feat(mnemosyne): add nexus/mnemosyne/entry.py

Part of #1216 — Project Mnemosyne Phase 1 Foundation

nexus/mnemosyne/entry.py

@@ -0,0 +1,44 @@
+"""Archive entry model for Mnemosyne.
+
+Each entry is a node in the holographic graph — a piece of meaning
+with metadata, content, and links to related entries.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+from datetime import datetime, timezone
+from typing import Optional
+import uuid
+
+
+@dataclass
+class ArchiveEntry:
+    """A single node in the Mnemosyne holographic archive."""
+
+    id: str = field(default_factory=lambda: str(uuid.uuid4()))
+    title: str = ""
+    content: str = ""
+    source: str = ""               # "mempalace", "event", "manual", etc.
+    source_ref: Optional[str] = None  # original MemPalace ID, event URI, etc.
+    topics: list[str] = field(default_factory=list)
+    metadata: dict = field(default_factory=dict)
+    created_at: str = field(default_factory=lambda: datetime.now(timezone.utc).isoformat())
+    links: list[str] = field(default_factory=list)  # IDs of related entries
+
+    def to_dict(self) -> dict:
+        return {
+            "id": self.id,
+            "title": self.title,
+            "content": self.content,
+            "source": self.source,
+            "source_ref": self.source_ref,
+            "topics": self.topics,
+            "metadata": self.metadata,
+            "created_at": self.created_at,
+            "links": self.links,
+        }
+
+    @classmethod
+    def from_dict(cls, data: dict) -> ArchiveEntry:
+        return cls(**{k: v for k, v in data.items() if k in cls.__dataclass_fields__})