From b18a0ee6ebdced3ee3fece4c54114cbd7abac800 Mon Sep 17 00:00:00 2001
From: cmorten <craig.morten@hotmail.co.uk>
Date: Sun, 16 Aug 2026 21:22:06 +0100
Subject: [PATCH] feat: implement backoff retry for install subcommand
 downloads

---
 src/commands/install/download-asset.ts | 78 ++++++++++++++++++++------
 1 file changed, 62 insertions(+), 16 deletions(-)

diff --git a/src/commands/install/download-asset.ts b/src/commands/install/download-asset.ts
index 2c0a331..1ad66a9 100644
--- a/src/commands/install/download-asset.ts
+++ b/src/commands/install/download-asset.ts
@@ -1,4 +1,4 @@
-import { createWriteStream } from "node:fs";
+import { createWriteStream, rmSync } from "node:fs";
 import { pipeline } from "node:stream/promises";
 import { EnvHttpProxyAgent, fetch } from "undici";
 import type { Asset } from "./types";
@@ -6,27 +6,73 @@ import { ERR_INSTALL_FAILED_TO_DOWNLOAD_ASSET } from "../../errors";
 
 const dispatcher = new EnvHttpProxyAgent();
 
+const DOWNLOAD_BACKOFFS = [500, 1000, 2000, 5000, 8000];
+
+function isRetryableDownloadError(error: unknown): boolean {
+  if (!(error instanceof Error)) {
+    return false;
+  }
+
+  const code = "code" in error ? error.code : undefined;
+
+  return [
+    "ECONNRESET",
+    "ECONNREFUSED",
+    "ECONNABORTED",
+    "ETIMEDOUT",
+    "EAI_AGAIN",
+  ].includes(code as string);
+}
+
+function delay(ms: number): Promise<void> {
+  return new Promise((resolve) => setTimeout(resolve, ms));
+}
+
 export async function downloadAsset(
   asset: Asset,
   source: string,
   destination: string,
 ): Promise<void> {
-  const response = await fetch(source, {
-    dispatcher,
-  });
+  let lastError: unknown;
 
-  if (!response.ok || !response.body) {
-    throw new Error(
-      `${ERR_INSTALL_FAILED_TO_DOWNLOAD_ASSET}: ${asset.asset} (${response.status} ${response.statusText})`,
-    );
-  }
+  for (let attempt = 0; attempt <= DOWNLOAD_BACKOFFS.length; attempt++) {
+    try {
+      const response = await fetch(source, {
+        dispatcher,
+      });
 
-  try {
-    await pipeline(response.body, createWriteStream(destination));
-  } catch (cause) {
-    throw new Error(
-      `${ERR_INSTALL_FAILED_TO_DOWNLOAD_ASSET}: ${asset.asset} (${response.status} ${response.statusText})`,
-      { cause },
-    );
+      if (!response.ok || !response.body) {
+        if (response.status >= 500 && attempt < DOWNLOAD_BACKOFFS.length) {
+          await delay(DOWNLOAD_BACKOFFS[attempt]);
+
+          continue;
+        }
+
+        throw new Error(
+          `${ERR_INSTALL_FAILED_TO_DOWNLOAD_ASSET}: ${asset.asset} (${response.status} ${response.statusText})`,
+        );
+      }
+
+      await pipeline(response.body, createWriteStream(destination));
+
+      return;
+    } catch (cause) {
+      lastError = cause;
+
+      rmSync(destination, { force: true });
+
+      if (
+        !isRetryableDownloadError(cause) ||
+        attempt >= DOWNLOAD_BACKOFFS.length
+      ) {
+        break;
+      }
+
+      await delay(DOWNLOAD_BACKOFFS[attempt]);
+    }
   }
+
+  throw new Error(`${ERR_INSTALL_FAILED_TO_DOWNLOAD_ASSET}: ${asset.asset}`, {
+    cause: lastError,
+  });
 }