diff --git a/app/api/v1/user_config.py b/app/api/v1/user_config.py
index 8b8d636..7e9fab7 100644
--- a/app/api/v1/user_config.py
+++ b/app/api/v1/user_config.py
@@ -1,12 +1,31 @@
-import json
+import json, os
 from fastapi import APIRouter, HTTPException, Header, Depends
 from pydantic import BaseModel
 from typing import Optional, List, Dict, Any
 import time
 from app.core.auth import decode_token
+from app.config import settings
 
 router = APIRouter()
 
+DATA_FILE = os.path.join(settings.PROCESSED_DIR, "user_configs.json")
+
+def _load_all():
+    if not os.path.exists(DATA_FILE):
+        return {"ai_configs": {}, "preferences": {}}
+    try:
+        with open(DATA_FILE, "r") as f:
+            return json.load(f)
+    except: return {"ai_configs": {}, "preferences": {}}
+
+def _save_all(ai_configs=None, preferences=None):
+    data = _load_all()
+    if ai_configs is not None: data["ai_configs"] = ai_configs
+    if preferences is not None: data["preferences"] = preferences
+    os.makedirs(os.path.dirname(DATA_FILE), exist_ok=True)
+    with open(DATA_FILE, "w") as f:
+        json.dump(data, f, indent=2)
+
 def _get_user_id(authorization):
     if not authorization or not authorization.startswith("Bearer "):
         return "anonymous"
@@ -16,9 +35,21 @@ def _get_user_id(authorization):
         return "anonymous"
     return payload.get("user_id", "anonymous")
 
-# In-memory / per-user AI provider configurations storage dictionary
-USER_AI_CONFIGS = {}
-USER_PREFERENCES = {}
+def _load_ai_configs():
+    data = _load_all()
+    return data.get("ai_configs", {})
+
+def _load_preferences():
+    data = _load_all()
+    return data.get("preferences", {})
+
+def _get_default_providers():
+    return [
+        {"id": "openai_default", "name": "OpenAI Official", "provider_type": "openai", "api_base_url": "https://api.openai.com/v1", "api_key": "", "model_name": "gpt-4o", "temperature": 0.7, "is_active": True},
+        {"id": "openai_compat_default", "name": "OpenAI Compatible (Ollama/LocalAI/DeepSeek)", "provider_type": "openai_compatible", "api_base_url": "http://localhost:11434/v1", "api_key": "ollama", "model_name": "deepseek-r1", "temperature": 0.7, "is_active": False},
+        {"id": "anthropic_default", "name": "Anthropic Claude", "provider_type": "anthropic", "api_base_url": "https://api.anthropic.com/v1", "api_key": "", "model_name": "claude-3-5-sonnet", "temperature": 0.7, "is_active": False},
+        {"id": "gemini_default", "name": "Google Gemini", "provider_type": "gemini", "api_base_url": "https://generativelanguage.googleapis.com", "api_key": "", "model_name": "gemini-1.5-pro", "temperature": 0.7, "is_active": False}
+    ]
 
 class AIProviderSetting(BaseModel):
     id: str
@@ -39,69 +70,34 @@ class SavePreferencesRequest(BaseModel):
 @router.get("/preferences")
 async def get_user_preferences(authorization: Optional[str] = Header(None)):
     uid = _get_user_id(authorization)
-    return {"success": True, "preferences": USER_PREFERENCES.get(uid, {})}
+    prefs = _load_preferences()
+    return {"success": True, "preferences": prefs.get(uid, {})}
 
 @router.post("/preferences")
 async def save_user_preferences(req: SavePreferencesRequest, authorization: Optional[str] = Header(None)):
     uid = _get_user_id(authorization)
-    USER_PREFERENCES[uid] = req.preferences
+    prefs = _load_preferences()
+    prefs[uid] = req.preferences
+    _save_all(preferences=prefs)
     return {"success": True, "message": "Đã lưu cấu hình người dùng."}
 
 @router.get("/config/ai")
 async def get_user_ai_config(authorization: Optional[str] = Header(None)):
     uid = _get_user_id(authorization)
-    if uid not in USER_AI_CONFIGS:
-        USER_AI_CONFIGS[uid] = [
-            {
-                "id": "openai_default",
-                "name": "OpenAI Official",
-                "provider_type": "openai",
-                "api_base_url": "https://api.openai.com/v1",
