From e6b7f021661a1c81949f9f4dd915d30191816916 Mon Sep 17 00:00:00 2001
From: Tiara Rodney <tiara.rodney@byteb4rb1e.me>
Date: Fri, 13 Mar 2026 23:29:09 +0100
Subject: [PATCH] feat(helper/stream): add browser-compatible Writable
 interface

Define Writable interface, ConsoleWritable (console.log), and
StderrWritable (console.error) as browser-safe stream abstractions.
Export DEFAULT_STREAM backed by StderrWritable to match Python's
sys.stderr default.
---
 src/helper/stream.ts | 33 ++++++++++++++++++++++++++++++++-
 1 file changed, 32 insertions(+), 1 deletion(-)

diff --git a/src/helper/stream.ts b/src/helper/stream.ts
index 297e20c..4102cf4 100644
--- a/src/helper/stream.ts
+++ b/src/helper/stream.ts
@@ -1,2 +1,33 @@
+/**
+ * Minimal writable stream interface for browser compatibility.
+ *
+ * This abstracts over Node.js streams and browser console output,
+ * providing a common write target for handlers.
+ */
+export interface Writable {
+    write(data: string): void;
+}
 
-export type MillisecondsSinceUnixEpoch = number;
+/**
+ * A Writable backed by console.log.
+ */
+export class ConsoleWritable implements Writable {
+    write(data: string): void {
+        console.log(data);
+    }
+}
+
+/**
+ * A Writable backed by console.error (stderr equivalent).
+ */
+export class StderrWritable implements Writable {
+    write(data: string): void {
+        console.error(data);
+    }
+}
+
+/**
+ * Default output stream. Uses console.error to match Python's default
+ * of writing to sys.stderr.
+ */
+export const DEFAULT_STREAM: Writable = new StderrWritable();