feat(chv): 完整 Chromium 改装数据盘

根盘只剩 ~600MB，playwright install chromium 装根盘 109 秒后
ENOSPC 失败（2026-11-08 构建 #8 驱动实证）。完整版改装数据盘
/home/chv/workspace/.chv-browsers（9.3G 空闲），仍不 bake 进
base、按需；full 引擎启动时直接传 executable_path（channel 与
executable_path 互斥，且驱动进程启动时才读 env，运行中改 env
无效）；status 增 full_browsers_dir，mount 失败报错给数据盘
安装命令。驱动的安装步同步改数据盘并 chown 给 chv-browser。

cloud/tests/test_chv_opt_stage3.py

@@ -111,7 +111,7 @@ class FakePlaywright:
         return False
 
 
-def _agent(pages, tmp):
+def _agent(pages, tmp, full_browsers_dir=None):
     ctx = FakeContext(pages)
     entered_holder = {}
 
@@ -126,7 +126,8 @@ def _agent(pages, tmp):
 
     agent = BROWSER.BrowserAgent(
         playwright_factory=lambda: PW(), shots_dir=tmp,
-        profile_dir=os.path.join(tmp, "profile"))
+        profile_dir=os.path.join(tmp, "profile"),
+        full_browsers_dir=full_browsers_dir)
     return agent, ctx, entered_holder
 
 
@@ -172,6 +173,45 @@ class FullPresentTest(unittest.TestCase):
             self.assertFalse(BROWSER.full_chromium_present(tmp))
 
 
+class FullBrowsersDirTest(unittest.TestCase):
+    def test_resolve_data_disk_path(self):
+        self.assertEqual(
+            BROWSER.resolve_full_browsers_dir(True, env={}),
+            BROWSER.FULL_BROWSERS_DATA_DIR)
+
+    def test_resolve_fallback_path(self):
+        self.assertEqual(
+            BROWSER.resolve_full_browsers_dir(False, env={}),
+            BROWSER.FULL_BROWSERS_FALLBACK_DIR)
+
+    def test_resolve_env_override_wins(self):
+        self.assertEqual(
+            BROWSER.resolve_full_browsers_dir(
+                True, env={"CHV_BROWSER_FULL_BROWSERS_DIR":
+                           "/data/browsers"}),
+            "/data/browsers")
+
+    def test_executable_found_ignores_headless_shell(self):
+        with tempfile.TemporaryDirectory() as tmp:
+            os.makedirs(os.path.join(
+                tmp, "chromium_headless_shell-1248", "chrome-linux"))
+            self.assertIsNone(BROWSER.full_chromium_executable(tmp))
+            exe_dir = os.path.join(
+                tmp, "chromium-141.0.7390.37", "chrome-linux")
+            os.makedirs(exe_dir)
+            exe = os.path.join(exe_dir, "chrome")
+            open(exe, "w").write("x")
+            self.assertEqual(BROWSER.full_chromium_executable(tmp), exe)
+
+    def test_status_reports_data_disk_dir(self):
+        with tempfile.TemporaryDirectory() as tmp:
+            agent, _c, _h = _agent([FakePage()], tmp,
+                                   full_browsers_dir=tmp)
+            st = agent.status()
+            self.assertEqual(st["full_browsers_dir"], tmp)
+            self.assertFalse(st["full_present"])
+
+
 class MultiSessionTest(unittest.TestCase):
     def test_two_sessions_do_not_interfere(self):
         with tempfile.TemporaryDirectory() as tmp:
@@ -423,25 +463,42 @@ class EngineSwitchTest(unittest.TestCase):
             # 回落后 shell 仍可工作。
             self.assertTrue(agent.open("https://example.com")["ok"])
 
-    def test_mount_unmount_full_switches_channel(self):
+    def test_mount_unmount_full_uses_executable_path(self):
         with tempfile.TemporaryDirectory() as tmp:
-            agent, _c, holder = _agent([FakePage()], tmp)
-            with mock.patch.object(BROWSER, "full_chromium_present",
-                                   return_value=True):
-                mounted = agent.mount_full()
+            exe_dir = os.path.join(
+                tmp, "chromium-141.0.7390.37", "chrome-linux")
+            os.makedirs(exe_dir)
+            exe = os.path.join(exe_dir, "chrome")
+            open(exe, "w").write("x")
+            agent, _c, holder = _agent([FakePage()], tmp,
+                                       full_browsers_dir=tmp)
+            mounted = agent.mount_full()
             self.assertTrue(mounted["ok"])
             self.assertEqual(mounted["engine"], "full")
             self.assertTrue(mounted["mounted_full"])
             entered = holder["entered"]
-            self.assertEqual(entered.calls[-1][1].get("channel"),
-                             "chromium")
+            kwargs = entered.calls[-1][1]
+            self.assertEqual(kwargs.get("executable_path"), exe)
+            self.assertNotIn("channel", kwargs)
             unmounted = agent.unmount_full()
             self.assertTrue(unmounted["ok"])
             self.assertEqual(unmounted["engine"], "shell")
             self.assertFalse(unmounted["mounted_full"])
             self.assertNotIn("channel", entered.calls[-1][1])
+            self.assertNotIn("executable_path", entered.calls[-1][1])
             self.assertTrue(agent.open("https://example.com")["ok"])
 
+    def test_mount_full_error_names_data_disk_install(self):
+        with tempfile.TemporaryDirectory() as tmp:
+            agent, _c, _h = _agent([FakePage()], tmp,
+                                   full_browsers_dir=os.path.join(
+                                       tmp, "browsers"))
+            resp = agent.mount_full()
+            self.assertFalse(resp["ok"])
+            self.assertTrue(resp["fallback"])
+            self.assertIn(os.path.join(tmp, "browsers"),
+                          resp["error"])
+
     def test_handle_request_routes_new_ops(self):
         with tempfile.TemporaryDirectory() as tmp:
             agent, _c, _h = _agent([FakePage()], tmp)