# QUEUE-09 — Long-short construction: capture the long-short edge net of costs

**Status:** QUEUED · **Priority:** P2 · **Effort:** custom strategy module + run

## Hypothesis (prove)
The compact stochastic signal's long-short spread is the real edge (L/S ann
Sharpe 4.54, exp 24; "edge is long-short, not long-only" — chat-ideas.md), but
all canonical constructions are long-only (TopkDropout buys topk, drops, holds).
A market-neutral book (long topk, short bottom topk) should realize more of the
spread net of costs than the long-only book, IF short-side financing + doubled
turnover cost stays below the added spread capture.

## Change vs exp-26 reference (ONE variable)
- **Strategy**: long-only TopkDropout (topk 10, n_drop 1) → custom
  `TopBottomDropoutStrategy` (long topk by rank, short bottom topk, equal
  weight per side, same risk_degree), realized in a workflow with a cost model
  that includes both sides (open/close cost symmetric).
- All signal/config unchanged.

## Acceptance
- `net_IR > 0.21` AND `net_ann_return > +2.13%` AND `total_cost` within ~2× the
  reference (doubled side count is the structural cost of this construction).
- Watch: benchmark neutrality (SPY beta ≈ 0) as a secondary sanity metric.

## Execution prerequisites
1. New contrib module `tac_qlib/contrib/strategy/top_bottom.py`
   (`TopBottomDropoutStrategy` subclassing `BaseSignalStrategy`), copy to the
   venv site-packages copy.
2. Workflow YAML wiring the strategy; PortAnaRecord benchmark SPY.
3. Trace + run + snapshot.