The trail-breach (and first-red) exit called close_position directly, but the
bracket stop/TP legs RESERVE the full quantity (held_for_orders). Alpaca then
rejects the market close 403 "insufficient qty available (available: 0)". The
position can never exit, so the manager retried every pass forever — observed
live: PLUG logged 191 identical 403s while a legitimate trail exit (+286) and
WPRT/ATPC stop-outs were all blocked.
Add _flatten(): cancel the symbol's active protective sell legs to release the
shares, THEN liquidate (retry the close so a not-yet-settled cancel doesn't
hang). Route the two full-close paths through it. Verified live: PLUG flattened
cleanly (0 dangling orders, profit locked), zero 403s after restart, remaining
book still fully stop-protected. Test: _flatten cancels protective then closes;
42 pass.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
