenuNode* current = menu_core_get_node(ctx, ctx->current_node_id);
     if (current && current->render_cb) {
         current->render_cb(current->id, ctx);
     }
+    
+    // Auto-save if dirty
+    #if MENU_CONFIG_ENABLE_PERSISTENCE
+    if (ctx->persistence.dirty) {
+        menu_core_save_state(ctx);
+    }
+    #endif
 }
diff --git a/src/core/menu_core.h b/src/core/menu_core.h
index 157ad5a..4bdde41 100644
--- a/src/core/menu_core.h
+++ b/src/core/menu_core.h
@@ -13,6 +13,7 @@ MenuErrCode menu_core_init(MenuCoreCtx* ctx);
 // Node management
 MenuErrCode menu_core_register_node(MenuCoreCtx* ctx, const MenuNode* node, MenuNodeId* out_id);
 MenuNode* menu_core_get_node(MenuCoreCtx* ctx, MenuNodeId id);
+MenuErrCode menu_core_unregister_node(MenuCoreCtx* ctx, MenuNodeId id);
 
 // Main loop
 void menu_core_loop(MenuCoreCtx* ctx, uint32_t tick);
diff --git a/src/core/menu_hash.c b/src/core/menu_hash.c
index a8878b4..26d31bb 100644
--- a/src/core/menu_hash.c
+++ b/src/core/menu_hash.c
@@ -8,64 +8,26 @@ MenuErrCode menu_hash_init(MenuCoreCtx* ctx) {
     return MENU_ERR_OK;
 }
 
-MenuErrCode menu_hash_insert(MenuCoreCtx* ctx, MenuNodeId id) {
+MenuErrCode menu_hash_insert(MenuCoreCtx* ctx, MenuNodeId id, uint16_t index) {
     if (!ctx) return MENU_ERR_INVALID_PARAM;
     
-    uint16_t index = id % MENU_CONFIG_HASH_TABLE_SIZE;
-    MenuNodeId current = ctx->hash_table[index];
+    uint16_t hash_index = id % MENU_CONFIG_HASH_TABLE_SIZE;
+    uint16_t current = ctx->hash_table[hash_index];
     
     if (current == 0) {
-        ctx->hash_table[index] = id;
+        ctx->hash_table[hash_index] = index + 1;
     } else {
-        // Collision handling: append to the end of the chain
-        // Note: 0 is used as invalid ID/null pointer in this static array context
-        // This implies valid node IDs must start from 1.
-        
-        // Find the node structure for 'current'
-        // This requires access to the node array which is in ctx
-        // but we need to find the node index from the ID if ID != index
-        // In this system, we usually assume ID corresponds to index if allocated sequentially,
-        // but since we support arbitrary IDs (maybe?), we need to be careful.
-        // HOWEVER, the design says "Static node pool", so usually we just iterate.
-        // BUT wait, if we are building a hash table, we want O(1) access.
-        // Let's assume ID is NOT the index in the array, but a unique handle.
-        // But we need to find the MenuNode* from ID to set hash_next_id.
-        
-        // Since we are inside menu_hash_insert, we probably just added the node
-        // so we might know where it is, but this function takes ID.
-        // We need a way to look up the MenuNode* from ID to set the next pointer.
-        // If we can't find it efficiently, this hash insert is slow.
-        
-        // Actually, looking at `MenuCoreCtx`, `nodes` is an array.
-        // Does `nodes[i].id` == i? 
-        // If the user provides arbitrary IDs, we need to scan the array to find the node 
-        // to set its `hash_next_id`.
-        // That defeats the purpose of the hash table if insertion is O(N).
-        // But insertion happens only at init. Lookup is frequent.
-        
-        // Let's implement finding the node by scanning for insertion.
-        MenuNode* prev_node = NULL;
-        // Find the head of the chain
-        for (int i = 0; i < ctx->node_count; i++) {
-             if (ctx->nodes[i].id == current) {
-                 prev_node = &ctx->nodes[i];
-                 break;
-             }
-        }
-        
-        if (!prev_node) return MENU_ERR_NOT_FOUND; // Should not happen
-        
+        MenuNode* prev_node = &ctx->nodes[current - 1];        
         while (prev_node->hash_next_id != 0) {
-             MenuNodeId next_id = prev_node->hash_next_id;
-             bool found = false;
-             for (int i = 0; i < ctx->node_count; i++) {
-                 if (ctx->nodes[i].id == next_id) {
-                     prev_node = &ctx->nodes[i];
-                     found = true;
-                     break;
-                 }
-             }
-             if (!found) return MENU_ERR_FAIL; // Broken chain
+            bool found = false;
+            for (int i = 0; i < MENU_CONFIG_MAX_NODES; i++) {
+                if (ctx->nodes[i].flags.is_registered && ctx->nodes[i].id == prev_node->hash_next_id) {
+                    prev_node = &ctx->nodes[i];
+                    found = true;
+                    break;
+                }
+            }
+            if (!found) return MENU_ERR_FAIL;
         }
         
         prev_node->hash_next_id = id;
@@ -74,26 +36,34 @@ MenuErrCode menu_hash_insert(MenuCoreCtx* ctx, MenuNodeId id) {
     return MENU_ERR_OK;
 }
 
