fix(gallery): preserve mobile preview height (#135)

* fix(gallery): preserve mobile preview height

* test(gallery): report routing failures directly

scripts/lint-render.py

@@ -667,6 +667,49 @@ def network_isolation_failures(context):
     return []
 
 
+def gallery_mobile_failures(context, gallery_path=None):
+    """Keep the wrapped gallery controls from collapsing its mobile preview."""
+    gallery_path = gallery_path or ASSET_DIR / "index.html"
+    failures = []
+    page = context.new_page()
+    page.set_viewport_size({"width": 390, "height": 844})
+    try:
+        page.goto(gallery_path.as_uri(), wait_until="load")
+        page.locator('[data-type="polar"]').click()
+        routed_source = page.locator("#preview").get_attribute("src")
+        if routed_source != "example-polar.html":
+            failures.append(
+                "gallery-mobile-routing: Polar routed to "
+                f"{routed_source!r}, expected 'example-polar.html'"
+            )
+        facts = page.evaluate(
+            """
+            () => {
+              const doc = document.documentElement;
+              const preview = document.querySelector('#preview');
+              const rect = preview.getBoundingClientRect();
+              return {
+                previewHeight: rect.height,
+                pageOverflow: doc.scrollWidth - doc.clientWidth,
+              };
+            }
+            """
+        )
+        if facts["previewHeight"] < 400:
+            failures.append(
+                "gallery-mobile-preview: iframe height "
+                f"{facts['previewHeight']:.1f}px is below the 400px minimum"
+            )
+        if facts["pageOverflow"] > TOLERANCE:
+            failures.append(
+                "gallery-mobile-overflow: page extends "
+                f"{facts['pageOverflow']:.1f}px past the mobile viewport"
+            )
+    finally:
+        page.close()
+    return failures
+
+
 def self_test(context):
     page = context.new_page()
     failures = []
@@ -736,6 +779,29 @@ def self_test(context):
     checks += 1
     failures += network_isolation_failures(context)
 
+    checks += 1
+    failures += gallery_mobile_failures(context)
+
+    # A broken route should be a targeted failure, not a delayed Playwright
+    # timeout or traceback that escapes the self-test report.
+    checks += 1
+    with tempfile.TemporaryDirectory() as directory:
+        broken_gallery = Path(directory) / "index.html"
+        gallery_source = (ASSET_DIR / "index.html").read_text(encoding="utf-8")
+        route_line = "const src = `example-${state.type}${state.variant}.html`;"
+        if gallery_source.count(route_line) != 1:
+            failures.append("gallery-mobile-routing-fixture: route source changed unexpectedly")
+        else:
+            broken_gallery.write_text(
+                gallery_source.replace(route_line, 'const src = "wrong-example.html";'),
+                encoding="utf-8",
+            )
+            route_failures = gallery_mobile_failures(context, broken_gallery)
+            if not any(
+                failure.startswith("gallery-mobile-routing:") for failure in route_failures
+            ):
+                failures.append("gallery-mobile-routing: broken route was not reported")
+
     if failures:
         print("self-test FAILED:")
         for failure in failures: