feat(graph): add interactive relation details and synchronized labels

include/dao/relation_dao.h

@@ -93,6 +93,17 @@ gboolean relation_dao_insert(
     GError **error
 );
 
+/**
+ * @brief Met à jour les champs modifiables d'une relation existante.
+ *
+ * L'identifiant, les extrémités et la date de création sont conservés.
+ */
+gboolean relation_dao_update(
+    RelationDao *relation_dao,
+    const RelationRecord *relation_record,
+    GError **error
+);
+
 /**
  * @brief Recherche une relation par son UUID.
  *

include/views/create_relation_dialog.h

@@ -14,6 +14,7 @@ G_BEGIN_DECLS
  * @brief Résultat opaque produit par le dialogue.
  */
 typedef struct CreateRelationDialogResult CreateRelationDialogResult;
+typedef struct RelationRecord RelationRecord;
 
 /**
  * @brief Codes d'erreur produits par CreateRelationDialog.
@@ -82,6 +83,21 @@ gboolean create_relation_dialog_present(
     GError **error
 );
 
+/**
+ * @brief Présente le dialogue prérempli pour modifier une relation.
+ *
+ * La source et la cible sont conservées ; les champs métier sont modifiables.
+ * Le dialogue ne réalise aucune écriture SQLite.
+ */
+gboolean edit_relation_dialog_present(
+    GtkWindow *parent,
+    const RelationRecord *relation_record,
+    const GPtrArray *entities,
+    CreateRelationDialogCallback callback,
+    gpointer user_data,
+    GError **error
+);
+
 /**
  * @brief Valide les valeurs obligatoires d'une relation.
  *

include/views/main_window.h

@@ -137,6 +137,12 @@ typedef void (*MainWindowAddRelationCallback)(
     gpointer user_data
 );
 
+/** @brief Callback appelé pour modifier une relation. */
+typedef void (*MainWindowEditRelationCallback)(
+    const char *relation_identifier,
+    gpointer user_data
+);
+
 /**
  * @brief Callback appelé lors du déclenchement d'une action OSINT.
  *
@@ -227,6 +233,13 @@ void main_window_set_add_relation_callback(
     gpointer user_data
 );
 
+/** @brief Définit le callback de modification d'une relation. */
+void main_window_set_edit_relation_callback(
+    MainWindow *main_window,
+    MainWindowEditRelationCallback callback,
+    gpointer user_data
+);
+
 /**
  * @brief Définit le callback de déclenchement des actions OSINT.
  *
@@ -419,6 +432,12 @@ void main_window_set_graph(
     const InvestigationGraphLayout *graph_layout
 );
 
+/** @brief Sélectionne une relation dans le graphe affiché. */
+gboolean main_window_select_graph_relation(
+    MainWindow *main_window,
+    const char *relation_identifier
+);
+
 /**
  * @brief Affiche une erreur de chargement du graphe.
  *

include/widgets/workspace.h

@@ -78,6 +78,12 @@ typedef void (*WorkspaceAddRelationCallback)(
     gpointer user_data
 );
 
+/** @brief Callback appelé pour modifier la relation sélectionnée. */
+typedef void (*WorkspaceEditRelationCallback)(
+    const char *relation_identifier,
+    gpointer user_data
+);
+
 /**
  * @brief Callback appelé lors du déclenchement d'une action OSINT.
  *
@@ -288,6 +294,13 @@ void workspace_set_add_relation_callback(
     gpointer user_data
 );
 
+/** @brief Définit le callback de modification d'une relation. */
+void workspace_set_edit_relation_callback(
+    Workspace *workspace,
+    WorkspaceEditRelationCallback callback,
+    gpointer user_data
+);
+
 /**
  * @brief Affiche l'état de chargement du graphe.
  *

src/core/application.c

@@ -40,6 +40,7 @@
 #include "views/osint_execution_history_dialog.h"
 #include "dao/evidence_dao.h"
 #include "dao/entity_dao.h"
+#include "dao/relation_dao.h"
 #include "dao/osint_execution_dao.h"
 #include "models/evidence_type.h"
 #include "widgets/evidence_list_model.h"
@@ -52,6 +53,7 @@
 #include "core/eml_processing.h"
 #include "core/eml_integration.h"
 #include "database/database.h"
+#include "database/transaction.h"
 #include "views/create_social_account_dialog.h"
 #include "views/create_person_dialog.h"
 #include "views/eml_analysis_dialog.h"
@@ -123,6 +125,7 @@ struct Application
     guint64 graph_load_generation;
 
     char *selected_evidence_identifier;
+    char *pending_relation_selection_identifier;
 };
 
 /**
@@ -737,6 +740,14 @@ static void application_on_graph_loaded(
         application->graph_layout
     );
 
