fix: finalize durable Pi lifecycle

backend/test/maintenance-gate.test.ts

@@ -1,5 +1,5 @@
 import { test, expect } from "vitest";
-import { existsSync, mkdtempSync, rmSync } from "node:fs";
+import { existsSync, mkdtempSync, rmSync, writeFileSync } from "node:fs";
 import { tmpdir } from "node:os";
 import { join } from "node:path";
 import { MaintenanceBarrier } from "../src/runtime/maintenance-gate.js";
@@ -45,3 +45,58 @@ test("durable activation survives recreation and deactivation removes the marker
     rmSync(directory, { recursive: true, force: true });
   }
 });
+
+test("activation reconciles active state when directory fsync fails after marker rename", async () => {
+  const directory = mkdtempSync(join(tmpdir(), "tht-maintenance-activate-fsync-"));
+  const marker = join(directory, "maintenance.json");
+  try {
+    const gate = new MaintenanceBarrier(marker, {
+      syncDirectory() { throw new Error("injected post-rename fsync failure"); },
+    });
+    await expect(gate.activate()).rejects.toThrow(/post-rename fsync failure/);
+    expect(existsSync(marker)).toBe(true);
+    expect(gate.status()).toEqual({ active: true, admissions: 0 });
+    expect(gate.acquire()).toBeUndefined();
+
+    const recovered = new MaintenanceBarrier(marker);
+    expect(recovered.status()).toEqual({ active: true, admissions: 0 });
+    expect(recovered.acquire()).toBeUndefined();
+  } finally {
+    rmSync(directory, { recursive: true, force: true });
+  }
+});
+
+test("deactivation reconciles inactive state when directory fsync fails after marker removal", async () => {
+  const directory = mkdtempSync(join(tmpdir(), "tht-maintenance-deactivate-fsync-"));
+  const marker = join(directory, "maintenance.json");
+  let failSync = false;
+  try {
+    const gate = new MaintenanceBarrier(marker, {
+      syncDirectory() {
+        if (failSync) throw new Error("injected post-remove fsync failure");
+      },
+    });
+    await gate.activate();
+    failSync = true;
+    expect(() => gate.deactivate()).toThrow(/post-remove fsync failure/);
+    expect(existsSync(marker)).toBe(false);
+    expect(gate.status()).toEqual({ active: false, admissions: 0 });
+    expect(gate.acquire()).toBeTypeOf("function");
+  } finally {
+    rmSync(directory, { recursive: true, force: true });
+  }
+});
+
+test("status and admission recover from a persistent marker even when memory started inactive", () => {
+  const directory = mkdtempSync(join(tmpdir(), "tht-maintenance-reconcile-"));
+  const marker = join(directory, "maintenance.json");
+  try {
+    const gate = new MaintenanceBarrier(marker);
+    expect(gate.status().active).toBe(false);
+    writeFileSync(marker, '{"version":1,"active":true}\n', { mode: 0o600 });
+    expect(gate.status()).toEqual({ active: true, admissions: 0 });
+    expect(gate.acquire()).toBeUndefined();
+  } finally {
+    rmSync(directory, { recursive: true, force: true });
+  }
+});