feat(client): infer utilities (#1096)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
* Introduced client type-inference utilities for inputs, body inputs,
outputs, body outputs, error maps, and aggregated error unions for oRPC
clients. No runtime changes.

* **Documentation**
* Added a "Utilities" section to client docs with descriptions and code
examples for the new inference helpers.

* **Tests**
  * Added type-level tests validating the new inference utilities.

* **Chores**
  * Expanded public type surface without breaking existing APIs.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: dinwwwh

README.md

@@ -211,7 +211,7 @@ This is a quick overview of how to use oRPC. For more details, please refer to t
 oRPC is inspired by existing solutions that prioritize type safety and developer experience. Special acknowledgments to:
 
 - [tRPC](https://trpc.io): For pioneering the concept of end-to-end type-safe RPC and influencing the development of type-safe APIs.
-- [ts-rest](https://ts-rest.com): For its emphasis on contract-first development and OpenAPI integration, which have greatly inspired oRPC’s feature set.
+- [ts-rest](https://ts-rest.com): For its emphasis on contract-first development and OpenAPI integration, which have greatly inspired oRPC's feature set.
 
 ## License
 

apps/content/docs/adapters/browser.md

@@ -87,7 +87,7 @@ clientPort.start()
 
 ## Advanced Relay Pattern
 
-In some advanced cases, direct communication between scripts isn’t possible. For example, a content script running in the ["MAIN" world](https://developer.chrome.com/docs/extensions/reference/manifest/content-scripts#world-timings) cannot directly communicate with the background script using `browser.runtime` or `chrome.runtime` APIs.
+In some advanced cases, direct communication between scripts isn't possible. For example, a content script running in the ["MAIN" world](https://developer.chrome.com/docs/extensions/reference/manifest/content-scripts#world-timings) cannot directly communicate with the background script using `browser.runtime` or `chrome.runtime` APIs.
 
 To work around this, you can use a **relay pattern** typically an additional content script running in the default **"ISOLATED" (default) world** to relay messages between the two contexts. This **relay pattern** acts as an intermediary, enabling communication where direct access is restricted.
 

apps/content/docs/best-practices/optimize-ssr.md

@@ -35,7 +35,7 @@ But how? A naive `typeof window === 'undefined'` check works, but exposes your r
 
 ## Implementation
 
-We’ll use `globalThis` to share the server client without bundling it into client code.
+We'll use `globalThis` to share the server client without bundling it into client code.
 
 ::: code-group
 

apps/content/docs/client/client-side.md

@@ -97,3 +97,103 @@ export const orpc = {
   c: clientC,
 }
 ```
+
+## Utilities
+
+::: info
+These utilities can be used for any kind of oRPC client.
+:::
+
+### Infer Client Inputs
+
+```ts twoslash
+import type { orpc as client } from './shared/planet'
+// ---cut---
+import type { InferClientInputs } from '@orpc/client'
+
+type Inputs = InferClientInputs<typeof client>
+
+type FindPlanetInput = Inputs['planet']['find']
+```
+
+Recursively infers the **input types** from a client. Produces a nested map where each endpoint's input type is preserved.
+
+### Infer Client Body Inputs
+
+```ts twoslash
+import type { orpc as client } from './shared/planet'
+// ---cut---
+import type { InferClientBodyInputs } from '@orpc/client'
+
+type BodyInputs = InferClientBodyInputs<typeof client>
+
+type FindPlanetBodyInput = BodyInputs['planet']['find']
+```
+
+Recursively infers the **body input types** from a client. If an endpoint's input includes `{ body: ... }`, only the `body` portion is extracted. Produces a nested map of body input types.
+
+### Infer Client Outputs
+
+```ts twoslash
+import type { orpc as client } from './shared/planet'
+// ---cut---
+import type { InferClientOutputs } from '@orpc/client'
+
+type Outputs = InferClientOutputs<typeof client>
+
+type FindPlanetOutput = Outputs['planet']['find']
+```
+
+Recursively infers the **output types** from a client. Produces a nested map where each endpoint's output type is preserved.
+
+### Infer Client Body Outputs
+
+```ts twoslash
+import type { orpc as client } from './shared/planet'
+// ---cut---
+import type { InferClientBodyOutputs } from '@orpc/client'
+
+type BodyOutputs = InferClientBodyOutputs<typeof client>
+
+type FindPlanetBodyOutput = BodyOutputs['planet']['find']
+```
+
+Recursively infers the **body output types** from a client. If an endpoint's output includes `{ body: ... }`, only the `body` portion is extracted. Produces a nested map of body output types.
+
+### Infer Client Errors
+
+```ts twoslash
+import type { orpc as client } from './shared/planet'
+// ---cut---
+import type { InferClientErrors } from '@orpc/client'
+
+type Errors = InferClientErrors<typeof client>
+
+type FindPlanetError = Errors['planet']['find']
+```
+
+Recursively infers the **error types** from a client when using [type-safe error handling](/docs/error-handling#type‐safe-error-handling). Produces a nested map where each endpoint's error type is preserved.
+
+### Infer Client Error Union
+
+```ts twoslash
+import type { orpc as client } from './shared/planet'
+// ---cut---
+import type { InferClientErrorUnion } from '@orpc/client'
+
+type AllErrors = InferClientErrorUnion<typeof client>
+```
+
+Recursively infers a **union of all error types** from a client when using [type-safe error handling](/docs/error-handling#type‐safe-error-handling). Useful when you want to handle all possible errors from any endpoint at once.
+
+### Infer Client Context
+
+```ts twoslash
+import type { orpc as client } from './shared/planet'
+// ---cut---
+import type { InferClientContext } from '@orpc/client'
+
+type Context = InferClientContext<typeof client>
+```
+
+Infers the client context type from a client.

apps/content/docs/client/rpc-link.md

@@ -43,7 +43,7 @@ export const client: RouterClient<typeof router> = createORPCClient(link)
 
 ## Using Client Context
 
-Client context lets you pass extra information when calling procedures and dynamically modify RPCLink’s behavior.
+Client context lets you pass extra information when calling procedures and dynamically modify RPCLink's behavior.
 