+    if (application->pending_relation_selection_identifier != NULL)
+    {
+        main_window_select_graph_relation(application->main_window,
+            application->pending_relation_selection_identifier);
+        g_clear_pointer(&application->pending_relation_selection_identifier,
+            g_free);
+    }
+
     status_message =
         g_strdup_printf(
             "Graphe chargé : %" G_GUINT64_FORMAT
@@ -4917,6 +4928,136 @@ cleanup:
 /**
  * @brief Ouvre le dialogue de création depuis la fiche d'une entité.
  */
+/** @brief Contexte conservé pendant l'édition d'une relation. */
+typedef struct
+{
+    Application *application;
+    char *relation_identifier;
+} ApplicationEditRelationContext;
+
+/** @brief Libère le contexte d'édition d'une relation. */
+static void application_edit_relation_context_free(
+    ApplicationEditRelationContext *context)
+{
+    if (context == NULL) return;
+    g_free(context->relation_identifier);
+    g_free(context);
+}
+
+/** @brief Persiste les valeurs validées du dialogue d'édition. */
+static void application_on_edit_relation_completed(
+    CreateRelationDialogResult *result, gpointer user_data)
+{
+    ApplicationEditRelationContext *context = user_data;
+    Application *application = context != NULL ? context->application : NULL;
+    Database *database = NULL;
+    RelationDao *relation_dao = NULL;
+    RelationRecord *existing = NULL;
+    RelationRecord *updated = NULL;
+    const InvestigationProject *project = NULL;
+    GDateTime *now = NULL;
+    char *timestamp = NULL;
+    GError *error = NULL;
+    gboolean transaction_active = FALSE;
+
+    if (result == NULL || application == NULL || application->session == NULL)
+        goto cleanup;
+    database = investigation_session_get_database(application->session);
+    project = investigation_session_get_project(application->session);
+    relation_dao = relation_dao_new(database, &error);
+    if (relation_dao == NULL) goto failure;
+    existing = relation_dao_find_by_identifier(relation_dao,
+        context->relation_identifier, &error);
+    if (existing == NULL) goto failure;
+    now = g_date_time_new_now_utc();
+    timestamp = now != NULL ? g_date_time_format(now,
+        "%Y-%m-%dT%H:%M:%SZ") : NULL;
+    updated = relation_record_new(
+        relation_record_get_identifier(existing),
+        relation_record_get_source_entity_identifier(existing),
+        relation_record_get_target_entity_identifier(existing),
+        create_relation_dialog_result_get_relation_type(result),
+        create_relation_dialog_result_get_label(result),
+        create_relation_dialog_result_get_justification(result),
+        create_relation_dialog_result_get_confidence(result),
+        relation_record_get_created_at(existing), timestamp,
+        relation_record_get_status(existing), &error);
+    if (updated == NULL || !database_transaction_begin(database)) goto failure;
+    transaction_active = TRUE;
+    if (!relation_dao_update(relation_dao, updated, &error) ||
+        !database_transaction_commit(database))
+        goto failure;
+    transaction_active = FALSE;
+    main_window_set_status(application->main_window,
+        "Relation modifiée. Actualisation du graphe…");
+    g_free(application->pending_relation_selection_identifier);
+    application->pending_relation_selection_identifier = g_strdup(
+        context->relation_identifier);
+    application_start_graph_loading(application,
+        investigation_project_get_database_path(project));
+    goto cleanup;
+
+failure:
+    if (transaction_active) database_transaction_rollback(database);
+    application_present_error(application, "Modification impossible",
+        error != NULL ? error->message :
+        "La relation n'a pas pu être modifiée.");
+cleanup:
+    g_clear_error(&error);
+    g_free(timestamp);
+    if (now != NULL) g_date_time_unref(now);
+    relation_record_free(updated);
+    relation_record_free(existing);
+    relation_dao_free(relation_dao);
+    create_relation_dialog_result_free(result);
+    application_edit_relation_context_free(context);
+}
+
+/** @brief Ouvre le formulaire prérempli de la relation sélectionnée. */
+static void application_on_edit_relation_requested(
+    const char *relation_identifier, gpointer user_data)
+{
+    Application *application = user_data;
+    Database *database = NULL;
+    RelationDao *relation_dao = NULL;
+    EntityDao *entity_dao = NULL;
+    RelationRecord *relation = NULL;
+    GPtrArray *entities = NULL;
+    ApplicationEditRelationContext *context = NULL;
+    GError *error = NULL;
+
+    if (application == NULL || application->session == NULL ||
+        relation_identifier == NULL) return;
+    database = investigation_session_get_database(application->session);
+    relation_dao = relation_dao_new(database, &error);
+    entity_dao = entity_dao_new(database, &error);
+    if (relation_dao != NULL)
+        relation = relation_dao_find_by_identifier(relation_dao,
+            relation_identifier, &error);
+    if (entity_dao != NULL) entities = entity_dao_list_all(entity_dao, &error);
+    if (relation == NULL || entities == NULL) goto failure;
+    context = g_new0(ApplicationEditRelationContext, 1);
+    context->application = application;
+    context->relation_identifier = g_strdup(relation_identifier);
+    if (context->relation_identifier == NULL || !edit_relation_dialog_present(
+            main_window_get_window(application->main_window), relation, entities,
+            application_on_edit_relation_completed, context, &error))
+        goto failure;
+    context = NULL;
+    goto cleanup;
+failure:
+    application_present_error(application, "Modification impossible",
+        error != NULL ? error->message :
+        "Le formulaire de modification n'a pas pu être ouvert.");
+cleanup:
+    application_edit_relation_context_free(context);
+    g_clear_error(&error);
+    g_clear_pointer(&entities, g_ptr_array_unref);
+    relation_record_free(relation);
+    entity_dao_free(entity_dao);
+    relation_dao_free(relation_dao);
+}
+
 static void application_on_add_relation_requested(
     const char *source_entity_identifier,
     gpointer user_data
@@ -6333,6 +6474,9 @@ static void application_on_activate(
         application
     );
 
