chore: Update cursor rules with more details

.cursor/environment.json

@@ -0,0 +1,12 @@
+{
+  "name": "Sentry JavaScript SDK Development",
+  "install": "curl https://get.volta.sh | bash && export VOLTA_HOME=\"$HOME/.volta\" && export PATH=\"$VOLTA_HOME/bin:$PATH\" && export VOLTA_FEATURE_PNPM=1 && yarn install",
+  "start": "export VOLTA_HOME=\"$HOME/.volta\" && export PATH=\"$VOLTA_HOME/bin:$PATH\" && export VOLTA_FEATURE_PNPM=1",
+  "terminals": [
+    {
+      "name": "Development",
+      "command": "export VOLTA_HOME=\"$HOME/.volta\" && export PATH=\"$VOLTA_HOME/bin:$PATH\" && export VOLTA_FEATURE_PNPM=1 && echo 'Volta setup complete. Node version:' && node --version && echo 'Yarn version:' && yarn --version",
+      "description": "Main development terminal with Volta environment configured"
+    }
+  ]
+}

.cursor/rules/sdk_dependency_upgrades.mdc

@@ -3,6 +3,7 @@ description: Use this rule if you are looking to upgrade a dependency in the Sen
 globs:
 alwaysApply: false
 ---
+
 # Yarn v1 Dependency Upgrades
 
 ## Upgrade Process
@@ -45,10 +46,12 @@ Avoid upgrading top-level dependencies (defined in `package.json`), especially i
 **STOP UPGRADE IMMEDIATELY** if upgrading any dependency with `opentelemetry` in the name and the new version or any of its dependencies uses forbidden OpenTelemetry versions.
 
 **FORBIDDEN VERSION PATTERNS:**
+
 - `2.x.x` versions (e.g., `2.0.0`, `2.1.0`)
 - `0.2xx.x` versions (e.g., `0.200.0`, `0.201.0`)
 
