diff --git a/tests/test_conflict_resolution_resume.sh b/tests/test_conflict_resolution_resume.sh
index 205b101..415083c 100644
--- a/tests/test_conflict_resolution_resume.sh
+++ b/tests/test_conflict_resolution_resume.sh
@@ -33,7 +33,11 @@ echo "gh $*" >> "$CALLS"
 if [[ "$1 $2" == "pr view" ]]; then
     case "$*" in
         *--json\ labels*)   printf '%s\n' "${MOCK_LABELS:-}";;
-        *--json\ comments*) cat "${MOCK_COMMENTS_FILE:-/dev/null}";;
+        *--json\ comments*)
+            # The comments file stands for our own comments only, so the query
+            # must restrict itself to those.
+            [[ "$*" == *viewerDidAuthor* ]] || { echo "comments query must filter by viewerDidAuthor" >&2; exit 1; }
+            cat "${MOCK_COMMENTS_FILE:-/dev/null}";;
         *) echo "unhandled pr view: $*" >&2; exit 1;;
     esac
 elif [[ "$1 $2" == "pr comment" ]]; then
@@ -167,5 +171,21 @@ grep -q -- "--base" "$CALLS" && fail "D: base must NOT be edited"
 [[ "$(git -C "$ORIGIN" rev-parse child)" == "$CHILD_BEFORE" ]] || fail "D: child was pushed"
 ok "D: missing target detected, no branch mutation, label removed"
 
+# ---------------------------------------------------------------------------
+echo "### Scenario E: malformed state marker -> internal error, die without touching the PR"
+setup_repo
+MOCK_LABELS="autorestack-needs-conflict-resolution"
+PR_BASE="parent"
+MOCK_COMMENTS_FILE="$WORK/comments.txt"
+{ echo "### conflict"; echo; echo '<!-- autorestack-state: base=parent target=main -->'; } > "$MOCK_COMMENTS_FILE"
+run_resume
+
+grep -q "EXIT=1" "$WORK/out.log" || fail "E: run must die on a malformed marker"
+grep -q "remove-label" "$CALLS" && fail "E: label must stay on"
+grep -q "gh pr comment" "$CALLS" && fail "E: no PR comment for an internal error"
+grep -q -- "--base" "$CALLS" && fail "E: base must NOT be edited"
+[[ "$(git -C "$ORIGIN" rev-parse child)" == "$CHILD_BEFORE" ]] || fail "E: child was pushed"
+ok "E: malformed marker dies, PR untouched, label kept"
+
 echo
 echo "All conflict-resume tests passed 🎉 ($PASS scenarios)"
diff --git a/update-pr-stack.sh b/update-pr-stack.sh
index dde781f..e3fec22 100755
--- a/update-pr-stack.sh
+++ b/update-pr-stack.sh
@@ -44,7 +44,8 @@ format_state_marker() {
 read_state_marker() {
     local PR_NUMBER="$1"
     local BODIES
-    if ! BODIES=$(gh pr view "$PR_NUMBER" --json comments --jq '.comments[].body'); then
+    if ! BODIES=$(gh pr view "$PR_NUMBER" --json comments \
+            --jq '.comments[] | select(.viewerDidAuthor) | .body'); then
         echo "Error: could not read comments of PR #$PR_NUMBER" >&2
         exit 1
     fi
@@ -307,6 +308,11 @@ continue_after_resolution() {
     read -r OLD_BASE NEW_TARGET SQUASH_HASH < <(parse_state_marker "$MARKER")
     echo "Recorded state: base=$OLD_BASE target=$NEW_TARGET squash=$SQUASH_HASH"
 
+    if [[ -z "$OLD_BASE" || -z "$NEW_TARGET" || -z "$SQUASH_HASH" ]]; then
+        echo "Error: malformed state marker on $PR_BRANCH: $MARKER" >&2
+        exit 1
+    fi
+
     # The PR was left based on the merged parent branch. If the payload shows a
     # different base, a human retargeted the PR; the recorded target is stale,
     # so step back before any mutation.