From 4f728d8c79a2ef12e108f033145d0a73edf867e6 Mon Sep 17 00:00:00 2001
From: Valerian Saliou <valerian@valeriansaliou.name>
Date: Fri, 7 Aug 2026 15:44:55 +0200
Subject: [PATCH] Fix race condition on large invoices (returning immediately
 before invoice PDF is fully flushed to disk

---
 lib/index.ts | 35 ++++++++++++++++++++++++-----------
 1 file changed, 24 insertions(+), 11 deletions(-)

diff --git a/lib/index.ts b/lib/index.ts
index 31e31d2..75a786e 100644
--- a/lib/index.ts
+++ b/lib/index.ts
@@ -303,22 +303,35 @@ export default class Microinvoice {
       const filePath = (typeof output === "string") ? output : output.path;
       const _stream = fs.createWriteStream(filePath);
 
+      const _promise = new Promise<void>((resolve, reject) => {
+        // Notice: resolve on the write stream 'close' event, not on the \
+        //   document 'end' event. The document only signals that all data \
+        //   has been handed over to the pipe, while the write stream \
+        //   signals that all data has been flushed to disk and that the \
+        //   file descriptor has been closed. Resolving any earlier lets \
+        //   callers read a truncated file.
+        _stream.on("close", () => {
+          return resolve(void 0);
+        });
+
+        _stream.on("error", (error) => {
+          return reject(error);
+        });
+
+        this.document.on("error", (error: Error) => {
+          return reject(error);
+        });
+      });
+
       this.document.pipe(_stream);
       this.document.end();
-    } else {
-      this.document.end();
-      return this.document;
+
+      return _promise;
     }
 
-    return new Promise((resolve, reject) => {
-      this.document.on("end", () => {
-        return resolve(void 0);
-      });
+    this.document.end();
 
-      this.document.on("error", () => {
-        return reject();
-      });
-    });
+    return this.document;
   }
 
   /**