diff --git a/.cursor/environment.json b/.cursor/environment.json
new file mode 100644
index 000000000000..0828f53fbd4a
--- /dev/null
+++ b/.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"
+    }
+  ]
+}
diff --git a/.cursor/rules/sdk_dependency_upgrades.mdc b/.cursor/rules/sdk_dependency_upgrades.mdc
index 826249108f01..becf0805eb91 100644
--- a/.cursor/rules/sdk_dependency_upgrades.mdc
+++ b/.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
diff --git a/.cursor/rules/sdk_development.mdc b/.cursor/rules/sdk_development.mdc
index 988703ddac81..088c94f47a23 100644
--- a/.cursor/rules/sdk_development.mdc
+++ b/.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
@@ -88,13 +98,16 @@ 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
@@ -102,16 +115,25 @@ Each package typically contains:
 - `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
@@ -119,10 +141,12 @@ Each package typically contains:
 - 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.
\ No newline at end of file
+
+**IMPORTANT**: When editing CLAUDE.md, also update .cursor/rules/sdk_development.mdc and vice versa to keep both files in sync.
diff --git a/CLAUDE.md b/CLAUDE.md
index 263b9eef97a4..e515c171303e 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -2,24 +2,32 @@
 
 This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
 
+# SDK Development Rules
+
+You are working on the Sentry JavaScript SDK, a critical production SDK used by thousands of applications. Follow these rules strictly.
+
+## Code Quality Requirements (MANDATORY)
+
+**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
+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 for development)
-- `yarn build:dev:filter <package>` - Build specific package and its dependencies
+- `yarn build:dev:watch` - Development build in watch mode (recommended)
+- `yarn build:dev:filter <package>` - Build specific package and dependencies
 - `yarn build:types:watch` - Watch mode for TypeScript types only
 - `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
 
@@ -27,44 +35,71 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 - `yarn fix` - Auto-fix linting and formatting issues
 - `yarn lint:es-compatibility` - Check ES compatibility
 
-### Package Management
+## Git Flow Branching Strategy
+
+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
 
-- `yarn clean` - Clean build artifacts and caches
-- `yarn clean:deps` - Clean and reinstall all dependencies
+- Features: `feat/descriptive-name`
+- Releases: `release/X.Y.Z`
 
 ## Repository Architecture
 
-This is a Lerna monorepo containing 40+ packages in the `@sentry/*` namespace. Key architectural components:
+This is a Lerna monorepo with 40+ packages in the `@sentry/*` namespace.
 
 ### Core Packages
 
-- `packages/core/` - Base SDK with interfaces, type definitions, and core functionality
-- `packages/types/` - Shared TypeScript type definitions (active)
+- `packages/core/` - Base SDK with interfaces, type definitions, core functionality
+- `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 follow naming: `packages/{framework}/` (react, vue, angular, etc.)
-- Each has client/server entry points where applicable (e.g., nextjs, nuxt, sveltekit)
-- Integration tests use Playwright (e.g., Remix, browser-integration-tests)
+- 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 support for replay
+- `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
+- `test-utils/` - Shared testing utilities
+- `bundle-analyzer-scenarios/` - Bundle analysis
+- `rollup-utils/` - Build utilities
+- GitHub Actions packages for CI/CD automation
+
+## Development Guidelines
+
 ### Build System
 
-- Uses Rollup for bundling with config files: `rollup.*.config.mjs`
-- TypeScript with multiple tsconfig files per package (main, test, types)
+- 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`
 
@@ -75,73 +110,42 @@ 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` - TypeScript configs
+- `tsconfig.json`, `tsconfig.test.json`, `tsconfig.types.json`
 - `test/` directory with corresponding test files
 
-### Development Packages (`dev-packages/`)
-
-Separate from main packages, containing development and testing utilities:
-
-- `browser-integration-tests/` - Playwright browser tests
-- `e2e-tests/` - End-to-end tests for 70+ framework combinations
-- `node-integration-tests/` - Node.js integration tests
-- `test-utils/` - Shared testing utilities
-- `bundle-analyzer-scenarios/` - Bundle analysis
-- `rollup-utils/` - Build utilities
-- GitHub Actions packages for CI/CD automation
-
 ### 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
-- Bundle outputs vary - check `build/bundles/` for specific files after builds
+- Never change the volta, yarn, or package manager setup in general unless explicitly asked for
 
-## Git Flow Branching Strategy
+### Notes for Background Tasks
 
-This repository uses **Git Flow** branching model. See [detailed documentation](docs/gitflow.md).
+- 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.
 
