trading/services/trade_executor/slack_notifier.py

"""Slack webhook notifier for trade-executor.

Posts a short message on each successful order submit and on
notable risk rejections. No-op when the webhook URL is empty.

Designed to fail-soft: a Slack outage MUST NOT bubble up and crash
the consumer loop. The trade has already happened on Alpaca — Slack
is a downstream observer, not a transactional dependency.
"""

from __future__ import annotations

import logging
from typing import Iterable

import httpx

from shared.constants.kevin import KEVIN_STRATEGY_UUID
from shared.schemas.trading import OrderResult, TradeSignal

logger = logging.getLogger(__name__)


# Reasons we DON'T want to spam Slack about. outside_market_hours fires
# every poll when a fresh signal lands after-hours — silencing it keeps
# Slack signal-to-noise high.
_DEFAULT_QUIET = frozenset({"outside_market_hours"})


class SlackNotifier:
    def __init__(
        self,
        webhook_url: str,
        quiet_rejections: Iterable[str] | None = None,
    ) -> None:
        self.webhook_url = webhook_url or ""
        self.quiet_rejections = frozenset(
            quiet_rejections if quiet_rejections is not None else _DEFAULT_QUIET
        )

    @property
    def enabled(self) -> bool:
        return bool(self.webhook_url)

    async def notify_trade(self, signal: TradeSignal, result: OrderResult) -> None:
        if not self.enabled:
            return
        text = self._format_trade(signal, result)
        await self._post(text)

    async def notify_rejection(self, signal: TradeSignal, reason: str) -> None:
        if not self.enabled:
            return
        if reason in self.quiet_rejections:
            return
        text = self._format_rejection(signal, reason)
        await self._post(text)

    # ------------------------------------------------------------------
    # Internal
    # ------------------------------------------------------------------

    def _strategy_tag(self, signal: TradeSignal) -> str:
        if signal.strategy_id == KEVIN_STRATEGY_UUID:
            return "Meet Kevin"
        return "trading-bot"

    def _format_trade(self, signal: TradeSignal, result: OrderResult) -> str:
        tag = self._strategy_tag(signal)
        price = (
            f"${result.filled_price:.2f}"
            if result.filled_price is not None
            else "—"
        )
        return (
            f":chart_with_upwards_trend: *{tag}*: "
            f"{result.side.value} {result.qty:g} {result.ticker} @ {price}  "
            f"(conviction {signal.strength:.2f}, status {result.status.value})"
        )

    def _format_rejection(self, signal: TradeSignal, reason: str) -> str:
        tag = self._strategy_tag(signal)
        return (
            f":no_entry: *{tag}*: REJECTED {signal.ticker} — {reason} "
            f"(conviction {signal.strength:.2f})"
        )

    async def _post(self, text: str) -> None:
        payload = {"text": text}
        try:
            async with httpx.AsyncClient(timeout=5.0) as client:
                await client.post(self.webhook_url, json=payload)
        except Exception as exc:
            logger.warning("Slack post failed (swallowed): %s", exc)