feat(slots): additive strategy fields + filter (REQ-116, BAT-055)

trex.slots.req wire 계약 additive 확장 — 기존 소비자(orb/tsl) backward compatible.

- PortfolioItem: strategy_name(Optional[str]) + markets(list) 필드 추가
- hub_read.py: get_portfolios()에서 strategy_name/markets 파싱 추가 (safe default)
- slot_to_dict(): strategy_name/strategy_params/markets 3필드 row에 추가 (SnapshotStore→PortfolioItem 경유)
- make_slots_rpc_handler(): strategy 요청 파라미터 → Python 레벨 후처리 필터 (available_slots 계산 이후, REQ-073 AC-6 불변)
- 테스트: AC-1~8 전수 + hub_read 파싱 + 회귀 갱신 (777 passed, 47 skipped)
- docs/interface-contract.md: 요청 파라미터·응답 행 스키마·소스 테이블·REQ-074 AC-5 주석 갱신

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VHtM5Ws1HKCKQ4JGi6GRb5

trex_core/application/messaging_handlers.py

@@ -228,11 +228,14 @@ def make_slots_rpc_handler(
     max_active_slots: Optional[int] = None,
     strategy_state_store=None,
 ):
-    """Build the RPC handler for `trex.slots.req` (REQ-073/074).
+    """Build the RPC handler for `trex.slots.req` (REQ-073/074/116).
 
-    Request: {filter?: str, spy?: bool}
+    Request: {filter?: str, spy?: bool, strategy?: str}
       filter: "all"|"inactive"|"pending"|"holding"|"error" (default "all")
       spy=true: watchdog not updated (operator view, REQ-034 CHG-01)
+      strategy: exact-match on strategy_name (REQ-116, optional). When specified
+        only slots whose strategy_name == strategy are returned. AND-combined with
+        filter. available_slots is always computed before this filter (REQ-073 AC-6).
 
     Response: {slots: [...], available_slots: int|null, degraded: bool,
                reason: str|null, message: str|null}
@@ -244,6 +247,9 @@ def make_slots_rpc_handler(
         body = req.payload or {}
         filter_val = str(body.get("filter") or "all").lower()
         spy = bool(body.get("spy", False))
+        # REQ-116 (BAT-055): optional strategy filter — exact-match on strategy_name.
+        # None means no filter (all slots returned regardless of strategy_name).
+        strategy_filter = _opt_str(body.get("strategy"))
 
         # issue #25: filter by status at the DB (REQ-002/006 list_slots
         # status_filter) instead of fetching every row and filtering in Python.
@@ -320,11 +326,19 @@ def make_slots_rpc_handler(
             reason = reason_code.value if reason_code is not None else None
             message = msg
 
+        # REQ-073 AC-6: available_slots computed from instance-wide active count —
+        # independent of strategy filter (REQ-116). Calculate before filtering.
         if max_active_slots is not None and max_active_slots > 0:
             available_slots = max(0, max_active_slots - slot_repo.count_active(instance_key))
         else:
             available_slots = None
 
+        # REQ-116 (BAT-055): strategy filter — Python-level post-filter after
+        # available_slots is already computed. AND-combined with status filter.
+        # Unmatched strategy (no slots) returns [] without error.
+        if strategy_filter is not None:
+            slot_rows = [r for r in slot_rows if r.get("strategy_name") == strategy_filter]
+
         return RpcResponse(payload={
             "slots": slot_rows,
             "available_slots": available_slots,