diff --git a/apps/browser-extension/package.json b/apps/browser-extension/package.json
index 7e65079cc..052a7fd7b 100644
--- a/apps/browser-extension/package.json
+++ b/apps/browser-extension/package.json
@@ -17,7 +17,7 @@
     "test": "vitest",
     "test:coverage": "vitest run --coverage",
     "test:e2e": "playwright test",
-    "test:e2e:build": "npm run build:chrome && playwright test",
+    "test:e2e:build": "node scripts/run-e2e.mjs",
     "lint": "eslint src",
     "lint:custom": "eslint",
     "lint:fix": "eslint src --fix",
diff --git a/apps/browser-extension/scripts/run-e2e.mjs b/apps/browser-extension/scripts/run-e2e.mjs
new file mode 100755
index 000000000..086b9fda6
--- /dev/null
+++ b/apps/browser-extension/scripts/run-e2e.mjs
@@ -0,0 +1,89 @@
+#!/usr/bin/env node
+// Build the Chrome extension for E2E testing and run the Playwright suite
+// against it.
+//
+// Resolves the local dev API URL from `dev.env` (or ALIASVAULT_API_URL / the
+// default) and exposes it to Playwright as ALIASVAULT_API_URL. The fixtures use
+// it to point the extension at that API instance at runtime and to create the
+// test user, so everything targets the same API.
+//
+// Usage:
+//   node scripts/run-e2e.mjs [extra playwright args]
+
+import { spawnSync } from "node:child_process";
+import { readFileSync } from "node:fs";
+import { fileURLToPath } from "node:url";
+import path from "node:path";
+import { argv, env, exit, platform } from "node:process";
+
+const scriptDir = path.dirname(fileURLToPath(import.meta.url));
+const extensionDir = path.resolve(scriptDir, "..");
+const repoRoot = path.resolve(extensionDir, "..", "..");
+const devEnvPath = path.join(repoRoot, "dev.env");
+
+// Default port layout, kept in sync with scripts/dev.sh.
+const DEFAULT_BASE_PORT = 5100;
+const DEFAULT_PORT_STRIDE = 10;
+
+/**
+ * Resolve the API URL the test extension should default to.
+ * @returns {string}
+ */
+function resolveApiUrl() {
+  if (env.ALIASVAULT_API_URL) {
+    return env.ALIASVAULT_API_URL;
+  }
+
+  try {
+    const devEnv = {};
+    for (const line of readFileSync(devEnvPath, "utf8").split("\n")) {
+      const match = line.match(/^\s*([A-Z_]+)\s*=\s*(.*?)\s*$/);
+      if (match) {
+        devEnv[match[1]] = match[2];
+      }
+    }
+
+    const base = Number(devEnv.AV_BASE_PORT ?? DEFAULT_BASE_PORT);
+    const stride = Number(devEnv.AV_PORT_STRIDE ?? DEFAULT_PORT_STRIDE);
+    const instance = Number(devEnv.AV_INSTANCE ?? 0);
+
+    if ([base, stride, instance].every(Number.isInteger)) {
+      return `http://localhost:${base + instance * stride}`;
+    }
+  } catch {
+    // No readable dev.env — fall through to the default below.
+  }
+
+  return `http://localhost:${DEFAULT_BASE_PORT}`;
+}
+
+const apiUrl = resolveApiUrl();
+console.log(`[e2e] Using API URL: ${apiUrl}`);
+
+// Expose the URL to the Playwright fixtures (global setup + per-test setup),
+// which configure the extension to talk to this API instance and create the
+// test user against it.
+const childEnv = {
+  ...env,
+  ALIASVAULT_API_URL: apiUrl,
+};
+
+/**
+ * Run a command with inherited stdio, exiting on failure.
+ * @param {string} command
+ * @param {string[]} commandArgs
+ */
+function run(command, commandArgs) {
+  const result = spawnSync(command, commandArgs, {
+    cwd: extensionDir,
+    env: childEnv,
+    stdio: "inherit",
+    shell: platform === "win32",
+  });
+  if (result.status !== 0) {
+    exit(result.status ?? 1);
+  }
+}
+
+run("npm", ["run", "build:chrome"]);
+run("npx", ["playwright", "test", ...argv.slice(2)]);
diff --git a/scripts/dev.sh b/scripts/dev.sh
index 1485a22f2..b12e9d27a 100755
--- a/scripts/dev.sh
+++ b/scripts/dev.sh
@@ -248,8 +248,7 @@ start_ext() {
     "Dev server  http://localhost:$EXT_PORT" \
     "API         http://localhost:$API_HTTP"
   cd "$ROOT_DIR/apps/browser-extension"
-  VITE_DEFAULT_API_URL="http://localhost:$API_HTTP" \
-    npm run dev:chrome -- --port "$EXT_PORT"
+  npm run dev:chrome -- --port "$EXT_PORT"
 }
 
 start_mobile() {