diff --git a/backend/app/routes.py b/backend/app/routes.py
index 6f99451..1e6e14c 100644
--- a/backend/app/routes.py
+++ b/backend/app/routes.py
@@ -186,17 +186,17 @@ def _create_or_update_tag(
             )
             db.add(history)
 
-            # Decrement ref_count on old artifact
-            old_ref_count = _decrement_ref_count(db, old_artifact_id)
-            logger.info(
-                f"Tag '{tag_name}' updated: decremented ref_count on artifact "
-                f"{old_artifact_id[:12]}... to {old_ref_count}"
-            )
-
             # Update tag to point to new artifact
+            # NOTE: SQL trigger (tags_ref_count_update_trigger) handles ref_count:
+            # - Decrements old artifact's ref_count
+            # - Increments new artifact's ref_count
             existing_tag.artifact_id = new_artifact_id
             existing_tag.created_by = user_id
 
+            logger.info(
+                f"Tag '{tag_name}' updated: {old_artifact_id[:12]}... -> {new_artifact_id[:12]}..."
+            )
+
             return existing_tag, False, old_artifact_id
         else:
             # Same artifact, no change needed
@@ -488,27 +488,29 @@ def delete_project(
     if not project:
         raise HTTPException(status_code=404, detail="Project not found")
 
-    # Get all packages in this project
+    # Get counts for logging
     packages = db.query(Package).filter(Package.project_id == project.id).all()
+    package_count = len(packages)
 
-    # Get all tags across all packages to decrement their artifact ref_counts
-    artifacts_decremented = {}
     total_tags = 0
-
+    artifact_ids = set()
     for package in packages:
         tags = db.query(Tag).filter(Tag.package_id == package.id).all()
         total_tags += len(tags)
-
         for tag in tags:
-            if tag.artifact_id not in artifacts_decremented:
-                new_ref_count = _decrement_ref_count(db, tag.artifact_id)
-                artifacts_decremented[tag.artifact_id] = new_ref_count
-                logger.info(
-                    f"Project '{project_name}' deletion: decremented ref_count on artifact "
-                    f"{tag.artifact_id[:12]}... to {new_ref_count}"
-                )
+            artifact_ids.add(tag.artifact_id)
 
-    # Audit log
+    logger.info(
+        f"Project '{project_name}' deletion: {package_count} packages, "
+        f"{total_tags} tags affecting {len(artifact_ids)} artifacts"
+    )
+
+    # Delete the project (cascade will delete packages, tags, etc.)
+    # NOTE: SQL triggers (tags_ref_count_delete_trigger) handle ref_count automatically
+    db.delete(project)
+    db.commit()
+
+    # Audit log (after commit)
     _log_audit(
         db,
         action="delete_project",
@@ -516,14 +518,11 @@ def delete_project(
         user_id=user_id,
         source_ip=request.client.host if request.client else None,
         details={
-            "packages_deleted": len(packages),
+            "packages_deleted": package_count,
             "tags_deleted": total_tags,
-            "artifacts_affected": list(artifacts_decremented.keys()),
+            "artifacts_affected": list(artifact_ids),
         },
     )
-
-    # Delete the project (cascade will delete packages, tags, etc.)
-    db.delete(project)
     db.commit()
 
     return None
@@ -868,21 +867,22 @@ def delete_package(
     if not package:
         raise HTTPException(status_code=404, detail="Package not found")
 
-    # Get all tags in this package to decrement their artifact ref_counts
+    # Get tags count and affected artifacts for logging
     tags = db.query(Tag).filter(Tag.package_id == package.id).all()
+    artifact_ids = list(set(tag.artifact_id for tag in tags))
+    tag_count = len(tags)
 
