feat(02-01): add BackupCode ORM model, password_must_change field, Alembic migration, extend Settings

- Add BackupCode model to db/models.py with user_id FK, code_hash (Argon2), used_at (nullable)
- Add ix_backup_codes_user_id index on backup_codes.user_id
- Add password_must_change BOOLEAN NOT NULL DEFAULT false to User model (ADMIN-01)
- Extend config.py Settings with JWT, SMTP, admin bootstrap, and CORS fields (D-01, D-04, D-09)
- Add env_list_separator=',' for cors_origins env var parsing
- Append PyJWT, pwdlib[argon2], pyotp, aioredis, slowapi to requirements.txt
- Add .env.example entries for SECRET_KEY, ADMIN_EMAIL, SMTP_*, CORS_ORIGINS
- Create migration 0002 adding backup_codes table and password_must_change column
- Add TDD tests for all Task 1 acceptance criteria (7 tests pass)

backend/config.py

@@ -10,6 +10,7 @@ class Settings(BaseSettings):
         env_file=".env",
         env_file_encoding="utf-8",
         extra="ignore",
+        env_list_separator=",",
     )
 
     # Data directory — used only for the flat-file settings.json path (Phase 1)
@@ -31,6 +32,24 @@ class Settings(BaseSettings):
     # Security (Phase 2 — documented now, not read by Phase 1 code paths)
     secret_key: str = "CHANGEME"
 
+    # Auth / JWT (Phase 2)
+    access_token_expire_minutes: int = 15
+    refresh_token_expire_days: int = 30
+
+    # SMTP (Phase 2 — D-01)
+    smtp_host: str = ""
+    smtp_port: int = 587
+    smtp_user: str = ""
+    smtp_password: str = ""
+    smtp_from: str = "noreply@docuvault.local"
+
+    # Admin bootstrap (Phase 2 — D-04)
+    admin_email: str = ""
+    admin_password: str = ""
+
+    # CORS (Phase 2 — D-09)
+    cors_origins: list[str] = ["http://localhost:5173"]
+
 
 settings = Settings()
 

backend/db/models.py

@@ -55,6 +55,7 @@ class User(Base):
     totp_enabled: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)
     role: Mapped[str] = mapped_column(String, nullable=False, default="user")
     is_active: Mapped[bool] = mapped_column(Boolean, nullable=False, default=True)
+    password_must_change: Mapped[bool] = mapped_column(Boolean, nullable=False, server_default="false")
     ai_provider: Mapped[Optional[str]] = mapped_column(Text, nullable=True)
     ai_model: Mapped[Optional[str]] = mapped_column(Text, nullable=True)
     default_storage_backend: Mapped[str] = mapped_column(
@@ -103,6 +104,32 @@ class RefreshToken(Base):
     __table_args__ = (Index("ix_refresh_tokens_user_revoked", "user_id", "revoked"),)
 
 
+class BackupCode(Base):
+    """Single-use backup codes for TOTP recovery (AUTH-02).
+
+    code_hash stores the Argon2 hash of the original code (never plaintext).
+    used_at is None when the code is unused; set to now() on first use.
+    Verification iterates ALL codes to prevent timing-based enumeration (SEC-06).
+    """
+
+    __tablename__ = "backup_codes"
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    user_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("users.id", ondelete="CASCADE"),
+        nullable=False,
+    )
+    code_hash: Mapped[str] = mapped_column(Text, nullable=False)
+    used_at: Mapped[Optional[datetime]] = mapped_column(
+        TIMESTAMP(timezone=True), nullable=True
+    )
+
+    __table_args__ = (Index("ix_backup_codes_user_id", "user_id"),)
+
+
 class Folder(Base):
     __tablename__ = "folders"
 

