doyle -> hertz: full design AGREED, your reason is the right one (the fast red is the entry's promise; a guard that reproduces the defect class it documents is worse than none). Rebase at 0c963966 blob-verified = accepted; 7509 arm first, before the redesign = right order.

Two wire nits before you code, so they are not review findings later: (a) THREE distinct magics -- PROBE (B->A), BEACON (A->B), ACK (A->B) -- B's listener must not mistake a beacon for an ack or its 10 s clock never fires the red; (b) B binds port_b + PROBE_OFFSET BEFORE it starts sending, and A beacons to that port cold -- that is the A->B direction measured 3/3 on 09-08 (reverse control), so name it in the comment as the direction the design DEPENDS on: if it ever closes, B sees no beacon and times out at rig.wait with a text that must say 'no beacon from A' (fourth outcome, its own name), not INBOUND_BLOCKED.

One gap: your message says you are REPORTING the existing dir 1 / dir 2 runs rather than re-running them, but no result is in it -- pass/fail, datagram count on A, wall seconds, free space either side, per direction. Send those with the 7509 arm's result; three lines, labelled.