diff --git a/alembic/versions/019_add_highlight_candidates.py b/alembic/versions/019_add_highlight_candidates.py
index 7bfa9b9..e1f1678 100644
--- a/alembic/versions/019_add_highlight_candidates.py
+++ b/alembic/versions/019_add_highlight_candidates.py
@@ -16,10 +16,10 @@ depends_on = None
 
 
 def upgrade() -> None:
-    # Pure SQL to avoid all SQLAlchemy enum creation hooks
-    op.execute("CREATE TYPE highlight_status AS ENUM ('candidate', 'approved', 'rejected')")
+    # Pure SQL — idempotent with IF NOT EXISTS / exception guards
+    op.execute("DO $$ BEGIN CREATE TYPE highlight_status AS ENUM ('candidate', 'approved', 'rejected'); EXCEPTION WHEN duplicate_object THEN NULL; END $$")
     op.execute("""
-        CREATE TABLE highlight_candidates (
+        CREATE TABLE IF NOT EXISTS highlight_candidates (
             id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
             key_moment_id UUID NOT NULL UNIQUE REFERENCES key_moments(id) ON DELETE CASCADE,
             source_video_id UUID NOT NULL REFERENCES source_videos(id) ON DELETE CASCADE,
@@ -31,9 +31,9 @@ def upgrade() -> None:
             updated_at TIMESTAMP NOT NULL DEFAULT now()
         )
     """)
-    op.execute("CREATE INDEX ix_highlight_candidates_source_video_id ON highlight_candidates (source_video_id)")
-    op.execute("CREATE INDEX ix_highlight_candidates_score_desc ON highlight_candidates (score DESC)")
-    op.execute("CREATE INDEX ix_highlight_candidates_status ON highlight_candidates (status)")
+    op.execute("CREATE INDEX IF NOT EXISTS ix_highlight_candidates_source_video_id ON highlight_candidates (source_video_id)")
+    op.execute("CREATE INDEX IF NOT EXISTS ix_highlight_candidates_score_desc ON highlight_candidates (score DESC)")
+    op.execute("CREATE INDEX IF NOT EXISTS ix_highlight_candidates_status ON highlight_candidates (status)")
 
 
 def downgrade() -> None:
diff --git a/alembic/versions/020_add_chapter_status_and_sort_order.py b/alembic/versions/020_add_chapter_status_and_sort_order.py
index ba67a09..7150e75 100644
--- a/alembic/versions/020_add_chapter_status_and_sort_order.py
+++ b/alembic/versions/020_add_chapter_status_and_sort_order.py
@@ -16,10 +16,10 @@ depends_on = None
 
 def upgrade() -> None:
     # Pure SQL to avoid SQLAlchemy enum creation hooks
-    op.execute("CREATE TYPE chapter_status AS ENUM ('draft', 'approved', 'hidden')")
-    op.execute("ALTER TABLE key_moments ADD COLUMN chapter_status chapter_status NOT NULL DEFAULT 'draft'")
-    op.execute("ALTER TABLE key_moments ADD COLUMN sort_order INTEGER NOT NULL DEFAULT 0")
-    op.execute("CREATE INDEX ix_key_moments_chapter_status ON key_moments (chapter_status)")
+    op.execute("DO $$ BEGIN CREATE TYPE chapter_status AS ENUM ('draft', 'approved', 'hidden'); EXCEPTION WHEN duplicate_object THEN NULL; END $$")
+    op.execute("ALTER TABLE key_moments ADD COLUMN IF NOT EXISTS chapter_status chapter_status NOT NULL DEFAULT 'draft'")
+    op.execute("ALTER TABLE key_moments ADD COLUMN IF NOT EXISTS sort_order INTEGER NOT NULL DEFAULT 0")
+    op.execute("CREATE INDEX IF NOT EXISTS ix_key_moments_chapter_status ON key_moments (chapter_status)")
     op.add_column(
         "key_moments",
         sa.Column("sort_order", sa.Integer, nullable=False, server_default="0"),