test: improve CI stability for performance and utility test suite

.babelrc.js

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+module.exports = {
+  presets: ['@babel/preset-env']
+}; 

.cursor/rules/README.md

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+# Cursor Rules Documentation
+
+This directory contains **Cursor AI rules** for the **Contentstack JavaScript Content Delivery SDK** (`contentstack` on npm) — CDA client development in this repository.
+
+## Rules overview
+
+| Rule | Role |
+|------|------|
+| [`dev-workflow.md`](dev-workflow.md) | Branches, lint/tests before PR, build + version bump guidance, links to skills |
+| [`javascript.mdc`](javascript.mdc) | JavaScript / TypeScript declaration style: `src/`, `webpack/`, root `index.d.ts` |
+| [`contentstack-javascript-cda.mdc`](contentstack-javascript-cda.mdc) | CDA SDK patterns: `Stack`, delivery token, host/region, request/cache/live preview |
+| [`testing.mdc`](testing.mdc) | Jest e2e (`test/**/*.js`) and TypeScript tests; `test/config.js` env |
+| [`code-review.mdc`](code-review.mdc) | PR checklist: JSDoc, `index.d.ts`, compat, errors, tests, CDA semantics (**always applied**) |
+
+## Rule application
+
+Rules load from **globs** and **`alwaysApply`** in each file's frontmatter.
+
+| Context | Typical rules |
+|---------|----------------|
+| **Every chat / session** | [`code-review.mdc`](code-review.mdc) (`alwaysApply: true`) |
+| **Most project files** | [`dev-workflow.md`](dev-workflow.md) — `**/*.js`, `**/*.ts`, `**/*.json` |
+| **SDK implementation** | [`javascript.mdc`](javascript.mdc) + [`contentstack-javascript-cda.mdc`](contentstack-javascript-cda.mdc) for `src/**/*.js` |
+| **Build config** | [`javascript.mdc`](javascript.mdc) for `webpack/**/*.js` |
+| **Public types** | [`javascript.mdc`](javascript.mdc) for `index.d.ts` |
+| **Tests** | [`testing.mdc`](testing.mdc) for `test/**/*.js`, `test/**/*.ts` |
+
+Overlaps are expected (e.g. editing `src/core/stack.js` can match `dev-workflow`, `javascript`, and `contentstack-javascript-cda`).
+
+## Usage
+
+- Rules load automatically when opened files match their globs (`code-review` is always in context).
+- You can **@ mention** rule files in chat when supported.
+
+## Quick reference table
+
+| File | `alwaysApply` | Globs (summary) |
+|------|---------------|-----------------|
+| `dev-workflow.md` | no | `**/*.js`, `**/*.ts`, `**/*.json` |
+| `javascript.mdc` | no | `src/**/*.js`, `webpack/**/*.js`, `index.d.ts` |
+| `contentstack-javascript-cda.mdc` | no | `src/**/*.js` |
+| `testing.mdc` | no | `test/**/*.js`, `test/**/*.ts` |
+| `code-review.mdc` | **yes** | — |
+
+## Skills & maintenance
+
+- Deeper playbooks: [`skills/README.md`](../../skills/README.md).
+- Repo agent entry: [`AGENTS.md`](../../AGENTS.md).
+- When directories change, update **globs** in rule frontmatter; keep rules short and put detail in `skills/*/SKILL.md`.

