chore: enforce erasable TypeScript syntax

packages/ai/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Changed
+
+- Changed source syntax to avoid TypeScript constructs that require JavaScript emit, keeping the package compatible with Node.js strip-only TypeScript checks.
+
 ### Fixed
 
 - Fixed OpenAI-compatible `streamSimple()` requests to stop sending model-derived default output token caps, avoiding context-window reservation failures on servers such as vLLM while preserving explicit `maxTokens` and required Anthropic `max_tokens` handling ([#4675](https://github.com/earendil-works/pi/issues/4675)).

packages/ai/src/utils/event-stream.ts

@@ -7,11 +7,12 @@ export class EventStream<T, R = T> implements AsyncIterable<T> {
 	private done = false;
 	private finalResultPromise: Promise<R>;
 	private resolveFinalResult!: (result: R) => void;
+	private isComplete: (event: T) => boolean;
+	private extractResult: (event: T) => R;
 
-	constructor(
-		private isComplete: (event: T) => boolean,
-		private extractResult: (event: T) => R,
-	) {
+	constructor(isComplete: (event: T) => boolean, extractResult: (event: T) => R) {
+		this.isComplete = isComplete;
+		this.extractResult = extractResult;
 		this.finalResultPromise = new Promise((resolve) => {
 			this.resolveFinalResult = resolve;
 		});