feat: channel deletion UI with full backend cleanup

Add Delete Channel button to channel settings modal with ConfirmDialog
confirmation. Fix backend DELETE route to disconnect voice users, clean
up attachment files from disk, and remove orphaned read_states. Make
deleteChannel federation-aware in spaceStore and clean up voiceUsers
on channel_deleted WebSocket event.

packages/server/src/routes/channels.ts

@@ -1,5 +1,5 @@
 import type { FastifyInstance } from 'fastify';
-import { eq, and } from 'drizzle-orm';
+import { eq, and, inArray } from 'drizzle-orm';
 import { getDb, schema } from '../db/index.js';
 import { authenticate } from '../utils/auth.js';
 import { generateSnowflake } from '../utils/snowflake.js';
@@ -7,6 +7,7 @@ import { isMember, hasPermission, getChannelSpaceId, PermissionBits, computePerm
 import { permissionsToString } from '@backspace/shared/src/permissions.js';
 import { connectionManager } from '../ws/handler.js';
 import { checkVoicePermissions } from '../ws/events.js';
+import { deleteAttachmentFiles } from '../utils/fileCleanup.js';
 import type {
   CreateChannelRequest,
   UpdateChannelRequest,
@@ -285,6 +286,21 @@ export async function channelRoutes(app: FastifyInstance): Promise<void> {
       return reply.code(403).send({ error: 'Missing MANAGE_CHANNELS permission', statusCode: 403 });
     }
 
+    // Disconnect voice users before deletion
+    const participants = connectionManager.getRoomParticipants(id);
+    if (participants.size > 0) {
+      for (const participantId of Array.from(participants)) {
+        connectionManager.leaveRoom(id, participantId);
+        connectionManager.clearVoiceUserStatus(participantId);
+        connectionManager.sendToSpace(spaceId, {
+          type: 'voice_state_update', channelId: id, userId: participantId, action: 'leave',
+        });
+        connectionManager.sendToUser(participantId, {
+          type: 'voice_disconnected', userId: participantId, channelId: id,
+        });
+      }
+    }
+
     // Collect viewers BEFORE deleting (overrides CASCADE-delete with the channel)
     const viewerIds: string[] = [];
     for (const [uid, spaceIds] of connectionManager.getUserSpaceEntries()) {
@@ -296,10 +312,26 @@ export async function channelRoutes(app: FastifyInstance): Promise<void> {
       }
     }
 
+    // Collect attachment filenames BEFORE cascade deletes DB records
+    const channelMsgIds = db.select({ id: schema.messages.id })
+      .from(schema.messages).where(eq(schema.messages.channelId, id)).all().map(m => m.id);
+
+    let attachmentRows: { filename: string }[] = [];
+    if (channelMsgIds.length > 0) {
+      attachmentRows = db.select({ filename: schema.attachments.filename })
+        .from(schema.attachments).where(inArray(schema.attachments.messageId, channelMsgIds)).all();
+    }
+
+    // Clean up read_states (no FK, rows would be orphaned)
+    db.delete(schema.readStates).where(eq(schema.readStates.channelId, id)).run();
+
     // Delete messages in channel (attachments cascade), then channel
     db.delete(schema.messages).where(eq(schema.messages.channelId, id)).run();
     db.delete(schema.channels).where(eq(schema.channels.id, id)).run();
 
+    // Delete attachment files from disk
+    deleteAttachmentFiles(attachmentRows);
+
     // Broadcast channel_deleted only to users who could see the channel
     const deleteEvent = { type: 'channel_deleted' as const, channelId: id, spaceId };
     for (const uid of viewerIds) {