 When upgrading OpenTelemetry dependencies:
+
 1. Check the dependency's `package.json` after upgrade
 2. Verify the package itself doesn't use forbidden version patterns
 3. Verify none of its dependencies use `@opentelemetry/*` packages with forbidden version patterns
@@ -153,6 +156,7 @@ yarn info <package-name> versions
 ```
 
 The `yarn info` command provides detailed dependency information without requiring installation, making it particularly useful for:
+
 - Verifying OpenTelemetry packages don't introduce forbidden version patterns (`2.x.x` or `0.2xx.x`)
 - Checking what dependencies a package will bring in before upgrading
 - Understanding package version history and compatibility

.cursor/rules/sdk_development.mdc

@@ -12,12 +12,13 @@ You are working on the Sentry JavaScript SDK, a critical production SDK used by
 **CRITICAL**: All changes must pass these checks before committing:
 
 1. **Always run `yarn lint`** - Fix all linting issues
-2. **Always run `yarn test`** - Ensure all tests pass  
+2. **Always run `yarn test`** - Ensure all tests pass
 3. **Always run `yarn build:dev`** - Verify TypeScript compilation
 
 ## Development Commands
 
 ### Build Commands
+
 - `yarn build` - Full production build with package verification
 - `yarn build:dev` - Development build (transpile + types)
 - `yarn build:dev:watch` - Development build in watch mode (recommended)
@@ -26,13 +27,11 @@ You are working on the Sentry JavaScript SDK, a critical production SDK used by
 - `yarn build:bundle` - Build browser bundles only
 
 ### Testing
-- `yarn test` - Run all tests (excludes integration tests)
-- `yarn test:unit` - Run unit tests only
-- `yarn test:pr` - Run tests affected by changes (CI mode)
-- `yarn test:pr:browser` - Run affected browser-specific tests
-- `yarn test:pr:node` - Run affected Node.js-specific tests
+
+- `yarn test` - Run all unit tests
 
 ### Linting and Formatting
+
 - `yarn lint` - Run ESLint and Prettier checks
 - `yarn fix` - Auto-fix linting and formatting issues
 - `yarn lint:es-compatibility` - Check ES compatibility
@@ -42,12 +41,17 @@ You are working on the Sentry JavaScript SDK, a critical production SDK used by
 This repository uses **Git Flow**. See [docs/gitflow.md](docs/gitflow.md) for details.
 
 ### Key Rules
+
 - **All PRs target `develop` branch** (NOT `master`)
 - `master` represents the last released state
 - Never merge directly into `master` (except emergency fixes)
 - Avoid changing `package.json` files on `develop` during pending releases
+- Never update dependencies, package.json content or build scripts unless explicitly asked for
+- When asked to do a task on a set of files, always make sure that all occurences in the codebase are covered. Double check that no files have been forgotten.
+- Unless explicitly asked for, make sure to cover all files, including files in `src/` and `test/` directories.
 
 ### Branch Naming
+
 - Features: `feat/descriptive-name`
 - Releases: `release/X.Y.Z`
 
@@ -56,27 +60,33 @@ This repository uses **Git Flow**. See [docs/gitflow.md](docs/gitflow.md) for de
 This is a Lerna monorepo with 40+ packages in the `@sentry/*` namespace.
 
 ### Core Packages
+
 - `packages/core/` - Base SDK with interfaces, type definitions, core functionality
-- `packages/types/` - Shared TypeScript type definitions (active)
+- `packages/types/` - Shared TypeScript type definitions - this is deprecated, never modify this package
 - `packages/browser-utils/` - Browser-specific utilities and instrumentation
+- `packages/node-core/` - Node Core SDK which contains most of the node-specific logic, excluding OpenTelemetry instrumentation.
 
 ### Platform SDKs
+
 - `packages/browser/` - Browser SDK with bundled variants
-- `packages/node/` - Node.js SDK with server-side integrations
+- `packages/node/` - Node.js SDK. All general Node code should go into node-core, the node package itself only contains OpenTelemetry instrumentation on top of that.
 - `packages/bun/`, `packages/deno/`, `packages/cloudflare/` - Runtime-specific SDKs
 
 ### Framework Integrations
+
 - Framework packages: `packages/{framework}/` (react, vue, angular, etc.)
 - Client/server entry points where applicable (nextjs, nuxt, sveltekit)
 - Integration tests use Playwright (Remix, browser-integration-tests)
 
 ### User Experience Packages
+
 - `packages/replay-internal/` - Session replay functionality
 - `packages/replay-canvas/` - Canvas recording for replay
 - `packages/replay-worker/` - Web worker support for replay
 - `packages/feedback/` - User feedback integration
 
 ### Development Packages (`dev-packages/`)
+
 - `browser-integration-tests/` - Playwright browser tests
 - `e2e-tests/` - End-to-end tests for 70+ framework combinations
 - `node-integration-tests/` - Node.js integration tests
@@ -88,41 +98,55 @@ This is a Lerna monorepo with 40+ packages in the `@sentry/*` namespace.
 ## Development Guidelines
 
 ### Build System
+
 - Uses Rollup for bundling (`rollup.*.config.mjs`)
 - TypeScript with multiple tsconfig files per package
 - Lerna manages package dependencies and publishing
 - Vite for testing with `vitest`
 
 ### Package Structure Pattern
+
 Each package typically contains:
+
 - `src/index.ts` - Main entry point
 - `src/sdk.ts` - SDK initialization logic
 - `rollup.npm.config.mjs` - Build configuration
 - `tsconfig.json`, `tsconfig.test.json`, `tsconfig.types.json`
 - `test/` directory with corresponding test files
 
 ### Key Development Notes
+
 - Uses Volta for Node.js/Yarn version management
 - Requires initial `yarn build` after `yarn install` for TypeScript linking
 - Integration tests use Playwright extensively
-- Native profiling requires Python <3.12 for binary builds
+- Never change the volta, yarn, or package manager setup in general unless explicitly asked for
+
+### Notes for Background Tasks
+
+- Make sure to use [volta](https://volta.sh/) for development. Volta is used to manage the node, yarn and pnpm version used.
+- Make sure that [PNPM support is enabled in volta](https://docs.volta.sh/advanced/pnpm). This means that the `VOLTA_FEATURE_PNPM` environment variable has to be set to `1`.
+- Yarn, Node and PNPM have to be used through volta, in the versions defined by the volta config. NEVER change any versions unless explicitly asked to.
 
 ## Testing Single Packages
+
 - Test specific package: `cd packages/{package-name} && yarn test`
 - Build specific package: `yarn build:dev:filter @sentry/{package-name}`
 
 ## Code Style Rules
+
 - Follow existing code conventions in each package
 - Check imports and dependencies - only use libraries already in the codebase
 - Look at neighboring files for patterns and style
 - Never introduce code that exposes secrets or keys
 - Follow security best practices
 
 ## Before Every Commit Checklist
+
 1. ✅ `yarn lint` (fix all issues)
 2. ✅ `yarn test` (all tests pass)
 3. ✅ `yarn build:dev` (builds successfully)
 4. ✅ Target `develop` branch for PRs (not `master`)
 
 ## Documentation Sync
-**IMPORTANT**: When editing CLAUDE.md, also update .cursor/rules/sdk_development.mdc and vice versa to keep both files in sync.
+
+**IMPORTANT**: When editing CLAUDE.md, also update .cursor/rules/sdk_development.mdc and vice versa to keep both files in sync.