feat(chat): propage l'intention chat → require_structured dans le pipeline de lancement

- Ajoute le champ cell_kind dans LaunchAgentRequestDto pour distinguer les demandes chat (custom CLI) des lancements PTY historiques
- Convertit cellKind:Chat en require_structured:true dans commands.rs et web-server/src/lib.rs
- Implémente la logique de routing structuré dans LaunchAgent::execute :
  - valide que require_structured implique un profil avec structured_adapter
  - remplace une session PTY existante quand require_structured est vrai
  - route vers structured seulement quand wants_structured est vrai
- Met à jour tous les appels historiques avec require_structured:false pour préserver le contrat PTY
- Ajoute les tests unitaires human_launcher_with_chat_intent_routes_structured_profile_to_chat_session et chat_intent_replaces_existing_pty_instead_of_returning_pty_session
- Wire les ports structured dans BackendCore pour le launcher humain

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

crates/backend/src/dto.rs

@@ -2823,6 +2823,11 @@ pub struct LaunchAgentRequestDto {
     /// refused).
     #[serde(default)]
     pub node_id: Option<String>,
+    /// Requested render/runtime kind for this launch. Omitted by historical callers
+    /// and native TUI cells, which keeps the backend on the PTY path. The custom chat
+    /// view sends `"chat"` to require a structured/headless session.
+    #[serde(default)]
+    pub cell_kind: Option<CellKind>,
 }
 
 impl From<LaunchAgentOutput> for TerminalSessionDto {

crates/backend/src/lib.rs

@@ -725,6 +725,7 @@ impl WakeSessionProvider for AppWakeSessionProvider {
                 conversation_id: None,
                 mcp_runtime: None,
                 allow_structured_alongside_pty: true,
+                require_structured: false,
             })
             .await
             .map_err(|err| WakeError::Session(err.to_string()))?;
@@ -844,6 +845,7 @@ impl AgentResumer for AppAgentResumer {
                 conversation_id,
                 mcp_runtime,
                 allow_structured_alongside_pty: false,
+                require_structured: false,
             })
             .await?;
 
@@ -2028,9 +2030,9 @@ impl BackendCore {
         // LaunchAgent shares the SAME pty_port and terminal_sessions as the terminal
         // use cases — indispensable for transport bridges to work correctly.
         //
-        // The human-facing launcher intentionally stays PTY-only: when the user opens an
-        // agent cell, they keep the native Claude/Codex CLI and its commands. Inter-agent
-        // delegation gets its own launcher below, wired to structured/headless sessions.
+        // The human-facing launcher defaults to PTY for native Claude/Codex TUI cells, but
+        // it also carries the structured ports so the custom chat CLI can explicitly
+        // request a structured/headless launch through the same Tauri command.
 
         // --- Permission projectors (lot LP3-5) ---
         // UN seul registre, source unique de vérité, injecté à l'identique dans
@@ -2084,7 +2086,11 @@ impl BackendCore {
                 clock: Arc::clone(&clock) as Arc<dyn Clock>,
             }) as Arc<dyn LiveStateLeanProvider>)
             .with_local_model_server(Arc::clone(&ensure_local_model_server))
-            .with_secret_store(Arc::clone(&secret_store_port)),
+            .with_secret_store(Arc::clone(&secret_store_port))
+            .with_structured(
+                Arc::clone(&session_factory),
+                Arc::clone(&structured_sessions),
+            ),
         );
 
         // Inter-agent launcher: same context, memory, permissions and live-state