Harden desktop recovery and pre-release stability checks

Bound IPC transport deadlines while preserving portal leases, supervise desktop helper and agent recovery, and reserve final floating window geometry during placement.

Stabilize CLI output and isolated tests, expand workspace CI, resolve formatting and lint failures, and bundle the MIT license with installer compatibility.

compositor/src/backends/mod.rs

@@ -21,6 +21,7 @@ pub struct LaunchConfig {
     pub(crate) session_policy: SessionPolicy,
     pub client: Vec<OsString>,
     pub client_capabilities: ClientCapabilities,
+    pub supervise_client: bool,
 }
 
 impl LaunchConfig {
@@ -35,6 +36,7 @@ impl LaunchConfig {
         let mut requested_backend = None;
         let mut client = Vec::new();
         let mut client_capabilities = ClientCapabilities::default();
+        let mut supervise_client = false;
 
         while let Some(argument) = args.next() {
             if argument == "--" {
@@ -52,6 +54,10 @@ impl LaunchConfig {
                 client_capabilities.insert(ClientCapabilities::EFFECTS);
                 continue;
             }
+            if argument == "--supervise-client" {
+                supervise_client = true;
+                continue;
+            }
             if argument == "--grant-shell-control" {
                 client_capabilities.insert(ClientCapabilities::SHELL_CONTROL);
                 continue;
@@ -75,6 +81,9 @@ impl LaunchConfig {
             BackendKind::Drm
         });
 
+        if supervise_client && client.is_empty() {
+            return Err("--supervise-client requires a client command".into());
+        }
         Ok(Self {
             backend,
             session_policy: match backend {
@@ -83,6 +92,7 @@ impl LaunchConfig {
             },
             client,
             client_capabilities,
+            supervise_client,
         })
     }
 }
@@ -119,6 +129,26 @@ mod tests {
         assert_eq!(config.session_policy, SessionPolicy::Embedded);
         assert_eq!(config.client, [OsString::from("foot")]);
         assert!(config.client_capabilities.is_empty());
+        assert!(!config.supervise_client);
+    }
+
+    #[test]
+    fn supervision_requires_an_explicit_client() {
+        assert!(LaunchConfig::parse([OsString::from("--supervise-client")], true).is_err());
+        let config = LaunchConfig::parse(
+            [
+                "--supervise-client",
+                "--grant-shell-control",
+                "--",
+                "ferese-session-shell",
+            ]
+            .map(OsString::from),
+            true,
+        )
+        .unwrap();
+        assert!(config.supervise_client);
+        assert_eq!(config.client, [OsString::from("ferese-session-shell")]);
+        assert!(config.client_capabilities.contains(ClientCapabilities::SHELL_CONTROL));
     }
 
     #[test]