diff --git a/.gitignore b/.gitignore
index de10c0b7..c64230cc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -45,3 +45,12 @@ dist/
 build/
 *.egg-info/
 .cow.pid
+
+# Desktop backend packaging: keep the source files (spec/requirements/script)
+# tracked even though the generic build/ rule above ignores them, but never
+# track the build outputs or local venv.
+!desktop/build/
+desktop/build/*
+!desktop/build/cowagent-backend.spec
+!desktop/build/requirements-desktop.txt
+!desktop/build/build-backend.sh
diff --git a/desktop/build/build-backend.sh b/desktop/build/build-backend.sh
new file mode 100755
index 00000000..940c1afa
--- /dev/null
+++ b/desktop/build/build-backend.sh
@@ -0,0 +1,79 @@
+#!/usr/bin/env bash
+#
+# Build the desktop backend into a self-contained onedir bundle via PyInstaller.
+# Run from anywhere; paths are resolved relative to the repo root.
+#
+# Usage:
+#   bash desktop/build/build-backend.sh            # build
+#   PYTHON=python3.11 bash desktop/build/build-backend.sh   # pick interpreter
+#
+# Output: desktop/build/dist/cowagent-backend/  (folder with the executable)
+set -euo pipefail
+
+# --- resolve paths --------------------------------------------------------
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
+BUILD_DIR="$SCRIPT_DIR"
+VENV_DIR="$BUILD_DIR/.venv-build"
+
+# Prefer Python 3.11 when available: on 3.13+ web.py must be installed from a
+# GitHub git source (the PyPI build fails), which is flaky on some networks.
+# 3.11 installs web.py straight from PyPI and has the best PyInstaller support.
+if [ -z "${PYTHON:-}" ]; then
+  for cand in \
+    "/Library/Frameworks/Python.framework/Versions/3.11/bin/python3.11" \
+    "python3.11" \
+    "python3.12" \
+    "python3"; do
+    if command -v "$cand" >/dev/null 2>&1; then
+      PYTHON="$cand"
+      break
+    fi
+  done
+fi
+# Prefer Python 3.11: it installs web.py from PyPI (no GitHub clone) and avoids
+# 3.13's removed-cgi compatibility shims. Override with PYTHON=... if needed.
+pick_python() {
+  if [ -n "${PYTHON:-}" ]; then echo "$PYTHON"; return; fi
+  for c in python3.11 python3.12 python3.10 python3; do
+    if command -v "$c" >/dev/null 2>&1; then echo "$c"; return; fi
+  done
+  echo python3
+}
+PYTHON="$(pick_python)"
+
+echo "==> Repo root: $ROOT"
+echo "==> Using Python: $($PYTHON --version 2>&1) ($PYTHON)"
+
+# --- isolated build venv --------------------------------------------------
+if [ ! -d "$VENV_DIR" ]; then
+  echo "==> Creating build venv at $VENV_DIR"
+  "$PYTHON" -m venv "$VENV_DIR"
+fi
+# shellcheck disable=SC1091
+source "$VENV_DIR/bin/activate"
+
+echo "==> Installing build dependencies"
+pip install -q --upgrade pip
+# Don't leave a half-populated venv behind if deps fail (e.g. flaky network):
+# the next run would otherwise reuse a broken venv.