-                "api_key": "",
-                "model_name": "gpt-4o",
-                "temperature": 0.7,
-                "is_active": True
-            },
-            {
-                "id": "openai_compat_default",
-                "name": "OpenAI Compatible (Ollama/LocalAI/DeepSeek)",
-                "provider_type": "openai_compatible",
-                "api_base_url": "http://localhost:11434/v1",
-                "api_key": "ollama",
-                "model_name": "deepseek-r1",
-                "temperature": 0.7,
-                "is_active": False
-            },
-            {
-                "id": "anthropic_default",
-                "name": "Anthropic Claude",
-                "provider_type": "anthropic",
-                "api_base_url": "https://api.anthropic.com/v1",
-                "api_key": "",
-                "model_name": "claude-3-5-sonnet",
-                "temperature": 0.7,
-                "is_active": False
-            },
-            {
-                "id": "gemini_default",
-                "name": "Google Gemini",
-                "provider_type": "gemini",
-                "api_base_url": "https://generativelanguage.googleapis.com",
-                "api_key": "",
-                "model_name": "gemini-1.5-pro",
-                "temperature": 0.7,
-                "is_active": False
-            }
-        ]
+    configs = _load_ai_configs()
+    if uid not in configs:
+        configs[uid] = _get_default_providers()
     return {
         "success": True,
-        "providers": USER_AI_CONFIGS[uid]
+        "providers": configs[uid]
     }
 
 @router.post("/config/ai")
 async def save_user_ai_config(req: SaveAIConfigRequest, authorization: Optional[str] = Header(None)):
     uid = _get_user_id(authorization)
-    USER_AI_CONFIGS[uid] = [p.dict() for p in req.providers]
+    configs = _load_ai_configs()
+    configs[uid] = [p.dict() for p in req.providers]
+    _save_all(ai_configs=configs)
     return {
         "success": True,
         "message": "Đã lưu cấu hình AI Providers thành công!"
diff --git a/app/static/js/app.jsx b/app/static/js/app.jsx
index 9390eb2..a88cb92 100644
--- a/app/static/js/app.jsx
+++ b/app/static/js/app.jsx
@@ -751,6 +751,21 @@ const TempoTrackLane = ({
         ctx.font = 'bold 9px Inter, sans-serif';
         ctx.textAlign = 'left';
         ctx.fillText(`${Math.ceil(beatNum / 4)}`, localX + 3, 11);
+      } else if (zoom >= 2) {
+        ctx.strokeStyle = 'rgba(255, 255, 255, 0.08)';
+        ctx.lineWidth = 1;
+        ctx.beginPath();
+        ctx.moveTo(localX, 0);
+        ctx.lineTo(localX, height);
+        ctx.stroke();
+        if (zoom >= 5) {
+          ctx.fillStyle = 'rgba(255, 255, 255, 0.4)';
+          ctx.font = '8px Inter, sans-serif';
+          ctx.textAlign = 'left';
+          const bar = Math.ceil(beatNum / 4);
+          const beat = ((beatNum - 1) % 4) + 1;
+          ctx.fillText(`${bar}:${beat}`, localX + 2, 9);
+        }
       } else {
         ctx.strokeStyle = 'rgba(255, 255, 255, 0.08)';
         ctx.lineWidth = 1;
@@ -2590,7 +2605,9 @@ const AIConfigModal = ({
     className: "text-xs uppercase font-bold text-slate-400 block mb-2"
   }, "Providers"), providers.map(p => /*#__PURE__*/React.createElement("button", {
     key: p.id,
+    tabIndex: 0,
     onClick: () => setSelectedId(p.id),
+    onKeyDown: e => { if (e.key === ' ') { e.preventDefault(); updateProviderField(p.id, 'is_active', !p.is_active); } },
     className: `w-full text-left px-3 py-2 rounded-lg text-xs font-semibold flex items-center justify-between transition ${selectedId === p.id ? 'bg-cyan-600 text-white shadow' : 'bg-[#1e1e1e] text-slate-300 hover:bg-[#2e2e2e]'}`
   }, /*#__PURE__*/React.createElement("span", {
     className: "truncate"
@@ -2627,7 +2644,15 @@ const AIConfigModal = ({
       }
     },
     className: "px-2 py-1 bg-red-800 hover:bg-red-700 text-white text-xs font-bold rounded"