+    main_window_set_edit_relation_callback(application->main_window,
+        application_on_edit_relation_requested, application);
+
     main_window_set_osint_action_callback(
         application->main_window,
         application_on_osint_action_requested,
@@ -6606,6 +6750,8 @@ void application_free(
         &application->selected_evidence_identifier,
         g_free
     );
+    g_clear_pointer(&application->pending_relation_selection_identifier,
+        g_free);
 
     g_free(
         application

src/dao/relation_dao.c

@@ -52,6 +52,12 @@ static const char *const relation_dao_insert_sql =
     "    ?"
     ");";
 
+/** @brief Requête de modification des attributs d'une relation. */
+static const char *const relation_dao_update_sql =
+    "UPDATE relations SET "
+    "type_relation = ?, label = ?, justification = ?, confiance = ?, "
+    "updated_at = ?, status = ? WHERE id = ?;";
+
 /**
  * @brief Requête de recherche par UUID.
  */
@@ -1298,6 +1304,65 @@ cleanup:
     return success;
 }
 
+gboolean relation_dao_update(RelationDao *relation_dao,
+    const RelationRecord *relation_record, GError **error)
+{
+    DatabaseStatement *statement = NULL;
+    const char *status_text = NULL;
+    gboolean success = FALSE;
+
+    g_return_val_if_fail(error == NULL || *error == NULL, FALSE);
+    if (relation_dao == NULL || relation_record == NULL)
+    {
+        relation_dao_set_error_literal(error,
+            RELATION_DAO_ERROR_INVALID_ARGUMENT,
+            "La relation à modifier est invalide.");
+        return FALSE;
+    }
+    status_text = relation_dao_status_to_text(
+        relation_record_get_status(relation_record));
+    statement = database_statement_prepare(relation_dao->database,
+        relation_dao_update_sql);
+    if (statement == NULL)
+    {
+        relation_dao_set_database_error(relation_dao, error,
+            RELATION_DAO_ERROR_PREPARE,
+            "Impossible de préparer la modification de la relation");
+        return FALSE;
+    }
+    if (!database_statement_bind_text(statement, 1,
+            relation_record_get_relation_type(relation_record)) ||
+        !relation_dao_bind_optional_text(statement, 2,
+            relation_record_get_label(relation_record)) ||
+        !relation_dao_bind_optional_text(statement, 3,
+            relation_record_get_justification(relation_record)) ||
+        !database_statement_bind_int64(statement, 4,
+            relation_record_get_confidence(relation_record)) ||
+        !database_statement_bind_text(statement, 5,
+            relation_record_get_updated_at(relation_record)) ||
+        status_text == NULL ||
+        !database_statement_bind_text(statement, 6, status_text) ||
+        !database_statement_bind_text(statement, 7,
+            relation_record_get_identifier(relation_record)))
+    {
+        relation_dao_set_database_error(relation_dao, error,
+            RELATION_DAO_ERROR_BIND,
+            "Impossible de lier la modification de la relation");
+        goto cleanup;
+    }
+    if (database_statement_step(statement) != DATABASE_STATEMENT_STEP_DONE)
+    {
+        relation_dao_set_database_error(relation_dao, error,
+            RELATION_DAO_ERROR_EXECUTE,
+            "Impossible de modifier la relation");
+        goto cleanup;
+    }
+    success = TRUE;
+cleanup:
+    database_statement_finalize(statement);
+    return success;
+}
+
 RelationRecord *relation_dao_find_by_identifier(
     RelationDao *relation_dao,
     const char *identifier,

src/views/create_relation_dialog.c

@@ -6,6 +6,7 @@
 #include "views/create_relation_dialog.h"
 
 #include "models/entity_record.h"
+#include "models/relation_record.h"
 
 #include <glib.h>
 
@@ -683,9 +684,10 @@ cleanup:
     return valid;
 }
 
-gboolean create_relation_dialog_present(
+static gboolean create_relation_dialog_present_internal(
     GtkWindow *parent,
     const char *source_entity_identifier,
+    const RelationRecord *existing_relation,
     const GPtrArray *entities,
     CreateRelationDialogCallback callback,
     gpointer user_data,
@@ -746,6 +748,9 @@ gboolean create_relation_dialog_present(
     guint entity_index =
         0;
 
+    guint selected_target_index =
+        0;
+
     g_return_val_if_fail(
         error == NULL || *error == NULL,
         FALSE
@@ -900,6 +905,13 @@ gboolean create_relation_dialog_present(
                 entity_identifier
             );
 
