store: Fix: Win percentage parsing robustness and None default in ScorebugData

graph/fixes/fix-win-percentage-parsing-robustness-and-none-default-in-sc-afbc47.md

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+---
+id: afbc470d-05a6-4f5a-8835-b3cdf6ecba8c
+type: fix
+title: "Fix: Win percentage parsing robustness and None default in ScorebugData"
+tags: [major-domo, scorebug, win-probability, fix, parsing, discord-bot]
+importance: 0.65
+confidence: 0.8
+created: "2026-02-20T20:06:11.768716+00:00"
+updated: "2026-02-20T20:06:11.768716+00:00"
+---
+
+# Fix: Win Percentage Parsing Robustness
+
+## Problem
+`ScorebugData.__init__` defaulted `win_percentage` to `50.0` when the field was absent or empty, causing the embed to show a misleading 50/50 probability bar instead of indicating unavailability.
+
+## Changes
+
+### `models/scorebug_data.py` (ScorebugData)
+- Changed default: `data.get("win_percentage")` instead of `data.get("win_percentage", 50.0)`
+- `win_percentage` is now `Optional[float]`, defaulting to `None`
+
+### `services/scorebug_service.py`
+Parsing now handles edge cases:
+- Empty string → `None`
+- Decimal range `0.0–1.0` → multiply by 100 (sheet may give raw probability)
+- Unparseable value → `None` with INFO log
+
+### `utils/scorebug_helpers.py`
+- When `win_percentage is None`, embed shows "-# Win probability unavailable" instead of a bar
+- Embed color logic guards against `None` comparison (no `TypeError` on `win_percentage > 50`)
+
+## Closes
+Issue #39. Branch: `fix/scorebug-bugs`.