-  }, "Xóa"))), activeProvider && /*#__PURE__*/React.createElement("form", {
+  }, "Xóa"), providers.length > 1 && /*#__PURE__*/React.createElement("button", {
+    onClick: function(e) { e.stopPropagation(); var provs = providers.slice(); var pos = -1; for (var pi = 0; pi < provs.length; pi++) { if (provs[pi].id === selectedId) { pos = pi; break; } } if (pos > 0) { var tmp = provs[pos]; provs[pos] = provs[pos-1]; provs[pos-1] = tmp; setProviders(provs); } },
+    className: "px-2 py-1 bg-zinc-700 hover:bg-zinc-600 text-white text-xs font-bold rounded",
+    title: "Di chuyển lên"
+  }, "▲"), providers.length > 1 && /*#__PURE__*/React.createElement("button", {
+    onClick: function(e) { e.stopPropagation(); var provs = providers.slice(); var pos = -1; for (var pi = 0; pi < provs.length; pi++) { if (provs[pi].id === selectedId) { pos = pi; break; } } if (pos < provs.length - 1) { var tmp = provs[pos]; provs[pos] = provs[pos+1]; provs[pos+1] = tmp; setProviders(provs); } },
+    className: "px-2 py-1 bg-zinc-700 hover:bg-zinc-600 text-white text-xs font-bold rounded",
+    title: "Di chuyển xuống"
+  }, "▼"))), activeProvider && /*#__PURE__*/React.createElement("form", {
     onSubmit: handleSave,
     className: "col-span-2 space-y-3.5"
   }, /*#__PURE__*/React.createElement("div", null, /*#__PURE__*/React.createElement("label", {
@@ -2993,6 +3018,8 @@ const App = () => {
   const [isPlaying, setIsPlaying] = useState(false);
   const [selectionStart, setSelectionStart] = useState(null);
   const [selectionEnd, setSelectionEnd] = useState(null);
+  const selectionRef = useRef({ start: null, end: null });
+  selectionRef.current = { start: selectionStart, end: selectionEnd };
   const [selectionMode, setSelectionMode] = useState(null); // 'global' (from ruler) | 'local' (from track)
   const [localSelectionTrackId, setLocalSelectionTrackId] = useState(null);
   const [localSelectionStart, setLocalSelectionStart] = useState(null);
@@ -7050,7 +7077,7 @@ const App = () => {
           if (window.DAWCommandDispatcher) {
             try {
               const cmdResult = window.DAWCommandDispatcher.execute(cmdName, fc.arguments);
-              setAiActionLog(prev => [...prev, { type: 'status', text: ` ✅ ${fc.name}: ${cmdResult.success ? 'thành công' : 'thất bại'}`, time: Date.now() }]);
+              setAiActionLog(prev => [...prev, { type: 'status', text: ` ✅ ${fc.name}: ${cmdResult.success ? 'thành công' : 'thất bại: ' + (cmdResult.error || 'unknown')}`, time: Date.now() }]);
             } catch (cmdErr) {
               setAiActionLog(prev => [...prev, { type: 'error', text: ` ❌ ${fc.name}: ${cmdErr.message}`, time: Date.now() }]);
             }
@@ -7372,6 +7399,7 @@ const App = () => {
         setSelectionMode('global');
         setSelectionStart(start);
         setSelectionEnd(end);
+        selectionRef.current = { start, end };
         return { success: true, start: parseFloat(start.toFixed(3)), end: parseFloat(end.toFixed(3)), length: parseFloat((end - start).toFixed(3)) };
       },
       cutAudio: (args) => {
@@ -7380,15 +7408,18 @@ const App = () => {
         if (!track) return { success: false, error: 'Track not found' };
         if (!track.buffer) return { success: false, error: 'Track has no audio buffer' };
         const barDur = 60 / parseInt(bpm || 120) * 4;
+        const sel = selectionRef.current;
         let rawStart, rawEnd;
-        if (args.start_time !== undefined) rawStart = args.start_time;
-        else if (args.start_bar !== undefined) rawStart = args.start_bar * barDur;
-        else if (selectionStart !== null) rawStart = selectionStart;
-        else return { success: false, error: 'No selection or start position provided. Use set_selection first or provide start_time/start_bar.' };
-        if (args.end_time !== undefined) rawEnd = args.end_time;
-        else if (args.length_bars !== undefined) rawEnd = rawStart + args.length_bars * barDur;
