diff --git a/data/content/articles/state-of-padel-q1-2026-de.md b/data/content/reports/state-of-padel-q1-2026-de.md
similarity index 100%
rename from data/content/articles/state-of-padel-q1-2026-de.md
rename to data/content/reports/state-of-padel-q1-2026-de.md
diff --git a/data/content/articles/state-of-padel-q1-2026-en.md b/data/content/reports/state-of-padel-q1-2026-en.md
similarity index 100%
rename from data/content/articles/state-of-padel-q1-2026-en.md
rename to data/content/reports/state-of-padel-q1-2026-en.md
diff --git a/web/src/padelnomics/migrations/versions/0020_articles_group_key.py b/web/src/padelnomics/migrations/versions/0020_articles_group_key.py
new file mode 100644
index 0000000..dfa2bfb
--- /dev/null
+++ b/web/src/padelnomics/migrations/versions/0020_articles_group_key.py
@@ -0,0 +1,24 @@
+"""Add group_key column to articles for cross-language static article grouping.
+
+Static cornerstone articles (e.g. padel-hall-cost-guide EN vs padel-halle-kosten DE)
+have different url_paths per language, so they cannot be grouped by url_path alone.
+The group_key (populated from the `cornerstone` frontmatter field, e.g. 'C2') is a
+shared key that pairs EN/DE variants of the same static article.
+
+pSEO articles leave group_key NULL and continue to group by url_path (unchanged).
+
+Also removes any state-of-padel articles that are being moved to the reports flow.
+"""
+
+
+def up(conn):
+    conn.execute(
+        "ALTER TABLE articles ADD COLUMN group_key TEXT DEFAULT NULL"
+    )
+    conn.execute(
+        "CREATE INDEX IF NOT EXISTS idx_articles_group_key"
+        " ON articles(group_key)"
+    )
+    # Remove state-of-padel rows — these are moving to the reports flow
+    # and would cause slug collisions (both EN/DE use slug 'state-of-padel-q1-2026')
+    conn.execute("DELETE FROM articles WHERE slug LIKE 'state-of-padel%'")