L16 Lotse-Chat für Monteure: Datenmodell, Provider mit Tool-Schleife, Vorschläge und Bestätigen über bestehende Services

Chatverlauf (LotseConversation/-Message) und Aktionskarten (LotseActionProposal) als
Mandantentabellen mit RLS; Schalter lotseChatEnabled. Tool-Use-Schleife mit Runden- und
Tokengrenze, Datenminimierung per Platzhalter, Auftragszuordnung im Sichtbarkeits-Scope,
Bestätigen/Verwerfen/Alle bestätigen mit Hash, Ablauf und Idempotenz, Transkriptions-API.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

prisma/schema.prisma

@@ -79,6 +79,8 @@ model TenantSettings {
   lotseAddressForm    String?  @map("lotse_address_form")
   // L10b (Spec §31): monthly AI token budget (input + output) per tenant; null = env AI_MONTHLY_TOKEN_LIMIT, 0 = unlimited
   aiMonthlyTokenLimit Int?     @map("ai_monthly_token_limit")
+  // L16 Lotse-Chat für Monteure: switch per tenant (effective only while the Lotse module is on)
+  lotseChatEnabled    Boolean  @default(true) @map("lotse_chat_enabled")
   createdAt           DateTime @default(now()) @map("created_at")
   updatedAt           DateTime @updatedAt @map("updated_at")
 
@@ -1433,3 +1435,85 @@ model BillingRecord {
   @@index([tenantId, workOrderId])
   @@map("billing_records")
 }
+
+// ---------- L16 Lotse-Chat für Monteure ----------
+
+enum LotseMessageRole {
+  user
+  assistant
+  tool
+}
+
+enum LotseProposalStatus {
+  proposed
+  confirmed
+  discarded
+  expired
+  failed
+}
+
+/// Chat of ONE user with the Lotse (only visible to that user). Optional work order context
+/// (chat opened from the order detail). Deleted by the Lotse retention (services/lotse/retention.ts).
+model LotseConversation {
+  id            String   @id @default(cuid())
+  tenantId      String   @map("tenant_id")
+  userId        String   @map("user_id")
+  workOrderId   String?  @map("work_order_id")
+  createdAt     DateTime @default(now()) @map("created_at")
+  updatedAt     DateTime @updatedAt @map("updated_at")
+  lastMessageAt DateTime @default(now()) @map("last_message_at")
+
+  messages  LotseMessage[]
+  proposals LotseActionProposal[]
+
+  @@index([tenantId, userId, lastMessageAt])
+  @@index([tenantId, lastMessageAt])
+  @@map("lotse_conversations")
+}
+
+/// One chat message. `text` = what the user sees; `content` = structured parts (chips, proposal ids,
+/// links, placeholder text sent to the model).
+model LotseMessage {
+  id             String           @id @default(cuid())
+  tenantId       String           @map("tenant_id")
+  conversationId String           @map("conversation_id")
+  role           LotseMessageRole
+  text           String
+  content        Json?
+  aiGenerationId String?          @map("ai_generation_id")
+  createdAt      DateTime         @default(now()) @map("created_at")
+
+  conversation LotseConversation @relation(fields: [conversationId], references: [id], onDelete: Cascade)
+
+  @@index([tenantId, conversationId, createdAt])
+  @@map("lotse_messages")
+}
+
+/// Action card proposed by the Lotse. Nothing is executed before the owner confirms it
+/// (services/lotse/chat/confirm.ts runs the existing services with the owner's context).
+model LotseActionProposal {
+  id             String              @id @default(cuid())
+  tenantId       String              @map("tenant_id")
+  conversationId String              @map("conversation_id")
+  messageId      String?             @map("message_id")
+  userId         String              @map("user_id")
+  workOrderId    String?             @map("work_order_id")
+  kind           String
+  payload        Json
+  payloadHash    String              @map("payload_hash")
+  status         LotseProposalStatus @default(proposed)
+  expiresAt      DateTime            @map("expires_at")
+  result         Json?
+  errorCode      String?             @map("error_code")
+  confirmedAt    DateTime?           @map("confirmed_at")
+  confirmedById  String?             @map("confirmed_by_id")
+  decidedAt      DateTime?           @map("decided_at")
+  createdAt      DateTime            @default(now()) @map("created_at")
+  updatedAt      DateTime            @updatedAt @map("updated_at")
+
+  conversation LotseConversation @relation(fields: [conversationId], references: [id], onDelete: Cascade)
+
+  @@index([tenantId, conversationId, createdAt])
+  @@index([tenantId, userId, status])
+  @@map("lotse_action_proposals")
+}