Metadata-Version: 2.4
Name: jenai
Version: 1.0.0
Summary: A terminal in a browser tab, for Google Colab and anywhere else a Python kernel runs.
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Dynamic: license-file

# jenai

Open a real terminal in a Google Colab cell — including the free tier.

```
!pip install jenai
%load_ext jenai
%xterm
```

[![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/xsideal/jenai/blob/main/demo.ipynb)

## What it is

A terminal server, a single-page client, and a notebook magic. The client is
one `<div>`; there is no toolbar, no status bar and no settings panel. The
server is a hand-written asyncio HTTP/1.1 + RFC 6455 implementation that drives
a real pty from the event loop itself — no threads in the data path, no
`StreamReader`, and one WebSocket per tab carrying raw bytes.

| | old | new |
| --- | --- | --- |
| transport | tornado + HTTP long-poll | one WebSocket, binary frames |
| client input | base64 in a URL path, batched every 100 ms | sent on the keystroke, as UTF-8 bytes |
| client output | base64 in a JSON body, polled | raw pty bytes |
| server data path | thread-pool `read()` on the pty master | `loop.add_reader` on the master fd |
| page | webpack bundle + separate assets | one inlined `index.html` (93 KiB brotli) |
| reload | started a new shell | re-attaches to the running one |

Measured on the same machine, against the previous implementation:

| metric | legacy | new |
| --- | --- | --- |
| echo round trip (p50 / p99) | 3.7 ms / 7.6 ms | see `make bench` |
| input ceiling | ~32 KiB per paste, base64 in a URL | unlimited (verified to 1 MiB and beyond) |
| added input latency | up to 100 ms of client batching | none |
| first-paint payload | 426 KiB JS + HTML | 91 KiB, single request |

Run `make bench` for the live numbers on your own hardware.

## Options

```
%xterm height=1000 port=10001
```

| option | description |
| --- | --- |
| `height` | height of the terminal panel, in pixels |
| `port` | server port |

## Development

Requires Python 3.11+ and Node 20+.

```bash
make install     # pip install -e '.[dev]' plus the client toolchain
make build       # bundle the client into jenai/client/dist/index.html
make test        # the whole suite (add -m "not slow" to skip shells/browser)
make lint        # ruff check, ruff format --check, mypy --strict, tsc --noEmit
make bench       # echo latency, ping, output and input throughput
make profile     # cProfile report: server, codec and bundle
```

### Layout

```
jenai/
  app.py          CLI entry point, uvloop setup, readiness handshake
  server.py       asyncio.Protocol HTTP+WebSocket server
  wsproto.py      RFC 6455 codec
  httpproto.py    HTTP/1.1 parsing and rendering
  assets.py       in-memory, pre-compressed static assets
  pty_session.py  pty sessions driven from the event loop
  wire.py         control-message protocol shared with the browser
  notebook.py     the %xterm magic
  client/
    build.ts      esbuild -> one inlined index.html
    src/          TypeScript: transport, terminal, protocol
```

### Testing

`tests/` runs against real sockets, real forked shells and — where Playwright
is installed — a real headless Chromium. The browser tests are not decoration:
they are what caught the client never wiring `onData` to the transport, which
no Python test could have seen.

```bash
make test                     # everything
make test-fast                # no shells, no browser
make test-browser             # Playwright only
pip install playwright && playwright install chromium   # for the browser tests
```

### Design notes

* **Binary frames carry pty bytes.** The old client base64-encoded input into a
  URL path and output into JSON; both put a ceiling on what a user could type
  or what the server could send. Binary frames have neither the ceiling nor the
  encoding cost.
* **No client-side batching.** The old client accumulated keystrokes for 100 ms
  before sending. Every keystroke now goes out immediately, and xterm.js
  coalesces renders on its own schedule.
* **Back-pressure pauses the pty.** If a browser falls behind, the server stops
  reading the pty master instead of buffering output in Python, so a runaway
  `cat` cannot balloon the server's memory.
* **A page reload re-attaches.** Session ids live in `sessionStorage`; the
  server keeps the shell alive across the reconnect.
* **The bundle is inlined.** One request, no waterfall, and `.gz`/`.br`
  siblings the server serves straight from memory.

## Screenshots

![](assets/colab-xterm.png)

## Credits

Built on [xterm.js](https://xtermjs.org/) and forked from
[colab-xterm](https://github.com/InfuseAI/colab-xterm), which got the idea.
