BREAKING CHANGE(core): major architectural refactoring with cross-platform support and SmartRequest rename

changelog.md

@@ -1,5 +1,34 @@
 # Changelog
 
+## 2025-07-28 - 4.0.0 - BREAKING CHANGE(core)
+Complete architectural overhaul with cross-platform support
+
+**Breaking Changes:**
+- Renamed `SmartRequestClient` to `SmartRequest` for simpler, cleaner API
+- Removed legacy API entirely (no more `/legacy` import path)
+- Major architectural refactoring:
+  - Added abstraction layer with `core_base` containing abstract classes
+  - Split implementations into `core_node` (Node.js) and `core_fetch` (browser)
+  - Dynamic implementation selection based on environment
+- Response streaming API changes:
+  - `stream()` now always returns web-style `ReadableStream<Uint8Array>`
+  - Added `streamNode()` for Node.js streams (throws error in browser)
+- Unified type system with single `ICoreRequestOptions` interface
+- Removed all "Abstract" prefixes from type names
+
+**Features:**
+- Full cross-platform support (Node.js and browsers)
+- Automatic platform detection using @push.rocks/smartenv
+- Consistent API across platforms with platform-specific capabilities
+- Web Streams API support in both environments
+- Better error messages for unsupported platform features
+
+**Documentation:**
+- Completely rewritten README with platform-specific examples
+- Added architecture overview section
+- Added migration guide from v2.x and v3.x
+- Updated all examples to use the new `SmartRequest` class name
+
 ## 2025-07-27 - 3.0.0 - BREAKING CHANGE(core)
 Major architectural refactoring with fetch-like API