feat(backends): onboard OpenCLI as cross-channel desktop backend

- new agent_reach/backends/opencli.py: probes install + daemon/extension
  state via `opencli daemon status` (pure query — `opencli doctor`
  auto-starts the daemon, a side effect health checks must avoid)
- `agent-reach install --channels opencli`: npm install + Chrome Web
  Store guide (extension install cannot be automated — Chrome security
  model — so we print the one-click path)
- server env skips OpenCLI (rides a real desktop Chrome session)
- channels will adopt it as a backend candidate in follow-up PRs

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/test_opencli_backend.py

@@ -0,0 +1,79 @@
+# -*- coding: utf-8 -*-
+"""Tests for the OpenCLI cross-channel backend probing."""
+
+from unittest.mock import patch
+
+from agent_reach.backends import opencli_status, opencli_summary
+from agent_reach.probe import ProbeResult
+
+
+def _status_with(version_probe, daemon_probe=None):
+    """Run opencli_status with probe_command patched per call."""
+    calls = []
+
+    def fake_probe(cmd, args=("--version",), **kwargs):
+        calls.append(list(args))
+        if list(args) == ["--version"]:
+            return version_probe
+        return daemon_probe or ProbeResult("missing")
+
+    with patch("agent_reach.backends.opencli.probe_command", side_effect=fake_probe):
+        return opencli_status(), calls
+
+
+def test_not_installed():
+    st, _ = _status_with(ProbeResult("missing"))
+    assert not st.installed
+    assert not st.ready
+    assert "未安装" in opencli_summary(st)
+
+
+def test_broken_node_env_gives_npm_hint():
+    st, _ = _status_with(ProbeResult("broken", hint="x"))
+    assert st.installed and st.broken
+    assert "npm install -g @jackwener/opencli" in st.hint
+    assert not st.ready
+
+
+def test_daemon_running_extension_connected_is_ready():
+    daemon_out = "Daemon: running (PID 37389)\nVersion: v1.8.3\nExtension: connected\n"
+    st, _ = _status_with(
+        ProbeResult("ok", output="1.8.3"),
+        ProbeResult("ok", output=daemon_out),
+    )
+    assert st.installed and st.daemon_running and st.extension_connected
+    assert st.ready
+    assert "1.8.3" in opencli_summary(st)
+
+
+def test_extension_disconnected_not_ready_with_store_guide():
+    daemon_out = "Daemon: running (PID 1)\nExtension: disconnected\n"
+    st, _ = _status_with(
+        ProbeResult("ok", output="1.8.3"),
+        ProbeResult("ok", output=daemon_out),
+    )
+    assert st.daemon_running and not st.extension_connected
+    assert not st.ready
+    assert "chromewebstore.google.com" in st.hint
+
+
+def test_daemon_not_running_parsed_correctly():
+    st, _ = _status_with(
+        ProbeResult("ok", output="1.8.3"),
+        ProbeResult("ok", output="Daemon: not running\n"),
+    )
+    assert st.installed
+    assert not st.daemon_running
+    assert not st.extension_connected
+    assert "自动启动" in opencli_summary(st)
+
+
+def test_probe_uses_daemon_status_not_doctor():
+    """`opencli doctor` auto-starts the daemon (side effect) — health checks
+    must only ever call `daemon status`."""
+    _, calls = _status_with(
+        ProbeResult("ok", output="1.8.3"),
+        ProbeResult("ok", output="Daemon: not running\n"),
+    )
+    assert ["daemon", "status"] in calls
+    assert ["doctor"] not in calls