diff --git a/backend/alembic/versions/0017_photos_list_index.py b/backend/alembic/versions/0017_photos_list_index.py
new file mode 100644
index 0000000..cfb7b65
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+++ b/backend/alembic/versions/0017_photos_list_index.py
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+"""Partial index for the photos list query
+
+Revision ID: 0017_photos_list_index
+Revises: 0016_nextcloud_integration
+Create Date: 2026-05-10
+
+The default photos-list query (GET /api/v1/photos?per_page=N&sort=taken_at&order=desc)
+filters `NOT is_trashed AND NOT is_hidden` and sorts by
+`(taken_at DESC NULLS LAST, id DESC)`. EXPLAIN ANALYZE on a 21k-row
+table showed a seq-scan + top-N heapsort (~20ms standalone, worse under
+concurrency) — Postgres can't use the single-column ix_photos_taken_at
+when the leading WHERE clause is two booleans.
+
+A partial index on the sort key, scoped to the visible subset, lets the
+planner index-scan in reverse and stop at LIMIT N. Two booleans select
+~95% of rows, so the partial predicate is tighter than the full table
+without losing common queries.
+"""
+from typing import Sequence, Union
+
+from alembic import op
+
+revision: str = "0017_photos_list_index"
+down_revision: Union[str, None] = "0016_nextcloud_integration"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.execute(
+        """
+        CREATE INDEX IF NOT EXISTS ix_photos_list_visible
+        ON photos (taken_at DESC NULLS LAST, id DESC)
+        WHERE NOT is_trashed AND NOT is_hidden
+        """
+    )
+
+
+def downgrade() -> None:
+    op.execute("DROP INDEX IF EXISTS ix_photos_list_visible")