PYRS Docs | Browser Playground

The browser playground lives at /playground. It auto-loads the website’s wasm-vm-probe bundle, pre-registers a curated stdlib subset from /wasm/stdlib_subset_v1.json, and provides a minimal REPL-focused interface. Runtime execution is handled in a dedicated Web Worker so command execution does not run on the page UI thread.

Quick Start

Open and run

# 1) Build browser wasm assets (repo root)
./scripts/build_wasm_website_bundle.sh

# 2) Start website dev server
pnpm --dir website dev

# 3) Open /playground, wait for runtime loaded, and run input

What The Playground Loads

Component	Behavior
Wasm runtime	The website bundle is built with `wasm-vm-probe`, so runtime execution is enabled in the worker.
Stdlib content	A curated virtual stdlib subset is registered before the REPL session starts; full CPython stdlib is not shipped in-browser.
Unsupported surfaces	Snippets that need missing modules or unsupported runtime capabilities return explicit stderr/blocker output.

Available Modules

Surface	Current scope	Notes
Available modules	83 public modules	Merged from the curated website pack at `/wasm/stdlib_subset_manifest_v1.json` and native/bootstrap modules exposed by `src/vm/vm_bootstrap_import.rs`.
Blocked modules	7 public modules	These are rejected by the browser capability policy instead of partially working.

Available modules (83 public modules)

__future__, abc, annotationlib, argparse, array, ast, asyncio, atexit, binascii
bisect, codecs, collections, collections.abc, contextlib, contextvars, copy, copyreg
dataclasses, datetime, decimal, difflib, dis, encodings, encodings.aliases, enum, errno
faulthandler, fractions, functools, gc, gettext, heapq, importlib, importlib.machinery
inspect, io, ipaddress, itertools, json, json.decoder, json.encoder, json.scanner, keyword
linecache, locale, marshal, math, mmap, numbers, opcode, operator, os, os.path, pathlib
platform, posix, pprint, pwd, pyexpat, random, re, reprlib, resource, select, signal, ssl
statistics, string, sysconfig, textwrap, threading, time, token, tokenize, types, typing
unicodedata, urllib, urllib.parse, uuid, warnings, weakref, zlib

Blocked public modules	Blocker key	Why blocked in browser mode
`ctypes`	`dynamic_library_load`	Dynamic library loading is not available in the wasm host.
`numpy`, `scipy`	`dynamic_library_load`	Standard distributions depend on native extension binaries.
`socket`	`network_sockets`	Raw socket capability is unavailable in browser mode.
`subprocess`, `multiprocessing`	`process_spawn`	Browser mode does not expose process creation or subprocess spawning.
`readline`	`interactive_terminal`	The browser playground does not provide a TTY-style interactive terminal surface.

Runtime Status Signals

State	Meaning	What to do
`loading`	The wasm bundle is still being initialized.	Wait for ready state before running snippets.
`ready`	Runtime loaded, worker ready, and the curated stdlib subset has been registered.	Run snippets normally.
`error`	The runtime failed to initialize.	Check browser console and confirm wasm assets are published.

Output Shape

Output class	Description
Input transcript	Every submitted command is echoed with `>>>` / `…` prompts.
stdout	Normal execution output from the wasm runtime.
stderr	Runtime errors, compile/syntax failures, missing-module messages, or unsupported capability messages.

Debug Route

For low-level diagnostics and worker/state contract probing, use the unlisted /debug route.