diff --git a/backend/pipeline/stages.py b/backend/pipeline/stages.py
index 4787658..f466636 100644
--- a/backend/pipeline/stages.py
+++ b/backend/pipeline/stages.py
@@ -936,6 +936,13 @@ def _capture_pipeline_metadata() -> dict:
 # ── Stage 5: Synthesis ───────────────────────────────────────────────────────
 
 
+def _serialize_body_sections(sections) -> list | dict | None:
+    """Convert body_sections to JSON-serializable form for DB storage."""
+    if isinstance(sections, list):
+        return [s.model_dump() if hasattr(s, 'model_dump') else s for s in sections]
+    return sections
+
+
 def _compute_page_tags(
     moment_indices: list[int],
     moment_group: list[tuple],
@@ -1513,7 +1520,7 @@ def stage5_synthesis(self, video_id: str, run_id: str | None = None) -> str:
                     # Update existing page
                     existing.title = page_data.title
                     existing.summary = page_data.summary
-                    existing.body_sections = page_data.body_sections
+                    existing.body_sections = _serialize_body_sections(page_data.body_sections)
                     existing.signal_chains = page_data.signal_chains
                     existing.plugins = page_data.plugins if page_data.plugins else None
                     page_tags = _compute_page_tags(page_moment_indices, moment_group, all_tags)
@@ -1528,7 +1535,7 @@ def stage5_synthesis(self, video_id: str, run_id: str | None = None) -> str:
                         topic_category=page_data.topic_category or category,
                         topic_tags=_compute_page_tags(page_moment_indices, moment_group, all_tags),
                         summary=page_data.summary,
-                        body_sections=page_data.body_sections,
+                        body_sections=_serialize_body_sections(page_data.body_sections),
                         signal_chains=page_data.signal_chains,
                         plugins=page_data.plugins if page_data.plugins else None,
                         source_quality=page_data.source_quality,