Crucible plugin privacy policy

Policy

This local profile reads only submitted paths under the workspace selected at launch. Tool output is returned to the connected client and its chosen model. No publisher service, telemetry endpoint, inference engine, or credential store is used by this profile. Do not include confidential data in the selected workspace unless that client and model are authorized to receive it.

What this plugin runs and handles

Hooks

This plugin has no hooks.

MCP server

The plugin starts one MCP server named crucible. Claude Code launches it with this command:

python3 -I -S -B ${CLAUDE_PLUGIN_ROOT}/server/serve.py --workspace ${user_config.workspace} --process-consent=${user_config.process_consent} --measure-command=${user_config.measure_command}

• python3 is the Python 3.11 or later on your PATH. The -I -S -B flags make Python ignore PYTHON* environment variables and your user site-packages, skip site-packages, and write no .pyc files.
• ${CLAUDE_PLUGIN_ROOT} is the folder where Claude Code installed the plugin.
• ${user_config.workspace} is the folder you choose when you enable the plugin. Crucible reads files only inside it.
• ${user_config.process_consent} is true or false. It is false unless you turn on "Allow this measurement command".
• ${user_config.measure_command} is the measurement command you enter, as a JSON list of arguments. It is empty unless you fill it in. Crucible refuses to start if you turn on consent without a command, or enter a command without consent.

With the defaults, the server offers two tools: crucible.assess and crucible.measurement_gate. Both only read files. With consent on and a command set, it also offers crucible.benchmark, which runs that one command.

Network

Crucible opens no network connection. At startup it blocks its own Python process from using sockets. It also blocks it from starting any other program, except the one measurement command you approve.

There is one exception. If you turn on the measurement command, Crucible runs that program once for each claim, up to 16 claims per call. It sends the program each claim's ID, hash, text and falsification test. That program is separate from Crucible. It runs with your user's permissions and can connect to any network address its own code chooses. Crucible cannot see or limit what it does.

Files written

With the defaults, Crucible writes no files.

With the measurement command on, each run of the program uses two temporary files in your system temp folder. One holds the claim sent to the program. The other holds the program's answer. Crucible deletes both as soon as that run ends, even when the run fails. If the server is stopped in the middle of a run, or your system refuses the delete, a file can stay in the temp folder until you or your system remove it. The measurement program itself may write any files its own code chooses.

Environment variables and credentials

Crucible reads no credentials, API keys or tokens from files or settings.

This list comes from running the server and recording every environment variable it looked up. The run covered startup, the tool list and each tool, once with the defaults and once with a measurement command.

Crucible's own code:

• With the defaults, Crucible's own code reads no environment variables.
• When the measurement command runs, Crucible goes through every environment variable you have, name and value, and keeps only SYSTEMROOT, WINDIR, TEMP and TMP. It passes those four to the measurement program so it can start and find your temp folder. It drops all the others in memory. It does not store them, log them, return them to Claude or pass them on. This means API keys or tokens in your environment are not passed on.

Python's standard library, which Crucible runs on:

• At startup, Python's argument parser reads LANG, LANGUAGE, LC_ALL and LC_MESSAGES to pick the language for its error messages. It also reads COLUMNS and LINES to size its help text.
• When the measurement command runs, Python's tempfile module reads TMPDIR, TEMP and TMP to choose the temp folder for the two temporary files. On Windows it also reads USERPROFILE and SYSTEMROOT to find fallback temp folders.

What it stores and sends

This profile stores nothing on disk and opens no network connection; the launcher denies Python socket and process operations. The optional measurement oracle runs only when the person who installs the plugin approves its exact command at launch. While it runs, Crucible passes each claim to it through two temporary files in your system temp folder and deletes them after each run. That oracle program may do whatever its own code does, including network access.

Retention and support

Crucible keeps no data after a call returns. Support and security reports: https://github.com/HarperZ9/crucible/issues

Source

This policy comes from client-plugin/PRIVACY.md in the Crucible repository.