diff --git a/src/cli/browser-cli-extension.test.ts b/src/cli/browser-cli-extension.test.ts
index 581813aa2..ab4ed334d 100644
--- a/src/cli/browser-cli-extension.test.ts
+++ b/src/cli/browser-cli-extension.test.ts
@@ -1,6 +1,7 @@
 import path from "node:path";
 import { Command } from "commander";
 import { beforeAll, beforeEach, describe, expect, it, vi } from "vitest";
+import { withEnvAsync } from "../test-utils/env.js";
 
 const copyToClipboard = vi.fn();
 const runtime = {
@@ -167,11 +168,8 @@ describe("browser extension install (fs-mocked)", () => {
   });
 
   it("copies extension path to clipboard", async () => {
-    const prev = process.env.OPENCLAW_STATE_DIR;
     const tmp = abs("/tmp/openclaw-ext-path");
-    process.env.OPENCLAW_STATE_DIR = tmp;
-
-    try {
+    await withEnvAsync({ OPENCLAW_STATE_DIR: tmp }, async () => {
       copyToClipboard.mockResolvedValue(true);
 
       const dir = path.join(tmp, "browser", "chrome-extension");
@@ -186,12 +184,6 @@ describe("browser extension install (fs-mocked)", () => {
 
       await program.parseAsync(["browser", "extension", "path"], { from: "user" });
       expect(copyToClipboard).toHaveBeenCalledWith(dir);
-    } finally {
-      if (prev === undefined) {
-        delete process.env.OPENCLAW_STATE_DIR;
-      } else {
-        process.env.OPENCLAW_STATE_DIR = prev;
-      }
-    }
+    });
   });
 });
diff --git a/src/config/sessions.test.ts b/src/config/sessions.test.ts
index 94d628dcd..13c2f6474 100644
--- a/src/config/sessions.test.ts
+++ b/src/config/sessions.test.ts
@@ -2,6 +2,7 @@ import fs from "node:fs/promises";
 import os from "node:os";
 import path from "node:path";
 import { afterAll, beforeAll, describe, expect, it } from "vitest";
+import { withEnv } from "../test-utils/env.js";
 import {
   buildGroupDisplayName,
   deriveSessionKey,
@@ -33,6 +34,9 @@ describe("sessions", () => {
     await fs.rm(fixtureRoot, { recursive: true, force: true });
   });
 
+  const withStateDir = <T>(stateDir: string, fn: () => T): T =>
+    withEnv({ OPENCLAW_STATE_DIR: stateDir }, fn);
+
   it("returns normalized per-sender key", () => {
     expect(deriveSessionKey("per-sender", { From: "whatsapp:+1555" })).toBe("+1555");
   });
@@ -428,9 +432,7 @@ describe("sessions", () => {
   });
 
   it("includes topic ids in session transcript filenames", () => {
-    const prev = process.env.OPENCLAW_STATE_DIR;
-    process.env.OPENCLAW_STATE_DIR = "/custom/state";
-    try {
+    withStateDir("/custom/state", () => {
       const sessionFile = resolveSessionTranscriptPath("sess-1", "main", 123);
       expect(sessionFile).toBe(
         path.join(
@@ -441,39 +443,23 @@ describe("sessions", () => {
           "sess-1-topic-123.jsonl",
         ),
       );
-    } finally {
-      if (prev === undefined) {
-        delete process.env.OPENCLAW_STATE_DIR;
-      } else {
-        process.env.OPENCLAW_STATE_DIR = prev;
-      }
-    }
+    });
   });
 
   it("uses agent id when resolving session file fallback paths", () => {
-    const prev = process.env.OPENCLAW_STATE_DIR;
-    process.env.OPENCLAW_STATE_DIR = "/custom/state";
-    try {
+    withStateDir("/custom/state", () => {
       const sessionFile = resolveSessionFilePath("sess-2", undefined, {
         agentId: "codex",
       });
       expect(sessionFile).toBe(
         path.join(path.resolve("/custom/state"), "agents", "codex", "sessions", "sess-2.jsonl"),
       );
-    } finally {
-      if (prev === undefined) {
-        delete process.env.OPENCLAW_STATE_DIR;
-      } else {
-        process.env.OPENCLAW_STATE_DIR = prev;
-      }
-    }
+    });
   });
 
   it("resolves cross-agent absolute sessionFile paths", () => {
-    const prev = process.env.OPENCLAW_STATE_DIR;
     const stateDir = path.resolve("/home/user/.openclaw");
-    process.env.OPENCLAW_STATE_DIR = stateDir;
-    try {
+    withStateDir(stateDir, () => {
       const bot2Session = path.join(stateDir, "agents", "bot2", "sessions", "sess-1.jsonl");
       // Agent bot1 resolves a sessionFile that belongs to agent bot2
       const sessionFile = resolveSessionFilePath(
@@ -482,19 +468,11 @@ describe("sessions", () => {
         { agentId: "bot1" },
       );
       expect(sessionFile).toBe(bot2Session);
-    } finally {
-      if (prev === undefined) {
-        delete process.env.OPENCLAW_STATE_DIR;
-      } else {
-        process.env.OPENCLAW_STATE_DIR = prev;
-      }
-    }
+    });
   });
 