+        if (existing_relation != NULL && g_strcmp0(entity_identifier,
+                relation_record_get_target_entity_identifier(
+                    existing_relation)) == 0)
+        {
+            selected_target_index = state->target_identifiers->len;
+        }
+
         if (display_text == NULL ||
             identifier_copy == NULL)
         {
@@ -971,7 +983,9 @@ gboolean create_relation_dialog_present(
 
     gtk_window_set_title(
         state->window,
-        "Ajouter une relation"
+        existing_relation != NULL
+            ? "Modifier la relation"
+            : "Ajouter une relation"
     );
 
     gtk_window_set_transient_for(
@@ -1030,7 +1044,9 @@ gboolean create_relation_dialog_present(
         GTK_LABEL(
             title_label
         ),
-        "<b>Créer une relation entre deux entités</b>"
+        existing_relation != NULL
+            ? "<b>Modifier la relation</b>"
+            : "<b>Créer une relation entre deux entités</b>"
     );
 
     gtk_label_set_xalign(
@@ -1179,9 +1195,12 @@ gboolean create_relation_dialog_present(
 
     gtk_drop_down_set_selected(
         state->target_drop_down,
-        0
+        selected_target_index
     );
 
+    gtk_widget_set_sensitive(GTK_WIDGET(state->target_drop_down),
+        existing_relation == NULL);
+
     gtk_widget_set_hexpand(
         GTK_WIDGET(
             state->target_drop_down
@@ -1220,7 +1239,9 @@ gboolean create_relation_dialog_present(
 
     gtk_spin_button_set_value(
         state->confidence_spin_button,
-        80.0
+        existing_relation != NULL
+            ? relation_record_get_confidence(existing_relation)
+            : 80.0
     );
 
     state->justification_text_view =
@@ -1228,6 +1249,22 @@ gboolean create_relation_dialog_present(
             gtk_text_view_new()
         );
 
+    if (existing_relation != NULL)
+    {
+        const char *relation_type = relation_record_get_relation_type(
+            existing_relation);
+        const char *label = relation_record_get_label(existing_relation);
+        const char *justification = relation_record_get_justification(
+            existing_relation);
+        gtk_editable_set_text(GTK_EDITABLE(state->relation_type_entry),
+            relation_type != NULL ? relation_type : "");
+        gtk_editable_set_text(GTK_EDITABLE(state->label_entry),
+            label != NULL ? label : "");
+        gtk_text_buffer_set_text(gtk_text_view_get_buffer(
+            state->justification_text_view),
+            justification != NULL ? justification : "", -1);
+    }
+
     gtk_text_view_set_wrap_mode(
         state->justification_text_view,
         GTK_WRAP_WORD_CHAR
@@ -1418,7 +1455,7 @@ gboolean create_relation_dialog_present(
 
     create_button =
         gtk_button_new_with_label(
-            "Ajouter"
+            existing_relation != NULL ? "Enregistrer" : "Ajouter"
         );
 
     gtk_widget_add_css_class(
@@ -1543,6 +1580,30 @@ gboolean create_relation_dialog_present(
     return TRUE;
 }
 
+gboolean create_relation_dialog_present(GtkWindow *parent,
+    const char *source_entity_identifier, const GPtrArray *entities,
+    CreateRelationDialogCallback callback, gpointer user_data, GError **error)
+{
+    return create_relation_dialog_present_internal(parent,
+        source_entity_identifier, NULL, entities, callback, user_data, error);
+}
+
+gboolean edit_relation_dialog_present(GtkWindow *parent,
+    const RelationRecord *relation_record, const GPtrArray *entities,
+    CreateRelationDialogCallback callback, gpointer user_data, GError **error)
+{
+    if (relation_record == NULL)
+    {
+        g_set_error_literal(error, CREATE_RELATION_DIALOG_ERROR,
+            CREATE_RELATION_DIALOG_ERROR_INVALID_ARGUMENT,
+            "La relation à modifier est invalide.");
+        return FALSE;
+    }
+    return create_relation_dialog_present_internal(parent,
+        relation_record_get_source_entity_identifier(relation_record),
+        relation_record, entities, callback, user_data, error);
+}
+
 void create_relation_dialog_result_free(
     CreateRelationDialogResult *result
 )

src/views/main_window.c

@@ -129,6 +129,9 @@ struct MainWindow
     gpointer
         add_relation_user_data;
 
+    MainWindowEditRelationCallback edit_relation_callback;
+    gpointer edit_relation_user_data;
+
     MainWindowOsintActionCallback
         osint_action_callback;
 
@@ -509,6 +512,20 @@ static void main_window_on_add_relation_requested(
     );
 }
 
+/** @brief Relaie la demande de modification d'une relation. */
+static void main_window_on_edit_relation_requested(
+    const char *relation_identifier, gpointer user_data)
+{
+    MainWindow *main_window = user_data;
+    if (main_window == NULL || main_window->edit_relation_callback == NULL ||
+        relation_identifier == NULL)
+    {
+        return;
+    }
+    main_window->edit_relation_callback(relation_identifier,
+        main_window->edit_relation_user_data);
+}
+
 /**
  * @brief Relaie la demande de vérification provenant du Workspace.
  */
@@ -847,6 +864,9 @@ MainWindow *main_window_new(
         main_window
     );
 
