refactor: finish declutter - test_flow removal, NOT NULL schema, parametrized tests, smoke harness, docs

backend/migrations/versions/e8f3a1c2b4d6_input_schema_not_null.py

@@ -0,0 +1,65 @@
+"""Backfill + require FlowVersion.input_schema.
+
+Revision ID: e8f3a1c2b4d6
+Revises: c4d8f2a1e6b9
+Create Date: 2026-09-30 00:00:00.000000
+
+Pre-Phase-3 rows have input_schema NULL. Backfill them from the stored
+langflow_json (same parser the write choke point uses); unparseable rows
+get the textarea fallback so reads never crash. Then enforce NOT NULL.
+"""
+
+from collections.abc import Sequence
+
+import sqlalchemy as sa
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision: str = "e8f3a1c2b4d6"
+down_revision: str | Sequence[str] | None = "c4d8f2a1e6b9"
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+_FALLBACK = {
+    "json_schema": {"type": "object", "properties": {}},
+    "ui_schema": {},
+    "fallback": "textarea",
+}
+
+
+def _derive(langflow_json) -> dict:
+    import json as stdlib_json
+
+    try:
+        from app.flows import input_schema as parser
+
+        if isinstance(langflow_json, str):
+            # SQLite stores JSON columns as TEXT; Postgres returns dict.
+            langflow_json = stdlib_json.loads(langflow_json)
+        return parser.extract_form_schema(langflow_json)
+    except Exception:  # noqa: BLE001 -- backfill must never fail the migration
+        return dict(_FALLBACK)
+
+
+def upgrade() -> None:
+    """Upgrade schema."""
+    import json as stdlib_json
+
+    connection = op.get_bind()
+    rows = connection.execute(
+        sa.text("SELECT id, langflow_json FROM flow_versions WHERE input_schema IS NULL")
+    ).all()
+    for row_id, langflow_json in rows:
+        schema = _derive(langflow_json)
+        connection.execute(
+            sa.text("UPDATE flow_versions SET input_schema = :schema WHERE id = :id"),
+            {"schema": stdlib_json.dumps(schema), "id": str(row_id)},
+        )
+    with op.batch_alter_table("flow_versions") as batch:
+        batch.alter_column("input_schema", existing_type=sa.JSON(), nullable=False)
+
+
+def downgrade() -> None:
+    """Downgrade schema (data kept, nullability restored)."""
+    with op.batch_alter_table("flow_versions") as batch:
+        batch.alter_column("input_schema", existing_type=sa.JSON(), nullable=True)