Initial MVP: multiplexer + chat DB

prisma/schema.prisma

@@ -0,0 +1,94 @@
+// Prisma schema for the personal chat DB + LLM call log
+
+generator client {
+  provider = "prisma-client-js"
+}
+
+datasource db {
+  provider = "sqlite"
+  url      = env("DATABASE_URL")
+}
+
+enum Provider {
+  openai
+  anthropic
+  xai
+}
+
+enum MessageRole {
+  system
+  user
+  assistant
+  tool
+}
+
+model User {
+  id        String   @id @default(cuid())
+  createdAt DateTime @default(now())
+  updatedAt DateTime @updatedAt
+
+  // minimal for now (single-user is fine). Keep extensible.
+  handle String? @unique
+
+  chats Chat[]
+}
+
+model Chat {
+  id        String   @id @default(cuid())
+  createdAt DateTime @default(now())
+  updatedAt DateTime @updatedAt
+
+  title String?
+
+  user   User?   @relation(fields: [userId], references: [id])
+  userId String?
+
+  messages Message[]
+  calls    LlmCall[]
+
+  @@index([userId])
+}
+
+model Message {
+  id        String      @id @default(cuid())
+  createdAt DateTime    @default(now())
+
+  chat   Chat   @relation(fields: [chatId], references: [id], onDelete: Cascade)
+  chatId String
+
+  role    MessageRole
+  content String
+
+  // for tool messages or attachments later
+  name     String?
+  metadata Json?
+
+  @@index([chatId, createdAt])
+}
+
+model LlmCall {
+  id        String   @id @default(cuid())
+  createdAt DateTime @default(now())
+
+  chat   Chat   @relation(fields: [chatId], references: [id], onDelete: Cascade)
+  chatId String
+
+  provider Provider
+  model    String
+
+  // request/response snapshots for debugging + replay
+  request  Json
+  response Json?
+
+  // usage/cost basics
+  inputTokens  Int?
+  outputTokens Int?
+  totalTokens  Int?
+
+  latencyMs Int?
+
+  error   String?
+
+  @@index([chatId, createdAt])
+  @@index([provider, model, createdAt])
+}