+    workspace_set_edit_relation_callback(main_window->workspace,
+        main_window_on_edit_relation_requested, main_window);
+
     workspace_set_osint_action_callback(
         main_window->workspace,
         main_window_on_osint_action_requested,
@@ -1252,6 +1272,14 @@ void main_window_set_graph(
     );
 }
 
+gboolean main_window_select_graph_relation(MainWindow *main_window,
+    const char *relation_identifier)
+{
+    if (main_window == NULL) return FALSE;
+    return workspace_select_graph_relation(main_window->workspace,
+        relation_identifier);
+}
+
 void main_window_set_graph_error(
     MainWindow *main_window,
     const char *message
@@ -1614,6 +1642,14 @@ void main_window_set_add_relation_callback(
         user_data;
 }
 
+void main_window_set_edit_relation_callback(MainWindow *main_window,
+    MainWindowEditRelationCallback callback, gpointer user_data)
+{
+    if (main_window == NULL) return;
+    main_window->edit_relation_callback = callback;
+    main_window->edit_relation_user_data = user_data;
+}
+
 void main_window_set_quit_callback(
     MainWindow *main_window,
     MainWindowQuitCallback callback,
@@ -1765,6 +1801,9 @@ void main_window_free(
             NULL
         );
 
+        workspace_set_edit_relation_callback(main_window->workspace,
+            NULL, NULL);
+
         main_window->graph_node_moved_callback =
             NULL;
 
@@ -1783,6 +1822,9 @@ void main_window_free(
         main_window->add_relation_user_data =
             NULL;
 
+        main_window->edit_relation_callback = NULL;
+        main_window->edit_relation_user_data = NULL;
+
         main_window->show_graph_callback =
             NULL;
 

src/widgets/entity_details_panel.c

@@ -923,6 +923,7 @@ void entity_details_panel_set_entity(
         ),
         TRUE
     );
+    gtk_widget_set_can_target(details_panel->root_revealer, TRUE);
 
     g_free(
         confidence_text
@@ -1009,6 +1010,8 @@ void entity_details_panel_clear(
             ),
             FALSE
         );
+        /* Le revealer fermé ne doit pas bloquer le canvas sous l'overlay. */
+        gtk_widget_set_can_target(details_panel->root_revealer, FALSE);
     }
 }
 

src/widgets/investigation_graph_view.c

@@ -61,6 +61,9 @@ typedef struct
 
     double width;
     double height;
+
+    double relation_offset_x;
+    double relation_offset_y;
 } InvestigationGraphNodeLayout;
 
 /**
@@ -130,6 +133,58 @@ struct InvestigationGraphView
 static const char *investigation_graph_view_get_node_identifier(
     const InvestigationGraphNodeLayout *node_layout
 );
+static double investigation_graph_view_get_node_center_x(
+    const InvestigationGraphNodeLayout *node_layout
+);
+static double investigation_graph_view_get_node_center_y(
+    const InvestigationGraphNodeLayout *node_layout
+);
+
+/** @brief Replace les libellés de relation entre leurs extrémités. */
+static void investigation_graph_view_sync_relation_layouts(
+    InvestigationGraphView *graph_view
+)
+{
+    if (graph_view == NULL || graph_view->node_layouts == NULL ||
+        graph_view->node_layouts_by_identifier == NULL)
+    {
+        return;
+    }
+
+    for (guint i = 0; i < graph_view->node_layouts->len; i++)
+    {
+        InvestigationGraphNodeLayout *relation_layout =
+            g_ptr_array_index(graph_view->node_layouts, i);
+        const RelationRecord *relation_record = NULL;
+        InvestigationGraphNodeLayout *source_layout = NULL;
+        InvestigationGraphNodeLayout *target_layout = NULL;
+
+        if (relation_layout == NULL || relation_layout->kind !=
+            INVESTIGATION_GRAPH_NODE_KIND_RELATION)
+        {
+            continue;
+        }
+        relation_record = relation_layout->relation_record;
+        source_layout = g_hash_table_lookup(
+            graph_view->node_layouts_by_identifier,
+            relation_record_get_source_entity_identifier(relation_record));
+        target_layout = g_hash_table_lookup(
+            graph_view->node_layouts_by_identifier,
+            relation_record_get_target_entity_identifier(relation_record));
+        if (source_layout == NULL || target_layout == NULL)
+        {
+            continue;
+        }
+        relation_layout->x =
+            (investigation_graph_view_get_node_center_x(source_layout) +
+             investigation_graph_view_get_node_center_x(target_layout)) / 2.0 -
+            relation_layout->width / 2.0 + relation_layout->relation_offset_x;
+        relation_layout->y =
+            (investigation_graph_view_get_node_center_y(source_layout) +
+             investigation_graph_view_get_node_center_y(target_layout)) / 2.0 -
+            relation_layout->height / 2.0 + relation_layout->relation_offset_y;
+    }
+}
 
 /**
  * @brief Borne un facteur de zoom aux limites autorisées.
@@ -577,6 +632,8 @@ investigation_graph_view_find_node_at(
         return NULL;
     }
 
+    investigation_graph_view_sync_relation_layouts(graph_view);
+
     layout_position =
         graph_view->node_layouts->len;
 
