Pure helpers: scaled_weights bridge + envelope-basis flow-excluded compute_exec_return (T1) →
multistrat_exec observed registry track (T2) → record_exec_track books the exec return via A's
run_track + carries position-state (T3) → wire execute_multistrat to the B2a envelope, flatten
on $0, record on --execute (T4). TDD, reuses ExecutionService/AlpacaBroker/A's observed machinery,
no new engine, no capital authorized (paper, dry-run default).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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