WASM Extension System

Status: Basic structure integrated, compiling successfully

This module provides Spacedrive's WebAssembly-based extension system, enabling secure, sandboxed plugins.

What's Implemented

Core Infrastructure

• manager.rs - PluginManager for loading/unloading WASM modules (Wasmer integration)
• host_functions.rs - Skeleton for host_spacedrive_call() and host_spacedrive_log()
• permissions.rs - Capability-based security with rate limiting
• types.rs - Extension manifest format and types

Dependencies Added

wasmer = "4.2"
wasmer-middlewares = "4.2"

The Design

Key Insight: ONE generic host function reuses the entire Wire/Registry infrastructure.

// WASM extensions import:
extern "C" {
    fn spacedrive_call(method, library_id, payload) -> result;
}

// Host function routes to existing registry:
host_spacedrive_call()
  ↓
RpcServer::execute_json_operation()  // EXISTING!
  ↓
LIBRARY_QUERIES/ACTIONS.get()        // EXISTING!
  ↓
Operation::execute()                  // EXISTING!

Result: Zero code duplication. WASM extensions use same operations as CLI/GraphQL/daemon clients.

What's NOT Implemented Yet

Pending Work

1. WASM Memory Interaction (host_functions.rs)

• Read/write strings from WASM linear memory
• Read/write JSON payloads
• UUID handling
• Guest allocator integration

2. Full Wire Bridge (host_functions.rs)

• Call RpcServer::execute_json_operation()
• Permission checking before operation
• Error handling and propagation

3. Extension Operations (core/src/ops/)

• ai.ocr - OCR operation
• ai.classify_text - AI classification
• credentials.store/get - Credential management
• vdfs.write_sidecar - Sidecar file operations

4. Test WASM Module

• Simple "hello world" .wasm file
• Calls spacedrive_call() to test integration
• Validates permission system

5. Extension SDK (separate crate)

• spacedrive-sdk Rust crate
• Type-safe wrapper around spacedrive_call()
• Ergonomic API for extension developers

Next Steps

Immediate (This Week)

1. Implement WASM Memory Helpers

   • Study Wasmer 4.2 API documentation
   • Implement read_string_from_wasm()
   • Implement write_json_to_wasm()
   • Test with simple WASM module

2. Complete host_spacedrive_call()

   • Bridge to execute_json_operation()
   • Add permission checking
   • Error handling

3. Create Test WASM Module

   • Rust project that compiles to WASM
   • Calls spacedrive_call() with test payload
   • Validates round-trip works

Week 2-3

4. Add Extension Operations

   • Implement ai.ocr (Tesseract integration)
   • Implement credentials.store/get
   • Implement vdfs.write_sidecar

5. Build Extension SDK

   • Create spacedrive-sdk crate
   • Type-safe wrappers
   • Documentation

Week 4+

6. Finance Extension
   • Email scanning
   • Receipt processing
   • Full end-to-end test

Architecture Documents

• WASM_ARCHITECTURE_FINAL.md - Quick reference
• EXTENSION_IPC_DESIGN.md - Detailed design
• EMAIL_INGESTION_EXTENSION_DESIGN.md - Finance extension
• PLATFORM_REVENUE_MODEL.md - Business model

Example Usage (Future)

// In Spacedrive Core
let mut plugin_manager = PluginManager::new(core.clone(), plugins_dir);
plugin_manager.load_plugin("finance").await?;

// Extension (WASM) calls:
let result = spacedrive_call(
    "query:ai.ocr",
    library_id,
    json!({ "data": pdf_bytes, "options": { "language": "eng" } })
);

Testing

# Check compilation
cd core && cargo check

# Run tests (once implemented)
cd core && cargo test extension

# Load test plugin (once implemented)
cargo run --bin spacedrive extension load ./plugins/test-plugin

Notes

• Memory Management: WASM modules must export wasm_alloc(size: i32) -> *mut u8
• Error Handling: Errors returned as JSON { "error": "message" }
• Permissions: Checked on every spacedrive_call()
• Rate Limiting: 1000 requests/minute default

Last Updated: October 2025 - Initial integration