/* =====================================================================
   CareFix: AI usage and cost tracking.  Run on CS_CAREFIX after 04.
   ===================================================================== */
USE CS_CAREFIX;
GO

CREATE TABLE dbo.CF_AI_USAGE (
    UsageId          BIGINT IDENTITY(1,1) PRIMARY KEY,
    TicketId         INT NULL,
    Purpose          NVARCHAR(20) NOT NULL,      -- Diagnosis, Verification, Learning
    Model            NVARCHAR(60) NOT NULL,
    InputTokens      INT NOT NULL DEFAULT 0,
    OutputTokens     INT NOT NULL DEFAULT 0,
    CacheWriteTokens INT NOT NULL DEFAULT 0,
    CacheReadTokens  INT NOT NULL DEFAULT 0,
    CostUsd          DECIMAL(12,6) NOT NULL DEFAULT 0,
    CreatedAt        DATETIME2 NOT NULL DEFAULT SYSUTCDATETIME()
);
CREATE INDEX IX_CF_AI_USAGE_Ticket ON dbo.CF_AI_USAGE(TicketId);
CREATE INDEX IX_CF_AI_USAGE_When ON dbo.CF_AI_USAGE(CreatedAt) INCLUDE (CostUsd);
GO