feat(config): expose paper broker tuning via env (REQ-010 AC-5, BAT-009)

Wire the existing PaperBroker scenario knobs (fill_after_polls /
qty_per_poll / reject_symbols) to daemon env so REQ-011 AC-2 e2e
scenarios (delayed / partial / reject) can be reproduced by a daemon
restart. Unset == prior PaperBroker() behaviour, byte-for-byte (no
regression).

- config.py: PaperBrokerConfig + from_env parsing (TREX_PAPER_*)
- daemon.py: _build_broker injects config.paper into PaperBroker
- .env.example: document the 3 paper tuning keys (paper-only, e2e)
- tests: paper broker defaults + env tuning parsing

SDLC: REQ-010 CHG-20260606-01 (AC-5 added) / -02 (Implemented);
BAT-009 batch-lite release-candidate; REL-001 feedback handoff records
pre-deployment e2e observations incl. event-publisher idle-drop and
paper correlation_id collision (GitHub #4, #5).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

trex_core/runtime/config.py

@@ -40,6 +40,19 @@ class PortfolioHubConfig:
     timeout: float = 5.0
 
 
+@dataclass(frozen=True)
+class PaperBrokerConfig:
+    """Paper broker tuning for e2e test scenarios (REQ-011).
+
+    Defaults reproduce immediate, full fills with no rejects, so an unset
+    environment is byte-for-byte the prior `PaperBroker()` behaviour.
+    """
+
+    fill_after_polls: int = 0
+    qty_per_poll: Optional[int] = None
+    reject_symbols: frozenset[str] = frozenset()
+
+
 @dataclass(frozen=True)
 class RabbitMQConfig:
     """RabbitMQ transport adapter config (REQ-022, dcy-006 OQ-6)."""
@@ -63,6 +76,8 @@ class DaemonConfig:
     broker: str                      # 'paper' | 'kis'
     execution_interval_sec: float
     kis: Optional[KISConfig] = None
+    # REQ-011: paper broker tuning (only consulted when broker == 'paper').
+    paper: PaperBrokerConfig = PaperBrokerConfig()
     # REQ-017/019: ledger writer config (None => in-memory stub ledger,
     # appropriate for slice-1 paper-broker integration tests).
     portfolio_hub: Optional[PortfolioHubConfig] = None
@@ -93,6 +108,15 @@ class DaemonConfig:
                 allow_live=os.environ.get("TREX_KIS_ALLOW_LIVE", "").lower() in ("1", "true", "yes"),
                 redis_url=os.environ.get("TREX_KIS_REDIS_URL", ""),
             )
+        qpp_raw = os.environ.get("TREX_PAPER_QTY_PER_POLL", "").strip()
+        reject_raw = os.environ.get("TREX_PAPER_REJECT_SYMBOLS", "")
+        paper = PaperBrokerConfig(
+            fill_after_polls=int(os.environ.get("TREX_PAPER_FILL_AFTER_POLLS", "0")),
+            qty_per_poll=int(qpp_raw) if qpp_raw else None,
+            reject_symbols=frozenset(
+                s.strip() for s in reject_raw.split(",") if s.strip()
+            ),
+        )
         portfolio_hub: Optional[PortfolioHubConfig] = None
         pf_base = os.environ.get("TREX_PORTFOLIO_HUB_BASE_URL", "").strip()
         if pf_base:
@@ -118,6 +142,7 @@ class DaemonConfig:
             broker=broker,
             execution_interval_sec=float(os.environ.get("TREX_EXECUTION_INTERVAL_SEC", "1.0")),
             kis=kis,
+            paper=paper,
             portfolio_hub=portfolio_hub,
             ledger_interval_sec=float(os.environ.get("TREX_LEDGER_INTERVAL_SEC", "1.0")),
             rabbitmq=rabbitmq,

trex_core/runtime/daemon.py

@@ -78,7 +78,11 @@ def _build_broker(config: DaemonConfig) -> BrokerPort:
             base_url=k.base_url, timeout=k.timeout, allow_live=k.allow_live,
             token_cache=token_cache,
         )
-    return PaperBroker()
+    return PaperBroker(
+        fill_after_polls=config.paper.fill_after_polls,
+        qty_per_poll=config.paper.qty_per_poll,
+        reject_symbols=set(config.paper.reject_symbols),
+    )
 
 
 def _build_ledger(config: DaemonConfig) -> LedgerPort: