Records PLAN.md section 17 and marks the phase row done. Four decisions (D12-D15),
what is on the pages, and the four defects only a live walk could find — two of
them in code phase 3 had already shipped: an unreachable refresh that erased the
server's description, and a "last reported" line reading the timestamp of our own
poll rather than of the server's last frame.
Also written down: why core's useAsync cannot poll, the real per-page cost of a
live count in the footer slot, and the test fake that was *nearly* core.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016wDDVXWMDz82WqE1i969r4