-        else if (selectionEnd !== null && selectionEnd > rawStart) rawEnd = selectionEnd;
-        else return { success: false, error: 'No end position provided. Use set_selection first or provide end_time/length_bars.' };
+        if (args.start_time !== undefined && args.start_time !== null) rawStart = args.start_time;
+        else if (args.start_bar !== undefined && args.start_bar !== null) rawStart = args.start_bar * barDur;
+        else if (sel.start !== null) rawStart = sel.start;
+        else rawStart = currentTime;
+        if (args.end_time !== undefined && args.end_time !== null) rawEnd = args.end_time;
+        else if (args.end_bar !== undefined && args.end_bar !== null) rawEnd = args.end_bar * barDur;
+        else if (args.length_bars !== undefined && args.length_bars !== null) rawEnd = rawStart + args.length_bars * barDur;
+        else if (sel.end !== null && sel.end > rawStart) rawEnd = sel.end;
+        else return { success: false, error: 'No end position provided. Provide end_time, end_bar, or length_bars.' };
+        if (rawEnd <= rawStart) return { success: false, error: 'End position must be after start position.' };
         const buffer = track.buffer;
         const ctx = getAudioContext();
         const snap = args.snap_silence !== false;
@@ -7424,6 +7455,7 @@ const App = () => {
           return updated;
         });
         setSelectedTrackId(newId);
+        selectionRef.current = { start: 0, end: slicedBuffer.duration };
         clearLocalSelection();
         setSelectionMode('global');
         setSelectionStart(0);
diff --git a/app/static/js/app.precompiled.js b/app/static/js/app.precompiled.js
index 2153860..0eae3ea 100644
--- a/app/static/js/app.precompiled.js
+++ b/app/static/js/app.precompiled.js
@@ -751,6 +751,21 @@ const TempoTrackLane = ({
         ctx.font = 'bold 9px Inter, sans-serif';
         ctx.textAlign = 'left';
         ctx.fillText(`${Math.ceil(beatNum / 4)}`, localX + 3, 11);
+      } else if (zoom >= 2) {
+        ctx.strokeStyle = 'rgba(255, 255, 255, 0.08)';
+        ctx.lineWidth = 1;
+        ctx.beginPath();
+        ctx.moveTo(localX, 0);
+        ctx.lineTo(localX, height);
+        ctx.stroke();
+        if (zoom >= 5) {
+          ctx.fillStyle = 'rgba(255, 255, 255, 0.4)';
+          ctx.font = '8px Inter, sans-serif';
+          ctx.textAlign = 'left';
+          const bar = Math.ceil(beatNum / 4);
+          const beat = (beatNum - 1) % 4 + 1;
+          ctx.fillText(`${bar}:${beat}`, localX + 2, 9);
+        }
       } else {
         ctx.strokeStyle = 'rgba(255, 255, 255, 0.08)';
         ctx.lineWidth = 1;
@@ -2590,7 +2605,14 @@ const AIConfigModal = ({
     className: "text-xs uppercase font-bold text-slate-400 block mb-2"
   }, "Providers"), providers.map(p => /*#__PURE__*/React.createElement("button", {
     key: p.id,
+    tabIndex: 0,
     onClick: () => setSelectedId(p.id),
+    onKeyDown: e => {
+      if (e.key === ' ') {
+        e.preventDefault();
+        updateProviderField(p.id, 'is_active', !p.is_active);
+      }
+    },
     className: `w-full text-left px-3 py-2 rounded-lg text-xs font-semibold flex items-center justify-between transition ${selectedId === p.id ? 'bg-cyan-600 text-white shadow' : 'bg-[#1e1e1e] text-slate-300 hover:bg-[#2e2e2e]'}`
   }, /*#__PURE__*/React.createElement("span", {
     className: "truncate"
@@ -2627,7 +2649,47 @@ const AIConfigModal = ({
       }
     },
     className: "px-2 py-1 bg-red-800 hover:bg-red-700 text-white text-xs font-bold rounded"
-  }, "Xóa"))), activeProvider && /*#__PURE__*/React.createElement("form", {
+  }, "Xóa"), providers.length > 1 && /*#__PURE__*/React.createElement("button", {
+    onClick: function (e) {
+      e.stopPropagation();
+      var provs = providers.slice();
+      var pos = -1;
+      for (var pi = 0; pi < provs.length; pi++) {
+        if (provs[pi].id === selectedId) {
+          pos = pi;
+          break;
