Document why snapshot_candidate intentionally performs a diagnostic-only deserialize before authoritative validation: the schema pins source_dirty to const:false, while the early check preserves the source-specific failure. Remove the dead first-publication setup from the mutable-object publication and resign test, and correct the archive-channel documentation to specify its sole staging-directory argument and verified ARCHIVED receipt on stdout. Co-Authored-By: OpenAI Codex <noreply@openai.com>