feat(agent): backend hot-swap profil (A0+A1) + inventaire reprise session (B1) — L15

Cadrage Architecture §15 (figé) : « agent = entité à session persistante ».

- A0 (domaine) : Agent::with_profile, LayoutTree::leaf, event AgentProfileChanged
  (+ DTO miroir DomainEventDto camelCase).
- A1 (application) : use case ChangeAgentProfile — no-op si profil identique,
  mutation manifeste, nettoyage conversation_id/agent_was_running sur layouts
  persistés, swap à chaud (kill PTY + relance même cellule via composition de
  LaunchAgent), event AgentProfileChanged. Décision : repartir à neuf (on garde
  .md + mémoire, on jette l'historique de conversation).
- B1 (application) : use case ListResumableAgents (lecture seule) — inventaire des
  cellules was_running||conversation_id, resume_supported selon profil, best-effort.

Aucun nouveau port/adapter (composition de l'existant). Hexagonal strict.
Tests : domaine 11 + app-tauri dto + ChangeAgentProfile 9 + ListResumableAgents 8,
suite application complète verte (0 régression).

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

crates/app-tauri/src/events.rs

@@ -47,6 +47,14 @@ pub enum DomainEventDto {
         /// Exit code.
         code: i32,
     },
+    /// An agent's runtime profile was changed (hot-swap of the AI engine).
+    #[serde(rename_all = "camelCase")]
+    AgentProfileChanged {
+        /// Agent id.
+        agent_id: String,
+        /// The new runtime profile id.
+        profile_id: String,
+    },
     /// A template was updated.
     #[serde(rename_all = "camelCase")]
     TemplateUpdated {
@@ -171,6 +179,13 @@ impl From<&DomainEvent> for DomainEventDto {
                 agent_id: agent_id.to_string(),
                 code: *code,
             },
+            DomainEvent::AgentProfileChanged {
+                agent_id,
+                profile_id,
+            } => Self::AgentProfileChanged {
+                agent_id: agent_id.to_string(),
+                profile_id: profile_id.to_string(),
+            },
             DomainEvent::TemplateUpdated {
                 template_id,
                 version,

crates/app-tauri/tests/dto.rs

@@ -13,7 +13,7 @@ use domain::{Direction, LayoutNode, LayoutTree, LeafCell, NodeId};
 
 use application::{AppError, HealthInput};
 use domain::events::DomainEvent;
-use domain::ids::{AgentId, SessionId};
+use domain::ids::{AgentId, ProfileId, SessionId};
 use domain::ProjectId;
 use domain::TemplateId;
 use domain::TemplateVersion;
@@ -93,6 +93,26 @@ fn domain_event_dto_maps_agent_launched() {
     assert_eq!(v["sessionId"], sid.to_string());
 }
 
+#[test]
+fn domain_event_dto_maps_agent_profile_changed() {
+    // LOT A0 : round-trip camelCase agentId/profileId du miroir DTO.
+    let aid = AgentId::from_uuid(Uuid::from_u128(1));
+    let pid = ProfileId::from_uuid(Uuid::from_u128(2));
+    let dto = DomainEventDto::from(&DomainEvent::AgentProfileChanged {
+        agent_id: aid,
+        profile_id: pid,
+    });
+    let v = serde_json::to_value(&dto).unwrap();
+    assert_eq!(
+        v,
+        json!({
+            "type": "agentProfileChanged",
+            "agentId": aid.to_string(),
+            "profileId": pid.to_string(),
+        })
+    );
+}
+
 #[test]
 fn domain_event_dto_maps_template_updated_version() {
     let tid = TemplateId::from_uuid(Uuid::nil());