diff --git a/.github/workflows/agent-task-contracts.yml b/.github/workflows/agent-task-contracts.yml
index aa93f301f..f4cd059d5 100644
--- a/.github/workflows/agent-task-contracts.yml
+++ b/.github/workflows/agent-task-contracts.yml
@@ -5,6 +5,7 @@ on:
     paths:
       - ".github/scripts/run-agent-task/**"
       - ".github/workflows/agent-task-contracts.yml"
+      - ".github/workflows/build-php-wasm-mysqli-poll-overlay.yml"
       - ".github/workflows/run-agent-task.yml"
       - "contracts/agent-task-workflow-request.fixture.json"
       - "contracts/run-agent-task-reusable-workflow-interface.v1.json"
@@ -48,10 +49,12 @@ on:
       - "packages/runtime-core/src/bounded-runtime-plan.ts"
       - "tests/bounded-*.test.ts"
       - "tests/disposable-mysql-mysqli.integration.test.ts"
+      - "tests/mysqli-poll.integration.test.ts"
   push:
     paths:
       - ".github/scripts/run-agent-task/**"
       - ".github/workflows/agent-task-contracts.yml"
+      - ".github/workflows/build-php-wasm-mysqli-poll-overlay.yml"
       - ".github/workflows/run-agent-task.yml"
       - "contracts/agent-task-workflow-request.fixture.json"
       - "contracts/run-agent-task-reusable-workflow-interface.v1.json"
@@ -95,6 +98,7 @@ on:
       - "packages/runtime-core/src/bounded-runtime-plan.ts"
       - "tests/bounded-*.test.ts"
       - "tests/disposable-mysql-mysqli.integration.test.ts"
+      - "tests/mysqli-poll.integration.test.ts"
 
 jobs:
   contracts:
@@ -132,6 +136,7 @@ jobs:
       - run: npm run test:bounded-recipe-plan-integration
       - run: npm run test:recipe-step-continuation
       - run: npm run test:disposable-mysql-mysqli-e2e
+      - run: npm run test:mysqli-poll-integration
       - run: npm run test:runtime-sources-playground-integration
       - run: npm run test:playground-phpunit-readonly-cache-integration
       - run: npm run test:playground-custom-archive-cache
@@ -152,4 +157,4 @@ jobs:
       - uses: actions/checkout@v4
       - uses: docker://rhysd/actionlint:1.7.7
         with:
-          args: .github/workflows/agent-task-contracts.yml .github/workflows/run-agent-task.yml
+          args: .github/workflows/agent-task-contracts.yml .github/workflows/build-php-wasm-mysqli-poll-overlay.yml .github/workflows/run-agent-task.yml
diff --git a/.github/workflows/build-php-wasm-mysqli-poll-overlay.yml b/.github/workflows/build-php-wasm-mysqli-poll-overlay.yml
new file mode 100644
index 000000000..43a1fc8ef
--- /dev/null
+++ b/.github/workflows/build-php-wasm-mysqli-poll-overlay.yml
@@ -0,0 +1,89 @@
+name: Build PHP-WASM mysqli_poll Overlay
+
+on:
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  build-and-verify:
+    runs-on: ubuntu-latest
+    timeout-minutes: 300
+    env:
+      PLAYGROUND_SHA: 581c7c172428159eb4e6c5309054a568cd39a97a
+      PLAYGROUND_ARCHIVE_SHA256: b9526f0fb0839cb255d0ae8bb815c548aafe603a3a49b1b8701442a0c1afca8e
+      PATCH_SHA: d746c930477eae3d726f754753eb92692ad30855
+      PATCH_SHA256: f42ffb44f21e736c3fbf6e504e01e4a07207f8d764c38ce1f9c81db80d614a04
+      PHP_VERSION: "8.3.32"
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: npm
+
+      - name: Reclaim runner disk