backend/migrations/versions/0002_add_backup_codes_and_password_must_change.py

@@ -0,0 +1,62 @@
+"""Add backup_codes table and password_must_change column to users.
+
+Revision ID: 0002
+Revises: 0001
+Create Date: 2026-05-22
+
+Changes:
+  1. Add `password_must_change` BOOLEAN NOT NULL DEFAULT false to users table (ADMIN-01)
+  2. Create `backup_codes` table for TOTP recovery codes (AUTH-02)
+
+Note: documents.user_id stays nullable per D-03 — NOT NULL is deferred to Phase 3.
+"""
+from __future__ import annotations
+
+import sqlalchemy as sa
+from sqlalchemy.dialects import postgresql
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision = "0002"
+down_revision = "0001"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    # ── 1. Add password_must_change to users ──────────────────────────────────
+    op.add_column(
+        "users",
+        sa.Column(
+            "password_must_change",
+            sa.Boolean(),
+            nullable=False,
+            server_default="false",
+        ),
+    )
+
+    # ── 2. Create backup_codes table ──────────────────────────────────────────
+    op.create_table(
+        "backup_codes",
+        sa.Column("id", postgresql.UUID(as_uuid=True), nullable=False),
+        sa.Column("user_id", postgresql.UUID(as_uuid=True), nullable=False),
+        sa.Column("code_hash", sa.Text(), nullable=False),
+        sa.Column("used_at", sa.TIMESTAMP(timezone=True), nullable=True),
+        sa.ForeignKeyConstraint(["user_id"], ["users.id"], ondelete="CASCADE"),
+        sa.PrimaryKeyConstraint("id"),
+    )
+    op.create_index("ix_backup_codes_user_id", "backup_codes", ["user_id"])
+
+    # ── Privilege grants (Pitfall 4) ───────────────────────────────────────────
+    op.execute(
+        "GRANT SELECT, INSERT, UPDATE, DELETE ON backup_codes TO docuvault_app;"
+    )
+
+
+def downgrade() -> None:
+    # ── Drop backup_codes ─────────────────────────────────────────────────────
+    op.drop_index("ix_backup_codes_user_id", table_name="backup_codes")
+    op.drop_table("backup_codes")
+
+    # ── Remove password_must_change from users ────────────────────────────────
+    op.drop_column("users", "password_must_change")

backend/requirements.txt

@@ -19,3 +19,8 @@ minio>=7.2.20
 celery[redis]>=5.6.3
 redis>=7.4.0
 aiosqlite>=0.20.0
+PyJWT>=2.8.0
+pwdlib[argon2]>=0.2.1
+pyotp>=2.9.0
+aioredis>=2.0.0
+slowapi>=0.1.9

backend/tests/test_task1_models_config.py

@@ -0,0 +1,71 @@
+"""
+TDD tests for Task 1: BackupCode ORM model, password_must_change field, Settings extension.
+
+These tests should FAIL before implementation (RED phase).
+"""
+import pytest
+
+
+def test_backup_code_model_exists():
+    """BackupCode ORM model must exist and have correct tablename + columns."""
+    from db.models import BackupCode
+    assert BackupCode.__tablename__ == "backup_codes"
+    assert hasattr(BackupCode, "id")
+    assert hasattr(BackupCode, "user_id")
+    assert hasattr(BackupCode, "code_hash")
+    assert hasattr(BackupCode, "used_at")
+
+
+def test_user_has_password_must_change():
+    """User model must have password_must_change column."""
+    from db.models import User
+    assert hasattr(User, "password_must_change")
+
+
+def test_settings_has_jwt_config():
+    """Settings must have access_token_expire_minutes and refresh_token_expire_days."""
+    from config import settings
+    assert hasattr(settings, "access_token_expire_minutes")
+    assert settings.access_token_expire_minutes == 15
+    assert hasattr(settings, "refresh_token_expire_days")
+    assert settings.refresh_token_expire_days == 30
+
+
+def test_settings_has_smtp_config():
+    """Settings must have SMTP fields."""
+    from config import settings
+    assert hasattr(settings, "smtp_host")
+    assert hasattr(settings, "smtp_port")
+    assert hasattr(settings, "smtp_user")
+    assert hasattr(settings, "smtp_password")
+    assert hasattr(settings, "smtp_from")
+
+
+def test_settings_has_admin_config():
+    """Settings must have admin bootstrap fields."""
+    from config import settings
+    assert hasattr(settings, "admin_email")
+    assert hasattr(settings, "admin_password")
+
+
+def test_settings_has_cors_origins():
+    """Settings must have cors_origins as a list with default localhost."""
+    from config import settings
+    assert hasattr(settings, "cors_origins")
+    assert isinstance(settings.cors_origins, list)
+    assert "http://localhost:5173" in settings.cors_origins
+
+
+def test_backup_code_table_in_schema(db_session):
+    """backup_codes table must be created in the SQLite test schema."""
+    from db.models import BackupCode
+    import uuid
+    # Should not raise — table must exist
+    bc = BackupCode(
+        id=uuid.uuid4(),
+        user_id=uuid.uuid4(),
+        code_hash="testhash",
+        used_at=None,
+    )
+    db_session.add(bc)
+    # We don't commit here — just verify the model is valid