Replace REQ-BLD-TUNNEL-AUTO-SWITCH with REQ-BLD-TUNNEL-MODE: one Tunnel button whose ghost defaults to Tunnel Entry and auto-switches to Tunnel Exit based on which end the hovered position would complete (via REQ-BLD-TUNNEL-PAIR), with a green connection preview and sub-tile mouse-proximity tie-break. Update REQ-UI-HOTKEYS (3 = Tunnel, 4 unused) and REQ-UI-BUILD-GRID (shared Tunnel button). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Y7N59FsLA5e2kuVdqe4Uhc