fix(review): four findings from adversarial Codex review round 1

- twitter: align backend selection with the two-phase findings pattern —
  an unauthenticated twitter-cli (warn) no longer blocks a fully-working
  OpenCLI (ok) further down the candidate list
- watch: use _is_newer_version like check-update (the != comparison kept
  the downgrade prompt this branch fixed elsewhere)
- uninstall: third copy of the skill-dir removal also gets the symlink
  guard (full `agent-reach uninstall` path)
- doctor: a stale active_backend from a previous check on the singleton
  channel no longer leaks into an errored result

+4 regression tests (162 total).

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

tests/test_cli.py

@@ -199,3 +199,26 @@ class TestVersionCompare:
     def test_unparseable_falls_back_to_inequality(self):
         assert cli._is_newer_version("2026.06-beta", "1.5.0") is True
         assert cli._is_newer_version("1.5.0", "1.5.0-dev") is True
+
+
+class TestWatchVersionCompare:
+    def test_watch_does_not_prompt_downgrade(self, monkeypatch, capsys):
+        """watch 与 check-update 同语义:本地领先远端 release 时不提示更新。"""
+        class R:
+            status_code = 200
+            headers = {}
+
+            @staticmethod
+            def json():
+                return {"tag_name": "v1.4.2", "body": ""}
+
+        monkeypatch.setattr(cli, "_github_get_with_retry", lambda *a, **k: (R(), None, 1))
+        monkeypatch.setattr(
+            "agent_reach.doctor.check_all",
+            lambda config: {"web": {"status": "ok", "name": "任意网页", "message": "ok",
+                            "tier": 0, "backends": ["Jina Reader"], "active_backend": "Jina Reader"}},
+        )
+        cli._cmd_watch()
+        out = capsys.readouterr().out
+        assert "新版本可用" not in out
+        assert "全部正常" in out

tests/test_doctor.py

@@ -104,3 +104,23 @@ class TestDoctor:
         assert "1/3 个渠道可用" in plain
         # Inactive optional channels should be summarized in one line
         assert "可选渠道可以解锁" in plain
+
+
+def test_stale_active_backend_does_not_leak_into_errored_result(monkeypatch):
+    """渠道单例上一轮的 active_backend 不得泄漏进本轮异常结果(Codex review 发现)。"""
+    from agent_reach import doctor
+
+    class _ExplodingChannel:
+        name = "boom"
+        description = "爆炸渠道"
+        tier = 0
+        backends = ["a", "b"]
+        active_backend = "a"  # 上一轮成功的残留
+
+        def check(self, config=None):
+            raise RuntimeError("boom")
+
+    monkeypatch.setattr(doctor, "get_all_channels", lambda: [_ExplodingChannel()])
+    results = doctor.check_all(config=None)
+    assert results["boom"]["status"] == "error"
+    assert results["boom"]["active_backend"] is None

tests/test_twitter_channel.py

@@ -152,3 +152,33 @@ def test_check_twitter_cli_broken_falls_back_to_bird():
     assert status == "ok"
     assert "bird" in message
     assert channel.active_backend == "bird CLI (legacy)"
+
+
+def test_unauthenticated_twitter_cli_does_not_block_working_opencli():
+    """warn 候选不得屏蔽排在后面的 ok 候选(Codex review 发现)。"""
+    channel = TwitterChannel()
+    with patch.object(
+        TwitterChannel, "_check_twitter_cli",
+        return_value=("warn", "twitter-cli 已安装但未认证"),
+    ), patch.object(
+        TwitterChannel, "_check_opencli",
+        return_value=("ok", "OpenCLI 可用（复用浏览器登录态）"),
+    ), patch.object(TwitterChannel, "_check_bird", return_value=None):
+        status, msg = channel.check()
+    assert status == "ok"
+    assert channel.active_backend == "OpenCLI"
+
+
+def test_all_warn_falls_back_to_first_warn():
+    channel = TwitterChannel()
+    with patch.object(
+        TwitterChannel, "_check_twitter_cli",
+        return_value=("warn", "twitter-cli 未认证"),
+    ), patch.object(
+        TwitterChannel, "_check_opencli",
+        return_value=("warn", "扩展未连接"),
+    ), patch.object(TwitterChannel, "_check_bird", return_value=None):
+        status, msg = channel.check()
+    assert status == "warn"
+    assert channel.active_backend == "twitter-cli"
+    assert "未认证" in msg