fix(image-gen): force-refresh plugin providers in long-lived sessions

hermes_cli/plugins.py

@@ -512,10 +512,23 @@ class PluginManager:
     # Public
     # -----------------------------------------------------------------------
 
-    def discover_and_load(self) -> None:
+    def discover_and_load(self, force: bool = False) -> None:
-        """Scan all plugin sources and load each plugin found."""
+        """Scan all plugin sources and load each plugin found.
-        if self._discovered:
+
+        When ``force`` is true, clear cached discovery state first so config
+        changes or newly-added bundled backends become visible in long-lived
+        sessions without requiring a full agent restart.
+        """
+        if self._discovered and not force:
             return
+        if force:
+            self._plugins.clear()
+            self._hooks.clear()
+            self._plugin_tool_names.clear()
+            self._cli_commands.clear()
+            self._plugin_commands.clear()
+            self._plugin_skills.clear()
+            self._context_engine = None
         self._discovered = True
 
         manifests: List[PluginManifest] = []
@@ -1029,9 +1042,13 @@ def get_plugin_manager() -> PluginManager:
     return _plugin_manager
 
 
-def discover_plugins() -> None:
+def discover_plugins(force: bool = False) -> None:
-    """Discover and load all plugins (idempotent)."""
+    """Discover and load all plugins.
-    get_plugin_manager().discover_and_load()
+
+    Default behavior is idempotent. Pass ``force=True`` to rescan plugin
+    manifests and reload state in the current process.
+    """
+    get_plugin_manager().discover_and_load(force=force)
 
 
 def invoke_hook(hook_name: str, **kwargs: Any) -> List[Any]:
@@ -1082,10 +1099,13 @@ def get_pre_tool_call_block_message(
     return None
 
 
-def _ensure_plugins_discovered() -> PluginManager:
+def _ensure_plugins_discovered(force: bool = False) -> PluginManager:
-    """Return the global manager after running idempotent plugin discovery."""
+    """Return the global manager after ensuring plugin discovery has run.
+
+    Pass ``force=True`` to rescan in the current process.
+    """
     manager = get_plugin_manager()
-    manager.discover_and_load()
+    manager.discover_and_load(force=force)
     return manager
 
 

tests/tools/test_image_generation_plugin_dispatch.py

@@ -0,0 +1,99 @@
+from __future__ import annotations
+
+import json
+import pytest
+
+from agent import image_gen_registry
+from agent.image_gen_provider import ImageGenProvider
+
+
+@pytest.fixture(autouse=True)
+def _reset_registry():
+    image_gen_registry._reset_for_tests()
+    yield
+    image_gen_registry._reset_for_tests()
+
+
+class _FakeCodexProvider(ImageGenProvider):
+    @property
+    def name(self) -> str:
+        return "codex"
+
+    def generate(self, prompt, aspect_ratio="landscape", **kwargs):
+        return {
+            "success": True,
+            "image": "/tmp/codex-test.png",
+            "model": "gpt-5.2-codex",
+            "prompt": prompt,
+            "aspect_ratio": aspect_ratio,
+            "provider": "codex",
+        }
+
+
+class TestPluginDispatch:
+    def test_dispatch_routes_to_codex_provider(self, monkeypatch, tmp_path):
+        from tools import image_generation_tool
+        from agent import image_gen_registry as registry_module
+        from hermes_cli import plugins as plugins_module
+
+        monkeypatch.setenv("HERMES_HOME", str(tmp_path))
+        (tmp_path / "config.yaml").write_text("image_gen:\n  provider: codex\n")
+        image_gen_registry.register_provider(_FakeCodexProvider())
+
+        monkeypatch.setattr(image_generation_tool, "_read_configured_image_provider", lambda: "codex")
+        monkeypatch.setattr(plugins_module, "_ensure_plugins_discovered", lambda: None)
+        monkeypatch.setattr(registry_module, "get_provider", lambda name: _FakeCodexProvider() if name == "codex" else None)
+
+        dispatched = image_generation_tool._dispatch_to_plugin_provider("draw cat", "square")
+        payload = json.loads(dispatched)
+
+        assert payload["success"] is True
+        assert payload["provider"] == "codex"
+        assert payload["image"] == "/tmp/codex-test.png"
+        assert payload["aspect_ratio"] == "square"
+
+    def test_dispatch_reports_missing_registered_provider(self, monkeypatch, tmp_path):
+        from tools import image_generation_tool
+        from hermes_cli import plugins as plugins_module
+
+        monkeypatch.setenv("HERMES_HOME", str(tmp_path))
+        (tmp_path / "config.yaml").write_text("image_gen:\n  provider: missing-codex\n")
+
+        monkeypatch.setattr(image_generation_tool, "_read_configured_image_provider", lambda: "missing-codex")
+        monkeypatch.setattr(plugins_module, "_ensure_plugins_discovered", lambda: None)
+
+        dispatched = image_generation_tool._dispatch_to_plugin_provider("draw cat", "landscape")
+        payload = json.loads(dispatched)
+
+        assert payload["success"] is False
+        assert payload["error_type"] == "provider_not_registered"
+        assert "image_gen.provider='missing-codex'" in payload["error"]
+
+    def test_dispatch_force_refreshes_plugins_when_provider_initially_missing(self, monkeypatch, tmp_path):
+        from tools import image_generation_tool
+        from hermes_cli import plugins as plugins_module
+        from agent import image_gen_registry as registry_module
+
+        monkeypatch.setenv("HERMES_HOME", str(tmp_path))
+        (tmp_path / "config.yaml").write_text("image_gen:\n  provider: codex\n")
+
+        monkeypatch.setattr(image_generation_tool, "_read_configured_image_provider", lambda: "codex")
+
+        calls = []
+        provider_state = {"provider": None}
+
+        def fake_ensure_plugins_discovered(force=False):
+            calls.append(force)
+            if force:
+                provider_state["provider"] = _FakeCodexProvider()
+
+        monkeypatch.setattr(plugins_module, "_ensure_plugins_discovered", fake_ensure_plugins_discovered)
+        monkeypatch.setattr(registry_module, "get_provider", lambda name: provider_state["provider"])
+
+        dispatched = image_generation_tool._dispatch_to_plugin_provider("draw hammy", "portrait")
+        payload = json.loads(dispatched)
+
+        assert calls == [False, True]
+        assert payload["success"] is True
+        assert payload["provider"] == "codex"
+        assert payload["aspect_ratio"] == "portrait"

tools/image_generation_tool.py

@@ -927,6 +927,16 @@ def _dispatch_to_plugin_provider(prompt: str, aspect_ratio: str):
         logger.debug("image_gen plugin dispatch skipped: %s", exc)
         return None
 
+    if provider is None:
+        try:
+            # Long-lived sessions may have discovered plugins before a bundled
+            # backend was patched in or before config changed. Retry once with
+            # a forced refresh before surfacing a missing-provider error.
+            _ensure_plugins_discovered(force=True)
+            provider = get_provider(configured)
+        except Exception as exc:
+            logger.debug("image_gen plugin force-refresh skipped: %s", exc)
+
     if provider is None:
         return json.dumps({
             "success": False,