study room

app/backend/src/app.module.ts

@@ -50,6 +50,7 @@ import { throttlerModuleProfiles } from "./config/rate-limit.config";
 import { EnvironmentParityModule } from "./environment-parity/environment-parity.module";
 import { IndexerLagModule } from "./indexer-lag";
 import { SupportBundleModule } from "./support-bundle/support-bundle.module";
+import { ChatModule } from "./chat/chat.module";
 
 type AppImport =
   | Type<unknown>
@@ -95,6 +96,7 @@ type AppImport =
       EnvironmentParityModule,
       IndexerLagModule,
       SupportBundleModule,
+      ChatModule,
     ];
 
     // In development, if SUPABASE_URL points to a localhost placeholder (i.e. you don't

app/backend/src/chat/chat.module.ts

@@ -0,0 +1,24 @@
+import { Module } from "@nestjs/common";
+
+import { SupabaseModule } from "../supabase/supabase.module";
+import { StudyRoomRepository } from "./study-room.repository";
+import { StudyRoomService } from "./study-room.service";
+import { StudyRoomController } from "./study-room.controller";
+
+/**
+ * ChatModule
+ *
+ * Provides topic-based study rooms: creation, membership, and messaging.
+ *
+ * Required Supabase tables (see migration below):
+ *   - study_rooms
+ *   - study_room_members
+ *   - study_room_messages
+ */
+@Module({
+  imports: [SupabaseModule],
+  controllers: [StudyRoomController],
+  providers: [StudyRoomRepository, StudyRoomService],
+  exports: [StudyRoomService],
+})
+export class ChatModule {}

app/backend/src/chat/dto/study-room.dto.ts

@@ -0,0 +1,166 @@
+import {
+  IsString,
+  IsOptional,
+  IsArray,
+  IsIn,
+  IsNumber,
+  IsNotEmpty,
+  MaxLength,
+  Min,
+  Max,
+  ArrayMaxSize,
+} from "class-validator";
+import { ApiProperty, ApiPropertyOptional } from "@nestjs/swagger";
+import { Type } from "class-transformer";
+
+import type { StudyRoomStatus } from "../entities/study-room.entity";
+
+// ---------------------------------------------------------------------------
+// Request DTOs
+// ---------------------------------------------------------------------------
+
+export class CreateStudyRoomDto {
+  @ApiProperty({
+    example: "rust",
+    description: "Topic slug that groups this room (e.g. rust, solidity, defi)",
+  })
+  @IsString()
+  @IsNotEmpty()
+  @MaxLength(100)
+  topic!: string;
+
+  @ApiProperty({ example: "Rust Ownership Deep Dive" })
+  @IsString()
+  @IsNotEmpty()
+  @MaxLength(120)
+  name!: string;
+
+  @ApiPropertyOptional({
+    example: "A room for discussing Rust ownership and borrowing",
+  })
+  @IsOptional()
+  @IsString()
+  @MaxLength(500)
+  description?: string;
+
+  @ApiPropertyOptional({
+    type: [String],
+    example: ["rust", "memory", "ownership"],
+    description: "Free-form tags for discoverability",
+  })
+  @IsOptional()
+  @IsArray()
+  @IsString({ each: true })
+  @ArrayMaxSize(10)
+  tags?: string[];
+
+  @ApiPropertyOptional({
+    example: 50,
+    description:
+      "Maximum number of participants allowed. Omit for unlimited.",
+    minimum: 1,
+    maximum: 1000,
+  })
+  @IsOptional()
+  @IsNumber()
+  @Min(1)
+  @Max(1000)
+  @Type(() => Number)
+  maxParticipants?: number;
+}
+
+export class UpdateStudyRoomDto {
+  @ApiPropertyOptional({ example: "Advanced Rust Ownership" })
+  @IsOptional()
+  @IsString()
+  @IsNotEmpty()
+  @MaxLength(120)
+  name?: string;
+
+  @ApiPropertyOptional({ example: "Updated description" })
+  @IsOptional()
+  @IsString()
+  @MaxLength(500)
+  description?: string;
+
+  @ApiPropertyOptional({
+    type: [String],
+    example: ["rust", "advanced"],
+  })
+  @IsOptional()
+  @IsArray()
+  @IsString({ each: true })
+  @ArrayMaxSize(10)
+  tags?: string[];
+
+  @ApiPropertyOptional({ enum: ["active", "archived"] })
+  @IsOptional()
+  @IsIn(["active", "archived"])
+  status?: StudyRoomStatus;
+
+  @ApiPropertyOptional({ minimum: 1, maximum: 1000 })
+  @IsOptional()
+  @IsNumber()
+  @Min(1)
+  @Max(1000)
+  @Type(() => Number)
+  maxParticipants?: number;
+}
+
+export class SendMessageDto {
+  @ApiProperty({ example: "Can someone explain lifetimes?" })
+  @IsString()
+  @IsNotEmpty()
+  @MaxLength(2000)
+  content!: string;
+}
+
+// ---------------------------------------------------------------------------
+// Response DTOs
+// ---------------------------------------------------------------------------
+
+export class StudyRoomResponseDto {
+  @ApiProperty() id!: string;
+  @ApiProperty() topic!: string;
+  @ApiProperty() name!: string;
+  @ApiPropertyOptional() description!: string | null;
+  @ApiProperty({ type: [String] }) tags!: string[];
+  @ApiProperty({ enum: ["active", "archived"] }) status!: StudyRoomStatus;
+  @ApiPropertyOptional() maxParticipants!: number | null;
+  @ApiProperty() createdByPublicKey!: string;
+  @ApiProperty() memberCount!: number;
+  @ApiProperty() createdAt!: string;
+  @ApiProperty() updatedAt!: string;
+}
+
+export class StudyRoomMessageResponseDto {
+  @ApiProperty() id!: string;
+  @ApiProperty() roomId!: string;
+  @ApiProperty() senderPublicKey!: string;
+  @ApiProperty() content!: string;
+  @ApiProperty() createdAt!: string;
+  @ApiPropertyOptional() editedAt!: string | null;
+}
+
+export class StudyRoomMemberResponseDto {
+  @ApiProperty() id!: string;
+  @ApiProperty() roomId!: string;
+  @ApiProperty() publicKey!: string;
+  @ApiProperty() joinedAt!: string;
+}
+
+export class StudyRoomListResponseDto {
+  @ApiProperty({ type: [StudyRoomResponseDto] }) items!: StudyRoomResponseDto[];
+  @ApiProperty() total!: number;
+  @ApiProperty() page!: number;
+  @ApiProperty() limit!: number;
+}
+
+export class MessageListResponseDto {
+  @ApiProperty({ type: [StudyRoomMessageResponseDto] })
+  items!: StudyRoomMessageResponseDto[];
+
+  @ApiProperty() total!: number;
+  @ApiProperty() page!: number;
+  @ApiProperty() limit!: number;
+}

