pi-ward

File access guard for pi. Declarative filesystem boundaries for the coding agent.

Installation

pi install npm:pi-ward

Or try without installing:

pi -e npm:pi-ward

Why

• Prevents the agent from reading secrets (.env, .pem, credentials)
• Blocks writes outside the project tree
• Stops accidental modification of .git internals
• Symlink-aware — no escape via symlink tricks
• Config-file self-protection — the agent can't weaken its own constraints
• Fail-closed on any error — never fails open

How it works

pi-ward intercepts file operations (read, write, edit) before they execute. It evaluates declarative rules from ward config files against the resolved real path.

Baseline policy (no config needed):

• Read/write within project root: allowed
• Any access outside project root: denied

When a path outside the project root is accessed and no explicit deny rule matches, ward prompts for approval (if a UI is available). You can approve or deny, scoped to a single attempt or the entire session. See DESIGN.md for details.

Config

Rules are loaded from ~/.pi/agent/ward.json (global) and .pi/ward.json files along the directory tree. Global rules always take precedence — inner configs can't weaken outer ones.

Example .pi/ward.json:

{
  "rules": [
    { "pattern": ".env*", "effect": "deny" },
    { "pattern": "*.pem", "effect": "deny" },
    { "pattern": ".git/", "operations": "write", "effect": "deny" },
    { "pattern": ".secret/", "effect": "deny" }
  ]
}

Absolute-path patterns (starting with /) can be used in ~/.pi/agent/ward.json to grant access to paths outside ~:

{
  "rules": [
    { "pattern": "/tmp/pi-github-repos/", "effect": "allow" }
  ]
}

Operations

The operations field controls the access level a rule grants or restricts. It defaults to "read" (restrictive).

effect	operations	Result
allow	"read" (default)	Grants read access only
allow	"write"	Grants full access (read + write)
deny	"read" (default)	Denies all access
deny	"write"	Denies writes only (read-only)

Rules are evaluated top-to-bottom, first match wins. See DESIGN.md for pattern syntax, trust scoping, and the full specification.

Design

See DESIGN.md for the full specification.