feat(schema): add agent_threads and agent_messages tables

User-scoped chat threads with FK to user table and cascade
delete. Handles existing tables from Go API by using ALTER
TABLE ADD COLUMN IF NOT EXISTS for the new user_id column.

Author: raghavyuva

drizzle/0044_agent_threads_messages.sql

@@ -0,0 +1,31 @@
+-- Add user_id column to existing agent_threads table (created by Go API)
+-- For existing rows, we set a placeholder that must be backfilled
+ALTER TABLE "agent_threads" ADD COLUMN IF NOT EXISTS "user_id" uuid;
+--> statement-breakpoint
+-- Backfill existing threads: assign to the first user in the org from metadata
+UPDATE "agent_threads" SET "user_id" = (
+  SELECT u.id FROM "user" u LIMIT 1
+) WHERE "user_id" IS NULL;
+--> statement-breakpoint
+-- Now make it NOT NULL
+ALTER TABLE "agent_threads" ALTER COLUMN "user_id" SET NOT NULL;
+--> statement-breakpoint
+DO $$ BEGIN
+ ALTER TABLE "agent_threads" ADD CONSTRAINT "agent_threads_user_id_user_id_fk" FOREIGN KEY ("user_id") REFERENCES "public"."user"("id") ON DELETE cascade ON UPDATE no action;
+EXCEPTION
+ WHEN duplicate_object THEN null;
+END $$;
+--> statement-breakpoint
+CREATE INDEX IF NOT EXISTS "idx_agent_threads_user" ON "agent_threads" USING btree ("user_id");
+--> statement-breakpoint
+-- Clean orphaned messages whose thread no longer exists
+DELETE FROM "agent_messages" WHERE "thread_id" NOT IN (SELECT "id" FROM "agent_threads");
+--> statement-breakpoint
+-- Ensure agent_messages has FK to agent_threads
+DO $$ BEGIN
+ ALTER TABLE "agent_messages" ADD CONSTRAINT "agent_messages_thread_id_agent_threads_id_fk" FOREIGN KEY ("thread_id") REFERENCES "public"."agent_threads"("id") ON DELETE cascade ON UPDATE no action;
+EXCEPTION
+ WHEN duplicate_object THEN null;
+END $$;
+--> statement-breakpoint
+CREATE INDEX IF NOT EXISTS "idx_agent_messages_thread_seq" ON "agent_messages" USING btree ("thread_id","seq");

drizzle/meta/_journal.json

@@ -309,6 +309,13 @@
       "when": 1776706898612,
       "tag": "0043_flippant_stark_industries",
       "breakpoints": true
+    },
+    {
+      "idx": 44,
+      "version": "7",
+      "when": 1778436000000,
+      "tag": "0044_agent_threads_messages",
+      "breakpoints": true
     }
   ]
 }

src/db/schema.ts

@@ -2308,3 +2308,62 @@ export const cliInstallations = pgTable(
     index("idx_cli_installations_event_type").on(table.eventType),
   ],
 );
+
+// ─── Agent Chat Threads & Messages ──────────────────────────────────────────
+
+export const agentThreads = pgTable(
+  "agent_threads",
+  {
+    id: text("id").primaryKey(),
+    userId: uuid("user_id")
+      .notNull()
+      .references(() => user.id, { onDelete: "cascade" }),
+    title: text("title").notNull().default(""),
+    metadata: text("metadata").default("{}"),
+    createdAt: timestamp("created_at", { withTimezone: true })
+      .defaultNow()
+      .notNull(),
+    updatedAt: timestamp("updated_at", { withTimezone: true })
+      .defaultNow()
+      .notNull(),
+  },
+  (table) => [
+    index("idx_agent_threads_user").on(table.userId),
+  ],
+);
+
+export const agentThreadsRelations = relations(agentThreads, ({ one, many }) => ({
+  user: one(user, {
+    fields: [agentThreads.userId],
+    references: [user.id],
+  }),
+  messages: many(agentMessages),
+}));
+
+export const agentMessages = pgTable(
+  "agent_messages",
+  {
+    id: text("id").primaryKey(),
+    threadId: text("thread_id")
+      .notNull()
+      .references(() => agentThreads.id, { onDelete: "cascade" }),
+    role: text("role").notNull(),
+    content: text("content").notNull().default(""),
+    toolCalls: text("tool_calls").default("[]"),
+    toolCallId: text("tool_call_id").default(""),
+    createdAt: timestamp("created_at", { withTimezone: true })
+      .defaultNow()
+      .notNull(),
+    seq: integer("seq").notNull(),
+  },
+  (table) => [
+    index("idx_agent_messages_thread_seq").on(table.threadId, table.seq),
+  ],
+);
+
+export const agentMessagesRelations = relations(agentMessages, ({ one }) => ({
+  thread: one(agentThreads, {
+    fields: [agentMessages.threadId],
+    references: [agentThreads.id],
+  }),
+}));