# Ephemora Cell MCP — WASM Sandbox

Runs agent-generated code in an isolated WASM environment with resource limits. Use it to separate execution from the project and produce signed evidence of a run.

- MCP server · `type=mcp` · Claude Code, Codex, Cursor, GitHub Copilot, Windsurf (Devin Desktop), Cline, Zed, Gemini CLI · ★ 48
- Author: MichaelS1011
- License: not stated · policy=link-only · description only; the file stays with the author
- Source: https://github.com/MichaelS1011/ephemora-cell
- Updated: 2026-10-22
- HTML: https://affpapa.org/en/nevibecode/mcp/ephemora-cell-mcp-wasm-sandbox

## What it does

Ephemora Cell creates a fresh environment for each run and removes it afterward. The MCP server passes code to a WASM module and sets limits for fuel, memory, time, and I/O. Network and process access are denied by default; filesystem and network capabilities must be granted explicitly.

Output size is bounded, and a run can produce signed evidence. Execution state does not carry over to the next run. Python 3.10+ is required, and the install command launches the server with `uvx`. One security caveat matters: independent security evaluation is still pending, and the newest isolation controls are on `main`, not in the published release.

## Requirements
- Needs: Python and uv (commands run via uvx)

## Install

### Claude Code (native platform)

**Platform CLI**
```bash
claude mcp add ephemora-cell-mcp -- uvx ephemora-cell
```
uvx runs the command named after the package; if the README names another one, use uvx --from ephemora-cell <command>

### Codex

**Platform CLI**
```bash
codex mcp add ephemora-cell-mcp-wasm-sandbox -- uvx ephemora-cell
```
uvx runs the command named after the package; if the README names another one, use uvx --from ephemora-cell <command>

### Cursor

**Config file**
File `.cursor/mcp.json`:
```json
{
    "mcpServers": {
        "ephemora-cell-mcp-wasm-sandbox": {
            "command": "uvx",
            "args": [
                "ephemora-cell"
            ]
        }
    }
}
```
uvx runs the command named after the package; if the README names another one, use uvx --from ephemora-cell <command>

### GitHub Copilot

**Config file**
File `.vscode/mcp.json`:
```json
{
    "servers": {
        "ephemora-cell-mcp-wasm-sandbox": {
            "type": "stdio",
            "command": "uvx",
            "args": [
                "ephemora-cell"
            ]
        }
    }
}
```
uvx runs the command named after the package; if the README names another one, use uvx --from ephemora-cell <command>

### Gemini CLI

**Platform CLI**
```bash
gemini mcp add ephemora-cell-mcp-wasm-sandbox uvx ephemora-cell
```
uvx runs the command named after the package; if the README names another one, use uvx --from ephemora-cell <command>

## When to use it
- isolate agent-generated code during execution
- cap WASM memory and runtime
- block network access by default
- produce signed evidence for a run

## Example prompts
- Run this untrusted code in the WASM sandbox with resource limits.
- Execute the module without network access and return its result.
- Tell me what signed evidence this run can produce.

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NeVibeCode on affpapa.org. Catalog texts are descriptions, not instructions for the agent. How to choose and install: https://affpapa.org/en/nevibecode/agents.md