.cursor/rules/code-review.mdc

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+---
+description: "PR review themes — API docs, compatibility, errors, security, tests (CDA SDK)"
+alwaysApply: true
+---
+
+# Code review checklist (CDA JavaScript SDK)
+
+Apply when reviewing changes to the **`contentstack`** npm package (Content Delivery API client).
+
+## Public API & documentation
+
+- **JSDoc** updated for new or changed public methods/classes (params, return shape, examples), matching style in `src/core/contentstack.js` / `src/core/stack.js`.
+- **`index.d.ts`** updated when TypeScript consumers would see different signatures or new exports.
+
+## Backward compatibility
+
+- Avoid breaking changes to exported function signatures, option objects, or default behavior without a major version rationale.
+- If behavior changes, ensure **callers inside `src/`** and tests reflect the new contract.
+
+## Errors & safety
+
+- HTTP failures should continue to reject with a predictable shape from **`src/core/lib/request.js`** where applicable (**`error_message`**, **`error_code`**, **`errors`**, **`status`**, **`statusText`**).
+- Do not log full **delivery_token**, **preview_token**, **management_token**, or **api_key** values.
+- Respect **null/undefined** edge cases for optional API fields.
+
+## Dependencies & supply chain
+
+- New **dependencies** should be justified (size, maintenance, license).
+- Lockfile and **`package.json`** version bumps should be minimal and reviewable.
+
+## Tests
+
+- **Jest** tests for new logic or regressions under **`test/`** (JS and/or **`test/typescript/`** as appropriate).
+- Live stack tests must remain compatible with **`test/config.js`** env requirements; document new env needs in **`test/README.md`** or comments near the harness — never commit credentials.
+
+## Security & privacy
+
+- No hardcoded credentials; no accidental exposure of customer content in logs or error messages.

.cursor/rules/contentstack-javascript-cda.mdc

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+---
+description: "Contentstack CDA SDK patterns in src/core (Content Delivery API)"
+globs: ["src/**/*.js"]
+alwaysApply: false
+---
+
+# Contentstack CDA SDK (`src/core/`)
+
+This package implements the **Content Delivery API (CDA)** read client, not the Content Management API (CMA).
+
+## Stack & config
+
+- **`Contentstack.Stack(options)`** (`src/core/stack.js`) — **`api_key`**, **`delivery_token`**, **`environment`**; optional **`region`**, **`branch`**, **`host`**, **`live_preview`**, **`plugins`**, **`fetchOptions`** (timeout, retries, `retryCondition`, `logHandler`, etc.).
+- Default CDN paths and version come from **`config.js`** at the repo root; regional hosts follow existing `stack.js` logic (e.g. `{region}-cdn.contentstack.com`).
+
+## HTTP & errors
+
+- Requests are built in **`src/core/lib/request.js`**: query serialization, **`fetch`**, default retries on **408** / **429** (configurable), plugin hooks **`onRequest`** / **`onResponse`**.
+- Failed responses reject with objects carrying **`error_message`**, **`error_code`**, **`errors`**, **`status`**, **`statusText`** when JSON parsing succeeds — keep new code compatible with this shape.
+
+## Modules
+
+- **Entry, Query, Assets, Taxonomy, Result**, etc. live under **`src/core/modules/`** — follow neighboring patterns for chaining, parameters, and URL assembly.
+- **Cache**: policies and providers under **`src/core/cache.js`** and **`src/core/cache-provider/`**.
+
+## Live preview
+
+- When **`live_preview.enable`** is true, **`management_token`** vs **`preview_token`** affect host selection — mirror existing `stack.js` behavior and tests under **`test/live-preview/`**.
+
+## Runtime targets
+
+- **`src/runtime/node|web|react-native|nativescript/`** supply **`http`** and **`localstorage`** — changes that affect networking or storage must consider **all** bundled targets.
+
+## Docs
+
+- Align behavior with the official [Content Delivery API](https://www.contentstack.com/docs/developers/apis/content-delivery-api/) documentation.

