diff --git a/AGENTS.md b/AGENTS.md
index d02f66d..4ca8ec3 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -27,3 +27,4 @@
 
 - MESHTASTIC.md — rules for Meshtastic communication (owner authority, language, response protocol); read before acting on mesh messages.
 - Hourly cron weather report job (`src/weather`): fetches Open-Meteo current conditions and broadcasts a one-line report to the mesh on the pinned send channel; env `WEATHER_CRON`/`WEATHER_LAT`/`WEATHER_LON`/`WEATHER_CITY`.
+- Channel-2 auto-responder (`src/commands`): event-driven — `CommandService.onRx()` is called by `MeshService` for every decoded rx text (right after the notify gate) and dispatches exact, case-sensitive `#command` matches on `COMMAND_CHANNEL` (env, default 2) through a single-registration-point registry (handlers registered in the constructor via `register(name, fn)`; handler gets `{ text, from?, id? }`, returns reply string or void = no reply). First command: `#ping` → replies `#pong!`. Replies ride `COMMAND_CHANNEL`: directed DM back to the sender when present, else broadcast. A failing handler/send only logs a warn. DI: provided by `CommandModule`'s factory (injects `MeshService`, attaches itself via `attachCommands()`) — no constructor-level cycle; `forwardRef` was tried and left one side null in NestJS 12's injector.
diff --git a/CHANGELOG.md b/CHANGELOG.md
index ae07d0a..470bb28 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,13 @@
 # Changelog
 
+## v0.18.0 — 2026-09-25 17:08
+
+- New channel-index-2 auto-responder (`src/commands`): an event-driven `CommandService` reacts to decoded rx text on `COMMAND_CHANNEL` (env, default `2`) and dispatches exact `#command` matches (case-sensitive, surrounding whitespace trimmed) through a single-registration-point registry — handlers registered in the constructor via `register(name, fn)` receive `{ text, from?, id? }` and return a reply string or void (= no reply). First command: `#ping` → replies `#pong!`.
+- Reply routing v1: directed DM back to the sender when present, else broadcast — always on `COMMAND_CHANNEL`, via the existing `MeshService.sendText(to, text, undefined, channel)` path. No threading/`replyId` in v1. A failing handler or send only logs a warn; it never crashes the app.
+- Wiring: `MeshService` gains an optional third constructor param (`commands?`) plus a public `attachCommands()` — the rx handler calls `this.commands?.onRx(channel, text, from, id)` right after `notifyRx()`, fire-and-forget like the notifier. DI note: a constructor-level MeshService ↔ CommandService cycle leaves one side null in NestJS 12's injector (verified empirically), so `CommandModule` provides `CommandService` via a factory that injects `MeshService` and attaches itself as a side effect — no `forwardRef`, no module cycle.
+- Tests: 106 → 121 specs — directed/broadcast replies on ch2, non-command-channel and non-command text ignored, case-sensitive exact match, whitespace trimming, `COMMAND_CHANNEL` override, void handler = no reply, extensibility (second registered command), failing handler/send swallowed; end-to-end over the fake bridge (`#ping` on ch2 answered with a directed `#pong!` tx record, ch3 not answered); DI spec asserts both sides of the wiring resolve to real instances.
+- Docs: AGENTS.md "Other" bullet + MESHTASTIC.md "Channels & sending" describe the auto-responder; README env list gains `COMMAND_CHANNEL`.
+
 ## v0.17.0 — 2026-09-25 16:18
 
 - The mesh→agent notify gate is now a comma-separated multi-channel list: `MESH_NOTIFY_CHANNEL` (default `3`) parses to channel indices, each entry trimmed, empty/invalid entries ignored (`"3,0"` → `[3, 0]`).
diff --git a/MESHTASTIC.md b/MESHTASTIC.md
index 2db4b86..51bd19e 100644
--- a/MESHTASTIC.md
+++ b/MESHTASTIC.md
@@ -22,6 +22,7 @@ Rules for how mesh-bot communicates over Meshtastic and how the agent should rea
 
 - All bot sends ride channel index 3 ("test") by design (`MESH_SEND_CHANNEL`, default "3") — never the primary channel.
 - Broadcasts show up in `/api/messages` as `failed` / `NO_RESPONSE` on this firmware — known quirk, not a real failure; the message was transmitted.
+- Channel index 2 carries the bot's auto-responder (`COMMAND_CHANNEL`, default 2): exact `#command` texts (case-sensitive) get an automatic reply on that channel — directed back to the sender when present, else broadcast. Currently only `#ping` → `#pong!`. This is a mechanical echo for testing the mesh path; it is not the agent and does not mean the owner has seen anything.
 