-### Key Points
-
-- **All PRs target `develop` branch** (not `master`)
-- `master` represents the last released state
-- Never merge directly into `master` (except emergency fixes)
-- Automated workflow syncs `master` → `develop` after releases
-- Avoid changing `package.json` files on `develop` during pending releases
-
-### Branch Naming
-
-- Features: `feat/descriptive-name`
-- Releases: `release/X.Y.Z`
-
-## Code Quality Requirements
-
-**CRITICAL**: This is a production SDK used by thousands of applications. All changes must be:
-
-### Mandatory Checks
-
-- **Always run `yarn lint`** - Fix all linting issues before committing
-- **Always run `yarn test`** - Ensure all tests pass
-- **Run `yarn build`** - Verify build succeeds without errors
-
-### Before Any Commit
+## Testing Single Packages
 
-1. `yarn lint` - Check and fix ESLint/Prettier issues
-2. `yarn test` - Run relevant tests for your changes
-3. `yarn build:dev` - Verify TypeScript compilation
+- Test specific package: `cd packages/{package-name} && yarn test`
+- Build specific package: `yarn build:dev:filter @sentry/{package-name}`
 
-### CI/CD Integration
+## Code Style Rules
 
-- All PRs automatically run full lint/test/build pipeline
-- Failed checks block merging
-- Use `yarn test:pr` for testing only affected changes
+- 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
 
-## Testing Single Packages
+## Before Every Commit Checklist
 
-To test a specific package: `cd packages/{package-name} && yarn test`
-To build a specific package: `yarn build:dev:filter @sentry/{package-name}`
+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`)
 
-## Cursor IDE Integration
+## Documentation Sync
 
-For Cursor IDE users, see [.cursor/rules/sdk_development.mdc](.cursor/rules/sdk_development.mdc) for complementary development rules.
+**IMPORTANT**: When editing CLAUDE.md, also update .cursor/rules/sdk_development.mdc and vice versa to keep both files in sync.
diff --git a/package.json b/package.json
index 591424f91ec5..f2cbefa5faa4 100644
--- a/package.json
+++ b/package.json
@@ -22,12 +22,12 @@
     "clean:all": "run-s clean:build clean:tarballs clean:caches clean:deps clean:watchman",
     "fix": "run-s fix:prettier fix:lerna",
     "fix:lerna": "lerna run fix",
-    "fix:prettier": "prettier \"**/*.{md,css,yml,yaml}\" \"packages/**/**.{ts,js,mjs,cjs,mts,cts,jsx,tsx,astro,vue}\" \"dev-packages/!(e2e-tests)/**/**.{ts,js,mjs,cjs,mts,cts,jsx,tsx,astro,vue}\" --write",
+    "fix:prettier": "prettier \"**/*.{md,css,yml,yaml,mdc}\" \"packages/**/**.{ts,js,mjs,cjs,mts,cts,jsx,tsx,astro,vue}\" \"dev-packages/!(e2e-tests)/**/**.{ts,js,mjs,cjs,mts,cts,jsx,tsx,astro,vue}\" --write",
     "changelog": "ts-node ./scripts/get-commit-list.ts",
     "link:yarn": "lerna exec yarn link",
     "lint": "run-s lint:prettier lint:lerna",
     "lint:lerna": "lerna run lint",
-    "lint:prettier": "prettier \"**/*.{md,css,yml,yaml}\" \"packages/**/**.{ts,js,mjs,cjs,mts,cts,jsx,tsx,astro,vue}\" --check",
+    "lint:prettier": "prettier \"**/*.{md,css,yml,yaml,mdc}\" \"packages/**/**.{ts,js,mjs,cjs,mts,cts,jsx,tsx,astro,vue}\" --check",
     "lint:es-compatibility": "lerna run lint:es-compatibility",
     "dedupe-deps:check": "yarn-deduplicate yarn.lock --list --fail",
     "dedupe-deps:fix": "yarn-deduplicate yarn.lock",
@@ -165,6 +165,13 @@
         "options": {
           "proseWrap": "preserve"
         }
+      },
+      {
+        "files": "*.mdc",
+        "options": {
+          "parser": "markdown",
+          "proseWrap": "preserve"
+        }
       }
     ]
   }