From c19c4ce9277424cd3784ff17238956d9fc53fa89 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Wed, 25 Mar 2026 22:00:08 +0000
Subject: [PATCH 1/2] Initial plan


From 4a86266c88bbece5d507141970a7a4d61edc8f91 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Wed, 25 Mar 2026 22:04:33 +0000
Subject: [PATCH 2/2] Fix nbodies==0 chunk dims exceeding zero-length HDF5
 dataspace

Co-authored-by: The9Cat <25960766+The9Cat@users.noreply.github.com>
Agent-Logs-Url: https://github.com/EXP-code/EXP/sessions/010b5b10-88a6-4331-b7ed-e0d62fae5309
---
 src/Component.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/Component.cc b/src/Component.cc
index 5daccbaeb..56e92ab26 100644
--- a/src/Component.cc
+++ b/src/Component.cc
@@ -2501,7 +2501,7 @@ void Component::write_HDF5(HighFive::Group& group, bool masses, bool IDs)
   auto dcplI = HighFive::DataSetCreateProps{};
   auto dcplD = HighFive::DataSetCreateProps{};
 
-  if (H5compress or H5chunk) {
+  if ((H5compress or H5chunk) and nbodies > 0) {
     int chunk = H5chunk;
 
     // Clamp chunk to [1, nbodies]: use nbodies/8 as a downsize when
@@ -2642,7 +2642,7 @@ void Component::write_H5(H5::Group& group)
 
     // This could be generalized by registering a user filter, like
     // blosc.  Right now, we're using the default (which is gzip)
-    if (H5compress or H5chunk) {
+    if ((H5compress or H5chunk) and h5_particles.size() > 0) {
       // Set chunking
       if (H5chunk) {
 	// Clamp chunk to [1, nbodies]: use nbodies/8 as a downsize when