diff --git a/README.md b/README.md
index 1d29bb7..6d603c4 100644
--- a/README.md
+++ b/README.md
@@ -631,6 +631,12 @@ data: [DONE]
 
 ## Changelog
 
+### v2.2.1 (2026-05-19)
+- **Auto-Install Build Tools** — `aapt2`, `ecj`, `d8`, `apksigner` auto-installed via `pkg` with full paths and retry logic
+- **Dev Tools Banner** — yellow warning banner on Coding/Agentic mode if tools missing, one-tap Install button
+- **Bootstrap + Tools in One Tap** — Install button auto-installs Termux bootstrap then build tools sequentially
+- Checks tool availability before every build attempt, auto-installs if missing
+
 ### v2.2.0 (2026-05-19)
 - **Build Pipeline Rewrite** — proven 7-step pipeline tested with Android SDK 36: resources → link → compile (R.java + sources) → DEX → package → sign
 - **Auto-Install Build Tools** — `aapt2`, `ecj`, `d8`, `apksigner` auto-installed via `pkg` on first build
diff --git a/android/app/build.gradle b/android/app/build.gradle
index c34e88d..da94c29 100644
--- a/android/app/build.gradle
+++ b/android/app/build.gradle
@@ -7,8 +7,8 @@ android {
         applicationId "ai.z.chat"
         minSdkVersion rootProject.ext.minSdkVersion
         targetSdkVersion rootProject.ext.targetSdkVersion
-        versionCode 13
-        versionName "2.2.0"
+        versionCode 14
+        versionName "2.2.1"
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
         aaptOptions {
             ignoreAssetsPattern = '!.svn:!.git:!.ds_store:!*.scc:.*:!CVS:!thumbs.db:!picasa.ini:!*~'
diff --git a/package.json b/package.json
index ed50b78..e10f0eb 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "zai-chat",
-  "version": "2.2.0",
+  "version": "2.2.1",
   "description": "Z.AI Chat - Full stack AI chat powered by GLM Coding Plan",
   "main": "index.js",
   "scripts": {
diff --git a/www/css/styles.css b/www/css/styles.css
index 07e625d..edc4fd6 100644
--- a/www/css/styles.css
+++ b/www/css/styles.css
@@ -1107,6 +1107,51 @@ a:hover { text-decoration: underline; }
     -webkit-overflow-scrolling: touch;
 }
 
+/* Dev Tools Banner */
+.dev-tools-banner {
+    display: flex;
+    align-items: center;
+    gap: 8px;
+    padding: 10px 14px;
+    margin: 8px 12px;
+    background: rgba(255, 165, 2, 0.1);
+    border: 1px solid var(--warning);
+    border-radius: var(--radius-sm);
+    font-size: 13px;
+    color: var(--text-primary);
+    animation: fadeIn 0.3s ease;
+}
+.dtb-icon {
+    font-size: 16px;
+    flex-shrink: 0;
+}
+.dtb-msg {
+    flex: 1;
+    line-height: 1.4;
+}
+.dtb-install-btn {
+    background: var(--accent);
+    color: white;
+    border: none;
+    padding: 6px 14px;
+    border-radius: 6px;
+    font-size: 12px;
+    font-weight: 700;
+    cursor: pointer;
+    flex-shrink: 0;
+    white-space: nowrap;
+}
+.dtb-install-btn:disabled { opacity: 0.6; cursor: not-allowed; }
+.dtb-dismiss-btn {
+    background: none;
+    border: none;
+    color: var(--text-muted);
+    font-size: 18px;
+    cursor: pointer;
+    padding: 0 4px;
+    flex-shrink: 0;
+}
+
 /* Responsive */
 @media (max-width: 480px) {
     .message { max-width: 92%; }
diff --git a/www/index.html b/www/index.html
index f7d0ad5..4a3f8c9 100644
--- a/www/index.html
+++ b/www/index.html
@@ -327,13 +327,23 @@
                     </div>
                     <div class="settings-section">
                         <h3>About</h3>
-                         <p class="about-text">Z.AI Chat v2.2.0</p>
+                         <p class="about-text">Z.AI Chat v2.2.1</p>
                         <p class="about-text">Built with Z.AI SDK &amp; GLM-5.1</p>
                         <p class="about-text">Compatible with Android 15/16</p>
                     </div>
                     <div class="settings-section">
                         <h3>Changelog</h3>
                         <ul class="changelog-list">
+                            <li>
+                                <span class="changelog-version">v2.2.1</span>
+                                <span class="changelog-date">2026-05-19</span>
+                                <ul>
+                                    <li><strong>Auto-Install Build Tools</strong> — aapt2/ecj/d8/apksigner auto-installed via pkg with full paths + retry logic</li>
+                                    <li><strong>Dev Tools Banner</strong> — warns on Coding/Agentic mode if tools missing, one-tap install button</li>
+                                    <li><strong>Bootstrap + Tools in One Tap</strong> — Install button auto-installs bootstrap then build tools</li>
+                                    <li>Checks tool availability before every build, auto-installs if missing</li>
+                                </ul>
+                            </li>
                             <li>
                                 <span class="changelog-version">v2.2.0</span>
                                 <span class="changelog-date">2026-05-19</span>
diff --git a/www/js/app.js b/www/js/app.js
index 1e1887f..1e2e951 100644
--- a/www/js/app.js
+++ b/www/js/app.js
@@ -549,6 +549,10 @@
             return;
         }
 
