Expose the encoded type from TestSchema.Encoding.encodeUnknownEffect

[fubhy]

Summary

TestSchema.Encoding.encodeUnknownEffect is typed as succeeding with the decoded Type even though it returns the Encoded value.

Important

This PR starts with focused failing reproduction tests. Add the implementation fix to this same branch; CI is expected to fail until that fix is included.

Encoding.encodeUnknownEffect exposes the decoded type

Module: TestSchema
Audit ID: core-s-z-testing-test-schema-encoded-type
Severity / confidence: medium / high

What happens

TestSchema.Encoding.encodeUnknownEffect is typed as succeeding with the decoded Type even though it returns the Encoded value.

Why it happens

The public property is annotated as Effect.Effect<S["Type"], ...> even though SchemaParser.encodeUnknownEffect returns Effect.Effect<S["Encoded"], ...>, breaking type-safe composition for transformed schemas.

Expected behavior

An encoding operation succeeds with the schema's Encoded type.

Relevant implementation

These links and excerpts are pinned to audit base c9b56ab507f224426ee8388dc450da447ec4715f.

• packages/effect/src/testing/TestSchema.ts:457-470
• packages/effect/src/SchemaParser.ts:600-610

View problematic code at packages/effect/src/testing/TestSchema.ts:457-470

export class Encoding<S extends Schema.Constraint> {
  readonly schema: S
  readonly encodeUnknownEffect: (
    input: unknown,
    options?: SchemaAST.ParseOptions
  ) => Effect.Effect<S["Type"], SchemaIssue.Issue, S["EncodingServices"]>
  readonly options?: {
    readonly parseOptions?: SchemaAST.ParseOptions | undefined
  } | undefined
  constructor(schema: S, options?: {
    readonly parseOptions?: SchemaAST.ParseOptions | undefined
  }) {
    this.schema = schema
    this.encodeUnknownEffect = SchemaParser.encodeUnknownEffect(schema)

View exact lines on GitHub

View problematic code at packages/effect/src/SchemaParser.ts:600-610

export function encodeUnknownEffect<S extends Schema.Constraint>(
  schema: S,
  options?: SchemaAST.ParseOptions
): (
  input: unknown,
  options?: SchemaAST.ParseOptions
) => Effect.Effect<S["Encoded"], SchemaIssue.Issue, S["EncodingServices"]> {
  const parser = run<S["Encoded"], S["EncodingServices"]>(SchemaAST.flip(schema.ast))
  return options === undefined
    ? parser
    : (input, overrideOptions) => parser(input, mergeParseOptions(options, overrideOptions))

View exact lines on GitHub

Reproduction

pnpm test-types packages/effect/typetest/TestSchema.tst.ts

Observed failure: TypeScript 5.9.3 and 6.0.3 report Effect<number, Issue> is not Effect<string, Issue>

Implementation handoff

The initial reproduction tests on this branch are the regression specification for the implementation fix that should follow in this PR.

1. Start with the pinned implementation excerpts and the Why it happens analysis above.
2. Change the implementation so it satisfies the stated Expected behavior; do not weaken or remove the reproduction assertions.
3. Run the focused reproduction command(s) and confirm the observed failures become passing tests:

pnpm test-types packages/effect/typetest/TestSchema.tst.ts

4. Run the affected package's existing tests, then the repository lint and type checks before requesting review.

Audit provenance

• Audit base: c9b56ab507f224426ee8388dc450da447ec4715f
• Reproduction base: c9b56ab507f224426ee8388dc450da447ec4715f
• Findings: core-s-z-testing-test-schema-encoded-type
• Initial patch: focused reproduction tests; implementation fix pending

[changeset-bot]

⚠️ No Changeset found

Latest commit: f16a03f

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[pullfrog]

Important

This PR currently adds only the failing reproduction test. The one-line implementation fix is still missing from packages/effect/src/testing/TestSchema.ts.

Reviewed changes

• Adds a TSTyche type test in packages/effect/typetest/TestSchema.tst.ts that asserts Encoding.encodeUnknownEffect for Schema.NumberFromString produces Effect<string, SchemaIssue.Issue>.

I ran the targeted type test and confirmed it fails as expected before the fix: the current type is Effect<number, Issue, never> because TestSchema.Encoding.encodeUnknownEffect is declared with S["Type"] instead of S["Encoded"].

⚠️ Implementation fix not yet included

The root cause is outside this diff, so it cannot be resolved by editing the test file alone. In packages/effect/src/testing/TestSchema.ts, the encodeUnknownEffect field is annotated as Effect.Effect<S["Type"], ...>, while the SchemaParser.encodeUnknownEffect call assigned to it returns Effect.Effect<S["Encoded"], ...>. Update the annotation to S["Encoded"] so the public type matches the runtime value.

Technical details

# Fix the `Encoding.encodeUnknownEffect` return type

## Affected sites
- `packages/effect/src/testing/TestSchema.ts:462` — `encodeUnknownEffect` uses `S["Type"]` instead of `S["Encoded"]`
- `packages/effect/typetest/TestSchema.tst.ts:10` — regression test that verifies `Effect<string, SchemaIssue.Issue>` for `NumberFromString`

## Required outcome
- `TestSchema.Encoding.encodeUnknownEffect` is typed as `Effect.Effect<S["Encoded"], SchemaIssue.Issue, S["EncodingServices"]>`.
- `pnpm test-types packages/effect/typetest/TestSchema.tst.ts` passes.

## Suggested approach
In `packages/effect/src/testing/TestSchema.ts`, change line 462 from:

```ts
) => Effect.Effect<S["Type"], SchemaIssue.Issue, S["EncodingServices"]>
```

to:

```ts
) => Effect.Effect<S["Encoded"], SchemaIssue.Issue, S["EncodingServices"]>
```

## Follow-ups
- Add a `.changeset` entry because this corrects an exported public API type.
- Run `pnpm lint`, `pnpm check`, and `pnpm test-types packages/effect/typetest/TestSchema.tst.ts` after applying the fix.

  ^{｜ ⚠️ this action is pinned to a commit SHA, which freezes the cleanup step — switch to @v0 or keep the SHA fresh with Dependabot ｜ Fix all ➔ ｜ Fix 👍s ➔ ｜ View workflow run ｜ Using Kimi K2 (free via Pullfrog for OSS) ｜ 𝕏}

[pullfrog]

This assertion is the correct regression spec. It currently fails because TestSchema.Encoding.encodeUnknownEffect is still declared with S["Type"] in packages/effect/src/testing/TestSchema.ts:462; once that annotation is corrected to S["Encoded"], this test should pass.