+        }
+      }
+      if (pos > 0) {
+        var tmp = provs[pos];
+        provs[pos] = provs[pos - 1];
+        provs[pos - 1] = tmp;
+        setProviders(provs);
+      }
+    },
+    className: "px-2 py-1 bg-zinc-700 hover:bg-zinc-600 text-white text-xs font-bold rounded",
+    title: "Di chuyển lên"
+  }, "▲"), providers.length > 1 && /*#__PURE__*/React.createElement("button", {
+    onClick: function (e) {
+      e.stopPropagation();
+      var provs = providers.slice();
+      var pos = -1;
+      for (var pi = 0; pi < provs.length; pi++) {
+        if (provs[pi].id === selectedId) {
+          pos = pi;
+          break;
+        }
+      }
+      if (pos < provs.length - 1) {
+        var tmp = provs[pos];
+        provs[pos] = provs[pos + 1];
+        provs[pos + 1] = tmp;
+        setProviders(provs);
+      }
+    },
+    className: "px-2 py-1 bg-zinc-700 hover:bg-zinc-600 text-white text-xs font-bold rounded",
+    title: "Di chuyển xuống"
+  }, "▼"))), activeProvider && /*#__PURE__*/React.createElement("form", {
     onSubmit: handleSave,
     className: "col-span-2 space-y-3.5"
   }, /*#__PURE__*/React.createElement("div", null, /*#__PURE__*/React.createElement("label", {
@@ -2993,6 +3055,14 @@ const App = () => {
   const [isPlaying, setIsPlaying] = useState(false);
   const [selectionStart, setSelectionStart] = useState(null);
   const [selectionEnd, setSelectionEnd] = useState(null);
+  const selectionRef = useRef({
+    start: null,
+    end: null
+  });
+  selectionRef.current = {
+    start: selectionStart,
+    end: selectionEnd
+  };
   const [selectionMode, setSelectionMode] = useState(null); // 'global' (from ruler) | 'local' (from track)
   const [localSelectionTrackId, setLocalSelectionTrackId] = useState(null);
   const [localSelectionStart, setLocalSelectionStart] = useState(null);
@@ -7117,7 +7187,7 @@ const App = () => {
               const cmdResult = window.DAWCommandDispatcher.execute(cmdName, fc.arguments);
               setAiActionLog(prev => [...prev, {
                 type: 'status',
-                text: ` ✅ ${fc.name}: ${cmdResult.success ? 'thành công' : 'thất bại'}`,
+                text: ` ✅ ${fc.name}: ${cmdResult.success ? 'thành công' : 'thất bại: ' + (cmdResult.error || 'unknown')}`,
                 time: Date.now()
               }]);
             } catch (cmdErr) {
@@ -7536,6 +7606,10 @@ const App = () => {
         setSelectionMode('global');
         setSelectionStart(start);
         setSelectionEnd(end);
+        selectionRef.current = {
+          start,
+          end
+        };
         return {
           success: true,
           start: parseFloat(start.toFixed(3)),
@@ -7555,14 +7629,16 @@ const App = () => {
           error: 'Track has no audio buffer'
         };
         const barDur = 60 / parseInt(bpm || 120) * 4;
+        const sel = selectionRef.current;
         let rawStart, rawEnd;
-        if (args.start_time !== undefined) rawStart = args.start_time;else if (args.start_bar !== undefined) rawStart = args.start_bar * barDur;else if (selectionStart !== null) rawStart = selectionStart;else return {
+        if (args.start_time !== undefined && args.start_time !== null) rawStart = args.start_time;else if (args.start_bar !== undefined && args.start_bar !== null) rawStart = args.start_bar * barDur;else if (sel.start !== null) rawStart = sel.start;else rawStart = currentTime;
+        if (args.end_time !== undefined && args.end_time !== null) rawEnd = args.end_time;else if (args.end_bar !== undefined && args.end_bar !== null) rawEnd = args.end_bar * barDur;else if (args.length_bars !== undefined && args.length_bars !== null) rawEnd = rawStart + args.length_bars * barDur;else if (sel.end !== null && sel.end > rawStart) rawEnd = sel.end;else return {
           success: false,
-          error: 'No selection or start position provided. Use set_selection first or provide start_time/start_bar.'
