hermes-agent/hermes_cli/plugins.py
N0nb0at b21b3bfd68 feat(plugins): namespaced skill registration for plugin skill bundles
Add ctx.register_skill() API so plugins can ship SKILL.md files under
a 'plugin:skill' namespace, preventing name collisions with built-in
Hermes skills. skill_view() detects the ':' separator and routes to
the plugin registry while bare names continue through the existing
flat-tree scan unchanged.

Key additions:
- agent/skill_utils: parse_qualified_name(), is_valid_namespace()
- hermes_cli/plugins: PluginContext.register_skill(), PluginManager
  skill registry (find/list/remove)
- tools/skills_tool: qualified name dispatch in skill_view(),
  _serve_plugin_skill() with full guards (disabled, platform,
  injection scan), bundle context banner with sibling listing,
  stale registry self-heal
- Hoisted _INJECTION_PATTERNS to module level (dedup)
- Updated skill_view schema description

Based on PR #9334 by N0nb0at. Lean P1 salvage — omits autogen shim
(P2) for a simpler first merge.

Closes #8422
2026-04-14 10:42:58 -07:00

744 lines
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"""
Hermes Plugin System
====================
Discovers, loads, and manages plugins from three sources:
1. **User plugins** ``~/.hermes/plugins/<name>/``
2. **Project plugins** ``./.hermes/plugins/<name>/`` (opt-in via
``HERMES_ENABLE_PROJECT_PLUGINS``)
3. **Pip plugins** packages that expose the ``hermes_agent.plugins``
entry-point group.
Each directory plugin must contain a ``plugin.yaml`` manifest **and** an
``__init__.py`` with a ``register(ctx)`` function.
Lifecycle hooks
---------------
Plugins may register callbacks for any of the hooks in ``VALID_HOOKS``.
The agent core calls ``invoke_hook(name, **kwargs)`` at the appropriate
points.
Tool registration
-----------------
``PluginContext.register_tool()`` delegates to ``tools.registry.register()``
so plugin-defined tools appear alongside the built-in tools.
"""
from __future__ import annotations
import importlib
import importlib.metadata
import importlib.util
import logging
import sys
import types
from dataclasses import dataclass, field
from pathlib import Path
from typing import Any, Callable, Dict, List, Optional, Set, Union
from hermes_constants import get_hermes_home
from utils import env_var_enabled
try:
import yaml
except ImportError: # pragma: no cover yaml is optional at import time
yaml = None # type: ignore[assignment]
logger = logging.getLogger(__name__)
# ---------------------------------------------------------------------------
# Constants
# ---------------------------------------------------------------------------
VALID_HOOKS: Set[str] = {
"pre_tool_call",
"post_tool_call",
"pre_llm_call",
"post_llm_call",
"pre_api_request",
"post_api_request",
"on_session_start",
"on_session_end",
"on_session_finalize",
"on_session_reset",
}
ENTRY_POINTS_GROUP = "hermes_agent.plugins"
_NS_PARENT = "hermes_plugins"
def _env_enabled(name: str) -> bool:
"""Return True when an env var is set to a truthy opt-in value."""
return env_var_enabled(name)
def _get_disabled_plugins() -> set:
"""Read the disabled plugins list from config.yaml."""
try:
from hermes_cli.config import load_config
config = load_config()
disabled = config.get("plugins", {}).get("disabled", [])
return set(disabled) if isinstance(disabled, list) else set()
except Exception:
return set()
# ---------------------------------------------------------------------------
# Data classes
# ---------------------------------------------------------------------------
@dataclass
class PluginManifest:
"""Parsed representation of a plugin.yaml manifest."""
name: str
version: str = ""
description: str = ""
author: str = ""
requires_env: List[Union[str, Dict[str, Any]]] = field(default_factory=list)
provides_tools: List[str] = field(default_factory=list)
provides_hooks: List[str] = field(default_factory=list)
source: str = "" # "user", "project", or "entrypoint"
path: Optional[str] = None
@dataclass
class LoadedPlugin:
"""Runtime state for a single loaded plugin."""
manifest: PluginManifest
module: Optional[types.ModuleType] = None
tools_registered: List[str] = field(default_factory=list)
hooks_registered: List[str] = field(default_factory=list)
enabled: bool = False
error: Optional[str] = None
# ---------------------------------------------------------------------------
# PluginContext handed to each plugin's ``register()`` function
# ---------------------------------------------------------------------------
class PluginContext:
"""Facade given to plugins so they can register tools and hooks."""
def __init__(self, manifest: PluginManifest, manager: "PluginManager"):
self.manifest = manifest
self._manager = manager
# -- tool registration --------------------------------------------------
def register_tool(
self,
name: str,
toolset: str,
schema: dict,
handler: Callable,
check_fn: Callable | None = None,
requires_env: list | None = None,
is_async: bool = False,
description: str = "",
emoji: str = "",
) -> None:
"""Register a tool in the global registry **and** track it as plugin-provided."""
from tools.registry import registry
registry.register(
name=name,
toolset=toolset,
schema=schema,
handler=handler,
check_fn=check_fn,
requires_env=requires_env,
is_async=is_async,
description=description,
emoji=emoji,
)
self._manager._plugin_tool_names.add(name)
logger.debug("Plugin %s registered tool: %s", self.manifest.name, name)
# -- message injection --------------------------------------------------
def inject_message(self, content: str, role: str = "user") -> bool:
"""Inject a message into the active conversation.
