Add TypeScript types to API layer files in `api-src/`

[jeremyckahn]

Problem

The API layer files in api-src/ have zero TypeScript type annotations. Both files use implicit any for request/response objects, data parameters, and local variables. This is inconsistent with the rest of the codebase which is 100% TypeScript.

Files to Type

api-src/get-market-data.ts

Currently untyped:

export default allowCors(async (req, res) => {
  const roomKey = getRoomName(req)
  const roomData = await getRoomData(roomKey, get, set)
  const { valueAdjustments } = roomData
  set(roomKey, JSON.stringify(roomData))
  res.status(200).json({ valueAdjustments })
})

Variables without types: req, res, roomKey, roomData, valueAdjustments

api-src/post-day-results.ts

Currently untyped:

const applyPositionsToMarket = (valueAdjustments, positions) => {
  return Object.keys(valueAdjustments).reduce(
    (acc, itemName) => { /* ... */ },
    { ...valueAdjustments }
  )
}

export default allowCors(async (req, res) => {
  const { body: { positions = {} } } = req
  const roomKey = getRoomName(req)
  const { valueAdjustments, ...roomData } = await getRoomData(roomKey, get, set)
  // ...
})

Variables without types: valueAdjustments, positions, acc, itemName, itemPositionChange, variance, req, res, roomKey, roomData

Implementation Plan

Step 1: Determine the framework types

Check if the project uses Express, Vercel serverless, or another framework for the API. Look at api-etc/utils.ts for clues about the request/response types.

Step 2: Define shared types

Create types for the data structures used by both API endpoints. These should import from src/farmhand.d.ts:

interface RoomData {
  valueAdjustments: Record<string, number>
  // ... other fields from the room state stored in Redis
}

interface MarketDataResponse {
  valueAdjustments: Record<string, number>
}

interface DayResultsRequest {
  body: {
    positions?: Record<string, number>
  }
}

interface DayResultsResponse {
  valueAdjustments: Record<string, number>
}

Step 3: Annotate api-src/get-market-data.ts

export default allowCors(async (req: Request, res: Response<MarketDataResponse>) => {
  const roomKey = getRoomName(req)
  const roomData = await getRoomData(roomKey, get, set) as RoomData
  const { valueAdjustments } = roomData
  set(roomKey, JSON.stringify(roomData))
  res.status(200).json({ valueAdjustments })
})

Step 4: Annotate api-src/post-day-results.ts

const applyPositionsToMarket = (
  valueAdjustments: Record<string, number>,
  positions: Record<string, number>
): Record<string, number> => {
  // ...
}

export default allowCors(async (req: Request<{}, DayResultsResponse, DayResultsRequest>, res: Response<DayResultsResponse>) => {
  // ...
})

Step 5: Run type checker

npm run check:types

Acceptance Criteria

• api-src/get-market-data.ts has explicit types on all parameters and variables
• api-src/post-day-results.ts has explicit types on all parameters and variables
• Shared types are defined and reused across both API files
• Zero implicit any types remain in api-src/
• npm run check:types passes with no errors