diff --git a/packages/devtools/README.md b/packages/devtools/README.md
index 67006d67..24320681 100644
--- a/packages/devtools/README.md
+++ b/packages/devtools/README.md
@@ -19,6 +19,8 @@ npm install @json-render/devtools
 
 This package is pulled in automatically by every framework adapter. Install it directly only if you're building your own adapter or using the stream tap utilities on the server.
 
+Adapters detect production through the bundler's `process.env.NODE_ENV` replacement, including in browsers without a `process` global.
+
 ## What you get
 
 - **Event store** — capped ring buffer with `push`, `subscribe`, `snapshot`, `clear`.
diff --git a/packages/devtools/src/prod-guard.test.ts b/packages/devtools/src/prod-guard.test.ts
index 2799373d..4fb3c08e 100644
--- a/packages/devtools/src/prod-guard.test.ts
+++ b/packages/devtools/src/prod-guard.test.ts
@@ -1,10 +1,19 @@
-import { afterEach, describe, expect, it } from "vitest";
+// @vitest-environment node
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { mkdtemp, readFile, rm } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { fileURLToPath } from "node:url";
+import { runInNewContext } from "node:vm";
+import { build } from "tsup";
 import { isProduction } from "./prod-guard";
 
 describe("isProduction", () => {
   const original = process.env.NODE_ENV;
   afterEach(() => {
-    process.env.NODE_ENV = original;
+    vi.unstubAllGlobals();
+    if (original === undefined) delete process.env.NODE_ENV;
+    else process.env.NODE_ENV = original;
   });
 
   it("returns false when NODE_ENV is not production", () => {
@@ -21,4 +30,31 @@ describe("isProduction", () => {
     delete process.env.NODE_ENV;
     expect(isProduction()).toBe(false);
   });
+
+  it("returns false in an unbundled browser without process", () => {
+    vi.stubGlobal("process", undefined);
+    expect(isProduction()).toBe(false);
+  });
+
+  it("detects a production bundle without a browser process global", async () => {
+    const outDir = await mkdtemp(join(tmpdir(), "json-render-prod-guard-"));
+    try {
+      await build({
+        entry: [fileURLToPath(new URL("./prod-guard.ts", import.meta.url))],
+        outDir,
+        format: ["cjs"],
+        config: false,
+        silent: true,
+        define: { "process.env.NODE_ENV": '"production"' },
+      });
+      const source = await readFile(join(outDir, "prod-guard.js"), "utf8");
+      expect(
+        runInNewContext(`${source}\nmodule.exports.isProduction()`, {
+          module: { exports: {} },
+        }),
+      ).toBe(true);
+    } finally {
+      await rm(outDir, { recursive: true, force: true });
+    }
+  });
 });
diff --git a/packages/devtools/src/prod-guard.ts b/packages/devtools/src/prod-guard.ts
index 098a23cb..20abc6e7 100644
--- a/packages/devtools/src/prod-guard.ts
+++ b/packages/devtools/src/prod-guard.ts
@@ -4,12 +4,13 @@
  * nothing in production builds.
  *
  * Tree-shaken bundlers will fold constant `process.env.NODE_ENV` checks.
- * Consumers that run in browsers without `process` also work because the
- * typeof check guards the access.
+ * Check the expression directly so bundler replacement still works when
+ * browsers have no `process` global. Unbundled browsers fall back to false.
  */
 export function isProduction(): boolean {
-  if (typeof process !== "undefined" && process.env) {
+  try {
     return process.env.NODE_ENV === "production";
+  } catch {
+    return false;
   }
-  return false;
 }