diff --git a/bin/install.js b/bin/install.js
index c65b7ac52..a4f18f17b 100755
--- a/bin/install.js
+++ b/bin/install.js
@@ -69,6 +69,7 @@ const hasCursor = args.includes('--cursor');
 const hasWindsurf = args.includes('--windsurf');
 const hasBoth = args.includes('--both'); // Legacy flag, keeps working
 const hasAll = args.includes('--all');
+const hasSdk = args.includes('--sdk');
 const hasUninstall = args.includes('--uninstall') || args.includes('-u');
 
 // Runtime selection - can be set by flags or interactive prompt
@@ -327,7 +328,7 @@ if (hasUninstall) {
 
 // Show help if requested
 if (hasHelp) {
-  console.log(`  ${yellow}Usage:${reset} npx get-shit-done-cc [options]\n\n  ${yellow}Options:${reset}\n    ${cyan}-g, --global${reset}              Install globally (to config directory)\n    ${cyan}-l, --local${reset}               Install locally (to current directory)\n    ${cyan}--claude${reset}                  Install for Claude Code only\n    ${cyan}--opencode${reset}                Install for OpenCode only\n    ${cyan}--gemini${reset}                  Install for Gemini only\n    ${cyan}--codex${reset}                   Install for Codex only\n    ${cyan}--copilot${reset}                 Install for Copilot only\n    ${cyan}--antigravity${reset}             Install for Antigravity only\n    ${cyan}--cursor${reset}                  Install for Cursor only\n    ${cyan}--windsurf${reset}                Install for Windsurf only\n    ${cyan}--all${reset}                     Install for all runtimes\n    ${cyan}-u, --uninstall${reset}           Uninstall GSD (remove all GSD files)\n    ${cyan}-c, --config-dir <path>${reset}   Specify custom config directory\n    ${cyan}-h, --help${reset}                Show this help message\n    ${cyan}--force-statusline${reset}        Replace existing statusline config\n\n  ${yellow}Examples:${reset}\n    ${dim}# Interactive install (prompts for runtime and location)${reset}\n    npx get-shit-done-cc\n\n    ${dim}# Install for Claude Code globally${reset}\n    npx get-shit-done-cc --claude --global\n\n    ${dim}# Install for Gemini globally${reset}\n    npx get-shit-done-cc --gemini --global\n\n    ${dim}# Install for Codex globally${reset}\n    npx get-shit-done-cc --codex --global\n\n    ${dim}# Install for Copilot globally${reset}\n    npx get-shit-done-cc --copilot --global\n\n    ${dim}# Install for Copilot locally${reset}\n    npx get-shit-done-cc --copilot --local\n\n    ${dim}# Install for Antigravity globally${reset}\n    npx get-shit-done-cc --antigravity --global\n\n    ${dim}# Install for Antigravity locally${reset}\n    npx get-shit-done-cc --antigravity --local\n\n    ${dim}# Install for Cursor globally${reset}\n    npx get-shit-done-cc --cursor --global\n\n    ${dim}# Install for Cursor locally${reset}\n    npx get-shit-done-cc --cursor --local\n\n    ${dim}# Install for Windsurf globally${reset}\n    npx get-shit-done-cc --windsurf --global\n\n    ${dim}# Install for Windsurf locally${reset}\n    npx get-shit-done-cc --windsurf --local\n\n    ${dim}# Install for all runtimes globally${reset}\n    npx get-shit-done-cc --all --global\n\n    ${dim}# Install to custom config directory${reset}\n    npx get-shit-done-cc --codex --global --config-dir ~/.codex-work\n\n    ${dim}# Install to current project only${reset}\n    npx get-shit-done-cc --claude --local\n\n    ${dim}# Uninstall GSD from Cursor globally${reset}\n    npx get-shit-done-cc --cursor --global --uninstall\n\n  ${yellow}Notes:${reset}\n    The --config-dir option is useful when you have multiple configurations.\n    It takes priority over CLAUDE_CONFIG_DIR / GEMINI_CONFIG_DIR / CODEX_HOME / COPILOT_CONFIG_DIR / ANTIGRAVITY_CONFIG_DIR / CURSOR_CONFIG_DIR / WINDSURF_CONFIG_DIR environment variables.\n`);
+  console.log(`  ${yellow}Usage:${reset} npx get-shit-done-cc [options]\n\n  ${yellow}Options:${reset}\n    ${cyan}-g, --global${reset}              Install globally (to config directory)\n    ${cyan}-l, --local${reset}               Install locally (to current directory)\n    ${cyan}--claude${reset}                  Install for Claude Code only\n    ${cyan}--opencode${reset}                Install for OpenCode only\n    ${cyan}--gemini${reset}                  Install for Gemini only\n    ${cyan}--codex${reset}                   Install for Codex only\n    ${cyan}--copilot${reset}                 Install for Copilot only\n    ${cyan}--antigravity${reset}             Install for Antigravity only\n    ${cyan}--cursor${reset}                  Install for Cursor only\n    ${cyan}--windsurf${reset}                Install for Windsurf only\n    ${cyan}--all${reset}                     Install for all runtimes\n    ${cyan}--sdk${reset}                     Also install GSD SDK CLI (gsd-sdk)\n    ${cyan}-u, --uninstall${reset}           Uninstall GSD (remove all GSD files)\n    ${cyan}-c, --config-dir <path>${reset}   Specify custom config directory\n    ${cyan}-h, --help${reset}                Show this help message\n    ${cyan}--force-statusline${reset}        Replace existing statusline config\n\n  ${yellow}Examples:${reset}\n    ${dim}# Interactive install (prompts for runtime and location)${reset}\n    npx get-shit-done-cc\n\n    ${dim}# Install for Claude Code globally${reset}\n    npx get-shit-done-cc --claude --global\n\n    ${dim}# Install for Gemini globally${reset}\n    npx get-shit-done-cc --gemini --global\n\n    ${dim}# Install for Codex globally${reset}\n    npx get-shit-done-cc --codex --global\n\n    ${dim}# Install for Copilot globally${reset}\n    npx get-shit-done-cc --copilot --global\n\n    ${dim}# Install for Copilot locally${reset}\n    npx get-shit-done-cc --copilot --local\n\n    ${dim}# Install for Antigravity globally${reset}\n    npx get-shit-done-cc --antigravity --global\n\n    ${dim}# Install for Antigravity locally${reset}\n    npx get-shit-done-cc --antigravity --local\n\n    ${dim}# Install for Cursor globally${reset}\n    npx get-shit-done-cc --cursor --global\n\n    ${dim}# Install for Cursor locally${reset}\n    npx get-shit-done-cc --cursor --local\n\n    ${dim}# Install for Windsurf globally${reset}\n    npx get-shit-done-cc --windsurf --global\n\n    ${dim}# Install for Windsurf locally${reset}\n    npx get-shit-done-cc --windsurf --local\n\n    ${dim}# Install for all runtimes globally${reset}\n    npx get-shit-done-cc --all --global\n\n    ${dim}# Install to custom config directory${reset}\n    npx get-shit-done-cc --codex --global --config-dir ~/.codex-work\n\n    ${dim}# Install to current project only${reset}\n    npx get-shit-done-cc --claude --local\n\n    ${dim}# Uninstall GSD from Cursor globally${reset}\n    npx get-shit-done-cc --cursor --global --uninstall\n\n  ${yellow}Notes:${reset}\n    The --config-dir option is useful when you have multiple configurations.\n    It takes priority over CLAUDE_CONFIG_DIR / GEMINI_CONFIG_DIR / CODEX_HOME / COPILOT_CONFIG_DIR / ANTIGRAVITY_CONFIG_DIR / CURSOR_CONFIG_DIR / WINDSURF_CONFIG_DIR environment variables.\n`);
   process.exit(0);
 }
 
