diff --git a/agents/entire-agent-pi/internal/pi/hooks.go b/agents/entire-agent-pi/internal/pi/hooks.go
index 187c2c1..02cf500 100644
--- a/agents/entire-agent-pi/internal/pi/hooks.go
+++ b/agents/entire-agent-pi/internal/pi/hooks.go
@@ -131,24 +131,31 @@ func (a *Agent) AreHooksInstalled() bool {
 
 func generateExtension() string {
 	return `import type { ExtensionAPI } from "@mariozechner/pi-coding-agent";
-import { execFileSync } from "node:child_process";
+import { execFile } from "node:child_process";
 
 export default function (pi: ExtensionAPI) {
-  function fireHook(hookName: string, data: Record<string, unknown>) {
-    try {
-      const json = JSON.stringify(data);
-      execFileSync("entire", ["hooks", "pi", hookName], {
-        input: json,
-        timeout: 10000,
-        stdio: ["pipe", "pipe", "pipe"],
-      });
-    } catch {
-      // best effort — don't block the agent
-    }
+  function fireHook(hookName: string, data: Record<string, unknown>): Promise<void> {
+    return new Promise((resolve) => {
+      try {
+        const child = execFile(
+          "entire",
+          ["hooks", "pi", hookName],
+          {
+            timeout: 10000,
+            windowsHide: true,
+          },
+          () => resolve(),
+        );
+        child.stdin?.end(JSON.stringify(data));
+      } catch {
+        // best effort — don't block the agent
+        resolve();
+      }
+    });
   }
 
   pi.on("session_start", async (_event, ctx) => {
-    fireHook("session_start", {
+    await fireHook("session_start", {
       type: "session_start",
       cwd: ctx.cwd,
       session_file: ctx.sessionManager.getSessionFile(),
@@ -156,7 +163,7 @@ export default function (pi: ExtensionAPI) {
   });
 
   pi.on("before_agent_start", async (event, ctx) => {
-    fireHook("before_agent_start", {
+    await fireHook("before_agent_start", {
       type: "before_agent_start",
       cwd: ctx.cwd,
       session_file: ctx.sessionManager.getSessionFile(),
@@ -165,7 +172,7 @@ export default function (pi: ExtensionAPI) {
   });
 
   pi.on("agent_end", async (_event, ctx) => {
-    fireHook("agent_end", {
+    await fireHook("agent_end", {
       type: "agent_end",
       cwd: ctx.cwd,
       session_file: ctx.sessionManager.getSessionFile(),
@@ -173,7 +180,7 @@ export default function (pi: ExtensionAPI) {
   });
 
   pi.on("session_shutdown", async () => {
-    fireHook("session_shutdown", {
+    await fireHook("session_shutdown", {
       type: "session_shutdown",
     });
   });
diff --git a/agents/entire-agent-pi/internal/pi/hooks_test.go b/agents/entire-agent-pi/internal/pi/hooks_test.go
index 3f3b435..24414d5 100644
--- a/agents/entire-agent-pi/internal/pi/hooks_test.go
+++ b/agents/entire-agent-pi/internal/pi/hooks_test.go
@@ -129,6 +129,69 @@ func TestParseHook_UnknownHook(t *testing.T) {
 	}
 }
 
+func TestGenerateExtension(t *testing.T) {
+	const want = `import type { ExtensionAPI } from "@mariozechner/pi-coding-agent";
+import { execFile } from "node:child_process";
+
+export default function (pi: ExtensionAPI) {
+  function fireHook(hookName: string, data: Record<string, unknown>): Promise<void> {
+    return new Promise((resolve) => {
+      try {
+        const child = execFile(
+          "entire",
+          ["hooks", "pi", hookName],
+          {
+            timeout: 10000,
+            windowsHide: true,
+          },
+          () => resolve(),
+        );
+        child.stdin?.end(JSON.stringify(data));
+      } catch {
+        // best effort — don't block the agent
+        resolve();
+      }
+    });
+  }
+
+  pi.on("session_start", async (_event, ctx) => {
+    await fireHook("session_start", {
+      type: "session_start",
+      cwd: ctx.cwd,
+      session_file: ctx.sessionManager.getSessionFile(),
+    });
+  });
+
+  pi.on("before_agent_start", async (event, ctx) => {
+    await fireHook("before_agent_start", {
+      type: "before_agent_start",
+      cwd: ctx.cwd,
+      session_file: ctx.sessionManager.getSessionFile(),
+      prompt: event.prompt,
+    });
+  });
+
+  pi.on("agent_end", async (_event, ctx) => {
+    await fireHook("agent_end", {
+      type: "agent_end",
+      cwd: ctx.cwd,
+      session_file: ctx.sessionManager.getSessionFile(),
+    });
+  });
+
+  pi.on("session_shutdown", async () => {
+    await fireHook("session_shutdown", {
+      type: "session_shutdown",
+    });
+  });
+}
+`
+
+	if got := generateExtension(); got != want {
+		t.Fatalf("generateExtension() mismatch\n--- got ---\n%s\n--- want ---\n%s", got, want)
+	}
+}
+
 func TestInstallAndUninstallHooks(t *testing.T) {
 	tmp := t.TempDir()
 	t.Setenv("ENTIRE_REPO_ROOT", tmp)
@@ -151,14 +214,13 @@ func TestInstallAndUninstallHooks(t *testing.T) {
 		t.Error("hooks should be installed after InstallHooks")
 	}
 
-	// Verify the extension file exists and contains expected content.
 	extPath := filepath.Join(tmp, extensionFile)
 	data, err := os.ReadFile(extPath)
 	if err != nil {
 		t.Fatal(err)
 	}
-	if len(data) == 0 {
-		t.Error("extension file is empty")
+	if string(data) != generateExtension() {
+		t.Fatal("installed extension does not match generated extension")
 	}
 
 	// Idempotent install should return 0.