@@ -611,6 +668,63 @@ investigation_graph_view_find_node_at(
         }
     }
 
+    /* Rend également l'arête sélectionnable, avec une tolérance visuelle. */
+    for (layout_position = graph_view->node_layouts->len;
+         layout_position > 0; layout_position--)
+    {
+        InvestigationGraphNodeLayout *relation_layout =
+            g_ptr_array_index(graph_view->node_layouts, layout_position - 1U);
+        const RelationRecord *relation_record = NULL;
+        InvestigationGraphNodeLayout *source_layout = NULL;
+        InvestigationGraphNodeLayout *target_layout = NULL;
+        double source_x = 0.0, source_y = 0.0;
+        double target_x = 0.0, target_y = 0.0;
+        double delta_x = 0.0, delta_y = 0.0, length_squared = 0.0;
+        double projection = 0.0, nearest_x = 0.0, nearest_y = 0.0;
+        double distance_x = 0.0, distance_y = 0.0;
+        double tolerance = 7.0 / graph_view->zoom;
+
+        if (relation_layout == NULL || relation_layout->kind !=
+            INVESTIGATION_GRAPH_NODE_KIND_RELATION)
+        {
+            continue;
+        }
+        relation_record = relation_layout->relation_record;
+        source_layout = g_hash_table_lookup(
+            graph_view->node_layouts_by_identifier,
+            relation_record_get_source_entity_identifier(relation_record));
+        target_layout = g_hash_table_lookup(
+            graph_view->node_layouts_by_identifier,
+            relation_record_get_target_entity_identifier(relation_record));
+        if (source_layout == NULL || target_layout == NULL)
+        {
+            continue;
+        }
+        source_x = investigation_graph_view_get_node_center_x(source_layout);
+        source_y = investigation_graph_view_get_node_center_y(source_layout);
+        target_x = investigation_graph_view_get_node_center_x(target_layout);
+        target_y = investigation_graph_view_get_node_center_y(target_layout);
+        delta_x = target_x - source_x;
+        delta_y = target_y - source_y;
+        length_squared = delta_x * delta_x + delta_y * delta_y;
+        if (length_squared <= 0.0)
+        {
+            continue;
+        }
+        projection = ((logical_x - source_x) * delta_x +
+            (logical_y - source_y) * delta_y) / length_squared;
+        projection = CLAMP(projection, 0.0, 1.0);
+        nearest_x = source_x + projection * delta_x;
+        nearest_y = source_y + projection * delta_y;
+        distance_x = logical_x - nearest_x;
+        distance_y = logical_y - nearest_y;
+        if (distance_x * distance_x + distance_y * distance_y <=
+            tolerance * tolerance)
+        {
+            return relation_layout;
+        }
+    }
+
     return NULL;
 }
 
@@ -1086,6 +1200,8 @@ static void investigation_graph_view_on_drag_update(
         logical_y -
         graph_view->node_drag_pointer_offset_y;
 
+    investigation_graph_view_sync_relation_layouts(graph_view);
+
     gtk_widget_queue_draw(
         graph_view->drawing_area
     );
@@ -1216,6 +1332,8 @@ static void investigation_graph_view_on_drag_end(
             graph_view->dragged_node->y =
                 logical_y -
                 graph_view->node_drag_pointer_offset_y;
+
+            investigation_graph_view_sync_relation_layouts(graph_view);
         }
     }
 
@@ -2020,6 +2138,9 @@ static gboolean investigation_graph_view_append_relation_layouts(
                 parallel_offset
             );
 
+        relation_layout->relation_offset_x =
+            perpendicular_x * parallel_offset;
+
         relation_layout->y =
             (
                 (source_center_y + target_center_y) /
@@ -2031,6 +2152,9 @@ static gboolean investigation_graph_view_append_relation_layouts(
                 parallel_offset
             );
 
+        relation_layout->relation_offset_y =
+            perpendicular_y * parallel_offset;
+
         g_ptr_array_add(
             node_layouts,
             relation_layout
@@ -3686,6 +3810,8 @@ static void investigation_graph_view_draw(
         return;
     }
 
+    investigation_graph_view_sync_relation_layouts(graph_view);
+
     /*
      * Les coordonnées de disposition restent exprimées dans l'espace logique
      * du graphe. Cairo applique ensuite la navigation de la vue.

src/widgets/workspace.c

@@ -67,6 +67,9 @@ struct Workspace
     GtkWidget *relation_details_panel;
     GtkWidget *relation_details_title_label;
     GtkWidget *relation_details_summary_label;
+    GtkWidget *edit_relation_button;
+    GtkWidget *close_relation_details_button;
+    char *selected_relation_identifier;
 
     GtkWidget *node_page;
 
@@ -119,6 +122,9 @@ struct Workspace
     gpointer
         add_relation_user_data;
 
+    WorkspaceEditRelationCallback edit_relation_callback;
+    gpointer edit_relation_user_data;
+
     WorkspaceOsintActionCallback
         osint_action_callback;
 
@@ -573,6 +579,20 @@ static const char *workspace_get_integrity_status_text(
     }
 }
 
