feat(#251): add Neo4j as a StoreKind

- domain : StoreKind.NEO4J ajouté à l'enum
- service : validation config par kind étendue (Neo4j requires non-empty index_name)
- frontend : Neo4jConfigForm (index_name + database optionnelle), dispatcher StoreConfigForm, dropdown kind, i18n FR/EN
- tests service : 2 cas Neo4j (create OK + missing index_name 422)

Auth (URI/user/password) reste pilotée par les variables d'environnement
globales (cf. infra/neo4j.py) — la config par store ne porte que les
paramètres routables (index, database).

document-parser/domain/value_objects.py

@@ -40,11 +40,11 @@ class DocumentLifecycleState(StrEnum):
 
 
 class StoreKind(StrEnum):
-    """Backing technology of a Store. Today only OpenSearch is implemented;
-    the enum is here so future backends (Pinecone, Qdrant, pgvector) can be
-    added without touching the persistence schema."""
+    """Backing technology of a Store. New backends plug in here without
+    touching the persistence schema."""
 
     OPENSEARCH = "opensearch"
+    NEO4J = "neo4j"
 
 
 class DocumentStoreLinkState(StrEnum):

document-parser/services/store_service.py

@@ -87,13 +87,17 @@ def _validate_slug(slug: str) -> None:
 
 
 def _validate_config_for_kind(kind: StoreKind, config: dict) -> None:
-    """Per-kind config schema. Today only OpenSearch is wired; new kinds plug
-    in here without touching the rest of the pipeline."""
+    """Per-kind config schema. New kinds plug in here without touching the
+    rest of the pipeline. Authentication for remote stores comes from the
+    deployment env (see `infra/settings.py`)."""
     if kind is StoreKind.OPENSEARCH:
         index_name = config.get("index_name") or config.get("indexName")
         if not isinstance(index_name, str) or not index_name.strip():
             raise StoreValidationError("OpenSearch config requires a non-empty 'index_name'")
-    # Future: add LlamaIndex / LangChain / pgvector branches here.
+    elif kind is StoreKind.NEO4J:
+        index_name = config.get("index_name") or config.get("indexName")
+        if not isinstance(index_name, str) or not index_name.strip():
+            raise StoreValidationError("Neo4j config requires a non-empty 'index_name'")
 
 
 class StoreService:

document-parser/tests/test_store_service.py

@@ -110,6 +110,27 @@ class TestCreate:
                 config={},
             )
 
+    async def test_create_neo4j_ok(self, service):
+        store = await service.create_store(
+            name="kg",
+            slug="kg",
+            kind=StoreKind.NEO4J,
+            embedder="bge-m3",
+            config={"index_name": "chunks-vec", "database": "neo4j"},
+        )
+        assert store.kind is StoreKind.NEO4J
+        assert store.config["index_name"] == "chunks-vec"
+
+    async def test_create_neo4j_rejects_missing_index_name(self, service):
+        with pytest.raises(StoreValidationError):
+            await service.create_store(
+                name="kg",
+                slug="kg",
+                kind=StoreKind.NEO4J,
+                embedder="bge-m3",
+                config={},
+            )
+
     async def test_create_default_clears_others(self, service):
         # The seeded 'default' store starts as is_default=True.
         new_default = await service.create_store(