app/backend/src/chat/entities/study-room.entity.ts

@@ -0,0 +1,30 @@
+export type StudyRoomStatus = "active" | "archived";
+
+export interface StudyRoom {
+  id: string;
+  topic: string;
+  name: string;
+  description: string | null;
+  tags: string[];
+  status: StudyRoomStatus;
+  maxParticipants: number | null;
+  createdByPublicKey: string;
+  createdAt: string;
+  updatedAt: string;
+}
+
+export interface StudyRoomMember {
+  id: string;
+  roomId: string;
+  publicKey: string;
+  joinedAt: string;
+}
+
+export interface StudyRoomMessage {
+  id: string;
+  roomId: string;
+  senderPublicKey: string;
+  content: string;
+  createdAt: string;
+  editedAt: string | null;
+}

app/backend/src/chat/migrations/001_create_study_rooms.sql

@@ -0,0 +1,61 @@
+-- Migration: create study rooms tables
+-- Run this against your Supabase project via the SQL Editor or supabase db push.
+
+-- ============================================================================
+-- study_rooms
+-- ============================================================================
+CREATE TABLE IF NOT EXISTS study_rooms (
+  id                    UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  topic                 TEXT NOT NULL,
+  name                  TEXT NOT NULL,
+  description           TEXT,
+  tags                  TEXT[]   NOT NULL DEFAULT '{}',
+  status                TEXT     NOT NULL DEFAULT 'active'
+                          CHECK (status IN ('active', 'archived')),
+  max_participants      INTEGER  CHECK (max_participants > 0),
+  created_by_public_key TEXT     NOT NULL,
+  created_at            TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+  updated_at            TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+-- Index for topic-based queries (most common filter)
+CREATE INDEX IF NOT EXISTS idx_study_rooms_topic
+  ON study_rooms (topic, status, created_at DESC);
+
+-- Index for creator lookup
+CREATE INDEX IF NOT EXISTS idx_study_rooms_created_by
+  ON study_rooms (created_by_public_key);
+
+-- ============================================================================
+-- study_room_members
+-- ============================================================================
+CREATE TABLE IF NOT EXISTS study_room_members (
+  id          UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  room_id     UUID NOT NULL REFERENCES study_rooms(id) ON DELETE CASCADE,
+  public_key  TEXT NOT NULL,
+  joined_at   TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+
+  CONSTRAINT uq_room_member UNIQUE (room_id, public_key)
+);
+
+CREATE INDEX IF NOT EXISTS idx_study_room_members_room
+  ON study_room_members (room_id, joined_at ASC);
+
+CREATE INDEX IF NOT EXISTS idx_study_room_members_key
+  ON study_room_members (public_key);
+
+-- ============================================================================
+-- study_room_messages
+-- ============================================================================
+CREATE TABLE IF NOT EXISTS study_room_messages (
+  id                 UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  room_id            UUID NOT NULL REFERENCES study_rooms(id) ON DELETE CASCADE,
+  sender_public_key  TEXT NOT NULL,
+  content            TEXT NOT NULL CHECK (char_length(content) <= 2000),
+  created_at         TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+  edited_at          TIMESTAMPTZ
+);
+
+-- Paginated message history (newest first per room)
+CREATE INDEX IF NOT EXISTS idx_study_room_messages_room
+  ON study_room_messages (room_id, created_at DESC);