fix(shot): mattermost hook v2 — interstitial appears on ANY first-visit route incl /login (proven byte-identical PNG); click 'View in Browser' best-effort then settle; unit test covers click + no-interstitial fallback; 207 pass, lint PASS

tests/unit/test_screenshot.py

@@ -138,14 +138,21 @@ def test_mattermost_screenshot_hook_lands_login():
         status = 200
 
     class _NavPage(_FakePage):
-        def __init__(self):
+        def __init__(self, click_raises=False):
             super().__init__([])
             self.urls = []
+            self.clicks = []
+            self._click_raises = click_raises
 
         def goto(self, url, wait_until=None, timeout=None):
             self.urls.append(url)
             return _Resp()
 
+        def click(self, selector, timeout=None):
+            self.clicks.append(selector)
+            if self._click_raises:
+                raise TimeoutError("no interstitial")
+
     tests_dir = os.path.join(os.path.dirname(__file__), "..")
     meta = meta_mod.load("mattermost-lts", tests_dir=tests_dir)
     hook = S._load_screenshot_hook(meta)
@@ -153,7 +160,14 @@ def test_mattermost_screenshot_hook_lands_login():
     page = _NavPage()
     hook(page, meta_mod.hook_ctx("mm.example.org", meta))
     assert page.urls == ["https://mm.example.org/login"]
-    assert page.idle_waits, "hook must settle before the harness snaps"
+    assert page.clicks == ["text=View in Browser"], "hook must click through the interstitial"
+    assert len(page.idle_waits) == 2, "hook must settle after nav AND after the click"
+
+    # no interstitial (already on the form): the click times out and the hook still succeeds
+    page2 = _NavPage(click_raises=True)
+    hook(page2, meta_mod.hook_ctx("mm.example.org", meta))
+    assert page2.clicks == ["text=View in Browser"]
+    assert len(page2.idle_waits) == 1, "failed click must skip the second settle, not raise"
 
 
 def test_screenshot_reachable_through_real_load_path(tmp_path):