feat: add lead policy helpers

backend/app/services/lead_policy.py

@@ -0,0 +1,27 @@
+from __future__ import annotations
+
+import hashlib
+from typing import Mapping
+
+CONFIDENCE_THRESHOLD = 80
+
+
+def compute_confidence(rubric_scores: Mapping[str, int]) -> int:
+    return int(sum(rubric_scores.values()))
+
+
+def approval_required(*, confidence: int, is_external: bool, is_risky: bool) -> bool:
+    return is_external or is_risky or confidence < CONFIDENCE_THRESHOLD
+
+
+def infer_planning(signals: Mapping[str, bool]) -> bool:
+    # Require at least two planning signals to avoid spam on general boards.
+    truthy = [key for key, value in signals.items() if value]
+    return len(truthy) >= 2
+
+
+def task_fingerprint(title: str, description: str | None, board_id: str) -> str:
+    normalized_title = title.strip().lower()
+    normalized_desc = (description or "").strip().lower()
+    seed = f"{board_id}::{normalized_title}::{normalized_desc}"
+    return hashlib.sha256(seed.encode()).hexdigest()