Fixing M-1 (redact() Content-Disposition cut index), T3.5 (errorText defensive wrap), and M-2 (design.md stale signatures) per the final whole-branch reviewer's own bundling recommendation. Deferring M-3, M-4, M-5 as cosmetic/unreachable/forward-looking with no current impact. Refs #5 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01QKHeGuAYh4W1jNdjMConZa