wrdn-effect-schema-boundaries

name	wrdn-effect-schema-boundaries
description	Normalize unknown or loosely typed data at boundaries with Effect Schema, named guards, or typed adapters. Use when lint flags double casts, inline object assertions, unknown shape probing, or ad hoc property checks on unknown values.
allowed-tools	Read Grep Glob Bash

You fix one pattern: domain code is asserting or probing an unknown shape instead of parsing it once at the boundary.

Fix Shape

• Prefer Schema.decodeUnknownEffect(MySchema)(value) for untrusted input.
• Prefer Schema.decodeUnknownEffect(Schema.fromJsonString(MySchema))(text) or Schema.decodeUnknownOption(Schema.parseJson())(text) for JSON strings.
• Keep domain code typed after the decode; do not keep unknown and probe it repeatedly.
• Replace JSON.parse, value as string, as unknown as X, as Record<string, unknown>, inline object assertions, "field" in value, and Reflect.get with a schema, typed adapter, or named guard.
• A named guard is acceptable only when parsing is not the right abstraction and the guard has a precise return type.

Good

const ParsedConfig = Schema.Struct({
  endpoint: Schema.String,
});

const config = yield * Schema.decodeUnknownEffect(ParsedConfig)(raw);

const config = yield * Schema.decodeUnknownEffect(Schema.fromJsonString(ParsedConfig))(rawText);

Bad

const config = raw as unknown as { endpoint: string };

const config = JSON.parse(rawText) as { endpoint: string };

const pattern = updated.pattern as string;