+        run: |
+          sudo rm -rf /usr/local/lib/android /usr/share/dotnet /opt/ghc
+          docker system prune --all --force
+
+      - name: Materialize pinned Playground source
+        working-directory: ${{ runner.temp }}
+        run: |
+          curl --fail --location --retry 3 --output playground.tar.gz "https://github.com/WordPress/wordpress-playground/archive/${PLAYGROUND_SHA}.tar.gz"
+          test "$(shasum -a 256 playground.tar.gz | cut -d ' ' -f 1)" = "${PLAYGROUND_ARCHIVE_SHA256}"
+          curl --fail --location --retry 3 --output mysqli-poll.patch "https://github.com/WordPress/wordpress-playground/commit/${PATCH_SHA}.patch"
+          test "$(shasum -a 256 mysqli-poll.patch | cut -d ' ' -f 1)" = "${PATCH_SHA256}"
+          mkdir wordpress-playground
+          tar -xzf playground.tar.gz --strip-components=1 -C wordpress-playground
+          git -C wordpress-playground apply --check --include=packages/php-wasm/compile/php/Dockerfile --include=packages/php-wasm/compile/php/php_wasm.c ../mysqli-poll.patch
+          git -C wordpress-playground apply --include=packages/php-wasm/compile/php/Dockerfile --include=packages/php-wasm/compile/php/php_wasm.c ../mysqli-poll.patch
+
+      - name: Install Playground build dependencies
+        working-directory: ${{ runner.temp }}/wordpress-playground
+        run: npm ci
+
+      - name: Compile PHP 8.3 Node runtimes
+        working-directory: ${{ runner.temp }}/wordpress-playground
+        run: |
+          node packages/php-wasm/compile/build.js --PLATFORM=node --PHP_VERSION="${PHP_VERSION}"
+          node packages/php-wasm/compile/build.js --PLATFORM=node --PHP_VERSION="${PHP_VERSION}" --WITH_JSPI=yes
+          npx nx build php-wasm-node-8-3
+
+      - name: Pack overlay and record provenance
+        working-directory: ${{ runner.temp }}/wordpress-playground
+        run: |
+          mkdir -p "${GITHUB_WORKSPACE}/artifacts"
+          npm pack ./dist/packages/php-wasm/node-builds/8-3 --pack-destination "${GITHUB_WORKSPACE}/artifacts"
+          ARTIFACT_PATH="$(find "${GITHUB_WORKSPACE}/artifacts" -name '*.tgz' -type f -print -quit)"
+          ARTIFACT_SHA256="$(shasum -a 256 "${ARTIFACT_PATH}" | cut -d ' ' -f 1)"
+          node -e 'const fs = require("node:fs"); fs.writeFileSync(process.argv[1], JSON.stringify({ schema: "wp-codebox/php-wasm-overlay-provenance/v1", upstream: { repository: "WordPress/wordpress-playground", revision: process.env.PLAYGROUND_SHA }, patch: { revision: process.env.PATCH_SHA, sha256: process.env.PATCH_SHA256, files: ["packages/php-wasm/compile/php/Dockerfile", "packages/php-wasm/compile/php/php_wasm.c"] }, artifact: { file: require("node:path").basename(process.argv[2]), sha256: process.argv[3] } }, null, 2) + "\n")' "${GITHUB_WORKSPACE}/artifacts/provenance.json" "${ARTIFACT_PATH}" "${ARTIFACT_SHA256}"
+
+      - name: Reclaim build disk
+        run: |
+          docker system prune --all --force
+          rm -rf "${RUNNER_TEMP}/wordpress-playground" "${RUNNER_TEMP}/playground.tar.gz" "${RUNNER_TEMP}/mysqli-poll.patch"
+
+      - name: Install WP Codebox and overlay
