app/cost.py

"""gpt-4o-mini cost calculator.

Pricing as of 2026-04. Verify against https://openai.com/api/pricing
before recording Video 3 — these constants are the only thing the VP
will see translated into dollars.
"""

from pydantic import BaseModel, ConfigDict

INPUT_COST_PER_M_USD = 0.15
OUTPUT_COST_PER_M_USD = 0.60


class CostBreakdown(BaseModel):
    model_config = ConfigDict(frozen=True)

    input_tokens: int
    output_tokens: int
    requests: int
    usd: float

    def format(self) -> str:
        return (
            f"${self.usd:.5f} "
            f"({self.input_tokens} in + {self.output_tokens} out, "
            f"{self.requests} req)"
        )


def cost_from_usage(usage) -> CostBreakdown:
    """Convert an openai-agents Usage object to a dollar breakdown."""
    usd = (
        usage.input_tokens * INPUT_COST_PER_M_USD
        + usage.output_tokens * OUTPUT_COST_PER_M_USD
    ) / 1_000_000
    return CostBreakdown(
        input_tokens=usage.input_tokens,
        output_tokens=usage.output_tokens,
        requests=usage.requests,
        usd=usd,
    )