feat(coding-agent): add PI_SKIP_VERSION_CHECK env variable

Skip new version check at startup when set. Useful for Nix or other
package manager installs where npm install is not used.

Also documents PI_CODING_AGENT_DIR and other environment variables
in the README.

closes #549

Co-authored-by: Aos Dabbagh <25783780+aos@users.noreply.github.com>

packages/coding-agent/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Added
+
+- `PI_SKIP_VERSION_CHECK` environment variable to disable new version notifications at startup ([#549](https://github.com/badlogic/pi-mono/pull/549) by [@aos](https://github.com/aos))
+
 ### Breaking Changes
 
 - `ctx.ui.custom()` factory signature changed from `(tui, theme, done)` to `(tui, theme, keybindings, done)` for consistency with other input-handling factories

packages/coding-agent/README.md

@@ -1183,6 +1183,15 @@ pi --tools read,grep,find,ls -p "Review the architecture"
 pi --export session.jsonl output.html
 ```
 
+### Environment Variables
+
+| Variable | Description |
+|----------|-------------|
+| `ANTHROPIC_API_KEY`, `OPENAI_API_KEY`, etc. | API keys for providers (see [API Keys & OAuth](#api-keys--oauth)) |
+| `PI_CODING_AGENT_DIR` | Override the agent config directory (default: `~/.pi/agent`) |
+| `PI_SKIP_VERSION_CHECK` | Skip new version check at startup (useful for Nix or other package manager installs) |
+| `VISUAL`, `EDITOR` | External editor for Ctrl+G (e.g., `vim`, `code --wait`) |
+
 ---
 
 ## Tools

packages/coding-agent/src/modes/interactive/interactive-mode.ts

@@ -489,6 +489,8 @@ export class InteractiveMode {
 	 * Check npm registry for a newer version.
 	 */
 	private async checkForNewVersion(): Promise<string | undefined> {
+		if (process.env.PI_SKIP_VERSION_CHECK) return undefined;
+
 		try {
 			const response = await fetch("https://registry.npmjs.org/@mariozechner/pi-coding-agent/latest");
 			if (!response.ok) return undefined;