 ## Notifications (mesh → agent)
 
diff --git a/README.md b/README.md
index d678592..ca3d247 100644
--- a/README.md
+++ b/README.md
@@ -121,6 +121,7 @@ Config lives in `.env` (gitignored) and is passed via compose environment — cr
 - `MESH_RECONNECT_MS` (default `5000`) — reconnect interval in ms
 - `MESH_SEND_CHANNEL` (default `3`) — channel index all sends target (`test`; never the primary channel)
 - `MESH_NOTIFY_CHANNEL` (default `3`) — comma-separated list of channel indices whose rx texts trigger the opencode notifier (see "Opencode notifier"; on ch0 only directed DMs notify, broadcasts ignored; synthetic injected messages, channel 0, are exempt and trigger it when `0` is in the list; messages from our own node are never notified)
+- `COMMAND_CHANNEL` (default `2`) — channel index of the auto-responder: exact `#command` texts on that channel get an automatic reply (directed back to the sender, else broadcast); currently only `#ping` → `#pong!`
 - `MESH_DB_PATH` (default `./data/mesh-bot.db`) — SQLite file backing the message history (parent dir created if missing; in Docker, mounted at `/app/data` via a named volume so it survives container recreation)
 - `MESH_POLL_MS` (default `1000`) — how often the poller re-upserts the message history into SQLite and prunes rows beyond the newest 1000
 - `PORT` (default `3000`) — HTTP listen port
diff --git a/package.json b/package.json
index 924ba23..4b83b83 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "mesh-bot",
-  "version": "0.17.0",
+  "version": "0.18.0",
   "description": "",
   "author": "",
   "private": true,
diff --git a/src/app.module.ts b/src/app.module.ts
index 73e7afc..177fa27 100644
--- a/src/app.module.ts
+++ b/src/app.module.ts
@@ -1,9 +1,10 @@
 import { Module } from '@nestjs/common';
 import { BatteryAlertModule } from './battery/battery.module.js';
+import { CommandModule } from './commands/command.module.js';
 import { MeshModule } from './mesh/mesh.module.js';
 import { WeatherModule } from './weather/weather.module.js';
 