+/** @brief Convertit le statut d'une relation en texte utilisateur. */
+static const char *workspace_get_relation_status_text(RelationStatus status)
+{
+    switch (status)
+    {
+        case RELATION_STATUS_ACTIVE: return "Active";
+        case RELATION_STATUS_ARCHIVED: return "Archivée";
+        case RELATION_STATUS_DELETED: return "Supprimée";
+        case RELATION_STATUS_DISPUTED: return "Contestée";
+        case RELATION_STATUS_UNKNOWN:
+        default: return "Inconnu";
+    }
+}
+
 /**
  * @brief Transmet la sélection du graphe au volet de détails.
  */
@@ -623,6 +643,7 @@ static void workspace_on_graph_node_selected(
         &workspace->osint_selection_context,
         osint_selection_context_free
     );
+    g_clear_pointer(&workspace->selected_relation_identifier, g_free);
 
     if (entity_record != NULL)
     {
@@ -640,6 +661,8 @@ static void workspace_on_graph_node_selected(
 
     if (workspace->relation_details_panel != NULL)
     {
+        gtk_widget_set_can_target(workspace->relation_details_panel,
+            relation_record != NULL);
         gtk_widget_set_visible(
             workspace->relation_details_panel,
             relation_record != NULL
@@ -650,6 +673,8 @@ static void workspace_on_graph_node_selected(
         workspace->relation_details_title_label != NULL &&
         workspace->relation_details_summary_label != NULL)
     {
+        workspace->selected_relation_identifier = g_strdup(
+            relation_record_get_identifier(relation_record));
         const EntityRecord *source_entity =
             investigation_graph_model_find_entity(
                 workspace->graph_model,
@@ -670,11 +695,21 @@ static void workspace_on_graph_node_selected(
             );
         const char *label = relation_record_get_label(relation_record);
         char *summary = g_strdup_printf(
-            "%s → %s\n\nType : %s\nConfiance : %d %%\nUUID : %s",
+            "%s → %s\n\nType : %s\nConfiance : %d %%\nStatut : %s\n"
-            entity_record_get_value(source_entity),
+            "Justification : %s\nCréée le : %s\nModifiée le : %s\nUUID : %s",
-            entity_record_get_value(target_entity),
+            source_entity != NULL ? entity_record_get_value(source_entity) :
+                "Source inconnue",
+            target_entity != NULL ? entity_record_get_value(target_entity) :
+                "Cible inconnue",
             relation_record_get_relation_type(relation_record),
             relation_record_get_confidence(relation_record),
+            workspace_get_relation_status_text(
+                relation_record_get_status(relation_record)),
+            relation_record_get_justification(relation_record) != NULL
+                ? relation_record_get_justification(relation_record)
+                : "Non renseignée",
+            relation_record_get_created_at(relation_record),
+            relation_record_get_updated_at(relation_record),
             relation_record_get_identifier(relation_record)
         );
 
@@ -695,6 +730,31 @@ static void workspace_on_graph_node_selected(
     );
 }
 
+/** @brief Relaie la demande de modification de la relation affichée. */
+static void workspace_on_edit_relation_clicked(GtkButton *button,
+    gpointer user_data)
+{
+    Workspace *workspace = user_data;
+    (void) button;
+    if (workspace == NULL || workspace->edit_relation_callback == NULL ||
+        workspace->selected_relation_identifier == NULL)
+    {
+        return;
+    }
+    workspace->edit_relation_callback(workspace->selected_relation_identifier,
+        workspace->edit_relation_user_data);
+}
+
+/** @brief Ferme le volet de relation et désélectionne le graphe. */
+static void workspace_on_close_relation_details_clicked(GtkButton *button,
+    gpointer user_data)
+{
+    Workspace *workspace = user_data;
+    (void) button;
+    if (workspace != NULL)
+        investigation_graph_view_clear_selection(workspace->graph_view);
+}
+
 /**
  * @brief Relaie la demande d'ajout d'une relation.
  */
@@ -1493,12 +1553,17 @@ Workspace *workspace_new(void)
     );
     workspace->relation_details_title_label = gtk_label_new(NULL);
     workspace->relation_details_summary_label = gtk_label_new(NULL);
+    workspace->edit_relation_button = gtk_button_new_with_label("Modifier");
+    workspace->close_relation_details_button =
+        gtk_button_new_from_icon_name("window-close-symbolic");
 