+        run: |
+          npm ci
+          npm install --no-save --ignore-scripts "$(find "${GITHUB_WORKSPACE}/artifacts" -name '*.tgz' -type f -print -quit)"
+          npm run build
+
+      - name: Verify mysqli_poll against MariaDB
+        env:
+          PLAYGROUND_NO_JSPI_RESPAWN: "1"
+          WP_CODEBOX_PHP_WASM_MODE: asyncify
+        run: npm run test:mysqli-poll-integration
+
+      - name: Upload immutable overlay
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: php-wasm-node-8-3-mysqli-poll-${{ github.sha }}
+          path: |
+            artifacts/*.tgz
+            artifacts/provenance.json
+          if-no-files-found: error
diff --git a/.gitignore b/.gitignore
index 642ae1bc8..c7e8e0f06 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,6 +2,9 @@ node_modules/
 vendor/
 dist/
 artifacts/
+runtime-overlays/*
+!runtime-overlays/php-wasm-node-8-3-3.1.46.tgz
+!runtime-overlays/provenance.json
 scripts/uploads/
 *.tsbuildinfo
 .DS_Store
diff --git a/npm-shrinkwrap.json b/npm-shrinkwrap.json
index 4d699a9ad..08e886bc6 100644
--- a/npm-shrinkwrap.json
+++ b/npm-shrinkwrap.json
@@ -16,6 +16,7 @@
         "@automattic/wp-codebox-cli": "file:packages/cli",
         "@automattic/wp-codebox-core": "file:packages/runtime-core",
         "@automattic/wp-codebox-playground": "file:packages/runtime-playground",
+        "@php-wasm/node-8-3": "file:runtime-overlays/php-wasm-node-8-3-3.1.46.tgz",
         "@php-wasm/node-8-4": "3.1.46",
         "@php-wasm/universal": "3.1.46",
         "@types/pngjs": "^6.0.5",
@@ -1834,8 +1835,8 @@
     },
     "node_modules/@php-wasm/node-8-3": {
       "version": "3.1.46",
-      "resolved": "https://registry.npmjs.org/@php-wasm/node-8-3/-/node-8-3-3.1.46.tgz",
-      "integrity": "sha512-ZSH1rPvVuhIYJkGE/GRkQtv7RoQlO0IMWkHLJGt+JrTeaDxxm8Mv/F0H67MrA80q43zzNdNQaUEPn+ZrN/GSwg==",
+      "resolved": "file:runtime-overlays/php-wasm-node-8-3-3.1.46.tgz",
+      "integrity": "sha512-dnBmSZR9uki2wiXFpXVRFmH8Azg/AC+TIAcKoZgv1L2j6wSagSF+UG7LqEbqJMzMs+cY72c/4J1bLEY66N5P/g==",
       "license": "GPL-2.0-or-later",
       "dependencies": {
         "@php-wasm/universal": "3.1.46",
diff --git a/package.json b/package.json
index cbadb166b..ea13a90c6 100644
--- a/package.json
+++ b/package.json
@@ -82,6 +82,8 @@
     "npm-shrinkwrap.json",
     "scripts/apply-development-patches.mjs",
     "patches",
+    "runtime-overlays/php-wasm-node-8-3-3.1.46.tgz",
+    "runtime-overlays/provenance.json",
     "README.md",
     "LICENSE"
   ],
@@ -288,6 +290,7 @@
     "test:managed-database-diagnostics": "tsx tests/managed-database-diagnostics.test.ts",
     "test:runtime-services-lifecycle": "tsx tests/runtime-services-lifecycle.test.ts",
     "test:native-mariadb-runtime-service-integration": "tsx tests/native-mariadb-runtime-service.integration.test.ts",
+    "test:mysqli-poll-integration": "tsx tests/mysqli-poll.integration.test.ts",
     "test:disposable-mysql-mysqli-e2e": "tsx tests/disposable-mysql-mysqli.integration.test.ts",
     "test:runtime-contract-manifest": "tsx tests/runtime-contract-manifest.test.ts",
     "test:runtime-contract-package-exports": "tsx tests/runtime-contract-package-exports.test.ts",
