effect-config-schema

• Validating request bodies, params, or external inputs
• Loading environment configuration with types

```ts

import { Config } from "effect"

const Server = Config.nested("SERVER")(Config.all({

host: Config.string("HOST"),

port: Config.number("PORT")

}))

```

```ts

import { Schema as S } from "effect"

const User = S.Struct({ id: S.Number, name: S.String })

const decodeUser = (u: unknown) => S.decodeUnknown(User)(u)

```

```ts

const IsoDate = S.String // then transform to Date in pipeline where needed

```

```ts

class AwsCredentials extends Effect.Service()("AwsCredentials", {

effect: Effect.gen(function* () {

const accessKeys = yield* Config.option(

Config.all([Config.string("CAP_AWS_ACCESS_KEY"), Config.string("CAP_AWS_SECRET_KEY")])

)

const vercelAwsRole = yield* Config.option(Config.string("VERCEL_AWS_ROLE_ARN"))

const credentials = yield Effect.gen(function () {

if (Option.isSome(vercelAwsRole)) return awsCredentialsProvider({ roleArn: vercelAwsRole.value })

if (Option.isSome(accessKeys)) {

const [accessKeyId, secretAccessKey] = accessKeys.value

return { accessKeyId, secretAccessKey }

}

return fromContainerMetadata()

})

return { credentials }

})

})

```

• Prefer schemas close to boundaries; keep core logic typed
• For branded types (Email, PositiveInt), use transform/brand helpers
• Validate early, map to domain errors in one place

• Accepting unknown into core → always decode first
• Large ad-hoc validation code → centralize in Schema

• HTTP & Routing for endpoint validation
• Foundations for operator style

CRITICAL: Search local Effect source before implementing

The full Effect source code is available at docs/effect-source/. Always search the actual implementation before writing Effect code.

Key Source Files

• Config: docs/effect-source/effect/src/Config.ts
• Schema: docs/effect-source/schema/src/Schema.ts

Example Searches

```bash

# Find Config patterns and options

grep -F "Config.string" docs/effect-source/effect/src/Config.ts

grep -F "Config.number" docs/effect-source/effect/src/Config.ts

grep -F "Config.option" docs/effect-source/effect/src/Config.ts

# Study Schema validation

grep -F "Struct" docs/effect-source/schema/src/Schema.ts

grep -F "decodeUnknown" docs/effect-source/schema/src/Schema.ts

# Find Schema transforms

grep -rF "transform" docs/effect-source/schema/src/

grep -rF "brand" docs/effect-source/schema/src/

# Look at Config test examples

grep -F "Config." docs/effect-source/effect/test/Config.test.ts

```

Workflow

1. Identify the Config or Schema API you need
2. Search docs/effect-source/effect/src/Config.ts or docs/effect-source/schema/src/Schema.ts
3. Study the types and validation patterns
4. Look at test files for usage examples
5. Write your code based on real implementations

Real source code > documentation > assumptions

• Agent Skills overview: https://www.anthropic.com/news/skills
• Skills guide: https://docs.claude.com/en/docs/claude-code/skills