feat(db): add Entry and DebtTarget models with initial migration

Entry stores one row per section entry (name, amount, timestamps).
DebtTarget is a singleton table (CHECK id = 1) with a nullable
foreign key to Entry using ON DELETE SET NULL so deleting the
referenced Debt Minimums row clears the pointer.

Refs #1

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

alembic.ini

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+# A generic, single database configuration.
+
+[alembic]
+# path to migration scripts.
+# this is typically a path given in POSIX (e.g. forward slashes)
+# format, relative to the token %(here)s which refers to the location of this
+# ini file
+script_location = %(here)s/alembic
+
+# template used to generate migration file names; The default value is %%(rev)s_%%(slug)s
+# Uncomment the line below if you want the files to be prepended with date and time
+# see https://alembic.sqlalchemy.org/en/latest/tutorial.html#editing-the-ini-file
+# for all available tokens
+# file_template = %%(year)d_%%(month).2d_%%(day).2d_%%(hour).2d%%(minute).2d-%%(rev)s_%%(slug)s
+# Or organize into date-based subdirectories (requires recursive_version_locations = true)
+# file_template = %%(year)d/%%(month).2d/%%(day).2d_%%(hour).2d%%(minute).2d_%%(second).2d_%%(rev)s_%%(slug)s
+
+# sys.path path, will be prepended to sys.path if present.
+# defaults to the current working directory.  for multiple paths, the path separator
+# is defined by "path_separator" below.
+prepend_sys_path = .
+
+
+# timezone to use when rendering the date within the migration file
+# as well as the filename.
+# If specified, requires the tzdata library which can be installed by adding
+# `alembic[tz]` to the pip requirements.
+# string value is passed to ZoneInfo()
+# leave blank for localtime
+# timezone =
+
+# max length of characters to apply to the "slug" field
+# truncate_slug_length = 40
+
+# set to 'true' to run the environment during
+# the 'revision' command, regardless of autogenerate
+# revision_environment = false
+
+# set to 'true' to allow .pyc and .pyo files without
+# a source .py file to be detected as revisions in the
+# versions/ directory
+# sourceless = false
+
+# version location specification; This defaults
+# to <script_location>/versions.  When using multiple version
+# directories, initial revisions must be specified with --version-path.
+# The path separator used here should be the separator specified by "path_separator"
+# below.
+# version_locations = %(here)s/bar:%(here)s/bat:%(here)s/alembic/versions
+
+# path_separator; This indicates what character is used to split lists of file
+# paths, including version_locations and prepend_sys_path within configparser
+# files such as alembic.ini.
+# The default rendered in new alembic.ini files is "os", which uses os.pathsep
+# to provide os-dependent path splitting.
+#
+# Note that in order to support legacy alembic.ini files, this default does NOT
+# take place if path_separator is not present in alembic.ini.  If this
+# option is omitted entirely, fallback logic is as follows:
+#
+# 1. Parsing of the version_locations option falls back to using the legacy
+#    "version_path_separator" key, which if absent then falls back to the legacy
+#    behavior of splitting on spaces and/or commas.
+# 2. Parsing of the prepend_sys_path option falls back to the legacy
+#    behavior of splitting on spaces, commas, or colons.
+#
+# Valid values for path_separator are:
+#
+# path_separator = :
+# path_separator = ;
+# path_separator = space
+# path_separator = newline
+#
+# Use os.pathsep. Default configuration used for new projects.
+path_separator = os
+
+# set to 'true' to search source files recursively
+# in each "version_locations" directory
+# new in Alembic version 1.10
+# recursive_version_locations = false
+
+# the output encoding used when revision files
+# are written from script.py.mako
+# output_encoding = utf-8
+
+# database URL.  This is consumed by the user-maintained env.py script only.
+# other means of configuring database URLs may be customized within the env.py
+# file.
+sqlalchemy.url = driver://user:pass@localhost/dbname
+
+
+[post_write_hooks]
+# post_write_hooks defines scripts or Python functions that are run
+# on newly generated revision scripts.  See the documentation for further
+# detail and examples
+
+# format using "black" - use the console_scripts runner, against the "black" entrypoint
+# hooks = black
+# black.type = console_scripts
+# black.entrypoint = black
+# black.options = -l 79 REVISION_SCRIPT_FILENAME
+
+# lint with attempts to fix using "ruff" - use the module runner, against the "ruff" module
+# hooks = ruff
+# ruff.type = module
+# ruff.module = ruff
+# ruff.options = check --fix REVISION_SCRIPT_FILENAME
+
+# Alternatively, use the exec runner to execute a binary found on your PATH
+# hooks = ruff
+# ruff.type = exec
+# ruff.executable = ruff
+# ruff.options = check --fix REVISION_SCRIPT_FILENAME
+
+# Logging configuration.  This is also consumed by the user-maintained
+# env.py script only.
+[loggers]
+keys = root,sqlalchemy,alembic
+
+[handlers]
+keys = console
+
+[formatters]
+keys = generic
+
+[logger_root]
+level = WARNING
+handlers = console
+qualname =
+
+[logger_sqlalchemy]
+level = WARNING
+handlers =
+qualname = sqlalchemy.engine
+
+[logger_alembic]
+level = INFO
+handlers =
+qualname = alembic
+
+[handler_console]
+class = StreamHandler
+args = (sys.stderr,)
+level = NOTSET
+formatter = generic
+
+[formatter_generic]
+format = %(levelname)-5.5s [%(name)s] %(message)s
+datefmt = %H:%M:%S

