Replace the comma-separated tags field with one field per linked entrée

field_entree_liee is multi-value, but the single #tags entity_autocomplete
rendered it as one comma-separated text box -- functionally correct but
easy to mistake for "only one entrée can be linked". Rebuilt as one
autocomplete field per link plus an "Ajouter une référence" button (the
classic Drupal multi-value pattern, matching the Répartition paragraphs
widget already used elsewhere in this form). Clearing a field's text
drops that link on save, rather than a "remove" button -- a remove
button would need to shift every later delta, which fights Drupal's own
value-restoration-on-AJAX-rebuild (verified live: that restoration only
works cleanly for pure appends at a stable delta, which is all
addItem() does).

Verified end-to-end via raw AJAX POSTs against a real 3-entrée versement:
initial load pre-fills 3 separate fields, "Ajouter" appends a 4th empty
one without disturbing the first 3, and submitting with one field
cleared and a new one filled saves exactly the expected set.

web/modules/custom/figli_compta_ledger/css/admin-chrome.css

@@ -36,6 +36,13 @@ html.gin--dark-mode .figli-page-nav a.is-active {
   color: #e8e9ea;
 }
 
+/* "Lier à une entrée client" modal (LinkEntreeForm): one autocomplete
+   field per linked entrée instead of a single comma-separated field --
+   tighten the default spacing between them a little. */
+#figli-entree-liee-items .form-item {
+  margin-bottom: 0.5rem;
+}
+
 /* Drupal status messages: fixed top-right, out of document flow, so they
    never shift the page layout the way the default in-flow placement does
    -- and shrunk to a fraction of Gin's default size, which is sized for a

web/modules/custom/figli_compta_ledger/src/Form/LinkEntreeForm.php

@@ -15,9 +15,15 @@ use Drupal\node\NodeInterface;
  * need to touch this one field to link a versement/achat/hébergement to
  * the entrée client(s) it pays out against. field_entree_liee is
  * multi-value (cardinality unlimited) since one payment sometimes covers
- * several client invoices at once; #tags renders that as a single
- * comma-separated autocomplete field instead of a Drupal "add another
- * item" widget.
+ * several client invoices at once; one autocomplete field per linked
+ * entrée plus an "Ajouter une référence" button, mirroring the classic
+ * Drupal multi-value widget (e.g. the ligne_comptable form's own
+ * Répartition paragraphs) rather than a single comma-separated field.
+ * Clearing a field's text (rather than a dedicated "remove" button)
+ * drops that link -- see submitForm() -- since a "remove" button would
+ * need to shift every later delta, which fights Drupal's own
+ * value-restoration-on-AJAX-rebuild (that only works cleanly for pure
+ * appends at a stable delta, which is all addItem() below ever does).
  */
 class LinkEntreeForm extends FormBase {
 
@@ -34,20 +40,50 @@ class LinkEntreeForm extends FormBase {
   public function buildForm(array $form, FormStateInterface $form_state, ?NodeInterface $node = NULL) {
     $form_state->set('node', $node);
 
-    $form['field_entree_liee'] = [
-      '#type' => 'entity_autocomplete',
-      '#title' => $this->t('Entrées clients liées'),
-      '#target_type' => 'node',
-      '#tags' => TRUE,
-      '#selection_handler' => 'figli_compta_ledger:entree_client',
-      '#selection_settings' => [
-        'target_bundles' => ['ligne_comptable' => 'ligne_comptable'],
-        // Narrows the autocomplete to the same client as this sortie --
-        // read by EntreeClientSelection::buildEntityQuery().
-        'entity' => $node,
-      ],
-      '#default_value' => $node->get('field_entree_liee')->referencedEntities(),
-      '#description' => $this->t('Laisser vide pour retirer tous les liens. Plusieurs entrées possibles (paiement en plusieurs fois) : séparez-les par une virgule.'),
+    // Number of entrée-liée fields to render -- seeded from the node's
+    // current values on first build, then only grown by addItem() across
+    // AJAX rebuilds. At least one field even when nothing is linked yet.
+    if ($form_state->get('items_count') === NULL) {
+      $existing_count = $node->get('field_entree_liee')->count();
+      $form_state->set('items_count', max($existing_count, 1));
+    }
+    $existing = $node->get('field_entree_liee')->referencedEntities();
+
+    $form['#tree'] = TRUE;
+    $form['items'] = [
+      '#type' => 'container',
+      '#attributes' => ['id' => 'figli-entree-liee-items'],
+    ];
+    for ($delta = 0; $delta < $form_state->get('items_count'); $delta++) {
+      $form['items'][$delta] = [
+        'target' => [
+          '#type' => 'entity_autocomplete',
+          '#title' => $this->t('Entrée cliente liée'),
+          '#title_display' => 'invisible',
+          '#target_type' => 'node',
+          '#selection_handler' => 'figli_compta_ledger:entree_client',
+          '#selection_settings' => [
+            'target_bundles' => ['ligne_comptable' => 'ligne_comptable'],
+            // Narrows the autocomplete to the same client as this sortie
+            // -- read by EntreeClientSelection::buildEntityQuery().
+            'entity' => $node,
+          ],
+          '#default_value' => $existing[$delta] ?? NULL,
+        ],
+      ];
+    }
+
+    $form['add'] = [
+      '#type' => 'submit',
+      '#value' => $this->t('+ Ajouter une référence'),
+      '#submit' => ['::addItem'],
+      '#ajax' => ['callback' => '::ajaxRefreshItems', 'wrapper' => 'figli-entree-liee-items'],
+      '#limit_validation_errors' => [],
+    ];
+
+    $form['description'] = [
+      '#weight' => -10,
+      '#markup' => '<p class="description">' . $this->t('Plusieurs entrées possibles (paiement en plusieurs fois) : une référence par champ, ajoutez-en avec le bouton ci-dessus. Vider un champ retire ce lien.') . '</p>',
     ];
 
     $form['actions'] = ['#type' => 'actions'];
@@ -62,17 +98,34 @@ class LinkEntreeForm extends FormBase {
     return $form;
   }
 
+  /**
+   * #submit for "+ Ajouter une référence".
+   */
+  public function addItem(array &$form, FormStateInterface $form_state) {
+    $form_state->set('items_count', $form_state->get('items_count') + 1);
+    $form_state->setRebuild();
+  }
+
+  /**
+   * #ajax callback for "Ajouter" -- replaces just the fields container,
+   * leaving the rest of the (still-open) modal alone.
+   */
+  public function ajaxRefreshItems(array &$form, FormStateInterface $form_state) {
+    return $form['items'];
+  }
+
   /**
    * {@inheritdoc}
    */
   public function submitForm(array &$form, FormStateInterface $form_state) {
     /** @var \Drupal\node\NodeInterface $node */
     $node = $form_state->get('node');
-    // #tags => TRUE normalizes the submitted value to the field API's own
-    // multi-value shape (an array of ['target_id' => ..., ...] items, one
-    // per comma-separated entry), so this is just field-API assignment,
-    // no manual tag-string parsing needed.
-    $values = $form_state->getValue('field_entree_liee') ?: [];
+    $values = [];
+    foreach ($form_state->getValue('items') as $item) {
+      if (!empty($item['target'])) {
+        $values[] = ['target_id' => $item['target']];
+      }
+    }
     $node->set('field_entree_liee', $values);
     $node->save();
   }