Remove merge conflict markers from a published page, and gate against them

docs/limitations.md

@@ -268,22 +268,17 @@ returning no rows.
 
 ## Vacuum and compaction
 
-<<<<<<< HEAD
 - `autovacuum_parallel_workers`, the per-table storage parameter PostgreSQL 19 adds
   for parallel autovacuum, is accepted on a columnar table and has no effect.
   pgColumnar implements its own vacuum, which marks the visibility map and retires
   fully-deleted row groups, and does no parallel work. The parameter cannot be
   refused: storage-parameter validation belongs to PostgreSQL and is driven by the
   relation kind rather than by the access method. Setting it is harmless and
   pointless.
-- `VACUUM FULL` and `CLUSTER` are not supported on a columnar table; the
-  copy-for-cluster path raises an error. Use `pgcolumnar.vacuum` or
-=======
 - `REPACK`, `VACUUM FULL` and `CLUSTER` are not supported on a columnar table; the
   copy-for-cluster path raises an error. `REPACK` arrives in PostgreSQL 19 and
   replaces the other two, and it dispatches through the same path, so it is
   refused for the same reason. Use `pgcolumnar.vacuum` or
->>>>>>> origin/main
   `pgcolumnar.vacuum_full` instead.
 - `pgcolumnar.vacuum` always rewrites the whole relation into full row groups. It
   accepts a `stripe_count` argument for compatibility with the interface, but it

test/docs_style.sh

@@ -79,6 +79,16 @@ check "the roadmap is in the documentation nav" "$([ "$nav_roadmap" -ge 1 ] && e
 check "and the page that nav entry points at exists" \
 	"$([ -f "$SRCDIR/docs/roadmap.md" ] && echo yes || echo no)" "yes"
 
+# Merge conflict markers. These reached main and were published: three of them sat
+# in docs/limitations.md under "Vacuum and compaction", and every other check in
+# this file passed with them there, because they are valid Markdown text.
+#
+# The STE checker reads prose and the nav check reads mkdocs.yml. Neither asks
+# whether the page is a coherent document. This does.
+conflicts=$(grep -rlE '^(<<<<<<< |>>>>>>> )' "$SRCDIR/docs" "$SRCDIR"/*.md 2>/dev/null | tr '\n' ' ')
+check "no document carries a merge conflict marker" \
+	"$([ -z "$conflicts" ] && echo none || echo "$conflicts")" "none"
+
 # CHANGELOG.md: dash characters only. See the scope note above.
 dashes=$(grep -c '—\|–' "$SRCDIR/CHANGELOG.md" || true)
 check "CHANGELOG.md carries no em or en dash" "$dashes" "0"