diff --git a/.agents/skills/aster-code-review/benchmark/overlay_skill.sh b/.agents/skills/aster-code-review/benchmark/overlay_skill.sh
index 68225c136..ec52be28a 100755
--- a/.agents/skills/aster-code-review/benchmark/overlay_skill.sh
+++ b/.agents/skills/aster-code-review/benchmark/overlay_skill.sh
@@ -9,10 +9,12 @@
 # The overlaid files (.agents, .claude) are untracked at the historical base,
 # so they do NOT show up in a `diff`-mode review.
 #
-# Guideline pages are deliberately NOT copied here:
+# Guideline pages are deliberately NOT copied into the worktree's tracked book/:
 # overwriting the snapshot's tracked book/ would pollute a `diff`-mode review.
-# The harness instead points the skill at current guidelines via ACR_GUIDELINE_ROOT
-# (a guidelines-only tree).
+# Instead, bundle a guidelines-only snapshot inside the overlaid skill package.
+# build_pass_prompt.sh uses that snapshot by default, so the review still uses
+# current guidelines even if the review agent does not preserve ACR_GUIDELINE_ROOT
+# when it later runs shell commands.
 #
 # CRITICAL (benchmark integrity):
 # this EXCLUDES benchmark/, which holds problems.yaml — the answer key.
@@ -26,6 +28,10 @@ rm -rf "$wt/.agents" "$wt/.claude"
 mkdir -p "$wt/.agents/skills"
 cp -r "$SKILL" "$wt/.agents/skills/aster-code-review"
 rm -rf "$wt/.agents/skills/aster-code-review/benchmark"   # <-- drop the answer key
+rm -rf "$wt/.agents/skills/aster-code-review/guideline-root"
+mkdir -p "$wt/.agents/skills/aster-code-review/guideline-root/book/src/to-contribute"
+cp -r "$HERE/../../../../book/src/to-contribute/coding-guidelines" \
+    "$wt/.agents/skills/aster-code-review/guideline-root/book/src/to-contribute/"
 
 # Claude Code discovers skills under .claude/skills; mirror the repo's symlink layout.
 mkdir -p "$wt/.claude/skills"
diff --git a/.agents/skills/aster-code-review/scripts/build_pass_prompt.sh b/.agents/skills/aster-code-review/scripts/build_pass_prompt.sh
index ad2cf7c01..5fc5c9842 100755
--- a/.agents/skills/aster-code-review/scripts/build_pass_prompt.sh
+++ b/.agents/skills/aster-code-review/scripts/build_pass_prompt.sh
@@ -22,16 +22,74 @@ set -euo pipefail
 HERE="$(cd "$(dirname "$0")" && pwd)"
 SKILLDIR="$(cd "$HERE/.." && pwd)"
 REPO="$(cd "$SKILLDIR/../../.." && pwd)"   # .agents/skills/aster-code-review -> repo root
+
 # Where to read the guideline pages from.
-# Defaults to the repo;
-# the benchmark overrides it (ACR_GUIDELINE_ROOT) to a guidelines-only tree,
-# so a historical worktree is reviewed with current guidelines without polluting its diff.
-GROOT="${ACR_GUIDELINE_ROOT:-$REPO}"
+# Priority:
+#   1. explicit ACR_GUIDELINE_ROOT, for tests or external harnesses;
+#   2. a guideline snapshot bundled beside the overlaid skill;
+#   3. the current repo, for normal in-tree use.
+#
+# The benchmark cannot rely on the review agent preserving ACR_GUIDELINE_ROOT
+# across its own shell commands, so overlay_skill.sh bundles a current snapshot
+# into the skill package. This keeps historical worktrees on current guidelines
+# without modifying their tracked book/ tree.
+if [[ -n "${ACR_GUIDELINE_ROOT:-}" ]]; then
+    GROOT="$ACR_GUIDELINE_ROOT"
+elif [[ -f "$SKILLDIR/guideline-root" ]]; then
+    GROOT="$SKILLDIR/guideline-root"
+else
+    GROOT="$REPO"
+fi
 
 input="${1:-}"; shift || true
 [[ -n "$input" && -f "$input" ]] || { echo "build_pass_prompt.sh: a readable <input-file> is required" >&2; exit 2; }
 [[ $# -ge 1 ]] || { echo "build_pass_prompt.sh: at least one <persona> is required" >&2; exit 2; }
 
+linked_guideline_pages() { # <guideline-page-path-relative-to-GROOT>
+    python3 - "$1" "$GROOT/$1" <<'PY'
+import posixpath
+import re
+import sys
+
+root_page = sys.argv[1]
+root_file = sys.argv[2]
+base_dir = posixpath.dirname(root_page)
+seen = set()
+
+with open(root_file, encoding="utf-8") as file:
+    page_text = file.read()
+
+for link in re.findall(r"\[[^\]]+\]\(([^)]+)\)", page_text):
+    link = link.split("#", 1)[0]
+    if not link or "://" in link or link.startswith("#"):
+        continue
+    if link.endswith("/"):
+        link += "README.md"
+    path = posixpath.normpath(posixpath.join(base_dir, link))
+    if not path.startswith("book/src/to-contribute/coding-guidelines/"):
+        continue
+    if path == root_page or path in seen:
+        continue
+    seen.add(path)
+    print(path)
+PY
+}
+
+inline_guidelines() { # <guideline-page-path-relative-to-GROOT>
+    local gp="$1" gfile="$GROOT/$gp" sub
+    [[ -f "$gfile" ]] || return 0
+
+    printf 'Rely on the inlined guideline material below as the authoritative guideline context for this pass. Do not re-read `book/src/to-contribute/coding-guidelines/` from the worktree under review for guideline content.\n\n'
+    printf -- '--- guideline page (%s) ---\n\n' "$gp"
+    cat "$gfile"; printf '\n'
+
+    while IFS= read -r sub; do
+        [[ -f "$GROOT/$sub" ]] || continue
+        printf '\n--- guideline subpage (%s) ---\n\n' "$sub"
+        cat "$GROOT/$sub"; printf '\n'
+    done < <(linked_guideline_pages "$gp")
+}
+
 # --- STABLE: the shared reviewer contract ------------------------------------
 cat "$SKILLDIR/scripts/pass_contract.md"
 printf '\n'
@@ -43,10 +101,7 @@ for persona in "$@"; do
     printf '===== PERSONA: %s =====\n\n' "$persona"
     cat "$pf"; printf '\n'
     gp="$(grep -oE 'book/[A-Za-z0-9/_-]+README\.md' "$pf" | head -1 || true)"
-    if [[ -n "$gp" && -f "$GROOT/$gp" ]]; then
-        printf -- '--- guideline page (%s) ---\n\n' "$gp"
-        cat "$GROOT/$gp"; printf '\n'
-    fi
+    [[ -n "$gp" ]] && inline_guidelines "$gp"
 done
 
 # --- VOLATILE: the review input (LAST; everything above is the cache prefix) ---