Add a dev memo-forwarding fixture and deduplicated intake notifications.

Pose, replay, and conflict stay on an injected transport with local retry
evidence. Notification receipts keep only memo id, question, class, and
submitter, and a resolve conflict stays readable.

Assistant: grok
Assistant-Session: 01a10329-31cb-78d3-b7a3-789e1fb83139

api/services/memo_notification.py

@@ -0,0 +1,67 @@
+"""Deduplicated informed-decision notification receipts.
+
+The signed-in overview is the review entry point. A receipt stores and
+announces only memo id, question, class, and submitter. Replays of the same
+delivery id return the retained receipt; a different body conflicts and leaves
+the original readable.
+"""
+from __future__ import annotations
+
+from sqlalchemy.exc import IntegrityError
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from api.models.agent_message import AgentMessage
+from api.models.memo_notification import MemoNotificationReceipt
+from api.services.informed_decision_contract import Notification
+from api.services.repository_aliases import canonicalize_repository_slug
+
+NOTIFICATION_SENDER = "informed-decision"
+NOTIFICATION_RECIPIENT = "bernd"
+
+
+class NotificationConflict(Exception):
+    def __init__(self, receipt: MemoNotificationReceipt) -> None:
+        self.receipt = receipt
+
+
+async def accept_notification(
+    session: AsyncSession, delivery_id: str, notice: Notification
+) -> tuple[MemoNotificationReceipt, bool]:
+    existing = await session.get(MemoNotificationReceipt, delivery_id)
+    if existing is not None:
+        if existing.body_digest != notice.body_digest:
+            raise NotificationConflict(existing)
+        return existing, True
+
+    message = AgentMessage(
+        from_agent=await canonicalize_repository_slug(session, NOTIFICATION_SENDER),
+        to_agent=await canonicalize_repository_slug(session, NOTIFICATION_RECIPIENT),
+        subject=notice.message_subject(),
+        body=notice.message_text(),
+        kind="message",
+    )
+    session.add(message)
+    await session.flush()
+    receipt = MemoNotificationReceipt(
+        delivery_id=delivery_id,
+        body_digest=notice.body_digest,
+        memo_id=notice.memo_id,
+        question=notice.question,
+        memo_class=notice.memo_class,
+        submitter=notice.submitter,
+        message_id=message.id,
+        authoritative_review="signed-in-overview",
+    )
+    session.add(receipt)
+    try:
+        await session.commit()
+    except IntegrityError:
+        await session.rollback()
+        existing = await session.get(MemoNotificationReceipt, delivery_id)
+        if existing is None:
+            raise
+        if existing.body_digest != notice.body_digest:
+            raise NotificationConflict(existing)
+        return existing, True
+    await session.refresh(receipt)
+    return receipt, False