@@ -4689,6 +4690,70 @@ function handleStatusline(settings, isInteractive, callback) {
   });
 }
 
+/**
+ * Install the GSD SDK globally via npm.
+ * @returns {boolean} true if install succeeded
+ */
+function installSdk() {
+  const sdkPkg = '@gsd-build/sdk@latest';
+  console.log(`\n  ${cyan}Installing GSD SDK...${reset}`);
+  console.log(`  ${dim}npm install -g ${sdkPkg}${reset}\n`);
+  try {
+    require('child_process').execSync(`npm install -g --force --no-fund --loglevel=error ${sdkPkg}`, { stdio: 'pipe' });
+    console.log(`\n  ${green}✓${reset} GSD SDK installed (${cyan}gsd-sdk${reset} command available)`);
+    return true;
+  } catch (e) {
+    console.log(`\n  ${yellow}⚠${reset} SDK install failed: ${e.message}`);
+    console.log(`  ${dim}You can install it manually: npm install -g ${sdkPkg}${reset}`);
+    return false;
+  }
+}
+
+/**
+ * Prompt the user to optionally install the GSD SDK.
+ * Called after runtime installation completes.
+ * @param {Function} callback - called with true/false
+ */
+function promptSdk(callback) {
+  if (!process.stdin.isTTY) {
+    callback(false);
+    return;
+  }
+
+  const rl = readline.createInterface({
+    input: process.stdin,
+    output: process.stdout
+  });
+
+  let answered = false;
+
+  rl.on('close', () => {
+    if (!answered) {
+      answered = true;
+      callback(false);
+    }
+  });
+
+  console.log(`
+  ${yellow}Also install the GSD SDK?${reset}
+
+  The SDK provides a standalone CLI for autonomous execution:
+    ${dim}gsd-sdk init @prd.md${reset}    Bootstrap a project from a PRD
+    ${dim}gsd-sdk auto${reset}            Run full autonomous lifecycle
+    ${dim}gsd-sdk run "prompt"${reset}    Execute a milestone from text
+
+  ${cyan}1${reset}) No
+  ${cyan}2${reset}) Yes ${dim}(runs: npm install -g @gsd-build/sdk)${reset}
+`);
+
+  rl.question(`  Choice ${dim}[1]${reset}: `, (answer) => {
+    answered = true;
+    rl.close();
+    const choice = answer.trim() || '1';
+    callback(choice === '2');
+  });
+}
+
 /**
  * Prompt for runtime selection
  */
@@ -4831,10 +4896,26 @@ function installAllRuntimes(runtimes, isGlobal, isInteractive) {
     }
   };
 
+  const afterFinalize = () => {
+    if (hasSdk) {
+      // --sdk flag: install without prompting
+      installSdk();
+    } else if (isInteractive) {
+      promptSdk((wantsSdk) => {
+        if (wantsSdk) installSdk();
+      });
+    }
+  };
+
+  const finalizeAndSdk = (shouldInstallStatusline) => {
+    finalize(shouldInstallStatusline);
+    afterFinalize();
+  };
+
   if (primaryStatuslineResult) {
-    handleStatusline(primaryStatuslineResult.settings, isInteractive, finalize);
+    handleStatusline(primaryStatuslineResult.settings, isInteractive, finalizeAndSdk);
   } else {
-    finalize(false);
+    finalizeAndSdk(false);
   }
 }
 
@@ -4882,6 +4963,8 @@ if (process.env.GSD_TEST_MODE) {
     writeManifest,
     reportLocalPatches,
     validateHookFields,
+    installSdk,
+    promptSdk,
   };
 } else {