fix: flush plugin-config OpenInference when the final session closes

Clear NeMo Relay plugin-config observability only after the last active Hermes session finalizes.

Use the plugin's async-safe awaitable helper for both initialize and clear so session rotation remains safe under active event loops.

Disable the direct ATIF fallback when plugins.toml already owns the ATIF exporter lifecycle to avoid duplicate trajectory export on finalization.

tests/plugins/test_nemo_relay_plugin.py

@@ -2,10 +2,13 @@
 
 from __future__ import annotations
 
+import asyncio
 import builtins
+import gc
 import importlib
 import json
 import sys
+import warnings
 from pathlib import Path
 from types import SimpleNamespace
 
@@ -37,7 +40,7 @@ class _FakeNemoRelay:
             call_end=self._tool_call_end,
             execute=self._tool_execute,
         )
-        self.plugin = SimpleNamespace(initialize=self._plugin_initialize)
+        self.plugin = SimpleNamespace(initialize=self._plugin_initialize, clear=self._plugin_clear)
         self.LLMRequest = _FakeLLMRequest
         self.AtofExporterConfig = _FakeAtofExporterConfig
         self.AtofExporterMode = SimpleNamespace(Append="append", Overwrite="overwrite")
@@ -93,6 +96,9 @@ class _FakeNemoRelay:
         self.events.append(("plugin.initialize", config))
         return {"diagnostics": []}
 
+    async def _plugin_clear(self):
+        self.events.append(("plugin.clear",))
+
 
 class _FakeLLMRequest:
     def __init__(self, headers, content):
@@ -445,6 +451,124 @@ output_directory = "{atif_dir}"
     assert atif_dir.is_dir()
 
 
+def test_nemo_relay_plugin_clears_plugins_toml_on_final_session_finalize_and_reinitializes(tmp_path, monkeypatch):
+    fake = _FakeNemoRelay()
+    plugin = _fresh_plugin(monkeypatch, fake)
+    plugins_toml = tmp_path / "plugins.toml"
+    plugins_toml.write_text(
+        """
+version = 1
+
+[[components]]
+kind = "observability"
+enabled = true
+""",
+        encoding="utf-8",
+    )
+    monkeypatch.setenv("HERMES_NEMO_RELAY_PLUGINS_TOML", str(plugins_toml))
+
+    plugin.on_session_start(session_id="s1")
+    plugin.on_session_finalize(session_id="s1", reason="shutdown")
+    plugin.on_session_start(session_id="s2")
+
+    event_names = [event[0] for event in fake.events]
+    assert event_names.count("plugin.initialize") == 2
+    assert event_names.count("plugin.clear") == 1
+
+
+def test_nemo_relay_plugin_keeps_plugins_toml_active_while_other_sessions_remain(tmp_path, monkeypatch):
+    fake = _FakeNemoRelay()
+    plugin = _fresh_plugin(monkeypatch, fake)
+    plugins_toml = tmp_path / "plugins.toml"
+    plugins_toml.write_text(
+        """
+version = 1
+
+[[components]]
+kind = "observability"
+enabled = true
+""",
+        encoding="utf-8",
+    )
+    monkeypatch.setenv("HERMES_NEMO_RELAY_PLUGINS_TOML", str(plugins_toml))
+
+    plugin.on_session_start(session_id="parent")
+    plugin.on_session_start(session_id="child")
+    plugin.on_session_finalize(session_id="child", reason="shutdown")
+    plugin.on_session_finalize(session_id="parent", reason="shutdown")
+
+    event_names = [event[0] for event in fake.events]
+    assert event_names.count("plugin.initialize") == 1
+    assert event_names.count("plugin.clear") == 1
+
+
+def test_nemo_relay_plugin_reinitializes_plugins_toml_inside_active_event_loop(tmp_path, monkeypatch):
+    fake = _FakeNemoRelay()
+    plugin = _fresh_plugin(monkeypatch, fake)
+    plugins_toml = tmp_path / "plugins.toml"
+    plugins_toml.write_text(
+        """
+version = 1
+
+[[components]]
+kind = "observability"
+enabled = true
+""",
+        encoding="utf-8",
+    )
+    monkeypatch.setenv("HERMES_NEMO_RELAY_PLUGINS_TOML", str(plugins_toml))
+
+    async def _drive() -> None:
+        plugin.on_session_start(session_id="s1")
+        plugin.on_session_finalize(session_id="s1", reason="shutdown")
+        plugin.on_session_start(session_id="s2")
+        await asyncio.sleep(0)
+
+    with warnings.catch_warnings(record=True) as caught:
+        warnings.simplefilter("always")
+        asyncio.run(_drive())
+        gc.collect()
+
+    assert not any("was never awaited" in str(w.message) for w in caught)
+    runtime = plugin._get_runtime()
+    assert runtime is not None
+    assert runtime._plugin_config_initialized is True
+    scope_push_names = [event[1] for event in fake.events if event[0] == "scope.push"]
+    assert "hermes-session-s2" in scope_push_names
+
+
+def test_nemo_relay_plugin_disables_direct_atif_when_plugins_toml_owns_atif(tmp_path, monkeypatch):
+    fake = _FakeNemoRelay()
+    plugin = _fresh_plugin(monkeypatch, fake)
+    plugins_toml = tmp_path / "plugins.toml"
+    plugins_toml.write_text(
+        f"""
+version = 1
+
+[[components]]
+kind = "observability"
+enabled = true
+
+[components.config.atif]
+enabled = true
+output_directory = "{(tmp_path / "managed-atif").as_posix()}"
+""",
+        encoding="utf-8",
+    )
+    monkeypatch.setenv("HERMES_NEMO_RELAY_PLUGINS_TOML", str(plugins_toml))
+    monkeypatch.setenv("HERMES_NEMO_RELAY_ATIF_ENABLED", "1")
+    monkeypatch.setenv("HERMES_NEMO_RELAY_ATIF_OUTPUT_DIRECTORY", str(tmp_path / "direct-atif"))
+
+    plugin.on_session_start(session_id="s1")
+    plugin.on_session_finalize(session_id="s1", reason="shutdown")
+
+    event_names = [event[0] for event in fake.events]
+    assert "plugin.initialize" in event_names
+    assert "plugin.clear" in event_names
+    assert "atif.register" not in event_names
+    assert not (tmp_path / "direct-atif" / "hermes-atif-s1.json").exists()
+
+
 def test_nemo_relay_adaptive_llm_execution_middleware_preserves_raw_response(tmp_path, monkeypatch):
     fake = _FakeNemoRelay()
     plugin = _fresh_plugin(monkeypatch, fake)