+if ! pip install -q -r "$BUILD_DIR/requirements-desktop.txt"; then
+  echo "!! Dependency install failed. Removing the build venv so a retry starts clean." >&2
+  deactivate || true
+  rm -rf "$VENV_DIR"
+  exit 1
+fi
+pip install -q pyinstaller
+
+# --- run pyinstaller from repo root so relative datas resolve -------------
+cd "$ROOT"
+echo "==> Running PyInstaller (onedir)"
+pyinstaller "$BUILD_DIR/cowagent-backend.spec" \
+  --noconfirm \
+  --distpath "$BUILD_DIR/dist" \
+  --workpath "$BUILD_DIR/build-work"
+
+echo ""
+echo "==> Done. Bundle at: $BUILD_DIR/dist/cowagent-backend/"
+du -sh "$BUILD_DIR/dist/cowagent-backend/" 2>/dev/null || true
+echo "==> Smoke test: COW_DESKTOP=1 \"$BUILD_DIR/dist/cowagent-backend/cowagent-backend\""
diff --git a/desktop/build/cowagent-backend.spec b/desktop/build/cowagent-backend.spec
new file mode 100644
index 00000000..9e20841e
--- /dev/null
+++ b/desktop/build/cowagent-backend.spec
@@ -0,0 +1,145 @@
+# -*- mode: python ; coding: utf-8 -*-
+"""
+PyInstaller spec for the CowAgent desktop backend (onedir).
+
+Produces a self-contained `cowagent-backend` folder that the Electron app
+spawns directly, so end users don't need Python installed.
+
+onedir is chosen over onefile because the backend reads data files via paths
+relative to the source tree (e.g. config-template.json, skills/, chat.html);
+onedir preserves that layout, while onefile's temp-extraction would break it.
+
+Build from the repo root:
+    pyinstaller desktop/build/cowagent-backend.spec --noconfirm
+"""
+import os
+from PyInstaller.utils.hooks import collect_submodules, collect_data_files
+
+# Resolve the repo root from the spec's own location (desktop/build/ -> root),
+# independent of the current working directory. PyInstaller exposes SPECPATH.
+ROOT = os.path.abspath(os.path.join(SPECPATH, '..', '..'))
+
+
+def rp(*parts):
+    """Absolute path under the repo root."""
+    return os.path.join(ROOT, *parts)
+
+# --- Hidden imports -------------------------------------------------------
+# Channels are imported dynamically by channel_factory via string names, so
+# PyInstaller's static analysis can't see them. List every channel we ship
+# (Feishu is intentionally excluded — lark-oapi is dropped from the desktop
+# build to save ~116MB).
+hiddenimports = [
+    # channels (dynamic import in channel/channel_factory.py)
+    'channel.web.web_channel',
+    'channel.terminal.terminal_channel',
+    'channel.weixin.weixin_channel',
+    'channel.wechatmp.wechatmp_channel',
+    'channel.wechatcom.wechatcomapp_channel',
+    'channel.wechat_kf.wechat_kf_channel',
+    'channel.dingtalk.dingtalk_channel',
+    'channel.wecom_bot.wecom_bot_channel',
+    'channel.qq.qq_channel',
+    'channel.telegram.telegram_channel',
+    'channel.slack.slack_channel',
+    'channel.discord.discord_channel',
+]
+
+# Agent tools and model providers are imported lazily in places; collect their
+# submodules so nothing is missed at runtime.
+hiddenimports += collect_submodules('agent.tools')
+hiddenimports += collect_submodules('models')
+hiddenimports += collect_submodules('voice')
+hiddenimports += collect_submodules('bridge')
+
+# Plugin framework: WebChannel -> ChatChannel imports `from plugins import *`,
+# so the framework package must be present even though desktop mode never loads
+# actual plugins (it's only ~tens of KB of code).
+hiddenimports += [
+    'plugins',
+    'plugins.event',
+    'plugins.plugin',
+    'plugins.plugin_manager',
+]
+
+# Third-party SDKs that use lazy/conditional imports internally.
+hiddenimports += collect_submodules('dashscope')
+hiddenimports += [
+    'tiktoken_ext',
+    'tiktoken_ext.openai_public',
+]
+
+# --- Data files -----------------------------------------------------------
+# Runtime-read files/dirs that must travel with the executable. Paths are
+# (source, dest_dir_in_bundle).
+datas = [
+    (rp('config-template.json'), '.'),
+    (rp('skills'), 'skills'),
+    # Web console served on the backend port: ship chat.html plus its static
+    # assets (~1.9MB) so the browser-based console works as a debug/fallback
+    # entry alongside the Electron UI.
