From 2b6b680341329015f7f5abd09b96bfa461767854 Mon Sep 17 00:00:00 2001
From: daylily <i@dayli.ly>
Date: Sat, 10 Jan 2026 23:16:04 +0800
Subject: [PATCH] Fix a small calculation error for buffer size

---
 firmware/src/app.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/firmware/src/app.rs b/firmware/src/app.rs
index 4d2eeed..f569ce3 100644
--- a/firmware/src/app.rs
+++ b/firmware/src/app.rs
@@ -124,7 +124,7 @@ impl App {
 
     async fn write_response<'a>(&mut self, resp: Response<'a>) {
         const SYSEX_MAX: usize = 1024 - 2; // 2-byte framing
-        const POSTCARD_WIRE_MAX: usize = SYSEX_MAX * 7 / 8; // 7-in-8 encoding overhead
+        const POSTCARD_WIRE_MAX: usize = (SYSEX_MAX - MAGIC_NUMBER_LEN) * 7 / 8; // 7-in-8 encoding overhead
         const USB_WIRE_MAX: usize = (SYSEX_MAX * 4).div_ceil(3); // USB MIDI muxing overhead
 
         let mut resp_buffer = [0u8; POSTCARD_WIRE_MAX];