diff --git a/src/agentstr/agents/agentstr.py b/src/agentstr/agents/agentstr.py
index 6b35f6a..3b2aa01 100644
--- a/src/agentstr/agents/agentstr.py
+++ b/src/agentstr/agents/agentstr.py
@@ -107,7 +107,7 @@ def checkpointer(self):
         checkpointer = None
         if self.database.conn_str.startswith("postgres"):
             key_manager = os.getenv("AGENT_VAULT_KEY_MANAGER")
-            key_manager_prefix = os.getenv("AGENT_VAULT_KEY_MANAGER_PREFIX", f"AGENTSTR-{self.name}-".upper().replace(' ', '-'))
+            key_manager_prefix = os.getenv("AGENT_VAULT_KEY_MANAGER_PREFIX", f"AGENTSTR-{self.name}-".upper().replace(' ', '-').replace('_', '-'))
             if key_manager:
                 try:
                     from agent_vault.langgraph import async_insecure_postgres_saver, async_secure_postgres_saver
diff --git a/src/agentstr/database/postgres.py b/src/agentstr/database/postgres.py
index b7c6551..840f3ec 100644
--- a/src/agentstr/database/postgres.py
+++ b/src/agentstr/database/postgres.py
@@ -91,7 +91,10 @@ async def add_message(
             self.agent_name,
             thread_id,
         )
-        created_at = datetime.now(timezone.utc)
+        # Use a naive UTC datetime for TIMESTAMP (without time zone) columns
+        # to avoid asyncpg errors mixing aware/naive datetimes. We still return
+        # an aware UTC datetime to callers.
+        created_at = datetime.now(timezone.utc).replace(tzinfo=None)
         await self.conn.execute(
             f"INSERT INTO {self.MESSAGE_TABLE_NAME} (agent_name, thread_id, idx, user_id, role, message, content, kind, satoshis, extra_inputs, extra_outputs, created_at) VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12)",
             self.agent_name,
@@ -119,7 +122,7 @@ async def add_message(
             satoshis=satoshis,
             extra_inputs=extra_inputs,
             extra_outputs=extra_outputs,
-            created_at=created_at.astimezone(timezone.utc),
+            created_at=created_at.replace(tzinfo=timezone.utc),
         )
 
     async def get_messages(
diff --git a/src/agentstr/models.py b/src/agentstr/models.py
index f2671c5..22ee189 100644
--- a/src/agentstr/models.py
+++ b/src/agentstr/models.py
@@ -93,6 +93,13 @@ def parse_json_field(val):
                 created_at = datetime.fromisoformat(created_at)
             except Exception:
                 created_at = datetime.now(timezone.utc)
+        # Normalize to aware UTC datetime
+        if isinstance(created_at, datetime):
+            if created_at.tzinfo is None:
+                # Treat DB naive timestamp as UTC
+                created_at = created_at.replace(tzinfo=timezone.utc)
+            else:
+                created_at = created_at.astimezone(timezone.utc)
         return cls(
             agent_name=row["agent_name"],
             thread_id=row["thread_id"],
@@ -105,7 +112,7 @@ def parse_json_field(val):
             satoshis=row.get("satoshis"),
             extra_inputs=parse_json_field(row.get("extra_inputs")),
             extra_outputs=parse_json_field(row.get("extra_outputs")),
-            created_at=created_at.astimezone(timezone.utc) if hasattr(created_at, "astimezone") else created_at,
+            created_at=created_at,
         )