Category overhaul (#20)

Reviewed-on: #20
Co-authored-by: Mathias <mathias2784@web.de>

alembic/versions/c18ae67f4b2a_merge_category_feature_heads.py

@@ -0,0 +1,23 @@
+"""merge category validity and budget migration branches
+
+Revision ID: c18ae67f4b2a
+Revises: d9c6533f8a1b, fe23064de1c5
+Create Date: 2026-10-27
+
+"""
+
+from collections.abc import Sequence
+
+# revision identifiers, used by Alembic.
+revision: str = "c18ae67f4b2a"
+down_revision: str | Sequence[str] | None = ("d9c6533f8a1b", "fe23064de1c5")
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+
+def upgrade() -> None:
+    pass
+
+
+def downgrade() -> None:
+    pass

alembic/versions/d9c6533f8a1b_add_category_validity.py

@@ -0,0 +1,102 @@
+"""add temporal validity to categories
+
+Revision ID: d9c6533f8a1b
+Revises: 78ec55b9e1d1
+Create Date: 2026-10-25 00:00:00.000000
+
+"""
+
+from collections.abc import Sequence
+
+import sqlalchemy as sa
+
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision: str = "d9c6533f8a1b"
+down_revision: str | Sequence[str] | None = "78ec55b9e1d1"
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+
+def upgrade() -> None:
+    with op.batch_alter_table("category") as batch_op:
+        batch_op.drop_constraint("uq_category_name_parent", type_="unique")
+        batch_op.add_column(
+            sa.Column(
+                "valid_from",
+                sa.DateTime(timezone=True),
+                nullable=True,
+                info={
+                    "description": "UTC start of validity; NULL means valid since the indefinite past."
+                },
+            )
+        )
+        batch_op.add_column(
+            sa.Column(
+                "valid_to",
+                sa.DateTime(timezone=True),
+                nullable=True,
+                info={
+                    "description": "UTC end of validity; NULL means the version is currently valid."
+                },
+            )
+        )
+        batch_op.add_column(
+            sa.Column(
+                "last_action",
+                sa.String(),
+                nullable=False,
+                server_default="created",
+                info={
+                    "description": "Most recent lifecycle action recorded for this category version."
+                },
+            )
+        )
+
+    # Existing rows predate temporal tracking, so their start is unbounded.
+    op.execute("UPDATE category SET last_action = 'migrated'")
+
+    # Separate root and non-root indexes so NULL parent IDs are unique too.
+    op.create_index(
+        "uq_category_active_name_parent",
+        "category",
+        ["name", "parent_id"],
+        unique=True,
+        sqlite_where=sa.text("valid_to IS NULL AND parent_id IS NOT NULL"),
+        postgresql_where=sa.text("valid_to IS NULL AND parent_id IS NOT NULL"),
+    )
+    op.create_index(
+        "uq_category_active_root_name",
+        "category",
+        ["name"],
+        unique=True,
+        sqlite_where=sa.text("valid_to IS NULL AND parent_id IS NULL"),
+        postgresql_where=sa.text("valid_to IS NULL AND parent_id IS NULL"),
+    )
+
+
+def downgrade() -> None:
+    bind = op.get_bind()
+    has_temporal_history = bind.execute(
+        sa.text(
+            "SELECT 1 FROM category "
+            "WHERE valid_from IS NOT NULL OR valid_to IS NOT NULL LIMIT 1"
+        )
+    ).first()
+    if has_temporal_history:
+        raise RuntimeError(
+            "Cannot downgrade category validity while temporal history exists; "
+            "the downgrade would discard it."
+        )
+
+    op.drop_index("uq_category_active_root_name", table_name="category")
+    op.drop_index("uq_category_active_name_parent", table_name="category")
+
+    with op.batch_alter_table("category") as batch_op:
+        batch_op.drop_column("last_action")
+        batch_op.drop_column("valid_to")
+        batch_op.drop_column("valid_from")
+        batch_op.create_unique_constraint(
+            "uq_category_name_parent", ["name", "parent_id"]
+        )

alembic/versions/fe23064de1c5_create_category_budget_table.py

@@ -0,0 +1,52 @@
+"""create category_budget table
+
+Revision ID: fe23064de1c5
+Revises: 78ec55b9e1d1
+Create Date: 2026-10-16 10:43:24.952699
+
+"""
+
+from collections.abc import Sequence
+
+import sqlalchemy as sa
+
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision: str = "fe23064de1c5"
+down_revision: str | Sequence[str] | None = "78ec55b9e1d1"
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+
+def upgrade() -> None:
+    """Upgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.create_table(
+        "category_budget",
+        sa.Column("id", sa.Integer(), autoincrement=True, nullable=False),
+        sa.Column("category_id", sa.Integer(), nullable=False),
+        sa.Column("amount_eur", sa.Numeric(precision=12, scale=2), nullable=False),
+        sa.Column("valid_from", sa.Date(), nullable=True),
+        sa.Column("valid_to", sa.Date(), nullable=True),
+        sa.ForeignKeyConstraint(
+            ["category_id"],
+            ["category.id"],
+        ),
+        sa.PrimaryKeyConstraint("id"),
+    )
+    op.create_index(
+        "ix_category_budget_category_id",
+        "category_budget",
+        ["category_id"],
+        unique=False,
+    )
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    """Downgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_index("ix_category_budget_category_id", table_name="category_budget")
+    op.drop_table("category_budget")
+    # ### end Alembic commands ###