   it("resolves cross-agent paths when OPENCLAW_STATE_DIR differs from stored paths", () => {
-    const prev = process.env.OPENCLAW_STATE_DIR;
-    process.env.OPENCLAW_STATE_DIR = path.resolve("/different/state");
-    try {
+    withStateDir(path.resolve("/different/state"), () => {
       const originalBase = path.resolve("/original/state");
       const bot2Session = path.join(originalBase, "agents", "bot2", "sessions", "sess-1.jsonl");
       // sessionFile was created under a different state dir than current env
@@ -504,19 +482,11 @@ describe("sessions", () => {
         { agentId: "bot1" },
       );
       expect(sessionFile).toBe(bot2Session);
-    } finally {
-      if (prev === undefined) {
-        delete process.env.OPENCLAW_STATE_DIR;
-      } else {
-        process.env.OPENCLAW_STATE_DIR = prev;
-      }
-    }
+    });
   });
 
   it("rejects absolute sessionFile paths outside agent sessions directories", () => {
-    const prev = process.env.OPENCLAW_STATE_DIR;
-    process.env.OPENCLAW_STATE_DIR = path.resolve("/home/user/.openclaw");
-    try {
+    withStateDir(path.resolve("/home/user/.openclaw"), () => {
       expect(() =>
         resolveSessionFilePath(
           "sess-1",
@@ -524,13 +494,7 @@ describe("sessions", () => {
           { agentId: "bot1" },
         ),
       ).toThrow(/within sessions directory/);
-    } finally {
-      if (prev === undefined) {
-        delete process.env.OPENCLAW_STATE_DIR;
-      } else {
-        process.env.OPENCLAW_STATE_DIR = prev;
-      }
-    }
+    });
   });
 
   it("updateSessionStoreEntry merges concurrent patches", async () => {
diff --git a/src/infra/session-cost-usage.test.ts b/src/infra/session-cost-usage.test.ts
index 5d584eefd..ba9e10b1f 100644
--- a/src/infra/session-cost-usage.test.ts
+++ b/src/infra/session-cost-usage.test.ts
@@ -3,6 +3,7 @@ import os from "node:os";
 import path from "node:path";
 import { describe, expect, it } from "vitest";
 import type { OpenClawConfig } from "../config/config.js";
+import { withEnvAsync } from "../test-utils/env.js";
 import {
   discoverAllSessions,
   loadCostUsageSummary,
@@ -12,6 +13,9 @@ import {
 } from "./session-cost-usage.js";
 
 describe("session cost usage", () => {
+  const withStateDir = async <T>(stateDir: string, fn: () => Promise<T>): Promise<T> =>
+    await withEnvAsync({ OPENCLAW_STATE_DIR: stateDir }, fn);
+
   it("aggregates daily totals with log cost and pricing fallback", async () => {
     const root = await fs.mkdtemp(path.join(os.tmpdir(), "openclaw-cost-"));
     const sessionsDir = path.join(root, "agents", "main", "sessions");
@@ -98,20 +102,12 @@ describe("session cost usage", () => {
       },
     } as unknown as OpenClawConfig;
 
-    const originalState = process.env.OPENCLAW_STATE_DIR;
-    process.env.OPENCLAW_STATE_DIR = root;
-    try {
+    await withStateDir(root, async () => {
       const summary = await loadCostUsageSummary({ days: 30, config });
       expect(summary.daily.length).toBe(1);
       expect(summary.totals.totalTokens).toBe(50);
       expect(summary.totals.totalCost).toBeCloseTo(0.03003, 5);
-    } finally {
-      if (originalState === undefined) {
-        delete process.env.OPENCLAW_STATE_DIR;
-      } else {
-        process.env.OPENCLAW_STATE_DIR = originalState;
-      }
-    }
+    });
   });
 
   it("summarizes a single session file", async () => {
@@ -225,22 +221,14 @@ describe("session cost usage", () => {
     const now = Date.now();
     await fs.utimes(sessionFile, now / 1000, now / 1000);
 
-    const originalState = process.env.OPENCLAW_STATE_DIR;
-    process.env.OPENCLAW_STATE_DIR = root;
-    try {
+    await withStateDir(root, async () => {
       const sessions = await discoverAllSessions({
         startMs: now - 7 * 24 * 60 * 60 * 1000,
         endMs: now - 24 * 60 * 60 * 1000,
       });
       expect(sessions.length).toBe(1);
       expect(sessions[0]?.sessionId).toBe("sess-late");
-    } finally {
-      if (originalState === undefined) {
-        delete process.env.OPENCLAW_STATE_DIR;
-      } else {
-        process.env.OPENCLAW_STATE_DIR = originalState;
-      }
-    }
+    });
   });
 
   it("resolves non-main absolute sessionFile using explicit agentId for cost summary", async () => {
@@ -270,9 +258,7 @@ describe("session cost usage", () => {
       "utf-8",
     );
 
