diff --git a/schemas/spec-driven/schema.yaml b/schemas/spec-driven/schema.yaml
index 45f61e222b..f97ba7a0d5 100644
--- a/schemas/spec-driven/schema.yaml
+++ b/schemas/spec-driven/schema.yaml
@@ -101,7 +101,12 @@ artifacts:
       - **Decisions**: Key technical choices with rationale (why X over Y?). Include alternatives considered for each decision.
       - **Risks / Trade-offs**: Known limitations, things that could go wrong. Format: [Risk] → Mitigation
       - **Migration Plan**: Steps to deploy, rollback strategy (if applicable)
-      - **Open Questions**: Outstanding decisions or unknowns to resolve
+      - **Open Questions**: Unknowns that can safely be answered later without
+        changing the specs, the approach, or the task breakdown. Omit if none.
+
+      Open questions are for genuinely deferrable unknowns, not decisions you
+      skipped. If a question would change the specs, the chosen approach, or
+      the task breakdown, resolve it now - ask the user instead of guessing.
 
       Focus on architecture and approach, not line-by-line implementation.
       Reference the proposal for motivation and specs for requirements.
@@ -117,6 +122,10 @@ artifacts:
     instruction: |
       Create the task list that breaks down the implementation work.
 
+      Before writing tasks, check design.md for Open Questions. If any of them
+      would change what gets built, resolve them with the user first - do not
+      bake an unstated assumption into the task list.
+
       **IMPORTANT: Follow the template below exactly.** The apply phase parses
       checkbox format to track progress. Tasks not using `- [ ]` won't be tracked.