Environment Variables

Pi uses environment variables in three ways:

• Variables such as PI_OFFLINE configure the Pi process.
• Pi sets PI_CODING_AGENT so child processes can detect that they run inside Pi.
• Commands run by the LLM-callable bash tool 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 PI_CODING_AGENT=true. Child processes inherit it and can use it to detect that they run inside Pi. It is not session-specific and is not set automatically when Pi is embedded through the SDK.

Bash Tool Session Environment

Commands run by the bash tool 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 bash 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 tool. They are not injected into user-entered ! or !! commands.

Custom Bash Tools

Bash tools created with createBashTool() 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 bashTool = createBashTool(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.