Environment Variables

Pi uses environment variables in three ways:

• Variables such as PI_OFFLINE configure the Pi process.
• Pi sets process markers so child processes can identify Pi as the launching agent.
• Commands run by the LLM-callable shell tools receive PI_* variables describing the current session.

Provider API-key variables are documented separately in Providers.

Process Marker

The CLI and RPC entry points set two process markers:

• AI_AGENT=pi is a generic marker that lets tooling identify Pi as the agent that launched the process.
• PI_CODING_AGENT=true is Pi-specific and lets child processes detect that they run inside Pi.

Child processes inherit both markers. They are not session-specific and are not set automatically when Pi is embedded through the SDK.

Shell Tool Session Environment

Commands run by the bash and powershell tools receive the current Pi session state:

The values are resolved when each command starts. Switching models or changing the reasoning level therefore affects the next shell command without restarting Pi. PI_PROVIDER and PI_MODEL identify the selected Pi model, not a different upstream model that a router may choose internally.

When asked which model or provider is running, inspect these variables instead of inferring the answer from the system prompt:

printf '%s/%s\n' "$PI_PROVIDER" "$PI_MODEL"
printf 'reasoning=%s session=%s\n' "$PI_REASONING_LEVEL" "$PI_SESSION_ID"

The session file can be inspected directly when the session is persistent:

if [ -n "$PI_SESSION_FILE" ]; then
  tail -n 1 "$PI_SESSION_FILE"
fi

These variables are injected into the LLM-callable bash and powershell tools. They are not injected into user-entered ! or !! commands.

Custom Shell Tools

Tools created with createBashTool() or createPowerShellTool() expose the session environment by default when registered with Pi. Injection happens before spawnHook, so a hook receives the variables in ctx.env:

const bashTool = createBashTool(cwd, {
  spawnHook: (ctx) => ({
    ...ctx,
    env: { ...ctx.env, CI: "1" },
  }),
});

Disable session metadata independently of the spawn hook:

const powershellTool = createPowerShellTool(cwd, {
  exposeSessionEnvironment: false,
  spawnHook: (ctx) => ctx,
});

When disabled, Pi removes inherited values for these variables so nested Pi processes do not expose stale parent-session metadata.

Pi Process Configuration

These variables are read by Pi itself:

Provider credentials such as ANTHROPIC_API_KEY, OPENAI_API_KEY, and cloud-provider configuration are listed in Providers.