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/mattermost-lts/recipe_meta.py

@@ -21,11 +21,17 @@ EXTRA_ENV = {"TIMEOUT": "600"}
 
 
 def SCREENSHOT(page, ctx):
-    """Land the real sign-in form for the CI card (phase-shot). The default landing capture gets
-    mattermost's "view in desktop app or browser?" interstitial at `/` — a real page but not
-    representative of the app. `/login` renders the standard login form directly. Credential-free
-    (empty fields, R7 secret-safety: never a page showing generated secrets); the harness snaps
-    the PNG after this returns."""
+    """Land the real sign-in form for the CI card (phase-shot). Mattermost serves a
+    "view in desktop app or browser?" interstitial on a browser's FIRST visit to ANY route
+    (including /login — proven by shot-proof2-mattermost-lts: byte-identical interstitial PNG with
+    and without a plain /login hook); a real user clicks "View in Browser" to reach the login
+    form, so the hook does exactly that. Click + second settle are best-effort (if the
+    interstitial is absent we are already on the form). Credential-free (empty fields, R7
+    secret-safety); the harness snaps the PNG after this returns. Waits are kept short (8s/3s/8s)
+    so the realistic hook path stays well inside the ~60s step budget — the 45s nav deadline is
+    only burned when the app never serves, and then the hook raises before any settle."""
+    import contextlib
+
     from harness import browser as harness_browser
     from harness import screenshot as screenshot_mod
 
@@ -36,4 +42,7 @@ def SCREENSHOT(page, ctx):
         deadline_seconds=screenshot_mod.NAV_DEADLINE_S,
         wait_until="domcontentloaded",
     )
-    screenshot_mod.settle(page)
+    screenshot_mod.settle(page, 8_000)
+    with contextlib.suppress(Exception):
+        page.click("text=View in Browser", timeout=3_000)
+        screenshot_mod.settle(page, 8_000)

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):