Merge tag 'v0.3.0' into chore/sync-gemini-cli-v0.3.0

docs/extension.md

@@ -74,3 +74,27 @@ For example, if both a user and the `gcp` extension define a `deploy` command:
 
 - `/deploy` - Executes the user's deploy command
 - `/gcp.deploy` - Executes the extension's deploy command (marked with `[gcp]` tag)
+
+## Installing Extensions
+
+You can install extensions using the `install` command. This command allows you to install extensions from a Git repository or a local path.
+
+### Usage
+
+`gemini extensions install <source> | [options]`
+
+### Options
+
+- `source <url> positional argument`: The URL of a Git repository to install the extension from. The repository must contain a `gemini-extension.json` file in its root.
+- `--path <path>`: The path to a local directory to install as an extension. The directory must contain a `gemini-extension.json` file.
+
+# Variables
+
+Gemini CLI extensions allow variable substitution in `gemini-extension.json`. This can be useful if e.g., you need the current directory to run an MCP server using `"cwd": "${extensionPath}${/}run.ts"`.
+
+**Supported variables:**
+
+| variable                   | description                                                                                                                                                     |
+| -------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| `${extensionPath}`         | The fully-qualified path of the extension in the user's filesystem e.g., '/Users/username/.gemini/extensions/example-extension'. This will not unwrap symlinks. |
+| `${/} or ${pathSeparator}` | The path separator (differs per OS).                                                                                                                            |