# WASM Support Fixes Summary

## Issues Resolved

### 1. ✅ WasmServerCore API Mismatch
**Problem**: `WasmServerCore` only had `new()` method, but SDK example called `add_tool()`
**Solution**: 
- Added tool registry with `HashMap<String, (String, ToolHandler)>`
- Implemented `add_tool()` method for registering tools
- Added proper MCP protocol handling (initialize, tools/list, tools/call)
- Used `RefCell` for interior mutability to track initialization state

### 2. ✅ Protocol Version Hardcoding
**Problem**: `src/server/core.rs` hardcoded "2024-11-05" instead of using constants
**Solution**: 
- Replaced all hardcoded versions with `crate::DEFAULT_PROTOCOL_VERSION`
- Ensures consistency across the SDK

### 3. ✅ WASM vs WASI Documentation
**Problem**: Unclear distinction between different WASM targets
**Solution**: 
- Created `docs/WASM_TARGETS.md` documenting:
  - `wasm32-unknown-unknown` for Cloudflare Workers
  - `wasm32-wasi` for WASI-compliant runtimes
  - `wasm32-wasi-preview2` for component model
- Listed which modules are available per target

### 4. ✅ Cloudflare Example Routing
**Problem**: Confusion about routing and entry points
**Solution**:
- Created `README_SDK.md` clarifying:
  - SDK version serves on `POST /mcp`
  - Original version serves on `POST /`
  - How to switch between implementations
  - Testing and deployment instructions

## Build Verification

The SDK now successfully compiles for WASM:

```bash
cargo build --target wasm32-unknown-unknown --no-default-features --features wasm
```

## Architecture Improvements

### WasmServerCore Implementation
```rust
pub struct WasmServerCore {
    name: String,
    version: String,
    tools: HashMap<String, (String, ToolHandler)>,
    initialized: RefCell<bool>,
}

// Now supports:
- Tool registration via add_tool()
- MCP initialize flow
- tools/list operation
- tools/call with proper error handling
```

### Module Organization
- **Native-only**: `ServerCore`, `ServerBuilder`, auth, cancellation, roots, subscriptions
- **WASM-compatible**: `WasmServerCore`, `WasiHttpAdapter`, simplified `ProtocolHandler`
- **Conditional compilation**: Properly gated based on target architecture

## Usage Example

```rust
// Cloudflare Worker with SDK
use pmcp::server::wasm_core::WasmServerCore;

let mut server = WasmServerCore::new("my-server".to_string(), "1.0.0".to_string());

server.add_tool("calculator".to_string(), "Math operations".to_string(), |args| {
    // Tool implementation
    Ok(json!({"result": 42}))
});

// Server is ready to handle MCP requests
```

## Remaining Considerations

1. **Tool Result Format**: Currently returns stringified JSON in Content::Text. Could be improved to use structured Content types.

2. **Error Codes**: Using correct ErrorCode constants (INVALID_REQUEST, METHOD_NOT_FOUND, etc.)

3. **Request Parsing**: WasmServerCore uses JSON serialization to extract method names - this is a pragmatic approach for WASM where we want to minimize dependencies.

4. **Testing**: The WASM implementation could benefit from integration tests running in a WASM environment.

## Summary

The SDK's WASM support is now functional and properly architected:
- ✅ Compiles for `wasm32-unknown-unknown`
- ✅ Provides working MCP server implementation
- ✅ Tool registration and execution supported
- ✅ Clear separation of native vs WASM code
- ✅ Documented target differences
- ✅ Example implementation provided