+        if ((state.currentMode === 'coding' || state.currentMode === 'agentic') && !termState.devToolsInstalled) {
+            checkDevEnvironment();
+        }
+
         if (!state.activeConversationId) {
             newConversation();
         }
@@ -1901,33 +1905,159 @@
     }
 
     async function ensureBuildTools() {
-        var check = await shellExec('command -v aapt2 && command -v ecj && (command -v d8 || command -v dx)', termState.homeDir, false);
-        if (check.exitCode === 0) return true;
-
-        termPrint('[*] Installing build tools...', 'info');
-        showStatusToast('Installing build tools (first time)...', 'info');
-
-        var installResult = await shellExec(
-            'apt update -y 2>&1 && apt install -y aapt2 ecj dx apksigner 2>&1 || pkg install -y aapt2 ecj dx apksigner 2>&1',
-            termState.homeDir, false
-        );
-
-        if (installResult.output) {
-            termPrint(installResult.output.replace(/\n$/, ''), '');
-        }
-
-        var recheck = await shellExec('command -v aapt2 && command -v ecj', termState.homeDir, false);
-        if (recheck.exitCode === 0) {
-            termPrint('[OK] Build tools installed', 'success');
-            showStatusToast('Build tools installed!', 'success');
+        var check = await shellExec('command -v aapt2 >/dev/null 2>&1 && command -v ecj >/dev/null 2>&1 && (command -v d8 >/dev/null 2>&1 || command -v dx >/dev/null 2>&1)', termState.homeDir, false);
+        if (check.exitCode === 0) {
+            termState.devToolsInstalled = true;
             return true;
         }
 
-        termPrint('[!] Failed to install build tools automatically', 'err');
-        termPrint('Please run manually: pkg install aapt2 ecj dx apksigner', 'warning');
+        if (Shell) {
+            var env = await Shell.getEnv();
+            termState.homeDir = env.HOME;
+            termState.toolsDir = env.TOOLS;
+            termState.projectsDir = env.PROJECTS;
+            termState.cwd = env.CWD || env.HOME;
+        }
+
+        var prefix = termState.homeDir ? termState.homeDir.replace('/home', '') + '/usr' : '';
+        var pkgBin = prefix + '/bin/pkg';
+        var aptBin = prefix + '/bin/apt';
+
+        var pkgExists = await shellExec('test -x "' + pkgBin + '"', termState.homeDir, false);
+        var aptExists = await shellExec('test -x "' + aptBin + '"', termState.homeDir, false);
+
+        if (pkgExists.exitCode !== 0 && aptExists.exitCode !== 0) {
+            termPrint('[!] No package manager found. Install Termux bootstrap first.', 'err');
+            termState.devToolsInstalled = false;
+            return false;
+        }
+
+        termPrint('[*] Installing build tools (aapt2, ecj, dx, apksigner)...', 'info');
+        termPrint('[*] This may take a few minutes on first run...', 'info');
+        showStatusToast('Installing build tools...', 'info');
+
+        var installCmd;
+        if (pkgExists.exitCode === 0) {
+            installCmd = pkgBin + ' update -y 2>&1 && ' + pkgBin + ' install -y aapt2 ecj dx apksigner 2>&1';
+        } else {
+            installCmd = aptBin + ' update -y 2>&1 && ' + aptBin + ' install -y aapt2 ecj dx apksigner 2>&1';
+        }
+
+        var installResult = await shellExec(installCmd, termState.homeDir, false);
+        if (installResult.output) {
+            var out = installResult.output;
+            if (out.length > 2000) out = out.substring(0, 1000) + '\n... truncated ...\n' + out.substring(out.length - 800);
+            termPrint(out.replace(/\n$/, ''), '');
+        }
+
+        var recheck = await shellExec('command -v aapt2 >/dev/null 2>&1 && command -v ecj >/dev/null 2>&1', termState.homeDir, false);
+        if (recheck.exitCode === 0) {
+            termPrint('[OK] Build tools installed successfully!', 'success');
+            showStatusToast('Build tools installed!', 'success');
+            termState.devToolsInstalled = true;
+            return true;
+        }
+
+        if (pkgExists.exitCode === 0 && installResult.exitCode !== 0) {
+            termPrint('[*] Retrying with apt directly...', 'info');
+            var retryResult = await shellExec(aptBin + ' update 2>&1 && ' + aptBin + ' install -y aapt2 ecj dx apksigner 2>&1', termState.homeDir, false);
+            if (retryResult.output) termPrint(retryResult.output.substring(0, 1500).replace(/\n$/, ''), '');
+
+            var recheck2 = await shellExec('command -v aapt2 >/dev/null 2>&1 && command -v ecj >/dev/null 2>&1', termState.homeDir, false);
+            if (recheck2.exitCode === 0) {
+                termPrint('[OK] Build tools installed!', 'success');
+                showStatusToast('Build tools installed!', 'success');
+                termState.devToolsInstalled = true;
+                return true;
+            }
+        }
+
+        termPrint('[!] Auto-install failed. Open Terminal and run:', 'err');
+        termPrint('    pkg update && pkg install aapt2 ecj dx apksigner', 'warning');
+        termState.devToolsInstalled = false;
         return false;
     }
 