 @Module({
-  imports: [MeshModule, WeatherModule, BatteryAlertModule],
+  imports: [MeshModule, WeatherModule, BatteryAlertModule, CommandModule],
 })
 export class AppModule {}
diff --git a/src/commands/command.module.ts b/src/commands/command.module.ts
new file mode 100644
index 0000000..3bf538b
--- /dev/null
+++ b/src/commands/command.module.ts
@@ -0,0 +1,22 @@
+import { Module } from '@nestjs/common';
+import { MeshModule } from '../mesh/mesh.module.js';
+import { MeshService } from '../mesh/mesh.service.js';
+import { CommandService } from './command.service.js';
+
+@Module({
+  imports: [MeshModule], // one-way only — the reverse edge is wired in the factory below, not via DI
+  providers: [
+    {
+      provide: CommandService,
+      useFactory: (mesh: MeshService) => {
+        const commands = new CommandService(mesh);
+        // break the cycle: MeshService can't inject us (its own factory would deadlock on this edge), so attach ourselves once we exist — mesh is guaranteed created here because it's our injected dependency
+        mesh.attachCommands(commands);
+        return commands;
+      },
+      inject: [MeshService],
+    },
+  ],
+  exports: [CommandService],
+})
+export class CommandModule {}
diff --git a/src/commands/command.service.spec.ts b/src/commands/command.service.spec.ts
new file mode 100644
index 0000000..8d0599f
--- /dev/null
+++ b/src/commands/command.service.spec.ts
@@ -0,0 +1,164 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+import { BROADCAST_ADDR } from '../mesh/codec.js';
+import {
+  startBridge,
+  textPacketFrame,
+  waitFor,
+  KAMIL_NUM,
+} from '../mesh/fake-bridge.js';
+import type { MeshService } from '../mesh/mesh.service.js';
+import { MeshService as RealMeshService } from '../mesh/mesh.service.js';
+import { CommandService } from './command.service.js';
+
+function makeService(
+  sendText?: ReturnType<typeof vi.fn>,
+): [CommandService, MeshService] {
+  const mesh = { sendText: sendText ?? vi.fn() } as unknown as MeshService;
+  return [new CommandService(mesh), mesh];
+}
+
+beforeEach(() => {
+  delete process.env.COMMAND_CHANNEL; // default channel 2 under test
+});
+
+describe('CommandService.onRx', () => {
+  it('answers #ping on the command channel with a directed DM back to the sender', async () => {
+    const [svc, mesh] = makeService();
+    await svc.onRx(2, '#ping', 42, 7);
+    expect(mesh.sendText).toHaveBeenCalledWith(42, '#pong!', undefined, 2);
+  });
+
+  it('broadcasts the reply when there is no sender', async () => {
+    const [svc, mesh] = makeService();
+    await svc.onRx(2, '#ping');
+    expect(mesh.sendText).toHaveBeenCalledWith(
+      BROADCAST_ADDR,
+      '#pong!',
+      undefined,
+      2,
+    );
+  });
+
+  it('ignores the same text on other channels (ch0 and ch3)', async () => {
+    const [svc, mesh] = makeService();
+    await svc.onRx(0, '#ping', 42);
+    await svc.onRx(3, '#ping', 42);
+    expect(mesh.sendText).not.toHaveBeenCalled();
+  });
+
+  it('ignores non-command text on the command channel', async () => {
+    const [svc, mesh] = makeService();
+    await svc.onRx(2, 'hello there', 42);
+    await svc.onRx(2, 'ping', 42); // no leading # — not a command trigger
+    expect(mesh.sendText).not.toHaveBeenCalled();
+  });
+
+  it('matches command names exactly and case-sensitively', async () => {
+    const [svc, mesh] = makeService();
+    await svc.onRx(2, '#Ping', 42);
+    await svc.onRx(2, '#ping!', 42); // extra char — no partial matches
+    expect(mesh.sendText).not.toHaveBeenCalled();
+  });
+
+  it('trims surrounding whitespace before matching', async () => {
+    const [svc, mesh] = makeService();
+    await svc.onRx(2, '  #ping  ', 42);
+    expect(mesh.sendText).toHaveBeenCalledWith(42, '#pong!', undefined, 2);
+  });
+
+  it('honors the COMMAND_CHANNEL env override', async () => {
+    process.env.COMMAND_CHANNEL = '5';
+    const [svc, mesh] = makeService();
+    await svc.onRx(2, '#ping', 42); // old default no longer triggers
+    expect(mesh.sendText).not.toHaveBeenCalled();
+    await svc.onRx(5, '#ping', 42);
+    expect(mesh.sendText).toHaveBeenCalledWith(42, '#pong!', undefined, 5);
+  });
+
+  it('sends nothing when a handler returns void', async () => {
+    const [svc, mesh] = makeService();
+    svc.register('silent', () => undefined);
+    await svc.onRx(2, '#silent', 42);
+    expect(mesh.sendText).not.toHaveBeenCalled();
+  });
+
+  it('is extensible: a second registered command dispatches through the same path', async () => {
+    const [svc, mesh] = makeService();
+    svc.register('status', (ctx) => `up from ${ctx.from ?? 'broadcast'}`);
+    await svc.onRx(2, '#status', 99, 5);
+    expect(mesh.sendText).toHaveBeenCalledWith(99, 'up from 99', undefined, 2);
+  });
+
+  it('swallows a failing handler (a bad command must not crash the app)', async () => {
+    const [svc, mesh] = makeService();
+    svc.register('boom', () => {
+      throw new Error('kaboom');
+    });
+    await expect(svc.onRx(2, '#boom', 42)).resolves.toBeUndefined();
+    expect(mesh.sendText).not.toHaveBeenCalled();
+  });
+
+  it('swallows a failing send (mesh down) without throwing', async () => {
+    const [svc] = makeService(
+      vi.fn().mockRejectedValue(new Error('no bridge')),
+    );
+    await expect(svc.onRx(2, '#ping', 42)).resolves.toBeUndefined();
+  });
+});
+
+describe('MeshService wiring (event-driven trigger)', () => {
+  it('calls onRx for decoded rx text and answers #ping over the wire', async () => {
+    const bridge = await startBridge();
+    process.env.MESH_HOST = '127.0.0.1';
+    process.env.MESH_PORT = String(bridge.port);
+    const svc = new RealMeshService();
+    try {
+      // wire the responder exactly like command.module.ts does in production
+      svc.attachCommands(new CommandService(svc));
+      svc.onModuleInit();
+      await waitFor(
+        () => bridge.sockets.length === 1 && svc.status().connected,
+      );
+
+      bridge.sockets[0].write(textPacketFrame(KAMIL_NUM, 42, '#ping', 2));
+
+      // rx record + the directed #pong! reply on channel 2 (newest first — the reply is [0])
+      await waitFor(() => svc.messages().length === 2);
+      expect(svc.messages()[0]).toMatchObject({
+        dir: 'tx',
+        to: KAMIL_NUM,
+        text: '#pong!',
+        channel: 2,
+      });
+    } finally {
+      svc.onModuleDestroy();
+      bridge.close();
+    }
+  });
+
+  it('does not answer #ping arriving on a non-command channel', async () => {
+    const bridge = await startBridge();
+    process.env.MESH_HOST = '127.0.0.1';
+    process.env.MESH_PORT = String(bridge.port);
+    const svc = new RealMeshService();
