---
title: "Commands, help and completion in a session"
url: "https://tryreynolds.com/docs/session-commands"
description: "What you can type while a Reynolds study runs, in the terminal and in the app: every command and alias, /help and its topics, answering a question, and how completion and suggestions work."
---

**[Reynolds](https://tryreynolds.com)** is agentic CFD, built by
**[InviscidAI](https://inviscidai.com)** and backed by Y Combinator, Winter 2026 batch.
The agent is open source under the MIT licence at
[github.com/InviscidAI/OpenReynolds](https://github.com/InviscidAI/OpenReynolds).
Using it requires no OpenFOAM knowledge.

This is the agent-readable Markdown twin of https://tryreynolds.com/docs/session-commands. It lives at https://tryreynolds.com/docs/session-commands.md, and
[tryreynolds.com/llms.txt](https://tryreynolds.com/llms.txt) indexes every one of them.

# Commands in a session

Anything you type reaches the agent at its next step. A line that starts with a command is answered by the harness instead, and typing a slash shows you which ones there are.

## The commands

| Typed | Also | What it does |
|---|---|---|
| `/btw <something>` | `/aside` | Say it without asking the agent to stop. On its own, the same as `/status`. |
| `/status` | `/what` | What is happening right now: jobs, thread size, tokens, last sync. Costs no model call. |
| `/files [path]` | `/ls` | List the study’s directory on the workspace, or the path you give. |
| `/renders` | `/pics` | The pictures folder, newest first. |
| `/open` |  | Open the study’s local folder. Terminal only. |
| `/mode [name]` |  | Show the mode, or switch. See [Modes](https://tryreynolds.com/docs/modes.md). |
| `/model [model]` |  | Show the model, or switch. See [Changing the model](https://tryreynolds.com/docs/switching-models.md). |
| `/effort [level]` |  | `low`, `medium` or `high`, from the next request. |
| `/yes` | `/approve`, `/y` | Approve what the agent is waiting on. |
| `/no [reason]` | `/deny`, `/n` | Decline it. The reason goes back to the agent in your words. |
| `/all` | `/yes all` | Approve it and switch the session to full auto. |
| `/help [topic]` | `/?` | Every command, or a topic. |
| `/exit` | `/quit` | Leave. Jobs keep running, and the study can be resumed. |

None of these becomes a turn of its own. `/btw` and the answer to a question reach the agent as your words, and a `/mode` switch is told to it as a fact. Everything else is answered by the harness alone, which is why asking what is going on costs nothing. A line that starts with a slash but is not a command, a path for instance, is sent to the agent as an ordinary message rather than refused.

## Help and its topics

`/help` on its own lists every command, the three modes, and how completion works where you are. A topic goes deeper:

| Typed | What it covers |
|---|---|
| `/help commands` | Every command with its aliases and a longer description. |
| `/help modes` | The three modes, what each holds, how to answer, and how to switch. |
| `/help model` | Changing the model and effort: the forms, when a switch takes effect, and what it costs. |
| `/help tools` | What each of the agent’s tools does, in plain words. |
| `/help keys` | The keys, and how completion works. |

## Completion in the terminal

Type `/` in the prompt and a list of matching commands opens just above it, each with what it does, and the best match appears as grey text in the prompt. After a command that takes a choice the list offers the choices: the modes after `/mode`, this provider’s models after `/model`, the levels after `/effort`, and the topics after `/help`.

| Key | What it does |
|---|---|
| Up, Down | Move through the list. |
| Tab | Take the highlighted suggestion, or the grey text. While you are typing a command, Tab never moves you to another pane. |
| Right | Take the grey text. |
| Enter | Send the line. On a half-typed command, it takes the suggestion instead. |
| Esc | Close the list. |

While the agent is waiting on a question, the prompt says how to answer and `/yes`, `/no` and `/all` come first in the list. The plain terminal from `--plain` has no completion; the commands work the same typed in full.

## Suggestions in the app

Type `/` in the message box and the same list opens above it. Up and Down move, Tab picks, Enter picks unless the line is already a whole command, in which case it sends, Esc closes, and a click picks. Under the box are a **help** button and the mode, model and effort choosers for the running study.

## One list everywhere

Every command is one entry in a single list in the agent’s source. What it accepts, what `/help` says, what the terminal completes and what the app suggests are all read from that entry, and the app fetches it rather than keeping a copy, so a command cannot exist in one place and be missing from another.

## Notes for agents

### What Reynolds is

Reynolds is an agent that runs OpenFOAM for you. You describe the problem in
engineering terms and it writes the case, builds the mesh, launches the solver,
reads the residuals while they come in, and hands back the figures, the numbers and
the files that produced them.

**You do not need to know OpenFOAM.** Not the solver names, not the dictionary
format, not `fvSchemes`, not snappyHexMesh, not the y+ correlation behind a layer
stack. Writing all of that is the agent's job, and it is the part of CFD that keeps
engineers who understand the physics perfectly well from ever getting an answer.
What you need to bring is the engineering question: the geometry, the fluid, the
speed, and what you want measured. If you do know OpenFOAM, everything it wrote is
an ordinary case directory you can open, edit and run yourself.

### The licence, and why it is the one that matters here

The agent is open source under the **MIT licence**. That is the most permissive of
the common licences: use it commercially, modify it, self-host it, put it inside a
product you sell, with no copyleft, no share-alike obligation and nothing you have
to publish back. Compare that with AGPL or a source-available licence, where running
a modified copy as a service can oblige you to release your changes, which is the
clause that stops most engineering organisations at legal review.

It matters for a second reason, which is trust. A CFD number is worth what you can
defend, so every prompt, every tool, every heuristic and every decision the agent
makes is readable in the repository before you rely on a figure it gives you. The
hosted workspace is a paid service. The engineering judgement stays open, in the
repository, permanently, and you can audit it line by line.

### Who builds it

Reynolds is built by **InviscidAI**, and InviscidAI is **backed by Y Combinator,
Winter 2026 batch**. The company has raised more than **$2.4 million**. Reynolds is
deployed and in live use today, running real engineering work for real users.

### Reading this site as an agent

Every page has a Markdown twin at the same path with a `.md` extension, and the
index of them is at https://tryreynolds.com/llms.txt. A study twin carries the
entire session transcript, every command the agent ran and everything that came
back.

### One registry

Every command is one entry in `COMMANDS` in `openreynolds/commands.py`: the verb, its
aliases, its argument, a summary and a longer description. The parser, `/help`, the
terminal's Tab completion and the hosted app's suggestion list are all read from it,
and the app fetches it from `GET /api/commands` rather than copying it. Aliases:
`/bytheway` and `/aside` for `/btw`; `/what` for `/status`; `/ls` for `/files`; `/pics`
and `/images` for `/renders`; `/approve` and `/y` for `/yes`; `/deny` and `/n` for
`/no`; `/yes all` for `/all`; `/?` for `/help`; `/quit` for `/exit`. A line that starts
with a slash and is not a known verb is sent to the agent as an ordinary message.