+    async function checkDevEnvironment() {
+        if (state.currentMode !== 'coding' && state.currentMode !== 'agentic') return;
+
+        if (!Bootstrap) return;
+        try {
+            var bsStatus = await Bootstrap.getStatus();
+            if (!bsStatus.installed) {
+                showDevToolsBanner('Termux not installed. Tap Dev Setup to install Linux environment + build tools.');
+                return;
+            }
+        } catch(e) {}
+
+        if (termState.devToolsInstalled) return;
+
+        var check = await shellExec('command -v aapt2 >/dev/null 2>&1 && command -v ecj >/dev/null 2>&1', termState.homeDir, false);
+        if (check.exitCode === 0) {
+            termState.devToolsInstalled = true;
+            return;
+        }
+
+        showDevToolsBanner('Build tools (aapt2, ecj, d8) not installed. Tap to auto-install.');
+    }
+
+    function showDevToolsBanner(msg) {
+        var existing = $('#dev-tools-banner');
+        if (existing) existing.remove();
+
+        var container = $('#messages');
+        if (!container) return;
+
+        var banner = document.createElement('div');
+        banner.id = 'dev-tools-banner';
+        banner.className = 'dev-tools-banner';
+        banner.innerHTML = '<span class="dtb-icon">&#9888;</span> ' +
+            '<span class="dtb-msg">' + msg + '</span>' +
+            '<button class="dtb-install-btn">Install</button>' +
+            '<button class="dtb-dismiss-btn">&times;</button>';
+
+        container.insertBefore(banner, container.firstChild);
+
+        banner.querySelector('.dtb-install-btn').addEventListener('click', async function() {
+            var btn = this;
+            btn.textContent = 'Installing...';
+            btn.disabled = true;
+
+            var bsStatus;
+            try { bsStatus = await Bootstrap.getStatus(); } catch(e) { bsStatus = { installed: false }; }
+
+            if (!bsStatus.installed) {
+                try {
+                    await Bootstrap.install();
+                    if (Shell) {
+                        var env = await Shell.getEnv();
+                        termState.homeDir = env.HOME;
+                        termState.toolsDir = env.TOOLS;
+                        termState.projectsDir = env.PROJECTS;
+                        termState.cwd = env.CWD || env.HOME;
+                    }
+                    updateCwdDisplay();
+                } catch(e) {
+                    btn.textContent = 'Bootstrap failed';
+                    return;
+                }
+            }
+
+            var ok = await ensureBuildTools();
+            if (ok) {
+                banner.remove();
+                showStatusToast('All tools installed!', 'success');
+            } else {
+                btn.textContent = 'Retry';
+                btn.disabled = false;
+            }
+        });
+
+        banner.querySelector('.dtb-dismiss-btn').addEventListener('click', function() {
+            banner.remove();
+        });
+    }
+
     async function autoExecuteActions(actions, conv) {
         var hasFiles = actions.some(function(a) { return a.type === 'create_file'; });
         var hasBuild = actions.some(function(a) { return a.type === 'build_apk'; });
@@ -2585,6 +2715,7 @@
                 updateModeSelector();
                 updateHeader();
                 updateTerminalVisibility();
+                checkDevEnvironment();
                 saveState();
             });
         });