feat(plugins): hot reload des plugins sans relancer IdeA — use case ReloadPlugin (invalidation registry/catalogue, resultat hashes+changed), tools MCP d'administration plugin agent-facing (mcp/plugins.rs + PluginToolProvider), evenement domaine plugin_reloaded relaye sur le wire (dto/events), exposition openai_tools rafraichie, wiring app-tauri — #271/#269 (QA verte #273: application 32, mcp_server 38, openai_tools 10, plugin_install_load 5, plugin 10, wire 1 — 96 tests ciblés; app-tauri compile sans desktop runtime)

crates/backend/src/events.rs

@@ -127,6 +127,18 @@ pub enum DomainEventDto {
         /// Installed version.
         version: String,
     },
+    /// A plugin package was hot-reloaded.
+    #[serde(rename_all = "camelCase")]
+    PluginReloaded {
+        /// Plugin id.
+        plugin_id: String,
+        /// Previous content hash.
+        old_content_hash: String,
+        /// New content hash.
+        new_content_hash: String,
+        /// Whether the content changed.
+        changed: bool,
+    },
     /// A plugin was enabled.
     #[serde(rename_all = "camelCase")]
     PluginEnabled {
@@ -782,6 +794,17 @@ impl From<&DomainEvent> for DomainEventDto {
                 plugin_id: plugin_id.to_string(),
                 version: version.as_str().to_owned(),
             },
+            DomainEvent::PluginReloaded {
+                plugin_id,
+                old_content_hash,
+                new_content_hash,
+                changed,
+            } => Self::PluginReloaded {
+                plugin_id: plugin_id.to_string(),
+                old_content_hash: old_content_hash.clone(),
+                new_content_hash: new_content_hash.clone(),
+                changed: *changed,
+            },
             DomainEvent::PluginEnabled { plugin_id } => Self::PluginEnabled {
                 plugin_id: plugin_id.to_string(),
             },
@@ -1327,6 +1350,24 @@ mod tests {
         assert_eq!(json["status"]["reused"], true);
     }
 
+    #[test]
+    fn plugin_reloaded_relays_hashes_and_changed_flag_to_wire() {
+        let plugin_id = domain::PluginId::new("dev.acme.gitgraph").unwrap();
+        let dto = DomainEventDto::from(&DomainEvent::PluginReloaded {
+            plugin_id,
+            old_content_hash: "abc123".to_owned(),
+            new_content_hash: "def456".to_owned(),
+            changed: true,
+        });
+
+        let json = serde_json::to_value(&dto).expect("serialisable");
+        assert_eq!(json["type"], "pluginReloaded");
+        assert_eq!(json["pluginId"], "dev.acme.gitgraph");
+        assert_eq!(json["oldContentHash"], "abc123");
+        assert_eq!(json["newContentHash"], "def456");
+        assert_eq!(json["changed"], true);
+    }
+
     #[test]
     fn model_server_status_changed_relays_downloading_to_dto_and_wire() {
         let dto = DomainEventDto::from(&DomainEvent::ModelServerStatusChanged {