 ```ts twoslash
 import { router } from './shared/planet'

apps/content/docs/context.md

@@ -5,7 +5,7 @@ description: Understanding context in oRPC
 
 # Context in oRPC
 
-oRPC’s context mechanism provides a type-safe dependency injection pattern. It lets you supply required dependencies either explicitly or dynamically through middleware. There are two types:
+oRPC's context mechanism provides a type-safe dependency injection pattern. It lets you supply required dependencies either explicitly or dynamically through middleware. There are two types:
 
 - **Initial Context:** Provided explicitly when invoking a procedure.
 - **Execution Context:** Generated during procedure execution, typically by middleware.
@@ -80,7 +80,7 @@ const getting = base.handler(async ({ context }) => {
 export const router = { getting }
 ```
 
-When using execution context, you don’t need to pass any context manually:
+When using execution context, you don't need to pass any context manually:
 
 ```ts twoslash
 import { os } from '@orpc/server'

apps/content/docs/contract-first/implement-contract.md

@@ -47,7 +47,7 @@ const os = implement(contract) // fully replaces the os from @orpc/server
 
 ## Implementing Procedures
 
-Define a procedure by attaching a `.handler` to its corresponding contract, ensuring it adheres to the contract’s specifications.
+Define a procedure by attaching a `.handler` to its corresponding contract, ensuring it adheres to the contract's specifications.
 
 ```ts twoslash
 import { contract } from './shared/planet'

apps/content/docs/error-handling.md

@@ -48,7 +48,7 @@ Do not pass sensitive data in the `ORPCError.data` field.
 
 ## Type‑Safe Error Handling
 
-For a fully type‑safe error management experience, define your error types using the `.errors` method. This lets the client infer the error’s structure and handle it accordingly. You can use any [Standard Schema](https://github.com/standard-schema/standard-schema?tab=readme-ov-file#what-schema-libraries-implement-the-spec) library to validate error data.
+For a fully type‑safe error management experience, define your error types using the `.errors` method. This lets the client infer the error's structure and handle it accordingly. You can use any [Standard Schema](https://github.com/standard-schema/standard-schema?tab=readme-ov-file#what-schema-libraries-implement-the-spec) library to validate error data.
 
 ```ts twoslash
 import { os } from '@orpc/server'

apps/content/docs/integrations/pinia-colada.md

@@ -5,7 +5,7 @@ description: Seamlessly integrate oRPC with Pinia Colada
 
 # Pinia Colada Integration
 
-[Pinia Colada](https://pinia-colada.esm.dev/) is the data fetching layer for Pinia and Vue. oRPC’s integration with Pinia Colada is lightweight and straightforward - there’s no extra overhead.
+[Pinia Colada](https://pinia-colada.esm.dev/) is the data fetching layer for Pinia and Vue. oRPC's integration with Pinia Colada is lightweight and straightforward - there's no extra overhead.
 
 ::: warning
 This documentation assumes you are already familiar with [Pinia Colada](https://pinia-colada.esm.dev/). If you need a refresher, please review the official Pinia Colada documentation before proceeding.

apps/content/docs/integrations/tanstack-query-old/basic.md

@@ -5,7 +5,7 @@ description: Seamlessly integrate oRPC with Tanstack Query
 
 # Tanstack Query Integration
 
-[Tanstack Query](https://tanstack.com/query/latest) is a robust solution for asynchronous state management. oRPC’s integration with Tanstack Query is lightweight and straightforward - there’s no extra overhead.
+[Tanstack Query](https://tanstack.com/query/latest) is a robust solution for asynchronous state management. oRPC's integration with Tanstack Query is lightweight and straightforward - there's no extra overhead.
 
 | Library | Tanstack Query | oRPC Integration          |
 | ------- | -------------- | ------------------------- |