+          error: 'No end position provided. Provide end_time, end_bar, or length_bars.'
         };
-        if (args.end_time !== undefined) rawEnd = args.end_time;else if (args.length_bars !== undefined) rawEnd = rawStart + args.length_bars * barDur;else if (selectionEnd !== null && selectionEnd > rawStart) rawEnd = selectionEnd;else return {
+        if (rawEnd <= rawStart) return {
           success: false,
-          error: 'No end position provided. Use set_selection first or provide end_time/length_bars.'
+          error: 'End position must be after start position.'
         };
         const buffer = track.buffer;
         const ctx = getAudioContext();
@@ -7615,6 +7691,10 @@ const App = () => {
           return updated;
         });
         setSelectedTrackId(newId);
+        selectionRef.current = {
+          start: 0,
+          end: slicedBuffer.duration
+        };
         clearLocalSelection();
         setSelectionMode('global');
         setSelectionStart(0);
diff --git a/app/static/js/services/aiGateway.js b/app/static/js/services/aiGateway.js
index 3ea9321..4a4340d 100644
--- a/app/static/js/services/aiGateway.js
+++ b/app/static/js/services/aiGateway.js
@@ -179,16 +179,17 @@ const AIGateway = (function() {
     }
   }, {
     name: 'cut_audio',
-    description: 'Cắt đoạn audio đang được chọn từ track nguồn, snap zero-crossing, tạo track mới chứa đoạn cắt',
+    description: 'Cắt một đoạn audio từ track nguồn. Tự động tạo selection, snap zero-crossing, và tạo track mới chứa đoạn cắt. Lệnh DUY NHẤT cho thao tác cắt - không cần gọi set_selection trước.',
     parameters: {
       type: 'object',
       properties: {
         track_id: { type: 'string', description: 'ID của track nguồn' },
-        start_time: { type: 'number', description: 'Vị trí bắt đầu cắt (giây). Mặc định: dùng selection hiện tại.' },
+        start_time: { type: 'number', description: 'Vị trí bắt đầu cắt (giây). Mặc định: dùng playhead hiện tại.' },
         end_time: { type: 'number', description: 'Vị trí kết thúc cắt (giây). Mặc định: dùng selection hiện tại.' },
         start_bar: { type: 'number', description: 'Bar bắt đầu cắt (0 = bar đầu). Dùng thay cho start_time.' },
-        length_bars: { type: 'number', description: 'Độ dài cắt (bar). Dùng cùng start_bar.' },
-        snap_silence: { type: 'boolean', description: 'Tự động snap vào điểm silence/gần silence gần nhất ở hai đầu (mặc định: true)' },
+        end_bar: { type: 'number', description: 'Bar kết thúc cắt. VD: end_bar=12 cắt đến bar 12. Dùng thay cho end_time.' },
+        length_bars: { type: 'number', description: 'Độ dài cắt (bar). Dùng cùng start_bar thay cho end_bar.' },
+        snap_silence: { type: 'boolean', description: 'Tự động snap vào điểm zero-crossing gần nhất ở hai đầu (mặc định: true)' },
         new_track_name: { type: 'string', description: 'Tên cho track mới. Mặc định: "Cut_<tên_track_gốc>"' }
       }
     }
diff --git a/app/storage/sonicforge.db b/app/storage/sonicforge.db
index 43baa1b..5c960fe 100644
Binary files a/app/storage/sonicforge.db and b/app/storage/sonicforge.db differ