docs: add per-task middleware section to tasks overview (#3197)

docs/tasks/overview.mdx

@@ -168,7 +168,7 @@ You can override this per-trigger by passing `ttl` in the trigger options, or se
 
 You can register global lifecycle hooks that are executed for all runs, regardless of the task. While you can still define these in the `trigger.config.ts` file, you can also register them anywhere in your codebase:
 
-```ts
+```typescript
 import { tasks } from "@trigger.dev/sdk";
 
 tasks.onStartAttempt(({ ctx, payload, task }) => {
@@ -262,7 +262,7 @@ tasks.onResume("db", async ({ ctx, payload, task }) => {
 
 You can access the database client using `getDb()` in your tasks `run` function and all your hooks (global or task specific):
 
-```ts
+```typescript
 import { getDb } from "./db";
 
 export const myTask = task({
@@ -273,6 +273,28 @@ export const myTask = task({
 });
 ```
 
+#### Per-task middleware
+
+You can also define middleware per task by passing the `middleware` option in the task definition. This runs after global middleware and before the `run` function. Use it when only specific tasks need certain locals or setup:
+
+```typescript
+import { task, locals } from "@trigger.dev/sdk";
+
+const myLocal = locals.create<string>("myLocal");
+
+export const myTask = task({
+  id: "my-task",
+  middleware: async ({ payload, ctx, next }) => {
+    locals.set(myLocal, "some-value");
+    await next();
+  },
+  run: async (payload) => {
+    const value = locals.getOrThrow(myLocal);
+    // ...
+  },
+});
+```
+
 ### `onStartAttempt` function
 
 <Info>The `onStartAttempt` function was introduced in v4.1.0</Info>
@@ -323,7 +345,7 @@ export const taskWithOnStartAttempt = task({
 
 These lifecycle hooks allow you to run code when a run is paused or resumed because of a wait:
 
-```ts
+```typescript
 export const myTask = task({
   id: "my-task",
   onWait: async ({ wait }) => {
@@ -466,7 +488,7 @@ Read more about `catchError` in our [Errors and Retrying guide](/errors-retrying
 
 You can define an `onCancel` hook that is called when a run is cancelled. This is useful if you want to clean up any resources that were allocated for the run.
 
-```ts
+```typescript
 tasks.onCancel(({ ctx, signal }) => {
   console.log("Run cancelled", signal);
 });
@@ -474,7 +496,7 @@ tasks.onCancel(({ ctx, signal }) => {
 
 You can use the `onCancel` hook along with the `signal` passed into the run function to interrupt a call to an external service, for example using the [streamText](https://ai-sdk.dev/docs/reference/ai-sdk-core/stream-text) function from the AI SDK:
 
-```ts
+```typescript
 import { logger, tasks, schemaTask } from "@trigger.dev/sdk";
 import { streamText } from "ai";
 import { z } from "zod";
@@ -528,7 +550,7 @@ export const interruptibleChat = schemaTask({
 
 The `onCancel` hook can optionally wait for the `run` function to finish, and access the output of the run:
 
-```ts
+```typescript
 import { logger, task } from "@trigger.dev/sdk";
 import { setTimeout } from "node:timers/promises";