diff --git a/templates/book_outline.yml b/templates/book_outline.yml
index f93769f3..a883acef 100644
--- a/templates/book_outline.yml
+++ b/templates/book_outline.yml
@@ -269,7 +269,17 @@ steps:
           [character state]. Dominant tension: [tension]. Closes with: [cliffhanger hook]."
           Also include the Voice & Tone Guide from the outline as the prose_style value --
           copy it exactly. This is a hard constraint for every sentence of the chapter.
-      - depends_on: the exact task_name of the PREVIOUS chapter (empty string for Chapter 1)
+      - depends_on: >
+          MANDATORY -- CHAIN RULE. This field MUST be set for EVERY chapter except the first.
+          For Chapter 1: set depends_on to an empty string "".
+          For Chapter 2: set depends_on to the EXACT task_name of Chapter 1 (e.g. "Write Chapter 1: The First Whisper").
+          For Chapter 3: set depends_on to the EXACT task_name of Chapter 2.
+          Continue chaining all the way to the last chapter.
+          NEVER leave depends_on blank for chapters 2 onwards.
+          PRE-FLIGHT CHECK: Before outputting, verify your action list. For actions 2..N, confirm
+          that depends_on exactly matches the task_name of the PRECEDING action. If any is missing
+          or incorrect, FIX IT before outputting. A chapter with no depends_on will run in
+          parallel with all other chapters -- this is a CRITICAL ERROR. Chapters MUST be sequential.
 
       The depends_on chain creates sequential writing -- each chapter waits for the previous to be committed.
     schema: