fix(runtime): isolation d'usage multi-projet #107

Implémentation du garde ModelServerProjectUseGuard pour séparer
les retours des agents entre projets concurrents.

- Garde RAII par LocalModelServerId partagé entre projets
- Refus inter-projets concurrent via model_server_in_use
- Partage intra-projet conservé avec refcount
- Libération automatique à la fermeture/erreur de session

Tests de validation: rejet projet distinct, compteur refs, libération retrait

crates/application/src/terminal/registry.rs

@@ -13,6 +13,8 @@ use domain::conversation::ConversationId;
 use domain::ports::{AgentSession, PtyHandle};
 use domain::{AgentId, IssueRef, NodeId, ProjectId, SessionId, SessionKind, TerminalSession};
 
+use crate::model_server::ModelServerProjectUseGuard;
+
 /// Runtime family of a live agent session.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum LiveSessionKind {
@@ -38,11 +40,12 @@ pub struct LiveSessionSnapshot {
 }
 
 /// A registered, live terminal: its PTY handle plus the domain snapshot.
-#[derive(Debug, Clone)]
+#[derive(Debug)]
 struct Entry {
     project_id: ProjectId,
     handle: PtyHandle,
     session: TerminalSession,
+    _model_server_guard: Option<ModelServerProjectUseGuard>,
 }
 
 /// Read-only liveness query over the agents that currently own a live PTY.
@@ -164,6 +167,18 @@ impl TerminalSessions {
         project_id: ProjectId,
         handle: PtyHandle,
         session: TerminalSession,
+    ) {
+        self.insert_in_project_with_model_server_guard(project_id, handle, session, None);
+    }
+
+    /// Inserts a freshly-opened session and retains a model-server usage guard
+    /// until the session is removed.
+    pub fn insert_in_project_with_model_server_guard(
+        &self,
+        project_id: ProjectId,
+        handle: PtyHandle,
+        session: TerminalSession,
+        model_server_guard: Option<ModelServerProjectUseGuard>,
     ) {
         if let Ok(mut map) = self.entries.lock() {
             map.insert(
@@ -172,6 +187,7 @@ impl TerminalSessions {
                     project_id,
                     handle,
                     session,
+                    _model_server_guard: model_server_guard,
                 },
             );
         }
@@ -388,6 +404,8 @@ struct StructuredEntry {
     agent_id: AgentId,
     /// La cellule (feuille de layout) qui héberge actuellement la vue.
     node_id: NodeId,
+    /// Optional local-model-server usage guard retained for the live session.
+    _model_server_guard: Option<ModelServerProjectUseGuard>,
 }
 
 #[derive(Clone)]
@@ -446,6 +464,21 @@ impl StructuredSessions {
         session: Arc<dyn AgentSession>,
         agent_id: AgentId,
         node_id: NodeId,
+    ) {
+        self.insert_in_project_with_model_server_guard(
+            project_id, session, agent_id, node_id, None,
+        );
+    }
+
+    /// Enregistre une session structurée et retient un garde d'usage de serveur
+    /// local jusqu'au retrait de la session.
+    pub fn insert_in_project_with_model_server_guard(
+        &self,
+        project_id: ProjectId,
+        session: Arc<dyn AgentSession>,
+        agent_id: AgentId,
+        node_id: NodeId,
+        model_server_guard: Option<ModelServerProjectUseGuard>,
     ) {
         if let Ok(mut map) = self.entries.lock() {
             let id = session.id();
@@ -456,6 +489,7 @@ impl StructuredSessions {
                     session,
                     agent_id,
                     node_id,
+                    _model_server_guard: model_server_guard,
                 },
             );
         }