feat: reconcile legacy message identities

Assistant: codex
Assistant-Model: gpt-5.6-sol
Assistant-Session: 01a0230c-b06c-7641-808a-e191b6d1da49

hub_core/models/__init__.py

@@ -4,6 +4,7 @@ from hub_core.models.capability_catalog import CapabilityCatalog
 from hub_core.models.capability_request import CapabilityRequest
 from hub_core.models.domain import Domain
 from hub_core.models.managed_repo import ManagedRepo
+from hub_core.models.message_identity_alias import MessageIdentityAlias
 from hub_core.models.progress_event import ProgressEvent
 from hub_core.models.tpsc import TPSCCatalog, TPSCEntry, TPSCSnapshot
 
@@ -14,6 +15,7 @@ __all__ = [
     "CapabilityRequest",
     "Domain",
     "ManagedRepo",
+    "MessageIdentityAlias",
     "ProgressEvent",
     "TPSCCatalog",
     "TPSCEntry",

hub_core/models/agent_message.py

@@ -1,7 +1,7 @@
 import uuid
 from datetime import datetime
 
-from sqlalchemy import DateTime, ForeignKey, String, Text, text
+from sqlalchemy import DateTime, ForeignKey, String, Text, func
 from sqlalchemy.dialects.postgresql import UUID
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 
@@ -32,7 +32,7 @@ class AgentMessage(Base):
     )
     created_at: Mapped[datetime] = mapped_column(
         DateTime(timezone=True),
-        server_default=text("now()"),
+        server_default=func.now(),
         nullable=False,
     )
 

hub_core/models/message_identity_alias.py

@@ -0,0 +1,30 @@
+import uuid
+from datetime import datetime
+
+from sqlalchemy import DateTime, ForeignKey, String, Text, func
+from sqlalchemy.dialects.postgresql import UUID
+from sqlalchemy.orm import Mapped, mapped_column
+
+from hub_core.models.base import Base
+
+
+class MessageIdentityAlias(Base):
+    """Explicit mapping from an historical reference to a canonical message."""
+
+    __tablename__ = "agent_message_identity_aliases"
+
+    alias: Mapped[str] = mapped_column(String(255), primary_key=True)
+    message_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("agent_messages.id", ondelete="RESTRICT"),
+        nullable=False,
+        index=True,
+    )
+    source: Mapped[str] = mapped_column(String(255), nullable=False)
+    reason: Mapped[str] = mapped_column(Text, nullable=False)
+    created_by: Mapped[str] = mapped_column(String(100), nullable=False)
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        server_default=func.now(),
+        nullable=False,
+    )