diff --git a/cli.py b/cli.py
index 985b9ba1af..ed3931afe1 100644
--- a/cli.py
+++ b/cli.py
@@ -2166,6 +2166,7 @@ class HermesCLI:
                 return False
             restored = self._session_db.get_messages_as_conversation(self.session_id)
             if restored:
+                restored = [m for m in restored if m.get("role") != "session_meta"]
                 self.conversation_history = restored
                 msg_count = len([m for m in restored if m.get("role") == "user"])
                 title_part = ""
@@ -2361,6 +2362,7 @@ class HermesCLI:
 
         restored = self._session_db.get_messages_as_conversation(self.session_id)
         if restored:
+            restored = [m for m in restored if m.get("role") != "session_meta"]
             self.conversation_history = restored
             msg_count = len([m for m in restored if m.get("role") == "user"])
             title_part = ""
diff --git a/run_agent.py b/run_agent.py
index bc05ef8450..ab10232332 100644
--- a/run_agent.py
+++ b/run_agent.py
@@ -2585,6 +2585,8 @@ class AIAgent:
             return tc.get("id", "") or ""
         return getattr(tc, "id", "") or ""
 
+    _VALID_API_ROLES = frozenset({"system", "user", "assistant", "tool", "function", "developer"})
+
     @staticmethod
     def _sanitize_api_messages(messages: List[Dict[str, Any]]) -> List[Dict[str, Any]]:
         """Fix orphaned tool_call / tool_result pairs before every LLM call.
@@ -2593,6 +2595,19 @@ class AIAgent:
         is present — so orphans from session loading or manual message
         manipulation are always caught.
         """
+        # --- Role allowlist: drop messages with roles the API won't accept ---
+        filtered = []
+        for msg in messages:
+            role = msg.get("role")
+            if role not in AIAgent._VALID_API_ROLES:
+                logger.debug(
+                    "Pre-call sanitizer: dropping message with invalid role %r",
+                    role,
+                )
+                continue
+            filtered.append(msg)
+        messages = filtered
+
         surviving_call_ids: set = set()
         for msg in messages:
             if msg.get("role") == "assistant":
diff --git a/tests/test_session_meta_filtering.py b/tests/test_session_meta_filtering.py
new file mode 100644
index 0000000000..08fc96e9fe
--- /dev/null
+++ b/tests/test_session_meta_filtering.py
@@ -0,0 +1,90 @@
+"""Tests for session_meta filtering — issue #4715.
+
+Ensures that transcript-only session_meta messages never reach the
+chat-completions API, via both the API-boundary guard in
+_sanitize_api_messages() and the CLI session-restore paths.
+"""
+
+import logging
+import types
+from unittest.mock import MagicMock, patch
+
+from run_agent import AIAgent
+
+
+# ---------------------------------------------------------------------------
+# Layer 1 — _sanitize_api_messages role-allowlist guard
+# ---------------------------------------------------------------------------
+
+class TestSanitizeApiMessagesRoleFilter:
+
+    def test_drops_session_meta_role(self):
+        msgs = [
+            {"role": "user", "content": "hello"},
+            {"role": "session_meta", "content": {"model": "gpt-4"}},
+            {"role": "assistant", "content": "hi"},
+        ]
+        out = AIAgent._sanitize_api_messages(msgs)
+        assert len(out) == 2
+        assert all(m["role"] != "session_meta" for m in out)
+
+    def test_preserves_valid_roles(self):
+        msgs = [
+            {"role": "system", "content": "you are helpful"},
+            {"role": "user", "content": "hello"},
+            {"role": "assistant", "content": "hi"},
+            {"role": "tool", "tool_call_id": "c1", "content": "ok"},
+        ]
+        # Need a matching assistant tool_call so the tool result isn't orphaned
+        msgs[2]["tool_calls"] = [{"id": "c1", "function": {"name": "t", "arguments": "{}"}}]
+        out = AIAgent._sanitize_api_messages(msgs)
+        roles = [m["role"] for m in out]
+        assert "system" in roles
+        assert "user" in roles
+        assert "assistant" in roles
+        assert "tool" in roles
+
+    def test_logs_warning_when_dropping(self, caplog):
+        msgs = [
+            {"role": "user", "content": "hello"},
+            {"role": "session_meta", "content": {"info": "test"}},
+        ]
+        with caplog.at_level(logging.DEBUG, logger="run_agent"):
+            AIAgent._sanitize_api_messages(msgs)
+        assert any("invalid role" in r.message and "session_meta" in r.message for r in caplog.records)
+
+    def test_drops_multiple_invalid_roles(self):
+        msgs = [
+            {"role": "user", "content": "hello"},
+            {"role": "session_meta", "content": {}},
+            {"role": "transcript_note", "content": "note"},
+            {"role": "assistant", "content": "hi"},
+        ]
+        out = AIAgent._sanitize_api_messages(msgs)
+        assert len(out) == 2
+        assert [m["role"] for m in out] == ["user", "assistant"]
+
+
+# ---------------------------------------------------------------------------
+# Layer 2 — CLI session-restore filters session_meta before loading
+# ---------------------------------------------------------------------------
+
+class TestCLISessionRestoreFiltering:
+
+    def test_restore_filters_session_meta(self):
+        """Simulates the CLI restore path and verifies session_meta is removed."""
+        # Build a fake restored message list (as returned by get_messages_as_conversation)
+        fake_restored = [
+            {"role": "session_meta", "content": {"model": "gpt-4"}},
+            {"role": "user", "content": "hello"},
+            {"role": "assistant", "content": "hi there"},
+            {"role": "session_meta", "content": {"tools": []}},
+        ]
+
+        # Apply the same filtering that the patched CLI code now does
+        filtered = [m for m in fake_restored if m.get("role") != "session_meta"]
+
+        assert len(filtered) == 2
+        assert all(m["role"] != "session_meta" for m in filtered)
+        assert filtered[0]["role"] == "user"
+        assert filtered[1]["role"] == "assistant"