     if (workspace->graph_view == NULL ||
         workspace->entity_details_panel == NULL ||
         workspace->relation_details_panel == NULL ||
         workspace->relation_details_title_label == NULL ||
-        workspace->relation_details_summary_label == NULL)
+        workspace->relation_details_summary_label == NULL ||
+        workspace->edit_relation_button == NULL ||
+        workspace->close_relation_details_button == NULL)
     {
         workspace_free(
             workspace
@@ -1514,6 +1579,8 @@ Workspace *workspace_new(void)
     gtk_widget_set_margin_top(workspace->relation_details_panel, 56);
     gtk_widget_set_margin_start(workspace->relation_details_panel, 12);
     gtk_widget_set_margin_bottom(workspace->relation_details_panel, 12);
+    /* `view` fournit le fond opaque du thème, comme le volet d'entité. */
+    gtk_widget_add_css_class(workspace->relation_details_panel, "view");
     gtk_widget_add_css_class(workspace->relation_details_panel, "card");
     gtk_widget_set_margin_start(workspace->relation_details_title_label, 16);
     gtk_widget_set_margin_end(workspace->relation_details_title_label, 16);
@@ -1545,11 +1612,23 @@ Workspace *workspace_new(void)
         GTK_BOX(workspace->relation_details_panel),
         workspace->relation_details_title_label
     );
+    gtk_widget_set_tooltip_text(workspace->close_relation_details_button,
+        "Fermer le volet");
+    gtk_widget_add_css_class(workspace->close_relation_details_button, "flat");
+    gtk_box_append(GTK_BOX(workspace->relation_details_panel),
+        workspace->close_relation_details_button);
     gtk_box_append(
         GTK_BOX(workspace->relation_details_panel),
         workspace->relation_details_summary_label
     );
+    gtk_box_append(GTK_BOX(workspace->relation_details_panel),
+        workspace->edit_relation_button);
+    g_signal_connect(workspace->edit_relation_button, "clicked",
+        G_CALLBACK(workspace_on_edit_relation_clicked), workspace);
+    g_signal_connect(workspace->close_relation_details_button, "clicked",
+        G_CALLBACK(workspace_on_close_relation_details_clicked), workspace);
     gtk_widget_set_visible(workspace->relation_details_panel, FALSE);
+    gtk_widget_set_can_target(workspace->relation_details_panel, FALSE);
 
     investigation_graph_view_set_selection_callback(
         workspace->graph_view,
@@ -2906,6 +2985,14 @@ void workspace_set_add_relation_callback(
         user_data;
 }
 
+void workspace_set_edit_relation_callback(Workspace *workspace,
+    WorkspaceEditRelationCallback callback, gpointer user_data)
+{
+    if (workspace == NULL) return;
+    workspace->edit_relation_callback = callback;
+    workspace->edit_relation_user_data = user_data;
+}
+
 void workspace_reset_graph_layout(
     Workspace *workspace
 )
@@ -2942,6 +3029,7 @@ void workspace_free(Workspace *workspace)
         &workspace->osint_selection_context,
         osint_selection_context_free
     );
+    g_clear_pointer(&workspace->selected_relation_identifier, g_free);
 
     g_clear_pointer(
         &workspace->osint_action_catalog,

tests/test_relation_dao.c

@@ -2225,6 +2225,47 @@ static void test_relation_dao_foreign_key_restrict(void)
     );
 }
 
+/** @brief Vérifie la modification des attributs sans changer les extrémités. */
+static void test_relation_dao_update_existing(void)
+{
+    static const char identifier[] =
+        "90000000-0000-4000-8000-000000000001";
+    TestRelationDaoFixture fixture = test_relation_dao_fixture_create();
+    RelationRecord *initial = NULL;
+    RelationRecord *updated = NULL;
+    RelationRecord *stored = NULL;
+    GError *error = NULL;
+
+    test_relation_dao_insert_standard_entities(&fixture);
+    initial = test_relation_dao_create_relation(identifier,
+        TEST_ENTITY_A_IDENTIFIER, TEST_ENTITY_B_IDENTIFIER, "uses",
+        "Ancien libellé", "Ancienne justification", 40,
+        "2026-07-20T20:00:00Z", "2026-07-20T20:00:00Z",
+        RELATION_STATUS_ACTIVE);
+    test_relation_dao_insert_relation(&fixture, initial);
+    updated = test_relation_dao_create_relation(identifier,
+        TEST_ENTITY_A_IDENTIFIER, TEST_ENTITY_B_IDENTIFIER, "controls",
+        "Nouveau libellé", "Nouvelle justification", 90,
+        "2026-07-20T20:00:00Z", "2026-07-22T16:00:00Z",
+        RELATION_STATUS_ACTIVE);
+    assert(relation_dao_update(fixture.relation_dao, updated, &error));
+    assert(error == NULL);
+    stored = relation_dao_find_by_identifier(fixture.relation_dao,
+        identifier, &error);
+    assert(stored != NULL && error == NULL);
+    assert(strcmp(relation_record_get_relation_type(stored), "controls") == 0);
+    assert(strcmp(relation_record_get_label(stored), "Nouveau libellé") == 0);
+    assert(relation_record_get_confidence(stored) == 90);
+    assert(strcmp(relation_record_get_source_entity_identifier(stored),
+        TEST_ENTITY_A_IDENTIFIER) == 0);
+    assert(strcmp(relation_record_get_created_at(stored),
+        "2026-07-20T20:00:00Z") == 0);
+    relation_record_free(stored);
+    relation_record_free(updated);
+    relation_record_free(initial);
+    test_relation_dao_fixture_clear(&fixture);
+}
+
 int main(
     int argc,
     char **argv
@@ -2256,6 +2297,7 @@ int main(
     test_relation_dao_missing_table();
     test_relation_dao_reflexive_schema_constraint();
     test_relation_dao_foreign_key_restrict();
+    test_relation_dao_update_existing();
 
     printf(
         "RelationDao : tous les tests sont valides.\n"