feat: persist story generation states and cache audio

backend/alembic/versions/0009_add_story_generation_statuses.py

@@ -0,0 +1,151 @@
+"""add story generation status fields
+
+Revision ID: 0009_add_story_generation_statuses
+Revises: 0008_add_pages_to_stories
+Create Date: 2026-04-17
+
+"""
+
+import sqlalchemy as sa
+from alembic import op
+
+
+# revision identifiers, used by Alembic.
+revision = "0009_add_story_generation_statuses"
+down_revision = "0008_add_pages_to_stories"
+branch_labels = None
+depends_on = None
+
+
+stories = sa.table(
+    "stories",
+    sa.column("id", sa.Integer),
+    sa.column("story_text", sa.Text),
+    sa.column("pages", sa.JSON),
+    sa.column("cover_prompt", sa.Text),
+    sa.column("image_url", sa.String(length=500)),
+    sa.column("generation_status", sa.String(length=32)),
+    sa.column("image_status", sa.String(length=32)),
+    sa.column("audio_status", sa.String(length=32)),
+)
+
+
+def _resolve_image_status(row: dict) -> str:
+    pages = row.get("pages") or []
+
+    expected_assets = 0
+    ready_assets = 0
+
+    if row.get("cover_prompt") or row.get("image_url"):
+        expected_assets += 1
+        if row.get("image_url"):
+            ready_assets += 1
+
+    for page in pages:
+        if not isinstance(page, dict):
+            continue
+        if not page.get("image_prompt") and not page.get("image_url"):
+            continue
+        expected_assets += 1
+        if page.get("image_url"):
+            ready_assets += 1
+
+    if expected_assets == 0:
+        return "not_requested"
+
+    if ready_assets == expected_assets:
+        return "ready"
+
+    return "failed"
+
+
+def _resolve_generation_status(
+    *,
+    story_text: str | None,
+    pages: list[dict] | None,
+    image_status: str,
+    audio_status: str,
+) -> str:
+    has_narrative = bool(story_text) or bool(pages)
+    if not has_narrative:
+        return "failed"
+
+    if "generating" in {image_status, audio_status}:
+        return "assets_generating"
+
+    if "failed" in {image_status, audio_status}:
+        return "degraded_completed"
+
+    if image_status == "not_requested" and audio_status == "not_requested":
+        return "narrative_ready"
+
+    return "completed"
+
+
+def upgrade() -> None:
+    op.add_column(
+        "stories",
+        sa.Column(
+            "generation_status",
+            sa.String(length=32),
+            nullable=False,
+            server_default="narrative_ready",
+        ),
+    )
+    op.add_column(
+        "stories",
+        sa.Column(
+            "image_status",
+            sa.String(length=32),
+            nullable=False,
+            server_default="not_requested",
+        ),
+    )
+    op.add_column(
+        "stories",
+        sa.Column(
+            "audio_status",
+            sa.String(length=32),
+            nullable=False,
+            server_default="not_requested",
+        ),
+    )
+    op.add_column("stories", sa.Column("last_error", sa.Text(), nullable=True))
+
+    connection = op.get_bind()
+    rows = connection.execute(
+        sa.select(
+            stories.c.id,
+            stories.c.story_text,
+            stories.c.pages,
+            stories.c.cover_prompt,
+            stories.c.image_url,
+        )
+    ).mappings()
+
+    for row in rows:
+        image_status = _resolve_image_status(row)
+        audio_status = "not_requested"
+        generation_status = _resolve_generation_status(
+            story_text=row.get("story_text"),
+            pages=row.get("pages"),
+            image_status=image_status,
+            audio_status=audio_status,
+        )
+
+        connection.execute(
+            stories.update()
+            .where(stories.c.id == row["id"])
+            .values(
+                generation_status=generation_status,
+                image_status=image_status,
+                audio_status=audio_status,
+            )
+        )
+
+
+def downgrade() -> None:
+    op.drop_column("stories", "last_error")
+    op.drop_column("stories", "audio_status")
+    op.drop_column("stories", "image_status")
+    op.drop_column("stories", "generation_status")