+    try {
+      svc.attachCommands(new CommandService(svc));
+      svc.onModuleInit();
+      await waitFor(
+        () => bridge.sockets.length === 1 && svc.status().connected,
+      );
+
+      bridge.sockets[0].write(textPacketFrame(KAMIL_NUM, 42, '#ping', 3));
+
+      await waitFor(() => svc.messages().length === 1); // only the rx record — no reply
+      expect(svc.messages()[0]).toMatchObject({
+        dir: 'rx',
+        text: '#ping',
+        channel: 3,
+      });
+    } finally {
+      svc.onModuleDestroy();
+      bridge.close();
+    }
+  });
+});
diff --git a/src/commands/command.service.ts b/src/commands/command.service.ts
new file mode 100644
index 0000000..a49bf5f
--- /dev/null
+++ b/src/commands/command.service.ts
@@ -0,0 +1,74 @@
+import { Injectable, Logger } from '@nestjs/common';
+import { BROADCAST_ADDR } from '../mesh/codec.js';
+// type-only: the instance comes from DI (command.module.ts factory) or direct construction in tests — no runtime import cycle with src/mesh
+import type { MeshService } from '../mesh/mesh.service.js';
+
+/** Context handed to a command handler: the trimmed text plus sender/packet id when present. */
+export interface CommandContext {
+  /** the trimmed rx text, e.g. `#ping` */
+  text: string;
+  /** sender node num — omitted for broadcasts/unknown senders */
+  from?: number;
+  /** packet id of the triggering message */
+  id?: number;
+}
+
+/** A command handler: returns the reply text to send back, or void/undefined for no reply. */
+export type CommandHandler = (
+  ctx: CommandContext,
+) => string | undefined | Promise<string | undefined>;
+
+@Injectable()
+export class CommandService {
+  private readonly logger = new Logger(CommandService.name);
+  // read at construction, like other services' env config
+  private readonly commandChannel = parseInt(
+    process.env.COMMAND_CHANNEL ?? '2',
+    10,
+  );
+  // single registration point: the constructor registers every built-in command — add the next one there (or via register())
+  private readonly commands = new Map<string, CommandHandler>();
+
+  /** mesh is optional so tests can construct without a bridge; production DI always passes one. */
+  constructor(private readonly mesh?: MeshService) {
+    this.register('ping', () => '#pong!');
+  }
+
+  /** Register a command handler (names are case-sensitive; the leading `#` is stripped before lookup). */
+  register(name: string, fn: CommandHandler): void {
+    this.commands.set(name, fn);
+  }
+
+  /**
+   * Event-driven entry point called by MeshService for every decoded rx text.
+   * No-op unless on COMMAND_CHANNEL with an exact `#command` match (case-sensitive).
+   * Replies ride COMMAND_CHANNEL: directed DM back to the sender when present, else broadcast.
+   * Never throws — a failed command must not crash the app.
+   */
+  async onRx(
+    channel: number,
+    text: string,
+    from?: number,
+    id?: number,
+  ): Promise<void> {
+    if (channel !== this.commandChannel) return;
+    const trimmed = text.trim();
+    if (!trimmed.startsWith('#')) return; // only `#command` texts trigger handlers
+    const handler = this.commands.get(trimmed.slice(1));
+    if (!handler) return; // exact, case-sensitive match — no partials
+    try {
+      const reply = await handler({ text: trimmed, from, id });
+      if (reply === undefined || reply === null) return; // void = no reply
+      await this.mesh?.sendText(
+        from ?? BROADCAST_ADDR,
+        reply,
+        undefined,
+        this.commandChannel,
+      );
+    } catch (err) {
+      this.logger.warn(
+        `[commands] '${trimmed}' failed: ${(err as Error).message}`,
+      );
+    }
+  }
+}
diff --git a/src/commands/di.spec.ts b/src/commands/di.spec.ts
new file mode 100644
index 0000000..84739db
--- /dev/null
+++ b/src/commands/di.spec.ts
@@ -0,0 +1,31 @@
+import { Test } from '@nestjs/testing';
+import { describe, expect, it } from 'vitest';
+import { MeshService } from '../mesh/mesh.service.js';
+import { CommandModule } from './command.module.js';
+import { CommandService } from './command.service.js';
+
+describe('DI wiring (module graph)', () => {
+  // compile() instantiates providers but does not run lifecycle hooks, so no TCP connection is opened.
+  it('resolves CommandService with MeshService provided by MeshModule', async () => {
+    process.env.MESH_DB_PATH = ':memory:'; // keep openMessageDb from touching the repo's ./data
+    const moduleRef = await Test.createTestingModule({
+      imports: [CommandModule],
+    }).compile();
+    expect(moduleRef.get(CommandService)).toBeInstanceOf(CommandService);
+    expect(moduleRef.get(MeshService)).toBeInstanceOf(MeshService);
+  });
+
+  // the MeshService <-> CommandService cycle must resolve to live references on both sides, not undefined
+  it('wires both sides of the circular dependency with real instances', async () => {
+    process.env.MESH_DB_PATH = ':memory:';
+    const moduleRef = await Test.createTestingModule({
+      imports: [CommandModule],
+    }).compile();
+    const mesh = moduleRef.get(MeshService);
+    const commands = moduleRef.get(CommandService);
+    expect((commands as unknown as { mesh?: MeshService }).mesh).toBe(mesh);
+    expect((mesh as unknown as { commands?: CommandService }).commands).toBe(
+      commands,
+    );
+  });
+});
diff --git a/src/mesh/mesh.service.ts b/src/mesh/mesh.service.ts
index 5b674b6..2b76794 100644
--- a/src/mesh/mesh.service.ts
+++ b/src/mesh/mesh.service.ts
@@ -11,6 +11,8 @@ import * as net from 'node:net';
 // type-only import: node:sqlite is only required at runtime by whoever opens a database (mesh.module.ts / tests)
 import type { DatabaseSync } from 'node:sqlite';
 import type * as Proto from '@meshtastic/protobufs';
+// type-only: the instance arrives via attachCommands() in production (command.module.ts) or the constructor in tests — no runtime import cycle with src/commands
+import type { CommandService } from '../commands/command.service.js';
 import { OpencodeService } from '../opencode/opencode.service.js';
 import {
   BROADCAST_ADDR,
@@ -211,11 +213,23 @@ export class MeshService implements OnModuleInit, OnModuleDestroy {
   private db: DatabaseSync | null = null;
   /** In-process opencode notifier for rx texts on the notify channel; null in tests that don't wire one. */
   private readonly opencode: OpencodeService | null;
+  /** Event-driven `#command` auto-responder (COMMAND_CHANNEL); null until wired — via the constructor (tests) or attachCommands() (DI). */
+  private commands: CommandService | null = null;
   private pollTimer: NodeJS.Timeout | null = null;
 