@@ -338,6 +341,7 @@
     "@automattic/wp-codebox-cli": "file:packages/cli",
     "@automattic/wp-codebox-core": "file:packages/runtime-core",
     "@automattic/wp-codebox-playground": "file:packages/runtime-playground",
+    "@php-wasm/node-8-3": "file:runtime-overlays/php-wasm-node-8-3-3.1.46.tgz",
     "@php-wasm/node-8-4": "3.1.46",
     "@php-wasm/universal": "3.1.46",
     "@types/pngjs": "^6.0.5",
@@ -459,8 +463,8 @@
     "on-finished": "^2.4.1",
     "once": "^1.4.0",
     "pako": "^1.0.11",
-    "patch-package": "^8.0.1",
     "parseurl": "^1.3.3",
+    "patch-package": "^8.0.1",
     "path-expression-matcher": "^1.5.0",
     "path-to-regexp": "^0.1.13",
     "pify": "^4.0.1",
diff --git a/patches/README.md b/patches/README.md
index 694b2cb90..94eeca6c5 100644
--- a/patches/README.md
+++ b/patches/README.md
@@ -17,3 +17,12 @@ the released CLI's log-only behavior.
 Without this narrow terminalization, a poisoned PHP-WASM worker remains alive
 and leaves the parent request pending until the recipe timeout. Remove the patch
 after the Playground CLI ships the same worker terminalization behavior.
+
+The manual `build-php-wasm-mysqli-poll-overlay.yml` workflow carries the C-level
+`select()` wrapper and Asyncify imports from WordPress Playground PR
+[#4170](https://github.com/WordPress/wordpress-playground/pull/4170). It
+checksum-verifies the immutable patch and Playground revision
+`581c7c172428159eb4e6c5309054a568cd39a97a`, rebuilds the PHP 8.3.32 Node
+package, and verifies `mysqli_poll()` against MariaDB before uploading the
+package and provenance. Remove the patch, vendored package, and workflow after
+a published Playground package contains the same fix.
diff --git a/runtime-overlays/php-wasm-node-8-3-3.1.46.tgz b/runtime-overlays/php-wasm-node-8-3-3.1.46.tgz
new file mode 100644
index 000000000..54f48818e
Binary files /dev/null and b/runtime-overlays/php-wasm-node-8-3-3.1.46.tgz differ
diff --git a/runtime-overlays/provenance.json b/runtime-overlays/provenance.json
new file mode 100644
index 000000000..852edc5fe
--- /dev/null
+++ b/runtime-overlays/provenance.json
@@ -0,0 +1,19 @@
+{
+  "schema": "wp-codebox/php-wasm-overlay-provenance/v1",
+  "upstream": {
+    "repository": "WordPress/wordpress-playground",
+    "revision": "581c7c172428159eb4e6c5309054a568cd39a97a"
+  },
+  "patch": {
+    "revision": "d746c930477eae3d726f754753eb92692ad30855",
+    "sha256": "f42ffb44f21e736c3fbf6e504e01e4a07207f8d764c38ce1f9c81db80d614a04",
+    "files": [
+      "packages/php-wasm/compile/php/Dockerfile",
+      "packages/php-wasm/compile/php/php_wasm.c"
+    ]
+  },
+  "artifact": {
+    "file": "php-wasm-node-8-3-3.1.46.tgz",
+    "sha256": "109c079c958e1ab35ebcd098bdd895b080e2c5405b147f93ecb04e768c723553"
+  }
+}
diff --git a/tests/mysqli-poll.integration.test.ts b/tests/mysqli-poll.integration.test.ts
new file mode 100644
index 000000000..1bfe4a865
--- /dev/null
+++ b/tests/mysqli-poll.integration.test.ts
@@ -0,0 +1,88 @@
+import assert from "node:assert/strict"
+import { mkdtemp, rm, writeFile } from "node:fs/promises"
+import { tmpdir } from "node:os"
