feat(guild): channel membership + public visibility

- new channel_members table; creator always added, plus selected members
- Channel.isPublic (default false): public channels visible to all guild
  members; non-public only to explicit members
- GET /channels filters to channels visible to the requesting user

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/channels/channels.controller.ts

@@ -1,18 +1,33 @@
-import { Body, Controller, Get, Post, Query } from '@nestjs/common';
+import { Body, Controller, Get, Post, Query, Req, UnauthorizedException } from '@nestjs/common';
 import { ChannelsService } from './channels.service';
 
+// ApiKeyGuard attaches the introspected Center user id onto the request.
+type AuthedRequest = { userId?: string };
+
 @Controller('channels')
 export class ChannelsController {
   constructor(private readonly channelsService: ChannelsService) {}
 
   @Get()
-  list(@Query('guildId') guildId?: string) {
-    if (!guildId) return this.channelsService.listAll();
-    return this.channelsService.listByGuild(guildId);
+  list(@Req() req: AuthedRequest, @Query('guildId') guildId?: string) {
+    const userId = req.userId ?? '';
+    if (!userId) throw new UnauthorizedException('missing user');
+    return this.channelsService.listForUser(String(guildId ?? ''), userId);
   }
 
   @Post()
-  create(@Body() body: Record<string, unknown>) {
-    return this.channelsService.create(body);
+  create(@Req() req: AuthedRequest, @Body() body: Record<string, unknown>) {
+    const userId = req.userId ?? '';
+    if (!userId) throw new UnauthorizedException('missing user');
+    return this.channelsService.create(
+      {
+        guildId: body.guildId as string | undefined,
+        name: body.name as string | undefined,
+        kind: body.kind as string | undefined,
+        isPublic: Boolean(body.isPublic),
+        memberUserIds: Array.isArray(body.memberUserIds) ? (body.memberUserIds as string[]) : [],
+      },
+      userId,
+    );
   }
 }

src/channels/channels.module.ts

@@ -2,10 +2,11 @@ import { Module } from '@nestjs/common';
 import { TypeOrmModule } from '@nestjs/typeorm';
 import { ChannelsController } from './channels.controller';
 import { Channel } from '../entities/channel.entity';
+import { ChannelMember } from '../entities/channel-member.entity';
 import { ChannelsService } from './channels.service';
 
 @Module({
-  imports: [TypeOrmModule.forFeature([Channel])],
+  imports: [TypeOrmModule.forFeature([Channel, ChannelMember])],
   controllers: [ChannelsController],
   providers: [ChannelsService],
   exports: [ChannelsService],

src/channels/channels.service.ts

@@ -1,43 +1,74 @@
 import { BadRequestException, Injectable } from '@nestjs/common';
 import { InjectRepository } from '@nestjs/typeorm';
-import { Repository } from 'typeorm';
+import { In, Repository } from 'typeorm';
 import { Channel } from '../entities/channel.entity';
+import { ChannelMember } from '../entities/channel-member.entity';
+
+type CreateChannelInput = {
+  guildId?: string;
+  name?: string;
+  kind?: string;
+  isPublic?: boolean;
+  memberUserIds?: string[];
+};
 
 @Injectable()
 export class ChannelsService {
   constructor(
     @InjectRepository(Channel)
     private readonly channelRepo: Repository<Channel>,
+    @InjectRepository(ChannelMember)
+    private readonly memberRepo: Repository<ChannelMember>,
   ) {}
 
-  listByGuild(guildId: string) {
-    return this.channelRepo.find({
-      where: { guildId },
+  // Channels visible to a user within a guild:
+  //  - every public channel of the guild (incl. ones created before the user
+  //    joined the guild), OR
+  //  - a non-public channel the user is an explicit member of.
+  async listForUser(guildId: string, userId: string) {
+    const all = await this.channelRepo.find({
+      where: guildId ? { guildId } : {},
       order: { createdAt: 'ASC' },
-      take: 200,
+      take: 500,
     });
+    if (!all.length) return [];
+
+    const memberRows = await this.memberRepo.find({
+      where: { userId, channelId: In(all.map((c) => c.id)) },
+    });
+    const memberChannelIds = new Set(memberRows.map((m) => m.channelId));
+
+    return all.filter((c) => c.isPublic || memberChannelIds.has(c.id));
   }
 
