From 1cf8f269f3c0a249c2aae10a55ccbbb8eca3023b Mon Sep 17 00:00:00 2001
From: DualFroz <me@dualfroz.com>
Date: Thu, 27 Aug 2026 23:35:07 +0200
Subject: [PATCH] fix: emit final 100% download progress for empty response
 body

onDownloadProgress never fired a completion event when the response
body was empty (e.g. a 200 with Content-Length: 0), since the final
callback in the transform stream's flush() was gated behind a chunk
having been read. Report the final progress unconditionally, falling
back to an empty chunk when the stream produced none.

Closes #878
---
 source/utils/body.ts |  4 +++-
 test/stream.ts       | 20 ++++++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/source/utils/body.ts b/source/utils/body.ts
index c3ba19c..035b6d9 100644
--- a/source/utils/body.ts
+++ b/source/utils/body.ts
@@ -70,8 +70,10 @@ const withProgress = (stream: ReadableStream<Uint8Array>, totalBytes: number, on
 		flush() {
 			if (previousChunk) {
 				transferredBytes += previousChunk.byteLength;
-				onProgress?.({percent: 1, totalBytes: Math.max(totalBytes, transferredBytes), transferredBytes}, previousChunk);
 			}
+
+			// Always report completion, even for an empty stream, so consumers can rely on a final 100% event.
+			onProgress?.({percent: 1, totalBytes: Math.max(totalBytes, transferredBytes), transferredBytes}, previousChunk ?? new Uint8Array());
 		},
 	}));
 };
diff --git a/test/stream.ts b/test/stream.ts
index b9b5729..c9bc21c 100644
--- a/test/stream.ts
+++ b/test/stream.ts
@@ -555,6 +555,26 @@ test('onDownloadProgress cancels original response body', async t => {
 	t.true(didReportProgress);
 });
 
+test('onDownloadProgress emits final 100% progress for empty response body', async t => {
+	const server = await createHttpTestServer(t);
+	server.get('/', (_request, response) => {
+		response.status(200).end();
+	});
+
+	const progressEvents: Progress[] = [];
+	await ky(server.url, {
+		onDownloadProgress(progress) {
+			progressEvents.push(progress);
+		},
+	}).text();
+
+	t.true(progressEvents.length > 0, 'Should emit at least one progress event');
+	const finalProgress = progressEvents.at(-1);
+	t.truthy(finalProgress);
+	t.is(finalProgress!.percent, 1);
+	t.is(finalProgress!.transferredBytes, finalProgress!.totalBytes);
+});
+
 test('forced retry custom request keeps upload progress', async t => {
 	const server = await createHttpTestServer(t, {bodyParser: false});
 	let requestCount = 0;