frontend/src/features/store/ui/Neo4jConfigForm.vue

@@ -0,0 +1,109 @@
+<template>
+  <div class="config-form">
+    <div class="field">
+      <label class="field-label" for="store-neo4j-index">{{
+        t('storeForm.neo4j.indexName')
+      }}</label>
+      <input
+        id="store-neo4j-index"
+        v-model="indexName"
+        class="field-input"
+        type="text"
+        placeholder="chunks-vec"
+        :aria-invalid="showError && !indexName.trim()"
+        @input="emitChange"
+      />
+      <p v-if="showError && !indexName.trim()" class="field-error">
+        {{ t('storeForm.required') }}
+      </p>
+      <p v-else class="field-help">{{ t('storeForm.neo4j.indexNameHelp') }}</p>
+    </div>
+
+    <div class="field">
+      <label class="field-label" for="store-neo4j-db">{{ t('storeForm.neo4j.database') }}</label>
+      <input
+        id="store-neo4j-db"
+        v-model="database"
+        class="field-input"
+        type="text"
+        placeholder="neo4j"
+        @input="emitChange"
+      />
+      <p class="field-help">{{ t('storeForm.neo4j.databaseHelp') }}</p>
+    </div>
+  </div>
+</template>
+
+<script setup lang="ts">
+import { ref, watch } from 'vue'
+import { useI18n } from '../../../shared/i18n'
+
+const props = defineProps<{
+  modelValue: Record<string, unknown>
+  showError?: boolean
+}>()
+
+const emit = defineEmits<{
+  (e: 'update:modelValue', value: Record<string, unknown>): void
+  (e: 'valid', value: boolean): void
+}>()
+
+const { t } = useI18n()
+
+const indexName = ref(String(props.modelValue.indexName ?? props.modelValue.index_name ?? ''))
+const database = ref(String(props.modelValue.database ?? ''))
+
+function emitChange() {
+  emit('update:modelValue', {
+    indexName: indexName.value,
+    database: database.value || undefined,
+  })
+  emit('valid', indexName.value.trim().length > 0)
+}
+
+watch(
+  () => props.modelValue,
+  (next) => {
+    const incomingIndex = String(next.indexName ?? next.index_name ?? '')
+    if (incomingIndex !== indexName.value) indexName.value = incomingIndex
+    const incomingDb = String(next.database ?? '')
+    if (incomingDb !== database.value) database.value = incomingDb
+  },
+)
+
+emit('valid', indexName.value.trim().length > 0)
+</script>
+
+<style scoped>
+.config-form {
+  display: flex;
+  flex-direction: column;
+  gap: 1rem;
+}
+.field {
+  display: flex;
+  flex-direction: column;
+  gap: 0.25rem;
+}
+.field-label {
+  font-weight: 500;
+  font-size: 0.875rem;
+}
+.field-input {
+  padding: 0.5rem 0.75rem;
+  border: 1px solid var(--color-border, #d1d5db);
+  border-radius: 0.375rem;
+  font-size: 0.875rem;
+}
+.field-input[aria-invalid='true'] {
+  border-color: #dc2626;
+}
+.field-help {
+  font-size: 0.75rem;
+  color: var(--color-text-muted, #6b7280);
+}
+.field-error {
+  font-size: 0.75rem;
+  color: #dc2626;
+}
+</style>

frontend/src/features/store/ui/StoreConfigForm.vue

@@ -10,6 +10,7 @@
 <script setup lang="ts">
 import { computed, ref, watch } from 'vue'
 import OpenSearchConfigForm from './OpenSearchConfigForm.vue'
+import Neo4jConfigForm from './Neo4jConfigForm.vue'
 
 const props = defineProps<{
   kind: string
@@ -37,6 +38,8 @@ const component = computed(() => {
   switch (props.kind) {
     case 'opensearch':
       return OpenSearchConfigForm
+    case 'neo4j':
+      return Neo4jConfigForm
     default:
       return OpenSearchConfigForm
   }

frontend/src/features/store/ui/StoreForm.vue

@@ -117,7 +117,10 @@ const emit = defineEmits<{
 
 const { t } = useI18n()
 
-const kindOptions = [{ value: 'opensearch', label: 'OpenSearch' }]
+const kindOptions = [
+  { value: 'opensearch', label: 'OpenSearch' },
+  { value: 'neo4j', label: 'Neo4j' },
+]
 
 const form = reactive<StoreCreatePayload>({
   name: props.initialValue?.name ?? '',

frontend/src/shared/i18n.ts

@@ -473,6 +473,12 @@ const messages: Messages = {
     'storeForm.opensearch.indexName': 'Nom de l\u2019index',
     'storeForm.opensearch.indexNameHelp':
       'Index OpenSearch cible (cr\u00e9\u00e9 \u00e0 la premi\u00e8re ingestion).',
+    'storeForm.neo4j.indexName': 'Nom de l\u2019index vectoriel',
+    'storeForm.neo4j.indexNameHelp':
+      'Index vector Neo4j (5.x+) cible. URI et auth viennent des variables d\u2019environnement.',
+    'storeForm.neo4j.database': 'Base',
+    'storeForm.neo4j.databaseHelp':
+      'Optionnel \u2014 par d\u00e9faut \u00ab\u00a0neo4j\u00a0\u00bb.',
     'storeForm.cancel': 'Annuler',
     'storeForm.save': 'Enregistrer',
     'storeForm.create': 'Cr\u00e9er',
@@ -962,6 +968,11 @@ const messages: Messages = {
     'storeForm.sectionConfig': 'Configuration',
     'storeForm.opensearch.indexName': 'Index name',
     'storeForm.opensearch.indexNameHelp': 'Target OpenSearch index (created on first ingestion).',
+    'storeForm.neo4j.indexName': 'Vector index name',
+    'storeForm.neo4j.indexNameHelp':
+      'Target Neo4j (5.x+) vector index. URI and auth come from environment variables.',
+    'storeForm.neo4j.database': 'Database',
+    'storeForm.neo4j.databaseHelp': 'Optional — defaults to "neo4j".',
     'storeForm.cancel': 'Cancel',
     'storeForm.save': 'Save',
     'storeForm.create': 'Create',