diff --git a/templates/book_chapter.yml b/templates/book_chapter.yml
index 456c543e..9f8e1802 100644
--- a/templates/book_chapter.yml
+++ b/templates/book_chapter.yml
@@ -293,9 +293,26 @@ steps:
         Start the chapter directly with the chapter title and first line.
         No preamble or commentary within the chapter text.
 
-  # Commit chapter draft now -- last_text() = self-check output (step 2). Must come before
-  # PASS 3 think so the character-state extraction does not overwrite last_text().
+  # Extract chapter_number and chapter_ref from the PASS 1 chapter text before any document
+  # steps run. Without this, {chapter_number}/{chapter_ref} are unresolved at document time
+  # and filenames become "Chapter_chapter-number_draft.md" (slug-cleaned literal key names).
+  # source_step: 1 = PASS 1 output, which begins "Chapter N: Title". Cheap call (max_tokens: 150).
+  - type: package
+    source_step: 1
+    max_tokens: 150
+    hint: |
+      The chapter draft above starts with a chapter title line such as "Chapter 5: Some Title".
+      Extract:
+      - chapter_number: the plain chapter number as a string (e.g. "5")
+      - chapter_ref: zero-padded two-digit format (e.g. "ch-05" for chapter 5)
+    schema:
+      chapter_number: string
+      chapter_ref: string
+
+  # Commit chapter draft now. chapter_number is in ContextVars from the package step above.
+  # source_step: 2 = SELF-CHECK output (step 2); required because LastText() now = package JSON.
   - type: document
+    source_step: 2
     filename: "Chapter_{chapter_number}_draft"
     primary_deliverable: true
     strip_before_marker: "---BEGIN CHAPTER---"
@@ -416,14 +433,15 @@ steps:
 
   - type: rag_write
     asset_id: "character-state"
-    source_step: 4   # PASS 3 character-state extraction; explicit to avoid last_text() falling back to chapter text
+    source_step: 5   # PASS 3 character-state extraction; explicit to avoid last_text() falling back to chapter text
     max_chars: 4000
 
   - type: document
+    source_step: 5
     filename: "character-state-{chapter_ref}"
 
   - type: package
-    source_step: 4   # PASS 3 -- character-state extraction (compact, describes permanent changes)
+    source_step: 5   # PASS 3 -- character-state extraction (compact, describes permanent changes)
     max_tokens: 4000
     hint: |
       The draft chapter has been written, self-checked, and committed.