From d94be89a60cf466ad4ad60814ede869f6d695d72 Mon Sep 17 00:00:00 2001
From: Chris Lu <chris.lu@gmail.com>
Date: Mon, 16 Mar 2026 17:43:40 -0700
Subject: [PATCH] Add CompactMapSegment overflow panic guard matching Go

---
 seaweed-volume/src/storage/needle_map/compact_map.rs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/seaweed-volume/src/storage/needle_map/compact_map.rs b/seaweed-volume/src/storage/needle_map/compact_map.rs
index debd5bf06..9dea94ce7 100644
--- a/seaweed-volume/src/storage/needle_map/compact_map.rs
+++ b/seaweed-volume/src/storage/needle_map/compact_map.rs
@@ -114,6 +114,14 @@ impl Segment {
             size,
         };
 
+        // Match Go panic: don't exceed segment capacity
+        if self.list.len() >= SEGMENT_CHUNK_SIZE as usize {
+            panic!(
+                "attempted to write more than {} entries on CompactMapSegment",
+                SEGMENT_CHUNK_SIZE
+            );
+        }
+
         if self.list.len() == SEGMENT_CHUNK_SIZE as usize - 1 {
             // Pin capacity to exact size when maxing out
             let mut new_list = Vec::with_capacity(SEGMENT_CHUNK_SIZE as usize);