-    const originalState = process.env.OPENCLAW_STATE_DIR;
-    process.env.OPENCLAW_STATE_DIR = root;
-    try {
+    await withStateDir(root, async () => {
       const summary = await loadSessionCostSummary({
         sessionId: "sess-worker-1",
         sessionEntry: {
@@ -284,13 +270,7 @@ describe("session cost usage", () => {
       });
       expect(summary?.totalTokens).toBe(18);
       expect(summary?.totalCost).toBeCloseTo(0.01, 5);
-    } finally {
-      if (originalState === undefined) {
-        delete process.env.OPENCLAW_STATE_DIR;
-      } else {
-        process.env.OPENCLAW_STATE_DIR = originalState;
-      }
-    }
+    });
   });
 
   it("resolves non-main absolute sessionFile using explicit agentId for timeseries", async () => {
@@ -316,9 +296,7 @@ describe("session cost usage", () => {
       "utf-8",
     );
 
-    const originalState = process.env.OPENCLAW_STATE_DIR;
-    process.env.OPENCLAW_STATE_DIR = root;
-    try {
+    await withStateDir(root, async () => {
       const timeseries = await loadSessionUsageTimeSeries({
         sessionId: "sess-worker-2",
         sessionEntry: {
@@ -330,13 +308,7 @@ describe("session cost usage", () => {
       });
       expect(timeseries?.points.length).toBe(1);
       expect(timeseries?.points[0]?.totalTokens).toBe(8);
-    } finally {
-      if (originalState === undefined) {
-        delete process.env.OPENCLAW_STATE_DIR;
-      } else {
-        process.env.OPENCLAW_STATE_DIR = originalState;
-      }
-    }
+    });
   });
 
   it("resolves non-main absolute sessionFile using explicit agentId for logs", async () => {
@@ -360,9 +332,7 @@ describe("session cost usage", () => {
       "utf-8",
     );
 
-    const originalState = process.env.OPENCLAW_STATE_DIR;
-    process.env.OPENCLAW_STATE_DIR = root;
-    try {
+    await withStateDir(root, async () => {
       const logs = await loadSessionLogs({
         sessionId: "sess-worker-3",
         sessionEntry: {
@@ -375,13 +345,7 @@ describe("session cost usage", () => {
       expect(logs).toHaveLength(1);
       expect(logs?.[0]?.content).toContain("hello worker");
       expect(logs?.[0]?.role).toBe("user");
-    } finally {
-      if (originalState === undefined) {
-        delete process.env.OPENCLAW_STATE_DIR;
-      } else {
-        process.env.OPENCLAW_STATE_DIR = originalState;
-      }
-    }
+    });
   });
 
   it("strips inbound and untrusted metadata blocks from session usage logs", async () => {
diff --git a/src/security/audit.test.ts b/src/security/audit.test.ts
index 6d7b155d6..876cbb3a4 100644
--- a/src/security/audit.test.ts
+++ b/src/security/audit.test.ts
@@ -4,6 +4,7 @@ import path from "node:path";
 import { afterAll, afterEach, beforeAll, beforeEach, describe, expect, it, vi } from "vitest";
 import type { ChannelPlugin } from "../channels/plugins/types.js";
 import type { OpenClawConfig } from "../config/config.js";
+import { withEnvAsync } from "../test-utils/env.js";
 import { collectPluginsCodeSafetyFindings } from "./audit-extra.js";
 import type { SecurityAuditOptions, SecurityAuditReport } from "./audit.js";
 import { runSecurityAudit } from "./audit.js";
@@ -102,19 +103,9 @@ describe("security audit", () => {
   };
 
   const withStateDir = async (label: string, fn: (tmp: string) => Promise<void>) => {
-    const prevStateDir = process.env.OPENCLAW_STATE_DIR;
     const tmp = await makeTmpDir(label);
-    process.env.OPENCLAW_STATE_DIR = tmp;
     await fs.mkdir(path.join(tmp, "credentials"), { recursive: true, mode: 0o700 });
-    try {
-      await fn(tmp);
-    } finally {
-      if (prevStateDir == null) {
-        delete process.env.OPENCLAW_STATE_DIR;
-      } else {
-        process.env.OPENCLAW_STATE_DIR = prevStateDir;
-      }
-    }
+    await withEnvAsync({ OPENCLAW_STATE_DIR: tmp }, async () => await fn(tmp));
   };
 
   beforeAll(async () => {
diff --git a/src/test-utils/env.test.ts b/src/test-utils/env.test.ts
index dce4e8946..07c01c097 100644
--- a/src/test-utils/env.test.ts
+++ b/src/test-utils/env.test.ts
@@ -53,4 +53,14 @@ describe("env test utils", () => {
 
     expect(process.env[key]).toBe(prev);
   });
+
+  it("withEnvAsync applies values only inside async callback", async () => {
+    const key = "OPENCLAW_ENV_TEST_ASYNC_OK";
+    const prev = process.env[key];
+
+    const seen = await withEnvAsync({ [key]: "inside" }, async () => process.env[key]);
+
+    expect(seen).toBe("inside");
+    expect(process.env[key]).toBe(prev);
+  });
 });