+    (rp('channel', 'web', 'chat.html'), 'channel/web'),
+    (rp('channel', 'web', 'static'), 'channel/web/static'),
+]
+
+# Some libraries (tiktoken encodings, etc.) ship data files.
+datas += collect_data_files('tiktoken_ext', include_py_files=False)
+
+# --- Excludes -------------------------------------------------------------
+# Keep the bundle lean: drop Feishu's heavy SDK, plugins (disabled in desktop
+# mode), tests/docs, and dev-only packages.
+excludes = [
+    'lark_oapi',          # Feishu — ~116MB, excluded from desktop build
+    'tests',
+    'pip',
+    'wheel',
+    'pytest',
+    'playwright',         # browser tool is opt-in, not bundled
+]
+
+block_cipher = None
+
+a = Analysis(
+    [rp('app.py')],
+    pathex=[ROOT],
+    binaries=[],
+    datas=datas,
+    hiddenimports=hiddenimports,
+    hookspath=[],
+    hooksconfig={},
+    runtime_hooks=[],
+    excludes=excludes,
+    win_no_prefer_redirects=False,
+    win_private_assemblies=False,
+    cipher=block_cipher,
+    noarchive=False,
+)
+
+pyz = PYZ(a.pure, a.zipped_data, cipher=block_cipher)
+
+exe = EXE(
+    pyz,
+    a.scripts,
+    [],
+    exclude_binaries=True,
+    name='cowagent-backend',
+    debug=False,
+    bootloader_ignore_signals=False,
+    strip=False,
+    upx=False,
+    console=True,
+    disable_windowed_traceback=False,
+    target_arch=None,
+    codesign_identity=None,
+    entitlements_file=None,
+)
+
+coll = COLLECT(
+    exe,
+    a.binaries,
+    a.datas,
+    strip=False,
+    upx=False,
+    upx_exclude=[],
+    name='cowagent-backend',
+)
diff --git a/desktop/build/requirements-desktop.txt b/desktop/build/requirements-desktop.txt
new file mode 100644
index 00000000..dc6c0776
--- /dev/null
+++ b/desktop/build/requirements-desktop.txt
@@ -0,0 +1,52 @@
+# Desktop backend dependencies (slimmed down from the full requirements).
+#
+# Goal: keep the package light. The desktop client only needs the web channel
+# (which Electron talks to) plus the agent core; the remaining IM channels are
+# cheap (~27MB total) so we keep them, but Feishu's `lark-oapi` (~116MB) is
+# dropped — it is by far the heaviest dependency and not needed for a C-end
+# desktop app. Feishu is hidden in desktop mode (see COW_DESKTOP in app.py).
+
+# ---- core ----
+numpy>=1.21
+aiohttp>=3.8.6,<3.10
+requests>=2.28.2
+chardet>=5.1.0
+Pillow
+python-dotenv>=1.0.0
+PyYAML>=6.0
+croniter>=2.0.0
+click>=8.0
+qrcode
+json-repair
+
+# ---- web framework (web channel) ----
+# web.py 0.62 fails to build on Python 3.13+ (cgi removed); use the GitHub fix.
+web.py; python_version < "3.13"
+web.py @ git+https://github.com/webpy/webpy.git ; python_version >= "3.13"
+legacy-cgi; python_version >= "3.13"
+
+# ---- AI model SDKs ----
+zai-sdk
+dashscope
+tenacity        # used by some dashscope submodules (retry logic)
+google-generativeai
+tiktoken>=0.3.2
+
+# ---- voice (TTS/ASR) — kept per product decision ----
+pydub>=0.25.1
+gTTS>=2.3.1
+
+# ---- document parsing (web_fetch / knowledge) ----
+pypdf
+python-docx
+openpyxl
+python-pptx
+
+# ---- IM channels (kept; lightweight). Feishu/lark-oapi intentionally excluded. ----
+wechatpy
+pycryptodome
+dingtalk_stream
+websocket-client>=1.4.0
+python-telegram-bot
+slack_bolt
+discord.py