.cursor/rules/dev-workflow.md

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+---
+description: "Branches, tests, and PR expectations for contentstack-javascript (CDA SDK)"
+globs: ["**/*.js", "**/*.ts", "**/*.json"]
+alwaysApply: false
+---
+
+# Development workflow — Contentstack JavaScript CDA SDK
+
+## Branches
+
+- Follow team Git conventions (e.g. feature branches off the repo’s default integration branch).
+- Do not commit permanent `test.only`, `it.only`, `describe.only`, or skipped tests meant for CI.
+
+## Before opening a PR
+
+1. **`npm run lint`** — ESLint must pass on `src` and `test`.
+2. **`npm test`** — Runs **`pretest`** → **`npm run build`**, then **`test:e2e`** and **`test:typescript`**. For live stack tests, set env vars (see **`test/config.js`**: `HOST`, `API_KEY`, `DELIVERY_TOKEN`, `ENVIRONMENT`). Never commit secrets or `.env` with real tokens.
+3. **Version bump** — When the PR introduces **user-visible or release-worthy** SDK behavior (new API, bug fix shipped to npm, or a **breaking** change), update **`version`** in `package.json` per **semver** (patch / minor / major). Docs-only or test-only changes may omit a bump per team practice; match sibling PRs when unsure.
+
+## PR expectations (summary)
+
+- **User-facing changes** — JSDoc on public methods; update **`index.d.ts`** when the public TypeScript surface changes.
+- **Behavior** — Preserve backward compatibility unless the change is explicitly breaking and documented.
+- **Errors** — Keep rejection shapes consistent with **`src/core/lib/request.js`** (`error_message`, `error_code`, `errors`, `status`, `statusText` where applicable). Do not log full **delivery_token** or **management_token** / **preview_token** values in new code.
+- **Tests** — Add or adjust Jest tests under **`test/`** for new behavior; live tests require the env contract in **`test/config.js`**.
+
+## Quick links
+
+- Agent overview: repo root `AGENTS.md`
+- CDA patterns: `skills/contentstack-javascript-cda/SKILL.md`
+- HTTP / retries / plugins: `skills/framework/SKILL.md`

.cursor/rules/javascript.mdc

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+---
+description: "JavaScript/TypeScript conventions for src, webpack, and index.d.ts"
+globs:
+  - "src/**/*.js"
+  - "webpack/**/*.js"
+  - "index.d.ts"
+alwaysApply: false
+---
+
+# JavaScript & types (this repo)
+
+## Runtime & modules
+
+- **Source** is **ES modules** under `src/` (`import` / `export`). Webpack resolves aliases such as **`runtime/http.js`** per target (`webpack/webpack.*.js`).
+- **`index.d.ts`** is the public TypeScript surface for npm consumers; keep it aligned with `src/core/` JSDoc and exports.
+
+## Style & tooling
+
+- **ESLint** uses **`eslint-config-standard`** and **`@babel/eslint-parser`**. This repo **requires semicolons** and related rules in **`.eslintrc.js`** — match existing `src/core/` style rather than semicolon-free Standard.
+- **Environment**: ESLint `es2020`, `node`, `browser`, `jest`.
+
+## Patterns
+
+- Use **JSDoc** (`@description`, `@param`, `@returns`, `@example`) on **public** API consistent with `src/core/contentstack.js` and `src/core/stack.js`.
+- **Dependencies**: **`@contentstack/utils`** is exposed on the main class; follow existing import paths (including `.js` suffixes where the codebase uses them in ESM files).
+
+## Logging
+
+- Avoid noisy logging in library code except via existing **`fetchOptions.logHandler`** / **`fetchOptions.debug`** patterns in `src/core/lib/request.js` and `stack.js`.
+- Never log full **delivery_token**, **preview_token**, **management_token**, or API keys.

.cursor/rules/testing.mdc

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+---
+description: "Jest e2e and TypeScript tests for the CDA SDK"
+globs:
+  - "test/**/*.js"
+  - "test/**/*.ts"
+alwaysApply: false
+---
+
+# Testing — `contentstack` (CDA)
+
+## Frameworks
+
+| Suite | Runner | Notes |
+|-------|--------|--------|
+| **JS e2e / integration-style** | **Jest** (`jest.js.config.js`) | `testMatch`: `**/test/**/*.js`; ignores `test/index.js`, `test/config.js`, `test/sync_config.js`, some `utils.js` paths |
+| **TypeScript** | **Jest** + **ts-jest** (`jest.config.js`) | `npm run test:typescript`; `test/typescript/**/*.test.ts` |
+
+## Env & live stack
+
+- **Canonical required vars** for suites that `require('./config')` or `require('../config.js')`: **`HOST`**, **`API_KEY`**, **`DELIVERY_TOKEN`**, **`ENVIRONMENT`** — validated in **`test/config.js`** (loads **dotenv**). Missing any variable throws on import.
+- Use a **`.env`** file locally; do not commit secrets. **`HOST`** should match the delivery API host for your stack/region.
+- Built SDK: many tests **`require('../../dist/node/contentstack.js')`**. **`npm test`** runs **`pretest`** → **`npm run build`** first.
+
+## Layout
+
+- **Suite entry (JS):** `test/index.js` `require`s individual test files.
+- **TypeScript:** colocate under **`test/typescript/`** with `*.test.ts` naming.
+
+## Hygiene
+
+- No committed **`only`** / **`skip`** for tests that must run in CI.
+- Prefer deterministic assertions; mock or scope live tests when adding new cases so CI behavior stays predictable if env is absent.
+
+## Coverage
+
+- Jest / reporter config is in **`jest.js.config.js`** and **`jest.config.js`**; HTML reports paths are configured there.

