Followup #5: after locking alpha, walking into beta's ring, stopping and
pressing Tab could still return `out_of_range` even when client and server
agreed on position (Δ=0). The freshness-kick move-stream POST and the
target/select POST race on separate HTTP connections so the select can be
validated against a stale stored snap.
Extend TargetSelectRequest v1 with an optional positionHint {x,y,z}.
Server uses the hint for the radius check and for the echoed
targetState.validity; the hint is advisory and does not write to the
position store (move-stream stays the sole write path). Client attaches
the hint automatically whenever set_freshness_kick(...) is wired, so
headless unit tests that skip the wiring fall through to the no-hint
behavior. Freshness kick is kept in place to refresh the stored snap for
later validity GETs but is no longer load-bearing for denial correctness.
Server: 3 new tests (hint accepts when stored is stale, hint-far denies,
hint never writes to position store). Client: 1 new test asserting the
hint is in the POST body when wired. All 62 server + 96 client tests
pass.
Plan Decision 8, review follow-up #5, manual QA section 6, and NEO-23
contract notes updated. New bruno request exercises the hint path.
VinPropane
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