alembic/README

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+Generic single-database configuration.

alembic/env.py

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+from logging.config import fileConfig
+
+from sqlalchemy import engine_from_config, pool
+
+from alembic import context
+
+from quartermaster.config import DB_URL
+from quartermaster.models import Base
+
+config = context.config
+config.set_main_option("sqlalchemy.url", DB_URL)
+
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+target_metadata = Base.metadata
+
+
+def run_migrations_offline() -> None:
+    url = config.get_main_option("sqlalchemy.url")
+    context.configure(
+        url=url,
+        target_metadata=target_metadata,
+        literal_binds=True,
+        dialect_opts={"paramstyle": "named"},
+        render_as_batch=True,
+    )
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def run_migrations_online() -> None:
+    connectable = engine_from_config(
+        config.get_section(config.config_ini_section, {}),
+        prefix="sqlalchemy.",
+        poolclass=pool.NullPool,
+    )
+    with connectable.connect() as connection:
+        context.configure(
+            connection=connection,
+            target_metadata=target_metadata,
+            render_as_batch=True,
+        )
+        with context.begin_transaction():
+            context.run_migrations()
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()

alembic/script.py.mako

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+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+Create Date: ${create_date}
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+# revision identifiers, used by Alembic.
+revision: str = ${repr(up_revision)}
+down_revision: Union[str, Sequence[str], None] = ${repr(down_revision)}
+branch_labels: Union[str, Sequence[str], None] = ${repr(branch_labels)}
+depends_on: Union[str, Sequence[str], None] = ${repr(depends_on)}
+
+
+def upgrade() -> None:
+    """Upgrade schema."""
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade() -> None:
+    """Downgrade schema."""
+    ${downgrades if downgrades else "pass"}

alembic/versions/f1ccdc4bc1bf_initial_schema.py

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+"""initial schema
+
+Revision ID: f1ccdc4bc1bf
+Revises: 
+Create Date: 2026-04-17 10:59:39.959411
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = 'f1ccdc4bc1bf'
+down_revision: Union[str, Sequence[str], None] = None
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    """Upgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.create_table('entry',
+    sa.Column('id', sa.Integer(), nullable=False),
+    sa.Column('section', sa.Enum('income', 'fixed_bill', 'debt_minimum', 'food', 'subscription', 'other', name='section', native_enum=False, length=32), nullable=False),
+    sa.Column('name', sa.String(length=128), nullable=False),
+    sa.Column('amount', sa.Numeric(precision=10, scale=2), nullable=False),
+    sa.Column('created_at', sa.DateTime(timezone=True), server_default=sa.text('(CURRENT_TIMESTAMP)'), nullable=False),
+    sa.Column('updated_at', sa.DateTime(timezone=True), server_default=sa.text('(CURRENT_TIMESTAMP)'), nullable=False),
+    sa.PrimaryKeyConstraint('id')
+    )
+    with op.batch_alter_table('entry', schema=None) as batch_op:
+        batch_op.create_index(batch_op.f('ix_entry_section'), ['section'], unique=False)
+
+    op.create_table('debt_target',
+    sa.Column('id', sa.Integer(), autoincrement=False, nullable=False),
+    sa.Column('debt_minimum_id', sa.Integer(), nullable=True),
+    sa.Column('updated_at', sa.DateTime(timezone=True), server_default=sa.text('(CURRENT_TIMESTAMP)'), nullable=False),
+    sa.CheckConstraint('id = 1', name='debt_target_singleton'),
+    sa.ForeignKeyConstraint(['debt_minimum_id'], ['entry.id'], ondelete='SET NULL'),
+    sa.PrimaryKeyConstraint('id')
+    )
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    """Downgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_table('debt_target')
+    with op.batch_alter_table('entry', schema=None) as batch_op:
+        batch_op.drop_index(batch_op.f('ix_entry_section'))
+
+    op.drop_table('entry')
+    # ### end Alembic commands ###

