From 9e79ea527d47988daabc9434f89415276b0f35fe Mon Sep 17 00:00:00 2001
From: Charles Lowell <cowboyd@frontside.com>
Date: Wed, 23 Sep 2026 13:48:00 -0500
Subject: [PATCH] =?UTF-8?q?=F0=9F=8F=B7=EF=B8=8F=20Infer=20parameter=20out?=
 =?UTF-8?q?puts=20from=20schemas?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 lib/param.ts | 15 ++++++++-------
 lib/types.ts |  6 +++++-
 2 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/lib/param.ts b/lib/param.ts
index 271a4c9..59d75b4 100644
--- a/lib/param.ts
+++ b/lib/param.ts
@@ -8,7 +8,7 @@ import {
   type Unary,
 } from "./pipeline.ts";
 import type { CLIBinding } from "./read.ts";
-import type { Definition, Schema } from "./types.ts";
+import type { Definition, OutputOf, Schema } from "./types.ts";
 
 export interface Param<K extends string, T> extends Definition<K> {
   schema: Schema<T>;
@@ -49,18 +49,19 @@ export function param<
   ) as Fold<Param<K, unknown>, E>;
 }
 
-export function schema<T>(
-  schema: Schema<T>,
-): TransformElement<SchemaTransform<T>> {
-  return mark<SchemaTransform<T>>((param: Param<string, unknown>) => ({
+export function schema<S extends Schema>(
+  schema: S,
+): TransformElement<SchemaTransform<S>> {
+  return mark<SchemaTransform<S>>((param: Param<string, unknown>) => ({
     ...param,
     schema,
   }));
 }
 
-interface SchemaTransform<T> extends Transform {
+interface SchemaTransform<S extends Schema> extends Transform {
   readonly input: Param<string, unknown>;
-  readonly output: this["input"] extends Param<infer N, unknown> ? Param<N, T>
+  readonly output: this["input"] extends Param<infer N, unknown>
+    ? Param<N, OutputOf<S>>
     : never;
 }
 
diff --git a/lib/types.ts b/lib/types.ts
index ef4b636..f04f3e2 100644
--- a/lib/types.ts
+++ b/lib/types.ts
@@ -6,7 +6,11 @@ import type { Result } from "./result.ts";
 import type { ValueSource } from "./values.ts";
 
 export type Issue = StandardSchemaV1.Issue;
-export type Schema<T> = StandardSchemaV1<T, T>;
+export type Schema<Input = unknown, Output = Input> = StandardSchemaV1<
+  Input,
+  Output
+>;
+export type OutputOf<S extends Schema> = StandardSchemaV1.InferOutput<S>;
 
 export interface Definition<N extends string> {
   readonly name: N;