diff --git a/quantecon/UPSTREAM-PRS.yml b/quantecon/UPSTREAM-PRS.yml
index 79f62002c..7e0008f02 100644
--- a/quantecon/UPSTREAM-PRS.yml
+++ b/quantecon/UPSTREAM-PRS.yml
@@ -60,6 +60,9 @@ upstream_candidates:
       - sha: 80bb9ecf
         local_pr: 28
         title: "feat(book): section-level scope for proof:* / figure / equation auto-prefix"
+      - sha: 043ddcb5
+        local_pr: 33
+        title: "feat(book): full title→heading chain in injectBookSectionDefaults"
     depends_on: []
     upstream:
       pr: null
@@ -67,7 +70,10 @@ upstream_candidates:
       merged_sha: null
     notes: |
       Could be split into two upstream PRs if maintainers prefer smaller
-      reviews; default plan is one bundled PR.
+      reviews; default plan is one bundled PR. #33 is a direct follow-up
+      to #22's injectBookSectionDefaults (extends the per-section wiring
+      from heading_1 to the full title→heading_1..6 chain) — naturally
+      part of the same upstream story.
 
   - id: book-parts
     title: Book parts dividers
diff --git a/quantecon/VERSION.yml b/quantecon/VERSION.yml
index 70f3b47a5..ee56a8b6f 100644
--- a/quantecon/VERSION.yml
+++ b/quantecon/VERSION.yml
@@ -32,7 +32,7 @@
 # Doing it in this order means anyone who `cat`s VERSION.yml at tag
 # `qe-v<N+1>` sees a self-consistent file (qe_version matches the tag).
 
-qe_version: qe-v4
+qe_version: qe-v5
 upstream_base: 1.9.0
 
 merged_features:
@@ -63,3 +63,10 @@ merged_features:
     local_pr: 26
     merge_sha: 5edc040d
     tag: qe-v4
+
+  - id: 5
+    name: book-section-heading-chain
+    description: Full title→heading_1..6 chain per section in injectBookSectionDefaults
+    local_pr: 33
+    merge_sha: 043ddcb5
+    tag: qe-v5