src/quartermaster/config.py

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+from __future__ import annotations
+
+import os
+from pathlib import Path
+
+PROJECT_ROOT = Path(__file__).resolve().parents[2]
+DEFAULT_DB_PATH = PROJECT_ROOT / "quartermaster.db"
+DB_URL = os.environ.get("QUARTERMASTER_DB_URL", f"sqlite:///{DEFAULT_DB_PATH}")

src/quartermaster/db.py

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+from __future__ import annotations
+
+from collections.abc import Iterator
+
+from sqlalchemy import create_engine, event
+from sqlalchemy.orm import Session, sessionmaker
+
+from quartermaster.config import DB_URL
+
+engine = create_engine(DB_URL, future=True)
+
+
+@event.listens_for(engine, "connect")
+def _enable_sqlite_foreign_keys(dbapi_connection, _):  # type: ignore[no-untyped-def]
+    cursor = dbapi_connection.cursor()
+    cursor.execute("PRAGMA foreign_keys=ON")
+    cursor.close()
+
+
+SessionLocal = sessionmaker(bind=engine, autoflush=False, expire_on_commit=False)
+
+
+def get_session() -> Iterator[Session]:
+    session = SessionLocal()
+    try:
+        yield session
+    finally:
+        session.close()

src/quartermaster/models.py

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+from __future__ import annotations
+
+import enum
+from datetime import datetime
+from decimal import Decimal
+
+from sqlalchemy import (
+    CheckConstraint,
+    DateTime,
+    Enum,
+    ForeignKey,
+    Numeric,
+    String,
+    func,
+)
+from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column, relationship
+
+
+class Section(str, enum.Enum):
+    income = "income"
+    fixed_bill = "fixed_bill"
+    debt_minimum = "debt_minimum"
+    food = "food"
+    subscription = "subscription"
+    other = "other"
+
+
+SECTION_LABELS: dict[Section, str] = {
+    Section.income: "Incomes",
+    Section.fixed_bill: "Fixed Amount Bills",
+    Section.debt_minimum: "Debt Minimums",
+    Section.food: "Food and Essentials",
+    Section.subscription: "Subscriptions",
+    Section.other: "Other",
+}
+
+
+class Base(DeclarativeBase):
+    pass
+
+
+class Entry(Base):
+    __tablename__ = "entry"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    section: Mapped[Section] = mapped_column(
+        Enum(Section, native_enum=False, length=32), nullable=False, index=True
+    )
+    name: Mapped[str] = mapped_column(String(128), nullable=False)
+    amount: Mapped[Decimal] = mapped_column(Numeric(10, 2), nullable=False)
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), nullable=False
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        server_default=func.now(),
+        onupdate=func.now(),
+        nullable=False,
+    )
+
+
+class DebtTarget(Base):
+    __tablename__ = "debt_target"
+    __table_args__ = (CheckConstraint("id = 1", name="debt_target_singleton"),)
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=False)
+    debt_minimum_id: Mapped[int | None] = mapped_column(
+        ForeignKey("entry.id", ondelete="SET NULL"), nullable=True
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        server_default=func.now(),
+        onupdate=func.now(),
+        nullable=False,
+    )
+
+    entry: Mapped[Entry | None] = relationship(Entry, lazy="joined")