Add optional command extensions

src/config.rs

@@ -136,6 +136,11 @@ pub struct ClientConfig {
     pub send_env: Vec<String>,
     #[serde(default)]
     pub set_env: HashMap<String, String>,
+    /// Optional client-side command extensions. These are just shell command
+    /// templates expanded into the remote session's startup input; Dosh does not
+    /// depend on the tools they name.
+    #[serde(default)]
+    pub extensions: HashMap<String, CommandExtension>,
 }
 
 #[derive(Debug, Clone, Default, Serialize, Deserialize)]
@@ -151,6 +156,22 @@ pub struct HostConfig {
     pub send_env: Option<Vec<String>>,
     #[serde(default)]
     pub set_env: HashMap<String, String>,
+    /// Per-host extension overrides. A host can replace a global extension or set
+    /// `disabled = true` to opt out of it.
+    #[serde(default)]
+    pub extensions: HashMap<String, CommandExtension>,
+}
+
+#[derive(Debug, Clone, Default, Serialize, Deserialize, PartialEq, Eq)]
+pub struct CommandExtension {
+    /// Remote shell command template. `{args}` expands to shell-quoted extra
+    /// words after the extension name. When absent, extra args are appended.
+    #[serde(default)]
+    pub command: Option<String>,
+    #[serde(default)]
+    pub description: Option<String>,
+    #[serde(default)]
+    pub disabled: bool,
 }
 
 #[derive(Debug, Clone, Default, Serialize, Deserialize)]
@@ -186,6 +207,7 @@ impl Default for ClientConfig {
             disconnect_status: true,
             send_env: default_send_env(),
             set_env: HashMap::new(),
+            extensions: HashMap::new(),
         }
     }
 }