-  constructor(db?: DatabaseSync, opencode?: OpencodeService) {
+  constructor(
+    db?: DatabaseSync,
+    opencode?: OpencodeService,
+    commands?: CommandService,
+  ) {
     this.db = db ?? null;
     this.opencode = opencode ?? null;
+    this.commands = commands ?? null;
+  }
+
+  /** Wire the `#command` auto-responder after construction — used by command.module.ts to break the DI cycle (a constructor-level MeshService <-> CommandService cycle leaves one side null in NestJS's injector). */
+  attachCommands(commands: CommandService): void {
+    this.commands = commands;
   }
 
   private socket: net.Socket | null = null;
@@ -736,6 +750,8 @@ export class MeshService implements OnModuleInit, OnModuleDestroy {
             at: Date.now(),
           });
           this.notifyRx(pkt.channel ?? 0, text, pkt.from, pkt.id, pkt.to);
+          // event-driven #command auto-responder (COMMAND_CHANNEL) — fire-and-forget like the notifier
+          void this.commands?.onRx(pkt.channel ?? 0, text, pkt.from, pkt.id);
         } else if (decoded && decoded.portnum === PORT_POSITION_APP) {
           // live position update: the Position is serialized in Data.payload
           let pos: Proto.Mesh.Position | undefined;