## Implementation Steps

+ [Why this pattern works](/explanation/parsing-codec-chaining)

### 1. Chain decoders for type safety
- Existing code example -
```typescript
import * as t from 'io-ts';
import { nonEmptyArray, JsonFromString, NumberFromString } from 'io-ts-types';
import { httpRequest, optional } from '@api-ts/io-ts-http';

// Define the Filter type for the JSON string
const Filter = t.type({
  category: t.string,
  tags: t.array(t.string),
  price: t.type({
    min: t.number,
    max: t.number,
  }),
});...Example continues......

# Type Safety in I/O Decoding

I am going to ask Designers to draw up a codec chaining diagram and post it here.

## Design Rationale

Though we know headers, URL parameters, and query parameters will be received as a
`string` or `string[]` value, due to a limitation in api-ts..... Continue...
but need to decode it with a codec that can only decode a narrower type. This pattern is
called codec chaining.

## Tradeoffs
- **Pros**: Enables gradual type refinement