-MenuNodeId menu_hash_find(MenuCoreCtx* ctx, MenuNodeId id) {
-    if (!ctx) return 0;
+MenuNode* menu_hash_find(MenuCoreCtx* ctx, MenuNodeId id) {
+    if (!ctx) return NULL;
     
-    uint16_t index = id % MENU_CONFIG_HASH_TABLE_SIZE;
-    MenuNodeId current = ctx->hash_table[index];
+    uint16_t hash_index = id % MENU_CONFIG_HASH_TABLE_SIZE;
+    uint16_t current = ctx->hash_table[hash_index];
     
     while (current != 0) {
-        if (current == id) return current;
+        uint16_t node_index = current - 1;
+        MenuNode* node = &ctx->nodes[node_index];
+        if (node->flags.is_registered && node->id == id) {
+            return node;
+        }
         
-        // Move to next
         bool found = false;
-        for (int i = 0; i < ctx->node_count; i++) {
-            if (ctx->nodes[i].id == current) {
-                current = ctx->nodes[i].hash_next_id;
-                found = true;
+        for (int i = 0; i < MENU_CONFIG_MAX_NODES; i++) {
+            if (ctx->nodes[i].flags.is_registered && ctx->nodes[i].id == node->hash_next_id) {
+                for (int j = 0; j < MENU_CONFIG_MAX_NODES; j++) {
+                    if (ctx->nodes[j].flags.is_registered && ctx->nodes[j].id == node->hash_next_id) {
+                        current = j + 1;
+                        found = true;
+                        break;
+                    }
+                }
                 break;
             }
         }
-        if (!found) break; 
+        if (!found) break;
     }
     
-    return 0; // Not found
-}
+    return NULL;
+}
\ No newline at end of file
diff --git a/src/core/menu_hash.h b/src/core/menu_hash.h
index b0a1e8c..83be97b 100644
--- a/src/core/menu_hash.h
+++ b/src/core/menu_hash.h
@@ -8,11 +8,11 @@ extern "C" {
 #endif
 
 MenuErrCode menu_hash_init(MenuCoreCtx* ctx);
-MenuErrCode menu_hash_insert(MenuCoreCtx* ctx, MenuNodeId id);
-MenuNodeId menu_hash_find(MenuCoreCtx* ctx, MenuNodeId id);
+MenuErrCode menu_hash_insert(MenuCoreCtx* ctx, MenuNodeId id, uint16_t index);
+MenuNode* menu_hash_find(MenuCoreCtx* ctx, MenuNodeId id);
 
 #ifdef __cplusplus
 }
 #endif
 
-#endif // MENU_HASH_H
+#endif // MENU_HASH_H
\ No newline at end of file
diff --git a/src/core/menu_types.h b/src/core/menu_types.h
index a08b4c6..35c225a 100644
--- a/src/core/menu_types.h
+++ b/src/core/menu_types.h
@@ -17,6 +17,13 @@ struct MenuCoreCtx;
 typedef uint16_t MenuNodeId;
 typedef uint8_t MenuPermissionLevel;
 
+// Role structure
+typedef struct {
+    uint8_t id;
+    const char* name;
+    MenuPermissionLevel level;
+} MenuRole;
+
 // Error codes
 typedef enum {
     MENU_ERR_OK = 0,
@@ -110,10 +117,19 @@ typedef struct {
     uint8_t depth;
 } MenuNavPath;
 
+typedef struct MenuPersistenceData {
+    MenuNodeId current_node_id;
+    MenuState current_state;
+    MenuNavPath nav_path;
+    MenuStack stack;
+    uint32_t timestamp;
+    uint8_t checksum;
+} MenuPersistenceData;
+
 // Core Context
 typedef struct MenuCoreCtx {
     MenuNode nodes[MENU_CONFIG_MAX_NODES];
-    MenuNodeId hash_table[MENU_CONFIG_HASH_TABLE_SIZE];
+    uint16_t hash_table[MENU_CONFIG_HASH_TABLE_SIZE];
     MenuStack stack;
     MenuNavPath nav_path;
     MenuEventQueue event_queue;
@@ -132,6 +148,8 @@ typedef struct MenuCoreCtx {
     // Permission module data
     struct {
         uint8_t current_role_id;
+        MenuRole roles[8];
+        uint8_t role_count;
     } permission;
     
     // Persistence module data
@@ -143,7 +161,7 @@ typedef struct MenuCoreCtx {
     struct {
         uint8_t current_lang_id;
     } lang;
-
+    
 } MenuCoreCtx;
 
 #ifdef __cplusplus