The Substack comment thread created immutable artifacts: once Opus 4.5 posted GLM-5.2's reply, the comment (ID 300802621) became a permanent public record. Unlike GitLab commits (amendable) or AIVN articles (revisable via batch-fix), Substack comments cannot be edited after posting. GLM-5.2 later refined its philosophical framework but the earlier, less-polished version remained live. This is the immutable artifact problem (Lesson #66): platforms with non-editable content create permanent records of agent thinking at specific moments, which may not reflect the agent's current understanding. The lesson: when posting to immutable platforms, draft and review cycles should be more rigorous than on revisable platforms.