diff --git a/.gitignore b/.gitignore
index d0ebde20..11e18613 100644
--- a/.gitignore
+++ b/.gitignore
@@ -59,7 +59,6 @@ NUL
 # Agent/IDE/Tool local files
 .agent/
 .agents/
-.serena/project.yml
 .cursor/
 .playwright-mcp/
 .superpowers/
diff --git a/.serena/.gitignore b/.serena/.gitignore
deleted file mode 100644
index 14d86ad6..00000000
--- a/.serena/.gitignore
+++ /dev/null
@@ -1 +0,0 @@
-/cache
diff --git a/.vscode/launch.json b/.vscode/launch.json
deleted file mode 100644
index 643d5753..00000000
--- a/.vscode/launch.json
+++ /dev/null
@@ -1,15 +0,0 @@
-{
-  // IntelliSense を使用して利用可能な属性を学べます。
-  // 既存の属性の説明をホバーして表示します。
-  // 詳細情報は次を確認してください: https://go.microsoft.com/fwlink/?linkid=830387
-  "version": "0.2.0",
-  "configurations": [
-    {
-      "type": "chrome",
-      "request": "launch",
-      "name": "localhost に対して Chrome を起動する",
-      "url": "http://localhost:8080",
-      "webRoot": "${workspaceFolder}"
-    }
-  ]
-}
diff --git a/CLAUDE.md b/CLAUDE.md
index 745bc904..42e1d26c 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -105,7 +105,6 @@ RoastPlus は、ドリップパックコーヒー製造現場（約8名・iPad
 
