Install SessionCost

Installing has two steps:

1. Put SessionCost on your computer, one way: one line, Python (PyPI) or Node (npm). A plugin from your agent (step 2) also does this step for that agent.
2. Connect your agent: Claude Code, Codex, Cursor, Antigravity, GitHub Copilot.

Where you type: two different places

This page uses two places. They can look alike, but they are not the same.

	Your agent’s chat	A terminal
What it is	Where you talk to Claude Code, Codex, Cursor, Antigravity or Copilot. The agent reads what you type and decides what to run	Your computer’s command line. What you type runs exactly as typed; no agent is involved
How to open it	Open the agent (in VS Code: click its icon)	Windows: press the Windows key, type powershell, press Enter (or in VS Code: Terminal → New Terminal). Mac: Cmd + Space, type terminal, press Enter
How it looks	A message box. Claude Code in a terminal (claude) is also a chat: a > box with a status line under it	A line ending in > or $ with a folder name, such as PS C:\Users\you>
What goes there	Lines that start with /, such as /sessioncost, /livesession, /plugin, and requests in plain words	Lines that start with python, sessioncost, npx, pip, irm, curl, codex, agy or claude plugin

If a terminal shows an agent’s chat (for example Claude Code’s > box), type /exit or open a new terminal before running a terminal line.

Which command to type in a terminal

The help pages write terminal commands as sessioncost …. Type them the way that matches how you installed:

You installed with	The report	Turn the guard on	Any other command
Way A (one line), pipx or uv tool	sessioncost	sessioncost guard on	sessioncost <command>
Way B (PyPI, pip)	python -m sessioncost	python -m sessioncost guard on	python -m sessioncost <command>
Way C (npm)	npx sessioncost	npx sessioncost guard on	npx sessioncost <command>

On Mac or Linux, use python3 if python is not found. In a chat, the commands are the same for everyone: /sessioncost, /sessioncost update, and so on.

Step 1: put SessionCost on your computer

Pick one way.

Way A: one line, no Python or Git needed

1. Open a terminal (see above).

2. Paste the line for your computer and press Enter.

   Windows

   irm https://raw.githubusercontent.com/kish21/sessioncost/main/install.ps1 | iex

   Mac / Linux

   curl -fsSL https://raw.githubusercontent.com/kish21/sessioncost/main/install.sh | sh

3. Wait about a minute. It ends with /sessioncost added for each agent it found (Claude Code, Codex, Cursor, Antigravity). Then open a new terminal, so the sessioncost command is found.

Way B: Python, from PyPI

Needs Python 3.10 or newer. In a terminal:

python -m pip install -U sessioncost     # -U also updates an older copy
python -m sessioncost setup              # adds /sessioncost to your agents

• python -m sessioncost works even when Windows cannot find the sessioncost command (common with the Microsoft Store Python).
• Prefer isolated tools? pipx install sessioncost or uv tool install sessioncost, then sessioncost setup.

Way C: Node, from npm

Needs Node (with npx). In a terminal:

npx sessioncost setup                    # answer y if npx asks to install the package

The first run installs SessionCost once into its own folder, ~/.sessioncost/npm/venv: with uv when you have it, which also fetches Python for you, otherwise with your Python 3.10 or newer. Your own Python is left as it is. From then on, type npx sessioncost … for every terminal command.

Step 2: connect your agent

setup (ways A, B, C) already added /sessioncost to Claude Code, Codex, Cursor and Antigravity. A plugin is the other way: it brings its own SessionCost (step 1 not needed for that agent), but needs Python 3.10 or newer and Git. Use one or the other in an agent, not both.

After either, restart the agent, open a chat and type /sessioncost (or ask: “run sessioncost”). The report opens in your browser.

Claude Code

Where you use it	Plugin install
Claude Code CLI (claude in a terminal)	In the chat: /plugin marketplace add kish21/sessioncost, then /plugin install sessioncost@sessioncost. Or type /plugin, open Marketplaces, add kish21/sessioncost, and install sessioncost from the Plugins tab.
Claude Code in VS Code (the chat panel)	It has no /plugin. In a terminal: claude plugin marketplace add kish21/sessioncost, then claude plugin install sessioncost@sessioncost. Then reload VS Code (Ctrl+Shift+P → Developer: Reload Window).

Both share one install: do it once, and the CLI and VS Code both have it. In the chat, /livesession turns on the guard for every chat, until /livesession off.

Codex

1. In a terminal: codex plugin marketplace add kish21/sessioncost.
2. Codex app: open Customize → Plugins, choose sessioncost, click Install plugin. Codex CLI: type /plugins, pick sessioncost, install it.
3. Start a new chat.

Cursor

Open Customize → Plugins, choose From GitHub Repository (or Add Marketplace), paste https://github.com/kish21/sessioncost, install sessioncost and restart Cursor. If no plugin shows up, use step 1 instead.

Antigravity

Command line: agy plugin install https://github.com/kish21/sessioncost, then start a new chat. Antigravity app: use step 1 instead.

GitHub Copilot

Copilot CLI and Copilot Chat in VS Code have no /sessioncost. Do step 1, then in a terminal, in your project folder, type the report command from the table above (for example python -m sessioncost): it reads Copilot’s chats too. For the guard, see Agents.

Where /sessioncost is added

Agent	Folder
Claude Code	~/.claude/skills/sessioncost (or the plugin)
Codex (CLI, IDE, app)	~/.codex/skills/sessioncost
Cursor	~/.cursor/skills/sessioncost
Antigravity	~/.gemini/config/skills/sessioncost

Installed another agent later? Run setup again (way A, B or C), or paste the line from way A again.

Stay up to date

The simple way: type /sessioncost update in a chat, or update in a terminal (sessioncost update, python -m sessioncost update or npx sessioncost update, as in the table). It updates every copy of SessionCost on the computer, each the right way, and tells you what it did. Then restart your agent.

Agent	New versions
Claude Code	CLI: once, /plugin → Marketplaces → sessioncost → Enable auto-update; from then on each new version arrives by itself. VS Code: in a terminal, claude plugin update sessioncost@sessioncost.
Codex	Codex looks for a new version when it starts. To be sure: codex plugin marketplace upgrade.
Cursor	Customize → the marketplace with SessionCost → Refresh.
Antigravity, and ways A, B, C	update as above, or install again the same way.

Next: Your first report.