diff --git a/.markdownlint.json b/.markdownlint.json
index 8f989cf..085bab1 100644
--- a/.markdownlint.json
+++ b/.markdownlint.json
@@ -1,7 +1,9 @@
 {
     "MD007": { "indent": 4 },
     "MD013": false,
+    "MD024": { "siblings_only": true },
     "MD029": false,
     "MD033": false,
+    "MD036": false,
     "MD041": false
 }
diff --git a/scripts/preflight.sh b/scripts/preflight.sh
index adc53bf..280858f 100755
--- a/scripts/preflight.sh
+++ b/scripts/preflight.sh
@@ -1,7 +1,9 @@
 #!/usr/bin/env bash
 # preflight.sh — pre-push gate. Blocks A/B/C verify config drift; Block D is a
-# headless `dotnet build` to catch compile-time API drift. Test execution lives
-# in the local Build-Suite repo and is NOT part of this preflight.
+# headless `dotnet build` to catch compile-time API drift; Block E runs
+# `dotnet csharpier check` against HellionChat/; Block F runs markdownlint
+# against the repo's *.md files. Test execution lives in the local Build-Suite
+# repo and is NOT part of this preflight.
 
 set -euo pipefail
 ROOT="$(cd "$(dirname "$0")/.." && pwd)"
@@ -19,4 +21,12 @@ echo "==> preflight: Block C — changelog sync"
 echo "==> preflight: Block D — plugin compile health"
 dotnet build HellionChat/HellionChat.csproj --configuration Release --nologo --verbosity quiet
 
+echo "==> preflight: Block E — csharpier reflow check"
+dotnet csharpier check HellionChat/
+
+echo "==> preflight: Block F — markdownlint"
+# npx --yes avoids a global install; first run caches into ~/.npm/_npx/.
+# Subsequent runs are sub-second.
+npx --yes markdownlint-cli2 "**/*.md" "#node_modules" "#bin" "#obj" "#.claude"
+
 echo "==> preflight: ALL GREEN"