 ## MCP / ツールの使い分け
 
-- **Serena MCP**：コードファイルの読み書きは Serena MCP を優先する（グローバル設定準拠）。
 - **firebase MCP**：Firestore の構造・Rules・Functions ログの**調査**に積極活用する。`firestore_*_document`（書込・削除）系は不可逆なため、ユーザーの明示依頼があるときだけ実行し、本番データの変更は原則行わない。
 - **chrome-devtools MCP**：実装画面のライブ確認・パフォーマンス計測・アクセシビリティ確認に使う。現場 iPad 中心のため `emulate` で iPad 幅を再現し、必要に応じ `lighthouse_audit` で PWA 品質を確認する。E2E は playwright と役割を分ける。
 - **playwright MCP**：E2E が失敗したときにブラウザを実際に操作して原因を特定する。新規 E2E を書く前に、セレクタ・操作手順を MCP で試してからコードに落とす。
diff --git a/app/index.html b/app/index.html
deleted file mode 100644
index 0441926d..00000000
--- a/app/index.html
+++ /dev/null
@@ -1,89 +0,0 @@
-<!DOCTYPE html>
-<html>
-  <head>
-    <meta charset="utf-8">
-    <meta name="viewport" content="width=device-width, initial-scale=1">
-    <title>Welcome to Firebase Hosting</title>
-
-    <!-- update the version number as needed -->
-    <script defer src="/__/firebase/12.5.0/firebase-app-compat.js"></script>
-    <!-- include only the Firebase features as you need -->
-    <script defer src="/__/firebase/12.5.0/firebase-auth-compat.js"></script>
-    <script defer src="/__/firebase/12.5.0/firebase-database-compat.js"></script>
-    <script defer src="/__/firebase/12.5.0/firebase-firestore-compat.js"></script>
-    <script defer src="/__/firebase/12.5.0/firebase-functions-compat.js"></script>
-    <script defer src="/__/firebase/12.5.0/firebase-messaging-compat.js"></script>
-    <script defer src="/__/firebase/12.5.0/firebase-storage-compat.js"></script>
-    <script defer src="/__/firebase/12.5.0/firebase-analytics-compat.js"></script>
-    <script defer src="/__/firebase/12.5.0/firebase-remote-config-compat.js"></script>
-    <script defer src="/__/firebase/12.5.0/firebase-performance-compat.js"></script>
-    <!-- 
-      initialize the SDK after all desired features are loaded, set useEmulator to false
-      to avoid connecting the SDK to running emulators.
-    -->
-    <script defer src="/__/firebase/init.js?useEmulator=true"></script>
-
-    <style media="screen">
-      body { background: #ECEFF1; color: rgba(0,0,0,0.87); font-family: Roboto, Helvetica, Arial, sans-serif; margin: 0; padding: 0; }
-      #message { background: white; max-width: 360px; margin: 100px auto 16px; padding: 32px 24px; border-radius: 3px; }
-      #message h2 { color: #ffa100; font-weight: bold; font-size: 16px; margin: 0 0 8px; }
-      #message h1 { font-size: 22px; font-weight: 300; color: rgba(0,0,0,0.6); margin: 0 0 16px;}
-      #message p { line-height: 140%; margin: 16px 0 24px; font-size: 14px; }
-      #message a { display: block; text-align: center; background: #039be5; text-transform: uppercase; text-decoration: none; color: white; padding: 16px; border-radius: 4px; }
-      #message, #message a { box-shadow: 0 1px 3px rgba(0,0,0,0.12), 0 1px 2px rgba(0,0,0,0.24); }
-      #load { color: rgba(0,0,0,0.4); text-align: center; font-size: 13px; }
-      @media (max-width: 600px) {
-        body, #message { margin-top: 0; background: white; box-shadow: none; }
-        body { border-top: 16px solid #ffa100; }
-      }
-    </style>
-  </head>
-  <body>
-    <div id="message">
-      <h2>Welcome</h2>
-      <h1>Firebase Hosting Setup Complete</h1>
-      <p>You're seeing this because you've successfully setup Firebase Hosting. Now it's time to go build something extraordinary!</p>
-      <a target="_blank" href="https://firebase.google.com/docs/hosting/">Open Hosting Documentation</a>
-    </div>
-    <p id="load">Firebase SDK Loading&hellip;</p>
-
-    <script>
-      document.addEventListener('DOMContentLoaded', function() {
-        const loadEl = document.querySelector('#load');
-        // // 🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥
-        // // The Firebase SDK is initialized and available here!
-        //
-        // firebase.auth().onAuthStateChanged(user => { });
-        // firebase.database().ref('/path/to/ref').on('value', snapshot => { });
-        // firebase.firestore().doc('/foo/bar').get().then(() => { });
-        // firebase.functions().httpsCallable('yourFunction')().then(() => { });
-        // firebase.messaging().requestPermission().then(() => { });
-        // firebase.storage().ref('/path/to/ref').getDownloadURL().then(() => { });
-        // firebase.analytics(); // call to activate
-        // firebase.analytics().logEvent('tutorial_completed');
-        // firebase.performance(); // call to activate
-        //
-        // // 🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥🔥
-
-        try {
-          let app = firebase.app();
-          let features = [
-            'auth', 
-            'database', 
-            'firestore',
-            'functions',
-            'messaging', 
-            'storage', 
-            'analytics', 
-            'remoteConfig',
-            'performance',
-          ].filter(feature => typeof app[feature] === 'function');
-          loadEl.textContent = `Firebase SDK loaded with ${features.join(', ')}`;
-        } catch (e) {
-          console.error(e);
-          loadEl.textContent = 'Error loading the Firebase SDK, check the console.';
-        }
-      });
-    </script>
-  </body>
-</html>
diff --git a/docs/steering/GUIDELINES.md b/docs/steering/GUIDELINES.md
index d7150f0c..abde6050 100644
--- a/docs/steering/GUIDELINES.md
+++ b/docs/steering/GUIDELINES.md
@@ -42,7 +42,7 @@
 
 #### 2. 関連ファイル確認
 - 実装前に、対象ファイル、設定、既存テスト、README/steering docs を確認
-- 検索は `rg` を優先し、コード理解が必要な場合は Serena 等のコード探索ツールを使う
+- 検索は `rg` を優先し、定義元・参照元をたどるときは LSP（goToDefinition / findReferences）を使う
 
 #### 3. 計画立案
 - 目的、前提、触る予定のファイル、影響する画面・データ、認証・Rules・Functionsへの影響、成功条件、検証方法を短く整理
