pi-minimal-permission-system

A minimal permission enforcement extension for the Pi coding agent.

This extension adds a lightweight permission layer to Pi. Instead of running unrestricted, built-in tool calls (read, edit, write, and bash) are checked against a simple policy that you control. MCP tools and other extensions are intentionally out of scope.

Philosophy

Pi is designed to be minimal. This extension follows the same approach:

• Built-in tools only — read, edit, write, and bash. MCP tools and extension-provided tools are intentionally not covered.
• No granular subagent permissions — just two layers: global and project-local.
• Granular tool-level control — read, edit, and write are governed independently, so you can allow read-only access to sensitive paths while blocking edits.

Installation

Install from npm with Pi:

pi install npm:pi-minimal-permission-system

To pin a specific release:

pi install npm:pi-minimal-permission-system@1.0.0

For local development, you can still clone it into ~/.pi/agent/extensions:

cd ~/.pi/agent/extensions
git clone https://github.com/milanglacier/pi-minimal-permission-system.git

Configuration

Permissions are defined in JSONC (JSON with comments) files.

Global config

~/.pi/agent/permissions.jsonc

Applies to every Pi session regardless of working directory.

Project-local config

<cwd>/.pi/agent/permissions.jsonc

Applies only when Pi's working directory is inside that project. Project rules are layered on top of global rules.

Format

{
  // "allow"   -> silently permit
  // "deny"    -> hard-block with an error
  // "ask"     -> prompt the user for confirmation (default when no rule matches)

  "read": {
    "**": "allow",
    "/etc/**": "deny",
    "**/.env*": "deny",
    "**/secrets/**": "ask",
  },

  "edit": {
    "**": "allow",
    "**/.env*": "deny",
    "**/package-lock.json": "deny",
  },

  "write": {
    "**": "allow",
    "/etc/**": "deny",
    "**/.ssh/**": "deny",
  },

  "bash": {
    ".*": "allow",
    "rm\\s+-rf\\s+/.*": "deny",
    "sudo\\b.*": "ask",
  },
}

Pattern matching

Tool	Pattern type	Notes
read, edit, write	picomatch glob	Matches absolute path, relative path (from cwd), raw input, and basename. dot: true is enabled.
bash	JavaScript RegExp	Matched against the full command string. Must be a valid regex (the pattern string is passed to new RegExp(pattern, "u")).

Precedence

1. Rules are evaluated in config order: global first, then project-local.
2. The last matching rule wins.
3. Global deny is special: if the last match is not a deny, the system still checks whether any global rule issues a deny. This means you can safely set a global hard boundary (e.g. deny /etc/**) that cannot be accidentally overridden by a project-local rule.

YOLO mode

Start Pi with --yolo or run /yolo during an interactive session to bypass all permission checks enforced by this extension. /yolo is a toggle; running it again restores normal permission enforcement.

When YOLO mode is enabled, bash, read, edit, and write tool calls are allowed without loading policy, checking rules, prompting, or honoring global deny rules.

Example workflows

Read-only mode for sensitive directories

{
  "read": {
    "**": "allow",
  },
  "edit": {
    "**/.ssh/**": "deny",
    "**/.gnupg/**": "deny",
    "**": "allow",
  },
  "write": {
    "**/.ssh/**": "deny",
    "**/.gnupg/**": "deny",
    "**": "allow",
  },
}

Interactive gate for destructive commands

{
  "bash": {
    ".*": "allow",
    "rm\\s+-rf\\s+/.*": "deny",
    "dropdb\\b.*": "ask",
    "sudo\\b.*": "ask",
  },
}

Per-project override

Global ~/.pi/agent/permissions.jsonc:

{
  "edit": {
    "**": "allow",
  },
}

Project my-app/.pi/agent/permissions.jsonc:

{
  "edit": {
    "**/package.json": "ask",
    "**": "allow",
  },
}

Editing package.json inside my-app will prompt for confirmation; everywhere else it is allowed.

Comparison with pi-permission-system

Feature	pi-minimal-permission-system (this project)	pi-permission-system
Philosophy	Minimal, aligned with Pi's design	More feature-rich
Permission layers	Global + project-local only	Global + project-local + granular subagent permissions
Subagent permissions	❌ Not supported (intentionally)	✅ Supported
Filesystem tool granularity	✅ read, edit, write controlled independently	❌ Not currently supported
Command filtering	✅ Regex-based bash rules	✅ Supported
MCP / extension tools	❌ Not supported (intentionally)	✅ Supported
Config format	JSONC	JSONC/YAML

When to choose this extension:

• You want a minimal permission system that stays out of your way.
• You do not need per-subagent or MCP tool permission overrides.
• You want granular filesystem control — for example, allowing the agent to read secrets but never edit or write them.

When to choose pi-permission-system:

• You need subagent-level permission granularity (e.g. different policies for different agent roles or chains).

Development

# Type-check
npm run typecheck

# Run tests
npm run test

# Both
npm run check