-    # Decrement ref_count for each artifact referenced by tags
-    artifacts_decremented = {}
-    for tag in tags:
-        if tag.artifact_id not in artifacts_decremented:
-            new_ref_count = _decrement_ref_count(db, tag.artifact_id)
-            artifacts_decremented[tag.artifact_id] = new_ref_count
-            logger.info(
-                f"Package '{package_name}' deletion: decremented ref_count on artifact "
-                f"{tag.artifact_id[:12]}... to {new_ref_count}"
-            )
+    logger.info(
+        f"Package '{package_name}' deletion: {tag_count} tags affecting "
+        f"{len(artifact_ids)} artifacts"
+    )
 
-    # Audit log
+    # Delete the package (cascade will delete tags, which triggers ref_count decrements)
+    # NOTE: SQL triggers (tags_ref_count_delete_trigger) handle ref_count automatically
+    db.delete(package)
+    db.commit()
+
+    # Audit log (after commit)
     _log_audit(
         db,
         action="delete_package",
@@ -890,13 +890,10 @@ def delete_package(
         user_id=user_id,
         source_ip=request.client.host if request.client else None,
         details={
-            "tags_deleted": len(tags),
-            "artifacts_affected": list(artifacts_decremented.keys()),
+            "tags_deleted": tag_count,
+            "artifacts_affected": artifact_ids,
         },
     )
-
-    # Delete the package (cascade will delete tags, uploads, consumers)
-    db.delete(package)
     db.commit()
 
     return None
@@ -982,8 +979,9 @@ def upload_artifact(
         .first()
     )
     if artifact:
-        # Artifact exists - increment ref_count (already locked)
-        artifact.ref_count += 1
+        # Artifact exists - this is a deduplicated upload
+        # NOTE: ref_count is managed by SQL triggers on tag INSERT/DELETE
+        # We don't manually increment here - the tag creation will trigger the increment
         deduplicated = True
         saved_bytes = storage_result.size
         # Merge metadata if new metadata was extracted
@@ -1001,6 +999,9 @@ def upload_artifact(
         # Refresh to get updated ref_count
         db.refresh(artifact)
     else:
+        # Create new artifact with ref_count=0
+        # NOTE: ref_count is managed by SQL triggers on tag INSERT/DELETE
+        # When a tag is created for this artifact, the trigger will increment ref_count
         artifact = Artifact(
             id=storage_result.sha256,
             size=storage_result.size,
@@ -1012,6 +1013,7 @@ def upload_artifact(
             created_by=user_id,
             s3_key=storage_result.s3_key,
             artifact_metadata=file_metadata or {},
+            ref_count=0,  # Triggers will manage this
         )
         db.add(artifact)
 
@@ -1910,14 +1912,16 @@ def delete_tag(
     db.add(history)
     db.flush()  # Flush history before deleting tag (cascade will delete history)
 
-    # Decrement ref_count on artifact
-    new_ref_count = _decrement_ref_count(db, artifact_id)
-    logger.info(
-        f"Tag '{tag_name}' deleted: decremented ref_count on artifact "
-        f"{artifact_id[:12]}... to {new_ref_count}"
-    )
+    # NOTE: ref_count decrement is handled by SQL trigger (tags_ref_count_delete_trigger)
+    # when the tag is deleted below
+    logger.info(f"Tag '{tag_name}' deleted for artifact {artifact_id[:12]}...")
 
-    # Audit log
+    # Delete the tag (SQL trigger will decrement ref_count)
+    db.delete(tag)
+    db.commit()
+
+    # Audit log (after commit so we can query the updated ref_count)
+    artifact = db.query(Artifact).filter(Artifact.id == artifact_id).first()
     _log_audit(
         db,
         action="delete_tag",
@@ -1926,13 +1930,10 @@ def delete_tag(
         source_ip=request.client.host if request.client else None,
         details={
             "artifact_id": artifact_id,
-            "new_ref_count": new_ref_count,
+            "ref_count_after": artifact.ref_count if artifact else 0,
         },
     )
-
-    # Delete the tag
-    db.delete(tag)
-    db.commit()
+    db.commit()  # Commit the audit log
 
     return None