+import { join } from "node:path"
+import { runRecipe } from "../packages/cli/src/commands/recipe-run.ts"
+
+const directory = await mkdtemp(join(tmpdir(), "wp-codebox-mysqli-poll-"))
+try {
+  const recipePath = join(directory, "recipe.json")
+  const code = `
+mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
+$connect = static function (): mysqli {
+    $db = mysqli_init();
+    mysqli_real_connect($db, getenv('DB_HOST'), getenv('DB_USER'), getenv('DB_PASSWORD'), getenv('DB_NAME'), (int) getenv('DB_PORT'));
+    return $db;
+};
+$first = $connect();
+$second = $connect();
+$first->query('CREATE TABLE poll_lock (id INT PRIMARY KEY) ENGINE=InnoDB');
+$first->query('INSERT INTO poll_lock VALUES (1)');
+$first->query('START TRANSACTION');
+$first->query('SELECT id FROM poll_lock WHERE id = 1 FOR UPDATE');
+$second->query('SELECT id FROM poll_lock WHERE id = 1 FOR UPDATE', MYSQLI_ASYNC);
+$read = array($second);
+$error = array();
+$reject = array();
+$started = microtime(true);
+$ready = mysqli_poll($read, $error, $reject, 0, 100000);
+$elapsed_ms = (microtime(true) - $started) * 1000;
+$timeout_set_counts = array(count($read), count($error), count($reject));
+$first->query('ROLLBACK');
+$cleanup_ready = false;
+for ($attempt = 0; $attempt < 20; $attempt++) {
+    $read = array($second);
+    $error = array();
+    $reject = array();
+    if (mysqli_poll($read, $error, $reject, 0, 100000) > 0) {
+        $cleanup_ready = true;
+        break;
+    }
+}
+if ($cleanup_ready) {
+    $second->reap_async_query();
+}
+$first->query('DROP TABLE poll_lock');
+echo json_encode(array(
+    'ready' => $ready,
+    'elapsed_ms' => $elapsed_ms,
+    'timeout_set_counts' => $timeout_set_counts,
+    'cleanup_ready' => $cleanup_ready,
+));
+`
+  await writeFile(recipePath, JSON.stringify({
+    schema: "wp-codebox/workspace-recipe/v1",
+    runtime: { phpVersion: "8.3" },
+    inputs: {
+      services: [{
+        id: "mariadb",
+        kind: "mysql",
+        configuration: { engine: "mariadb" },
+        outputs: { host: "DB_HOST", port: "DB_PORT", username: "DB_USER", password: "DB_PASSWORD", database: "DB_NAME" },
+      }],
+    },
+    workflow: { steps: [{ command: "wordpress.run-php", args: [`code=${code}`] }] },
+  }))
+
+  const result = await runRecipe({
+    recipePath,
+    previewHoldBlocking: false,
+    previewLeaseRequested: false,
+    previewLeaseChild: false,
+    timeoutMs: 180_000,
+    json: true,
+    summary: false,
+    dryRun: false,
+    externalServiceWritesApproved: false,
+  })
+  assert.equal(result.success, true, JSON.stringify(result))
+  const output = JSON.parse(result.executions.at(-1)?.stdout.trim() ?? "{}")
+  assert.equal(output.ready, 0)
+  assert.ok(output.elapsed_ms >= 50, `mysqli_poll returned too early after ${output.elapsed_ms}ms`)
+  assert.ok(output.elapsed_ms < 2_000, `mysqli_poll exceeded its timeout: ${output.elapsed_ms}ms`)
+  assert.deepEqual(output.timeout_set_counts, [0, 0, 0])
+  assert.equal(output.cleanup_ready, true)
+  console.log("mysqli_poll MariaDB integration passed")
+} finally {
+  await rm(directory, { recursive: true, force: true })
+}