From a9e6c4cde3d091144f7bc2f2af241dd7eb2df729 Mon Sep 17 00:00:00 2001
From: Alex Dioso <adioso@gmail.com>
Date: Wed, 8 Apr 2026 11:29:07 -0700
Subject: [PATCH] Document plugin formats and environment variables

Added sections on plugin formats and environment variables.
---
 docs/copilot/customization/agent-plugins.md | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/docs/copilot/customization/agent-plugins.md b/docs/copilot/customization/agent-plugins.md
index 06410e0a60..6592ce6f04 100644
--- a/docs/copilot/customization/agent-plugins.md
+++ b/docs/copilot/customization/agent-plugins.md
@@ -56,6 +56,21 @@ Once installed, plugin-provided customizations appear alongside your locally def
 > [!CAUTION]
 > Plugins can include hooks and MCP servers that run code on your machine. Review the plugin contents and publisher before installing, especially for plugins from community marketplaces.
 
+## Plugin Formats
+The plugin format is auto-selected based on the plugin file path (relative to the plugin root).
+| Plugin format | Plugin file path(s) |
+|---------------|------------------|
+| Claude | `.claude-plugin/plugin.json` |
+| Copilot | `plugin.json`, `.github/plugin/plugin.json` |
+| OpenPlugin | `.plugin/plugin.json` |
+
+### Plugin Environment Variables
+| Plugin format | Plugin root |
+|---------------|------------------|
+| Claude | `${CLAUDE_PLUGIN_ROOT}` |
+| Copilot | (Not Defined) |
+| OpenPlugin | `${PLUGIN_ROOT}` |
+
 ## Hooks in plugins
 
 Plugins can include [hooks](/docs/copilot/customization/hooks.md) that run shell commands at agent lifecycle points. Plugin hooks work alongside your workspace and user-level hooks. When a plugin is enabled, its hooks fire in addition to any other hooks configured for the same event.