feat: add ESLint with error-handling rules

Add ESLint v9.35+ with typescript-eslint recommended config and
error-handling rules: preserve-caught-error (enforces { cause } when
re-throwing), no-unused-vars with caughtErrors:all, and
eslint-plugin-no-catch-all (warns on catch blocks that don't rethrow).

Fix existing violations: add error cause to container-runtime rethrow,
prefix unused vars with underscore, remove unused imports.

https://claude.ai/code/session_01JPjzhBp9PR5LtfLWVDrYrH

src/channels/registry.test.ts

@@ -1,4 +1,4 @@
-import { describe, it, expect, beforeEach } from 'vitest';
+import { describe, it, expect } from 'vitest';
 
 import {
   registerChannel,

src/container-runner.ts

@@ -698,7 +698,7 @@ export function writeGroupsSnapshot(
   groupFolder: string,
   isMain: boolean,
   groups: AvailableGroup[],
-  registeredJids: Set<string>,
+  _registeredJids: Set<string>,
 ): void {
   const groupIpcDir = resolveGroupIpcPath(groupFolder);
   fs.mkdirSync(groupIpcDir, { recursive: true });

src/container-runtime.ts

@@ -96,7 +96,7 @@ export function ensureContainerRuntimeRunning(): void {
     console.error(
       '╚════════════════════════════════════════════════════════════════╝\n',
     );
-    throw new Error('Container runtime is required but failed to start');
+    throw new Error('Container runtime is required but failed to start', { cause: err });
   }
 }
 

src/group-queue.test.ts

@@ -40,7 +40,7 @@ describe('GroupQueue', () => {
     let concurrentCount = 0;
     let maxConcurrent = 0;
 
-    const processMessages = vi.fn(async (groupJid: string) => {
+    const processMessages = vi.fn(async (_groupJid: string) => {
       concurrentCount++;
       maxConcurrent = Math.max(maxConcurrent, concurrentCount);
       // Simulate async work
@@ -69,7 +69,7 @@ describe('GroupQueue', () => {
     let maxActive = 0;
     const completionCallbacks: Array<() => void> = [];
 
-    const processMessages = vi.fn(async (groupJid: string) => {
+    const processMessages = vi.fn(async (_groupJid: string) => {
       activeCount++;
       maxActive = Math.max(maxActive, activeCount);
       await new Promise<void>((resolve) => completionCallbacks.push(resolve));
@@ -104,7 +104,7 @@ describe('GroupQueue', () => {
     const executionOrder: string[] = [];
     let resolveFirst: () => void;
 
-    const processMessages = vi.fn(async (groupJid: string) => {
+    const processMessages = vi.fn(async (_groupJid: string) => {
       if (executionOrder.length === 0) {
         // First call: block until we release it
         await new Promise<void>((resolve) => {

src/group-queue.ts

@@ -351,7 +351,7 @@ export class GroupQueue {
     // via idle timeout or container timeout. The --rm flag cleans them up on exit.
     // This prevents WhatsApp reconnection restarts from killing working agents.
     const activeContainers: string[] = [];
-    for (const [jid, state] of this.groups) {
+    for (const [_jid, state] of this.groups) {
       if (state.process && !state.process.killed && state.containerName) {
         activeContainers.push(state.containerName);
       }

src/index.ts

@@ -33,7 +33,6 @@ import {
   getAllTasks,
   getMessagesSince,
   getNewMessages,
-  getRegisteredGroup,
   getRouterState,
   initDatabase,
   setRegisteredGroup,

src/remote-control.test.ts

@@ -37,7 +37,7 @@ describe('remote-control', () => {
   let readFileSyncSpy: ReturnType<typeof vi.spyOn>;
   let writeFileSyncSpy: ReturnType<typeof vi.spyOn>;
   let unlinkSyncSpy: ReturnType<typeof vi.spyOn>;
-  let mkdirSyncSpy: ReturnType<typeof vi.spyOn>;
+  let _mkdirSyncSpy: ReturnType<typeof vi.spyOn>;
   let openSyncSpy: ReturnType<typeof vi.spyOn>;
   let closeSyncSpy: ReturnType<typeof vi.spyOn>;
 
@@ -50,7 +50,7 @@ describe('remote-control', () => {
     stdoutFileContent = '';
 
     // Default fs mocks
-    mkdirSyncSpy = vi
+    _mkdirSyncSpy = vi
       .spyOn(fs, 'mkdirSync')
       .mockImplementation(() => undefined as any);
     writeFileSyncSpy = vi

src/routing.test.ts

@@ -1,6 +1,6 @@
 import { describe, it, expect, beforeEach } from 'vitest';
 
-import { _initTestDatabase, getAllChats, storeChatMetadata } from './db.js';
+import { _initTestDatabase, storeChatMetadata } from './db.js';
 import { getAvailableGroups, _setRegisteredGroups } from './index.js';
 
 beforeEach(() => {

src/sender-allowlist.test.ts

@@ -1,7 +1,7 @@
 import fs from 'fs';
 import os from 'os';
 import path from 'path';
-import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { afterEach, beforeEach, describe, expect, it } from 'vitest';
 
 import {
   isSenderAllowed,