Extract shared _SpendingTotals base for spending summary models #111
Description
Problem
AgentSpending, DepartmentSpending, and PeriodSpending in budget/spending_summary.py each independently define the same 4 fields:
total_cost: Decimal
total_input_tokens: int
total_output_tokens: int
record_count: intThis is ~48 lines of duplicated field definitions + docstrings across 3 models. Changes to field constraints, types, or descriptions must be made in 3 places.
Proposed Solution
Extract a shared _SpendingTotals base:
class _SpendingTotals(BaseModel):
model_config = ConfigDict(frozen=True)
total_cost: Decimal = Field(ge=0, description="Sum of cost_usd across records")
total_input_tokens: int = Field(ge=0, description="Sum of input tokens")
total_output_tokens: int = Field(ge=0, description="Sum of output tokens")
record_count: int = Field(ge=0, description="Number of cost records")
class AgentSpending(_SpendingTotals):
agent_id: NotBlankStr = Field(description="Agent identifier")
class DepartmentSpending(_SpendingTotals):
department: NotBlankStr = Field(description="Department name")
class PeriodSpending(_SpendingTotals):
start: datetime = Field(description="Period start (inclusive)")
end: datetime = Field(description="Period end (exclusive)")Acceptance Criteria
-
_SpendingTotalsbase class with the 4 shared fields -
AgentSpending,DepartmentSpending,PeriodSpendingextend it - Individual whitespace validators replaced with
NotBlankStr(depends on NotBlankStr adoption issue) - Net reduction of ~30-40 lines
- All existing tests pass
- Public API unchanged (
model_dump()output identical) - Verify DESIGN_SPEC.md §10.2 implementation note and §15.5 remain consistent after implementation