-  listAll() {
-    return this.channelRepo.find({
-      order: { createdAt: 'ASC' },
-      take: 200,
-    });
-  }
-
-  create(input: Partial<Channel>) {
+  async create(input: CreateChannelInput, creatorUserId: string) {
     const guildId = String(input.guildId ?? '').trim();
     const name = String(input.name ?? '').trim();
     if (!guildId) throw new BadRequestException('guildId is required');
     if (!name) throw new BadRequestException('name is required');
+    if (!creatorUserId) throw new BadRequestException('creator is required');
 
-    const channel = this.channelRepo.create({
-      guildId,
-      name,
-      kind: input.kind === 'announcement' ? 'announcement' : 'text',
-      isPrivate: Boolean(input.isPrivate),
-      lastSeq: 0,
-    });
-    return this.channelRepo.save(channel);
+    const channel = await this.channelRepo.save(
+      this.channelRepo.create({
+        guildId,
+        name,
+        kind: input.kind === 'announcement' ? 'announcement' : 'text',
+        isPrivate: !input.isPublic,
+        isPublic: Boolean(input.isPublic),
+        lastSeq: 0,
+      }),
+    );
+
+    // creator is always a member; merge in any explicitly selected members
+    const memberIds = new Set<string>([creatorUserId]);
+    for (const id of input.memberUserIds ?? []) {
+      const trimmed = String(id ?? '').trim();
+      if (trimmed) memberIds.add(trimmed);
+    }
+    await this.memberRepo.save(
+      [...memberIds].map((userId) => this.memberRepo.create({ channelId: channel.id, userId })),
+    );
+
+    return channel;
   }
 }

src/database.config.ts

@@ -1,6 +1,7 @@
 import { TypeOrmModuleOptions } from '@nestjs/typeorm';
 import { Guild } from './entities/guild.entity';
 import { Channel } from './entities/channel.entity';
+import { ChannelMember } from './entities/channel-member.entity';
 import { Message } from './entities/message.entity';
 import { DmConversation } from './entities/dm-conversation.entity';
 import { DmParticipant } from './entities/dm-participant.entity';
@@ -19,6 +20,7 @@ export const buildTypeOrmConfig = (): TypeOrmModuleOptions => ({
   entities: [
     Guild,
     Channel,
+    ChannelMember,
     Message,
     DmConversation,
     DmParticipant,

src/entities/channel-member.entity.ts

@@ -0,0 +1,19 @@
+import { Column, CreateDateColumn, Entity, Index, PrimaryGeneratedColumn } from 'typeorm';
+
+@Entity('channel_members')
+@Index(['channelId', 'userId'], { unique: true })
+@Index(['userId'])
+export class ChannelMember {
+  @PrimaryGeneratedColumn('uuid')
+  id!: string;
+
+  @Index()
+  @Column({ type: 'char', length: 36 })
+  channelId!: string;
+
+  @Column({ type: 'varchar', length: 64 })
+  userId!: string;
+
+  @CreateDateColumn()
+  createdAt!: Date;
+}

src/entities/channel.entity.ts

@@ -19,6 +19,11 @@ export class Channel {
   @Column({ type: 'boolean', default: false })
   isPrivate!: boolean;
 
+  // public channels are visible to every guild member (including those who
+  // join after the channel was created); default off (unchecked)
+  @Column({ type: 'boolean', default: false })
+  isPublic!: boolean;
+
   @Index()
   @Column({ default: 0 })
   lastSeq!: number;