OS Mode Features

Multi-Language Runtimes

Language runtimes are fetched from wasmhub and cached locally at ~/.wasmrun/runtimes/:

Language	Runtime	Detection
Node.js / JavaScript	QuickJS	package.json
Python	RustPython	requirements.txt, pyproject.toml
Rust	Rust WASM runtime	Cargo.toml
Go	Go WASM runtime	go.mod

Runtimes are downloaded on first use with SHA-256 checksum validation.

Browser UI

The OS mode UI provides several panels:

• Console — live stdout/stderr with color-coded streams (green for stdout, red for stderr, blue for system) and timestamps
• Filesystem — browse the WASI virtual filesystem populated from your project files
• Kernel Status — active processes, memory usage, WASI capabilities, supported languages
• Logs — structured log trail from kernel, server, and runtime events
• Application — iframe for app output (when running web servers)

Virtual Filesystem

Project files are served via GET /api/project/files as a base64-encoded JSON bundle:

• .gitignore patterns respected (glob matching with *, **, ?, negation)
• Default ignore patterns for node_modules, target, .git, __pycache__, binary files
• Size limits: 10MB per file, 50MB total, 5000 file cap
• Files are decoded in the browser and written to the WASI virtual FS

Network Isolation

Each process runs in its own network namespace:

• Isolated port bindings (no conflicts between processes)
• Port forwarding from guest to host
• Connection tracking and stats
• Per-process network statistics

See Network Isolation for details.

Port Forwarding

Expose services running in isolated namespaces:

wasmrun os ./app --forward 8080:3000

See Port Forwarding for details.

Public Tunneling

Expose local apps to the internet via bore.pub:

• Built-in bore client (Rust implementation)
• Automatic reconnection
• Optional authentication for private servers
• Start/stop/status via REST API

See Public Tunneling for details.

REST API

OS mode exposes a JSON API:

Endpoint	Method	Description
/api/kernel/stats	GET	Kernel statistics (processes, memory, capabilities)
/api/fs/stats	GET	Filesystem statistics
/api/fs/read/<path>	GET	Read file contents
/api/fs/list/<path>	GET	List directory
/api/fs/write/<path>	POST	Write file
/api/fs/mkdir/<path>	POST	Create directory
/api/fs/delete/<path>	POST	Delete file
/api/project/files	GET	Get all project files (base64 bundle)
/api/runtime/<language>	GET	Serve cached runtime WASM binary
/api/runtimes	GET	Available runtimes manifest
/api/logs	GET	All structured logs
/api/logs/recent	GET	Recent logs
/api/kernel/start	POST	Start project
/api/kernel/restart	POST	Restart project
/api/tunnel/start	POST	Start bore tunnel
/api/tunnel/status	GET	Tunnel status
/api/tunnel/stop	POST	Stop tunnel
/api/processes/<pid>/ports	GET	List port mappings
/api/processes/<pid>/forward	POST	Create port forward