pi-fnox

A pi extension for fnox — automatic secret injection and scrubbing for AI agents.

What it does

• Injects fnox vault secrets into process.env at startup — so anything reading env vars in-process (runline plugin env: fallbacks, custom scripts, etc.) finds them. This is the main reason this extension exists.
• Injects the same secrets into bash subprocesses spawned by Pi's built-in tool and user ! commands.
• Scrubs secret values from all tool output — bash, read, grep, everything the LLM sees — as a safety net.
• Tells the LLM which secrets are available via the system prompt (names only, never values).

You: "deploy using the stripe key"

Agent runs: env | grep STRIPE_SECRET_KEY
            → STRIPE_SECRET_KEY=sk_live_…
Agent sees: STRIPE_SECRET_KEY=[REDACTED:STRIPE_SECRET_KEY]

The agent orchestrates. fnox holds the secrets (age-encrypted at rest in ~/.config/fnox/config.toml). The values never touch the context window.

Install

# Requires fnox on PATH
#   mise use -g fnox      # OR: brew install fnox, scoop install fnox, etc.

# Install the extension
pi install npm:@kickythrust/pi-fnox

Restart Pi. You should see [pi-fnox] loaded N secrets from … in stderr.

Setup

# Initialize fnox and add secrets (fnox's age provider is what we expect)
fnox init
fnox set STRIPE_KEY
fnox set DATABASE_URL

# Start pi — secrets automatically injected into every bash + process.env
pi

To scope to a subset of secrets, filter by fnox profile (the extension honors FNOX_PROFILE).

Commands

Command	Description
/fnox-list	Show loaded secret names (never values)
/fnox-reload	Re-read fnox from disk (use after fnox set / fnox remove)

Config (env vars)

Env var	Default	Effect
FNOX_CONFIG	~/.config/fnox/config.toml	Path to the fnox.toml to load from
FNOX_PROFILE	unset	fnox profile name to select (e.g. prod, staging)

Why this exists

Runline's plugin loader resolves connection config via applyEnvOverrides, which reads process.env at connection-resolution time. Plugins whose schema fields declare env: "FOO_TOKEN" (github, cloudflareAccess, supabase, bugsink, etc.) need the parent Pi process to have the env loaded before Runline.fromProject() runs. Without this extension, those secrets would only reach bash subprocesses, leaving runline's in-process sandbox unauthenticated.

This extension hydrates process.env at Pi startup so runline plugins (and any other in-process tool) see the same env that bash subprocesses do.

How it works

1. On startup, the extension runs fnox -c ~/.config/fnox/config.toml export -f json and decrypts the result with the local age key.
2. Secrets are merged into process.env.
3. The same secrets are injected into every bash invocation via spawnHook (built-in tool) and user_bash exec (user ! commands).
4. After any tool completes, tool_result scrubs any leaked secret value out of the returned text.
5. before_agent_start adds the list of loaded secret names to the system prompt so the LLM knows to use $SECRET_NAME in bash.

Why fnox

• No biometric prompt. fnox decrypts locally with age — sub-100ms, no UI prompts, no human in the loop.
• Committed to git. fnox.toml stores only age-encrypted blobs. Audit-friendly, review-friendly, reproducible.
• One tool. fnox is the secret bus.

License

MIT