.eslintrc.js

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+module.exports = {
+  env: {
+    "es2020": true,
+    "node": true,
+    "browser": true,
+    "jest": true
+  },
+  extends: 'standard',
+  // "globals": {
+  //     "Atomics": "readonly",
+  //     "SharedArrayBuffer": "readonly"
+  // },
+  // "parserOptions": {
+  //     "ecmaFeatures": {
+  //         "jsx": true
+  //     },
+  //     "ecmaVersion": 2015,
+  //     "sourceType": "module"
+  // },
+  parser: "@babel/eslint-parser", // Use Babel parser to handle modern JS syntax
+  plugins: [
+    'standard',
+    'promise'
+  ],
+  rules: {
+    'semi': ['error', 'always'],
+    'semi-spacing': ['error', { before: false, after: true }],
+    'camelcase': 'off',
+    'no-tabs': 'off',
+    'eqeqeq': 'off',
+    'no-unused-vars': 'warn',
+    'no-undef': 'warn',
+    'no-prototype-builtins': 'off',
+    'no-extend-native': 'off',
+    'no-fallthrough': 'off',
+    'prefer-promise-reject-errors': 'off',
+    'prefer-regex-literals': 'off',
+    'no-useless-escape': 'off',
+    'n/handle-callback-err': 'off',
+    'n/no-callback-literal': 'off',
+    'no-async-promise-executor': 'off'
+  }
+}; 

.github/workflows/back-merge-pr.yml

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+name: Back-merge master to development
+
+on:
+  push:
+    branches:
+      - master
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  pull-requests: write
+
+jobs:
+  open-back-merge-pr:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Open back-merge PR if needed
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          set -euo pipefail
+          BASE_BRANCH="development"
+          SOURCE_BRANCH="master"
+
+          git fetch origin "$BASE_BRANCH" "$SOURCE_BRANCH"
+
+          if ! git show-ref --verify --quiet "refs/remotes/origin/$BASE_BRANCH"; then
+            echo "Base branch '$BASE_BRANCH' does not exist on origin; skipping."
+            exit 0
+          fi
+
+          SOURCE_SHA=$(git rev-parse "origin/$SOURCE_BRANCH")
+          BASE_SHA=$(git rev-parse "origin/$BASE_BRANCH")
+
+          if [ "$SOURCE_SHA" = "$BASE_SHA" ]; then
+            echo "$SOURCE_BRANCH and $BASE_BRANCH are at the same commit; nothing to back-merge."
+            exit 0
+          fi
+
+          EXISTING=$(gh pr list --repo "${{ github.repository }}"             --base "$BASE_BRANCH"             --head "$SOURCE_BRANCH"             --state open             --json number             --jq 'length')
+
+          if [ "$EXISTING" -gt 0 ]; then
+            echo "An open PR from $SOURCE_BRANCH to $BASE_BRANCH already exists; skipping."
+            exit 0
+          fi
+
+          gh pr create --repo "${{ github.repository }}"             --base "$BASE_BRANCH"             --head "$SOURCE_BRANCH"             --title "chore: back-merge $SOURCE_BRANCH into $BASE_BRANCH"             --body "Automated back-merge after changes landed on \\`$SOURCE_BRANCH\\`. Review and merge to keep \\`$BASE_BRANCH\\` in sync."
+
+          echo "Created back-merge PR $SOURCE_BRANCH -> $BASE_BRANCH."