If the agent is idle (waiting for user input), this starts a new turn.
If the agent is running, this interrupts and injects the message.
This enables plugins (e.g. remote control viewers, messaging bridges)
to send messages into the conversation from external sources.
Returns True if the message was queued successfully.
"""
cli = self._manager._cli_ref
if cli is None:
logger.warning("inject_message: no CLI reference (not available in gateway mode)")
return False
msg = content if role == "user" else f"[{role}] {content}"
if getattr(cli, "_agent_running", False):
# Agent is mid-turn — interrupt with the message
cli._interrupt_queue.put(msg)
else:
# Agent is idle — queue as next input
cli._pending_input.put(msg)
return True
# -- CLI command registration --------------------------------------------
def register_cli_command(
self,
name: str,
help: str,
setup_fn: Callable,
handler_fn: Callable | None = None,
description: str = "",
) -> None:
"""Register a CLI subcommand (e.g. ``hermes honcho ...``).
The *setup_fn* receives an argparse subparser and should add any
arguments/sub-subparsers. If *handler_fn* is provided it is set
as the default dispatch function via ``set_defaults(func=...)``."""
self._manager._cli_commands[name] = {
"name": name,
"help": help,
"description": description,
"setup_fn": setup_fn,
"handler_fn": handler_fn,
"plugin": self.manifest.name,
}
logger.debug("Plugin %s registered CLI command: %s", self.manifest.name, name)
# -- context engine registration -----------------------------------------
def register_context_engine(self, engine) -> None:
"""Register a context engine to replace the built-in ContextCompressor.
Only one context engine plugin is allowed. If a second plugin tries
to register one, it is rejected with a warning.
The engine must be an instance of ``agent.context_engine.ContextEngine``.
"""
if self._manager._context_engine is not None:
logger.warning(
"Plugin '%s' tried to register a context engine, but one is "
"already registered. Only one context engine plugin is allowed.",
self.manifest.name,
)
return
# Defer the import to avoid circular deps at module level
from agent.context_engine import ContextEngine
if not isinstance(engine, ContextEngine):
logger.warning(
"Plugin '%s' tried to register a context engine that does not "
"inherit from ContextEngine. Ignoring.",
self.manifest.name,
)
return
self._manager._context_engine = engine
logger.info(
"Plugin '%s' registered context engine: %s",
self.manifest.name, engine.name,
)
# -- hook registration --------------------------------------------------
def register_hook(self, hook_name: str, callback: Callable) -> None:
"""Register a lifecycle hook callback.
Unknown hook names produce a warning but are still stored so
forward-compatible plugins don't break.
"""
if hook_name not in VALID_HOOKS:
logger.warning(
"Plugin '%s' registered unknown hook '%s' "
"(valid: %s)",
self.manifest.name,
hook_name,
", ".join(sorted(VALID_HOOKS)),
)
self._manager._hooks.setdefault(hook_name, []).append(callback)
logger.debug("Plugin %s registered hook: %s", self.manifest.name, hook_name)
# -- skill registration -------------------------------------------------
def register_skill(
self,
name: str,
path: Path,
description: str = "",
) -> None:
"""Register a read-only skill provided by this plugin.
The skill becomes resolvable as ``'<plugin_name>:<name>'`` via
``skill_view()``. It does **not** enter the flat
``~/.hermes/skills/`` tree and is **not** listed in the system
prompt's ``<available_skills>`` index — plugin skills are
opt-in explicit loads only.
Raises:
ValueError: if *name* contains ``':'`` or invalid characters.
FileNotFoundError: if *path* does not exist.
"""
from agent.skill_utils import _NAMESPACE_RE
if ":" in name:
raise ValueError(
f"Skill name '{name}' must not contain ':' "
f"(the namespace is derived from the plugin name "
f"'{self.manifest.name}' automatically)."
)
if not name or not _NAMESPACE_RE.match(name):
raise ValueError(
f"Invalid skill name '{name}'. Must match [a-zA-Z0-9_-]+."
)
if not path.exists():
raise FileNotFoundError(f"SKILL.md not found at {path}")
qualified = f"{self.manifest.name}:{name}"
self._manager._plugin_skills[qualified] = {
"path": path,
"plugin": self.manifest.name,
"bare_name": name,
"description": description,
}
logger.debug(
"Plugin %s registered skill: %s",
self.manifest.name, qualified,
)
# ---------------------------------------------------------------------------
# PluginManager
# ---------------------------------------------------------------------------
class PluginManager:
"""Central manager that discovers, loads, and invokes plugins."""
def __init__(self) -> None:
self._plugins: Dict[str, LoadedPlugin] = {}
self._hooks: Dict[str, List[Callable]] = {}
self._plugin_tool_names: Set[str] = set()
self._cli_commands: Dict[str, dict] = {}
self._context_engine = None # Set by a plugin via register_context_engine()
self._discovered: bool = False
self._cli_ref = None # Set by CLI after plugin discovery
# Plugin skill registry: qualified name → metadata dict.
self._plugin_skills: Dict[str, Dict[str, Any]] = {}
# -----------------------------------------------------------------------
# Public
# -----------------------------------------------------------------------
def discover_and_load(self) -> None:
"""Scan all plugin sources and load each plugin found."""
if self._discovered:
return
self._discovered = True
manifests: List[PluginManifest] = []
# 1. User plugins (~/.hermes/plugins/)
user_dir = get_hermes_home() / "plugins"
manifests.extend(self._scan_directory(user_dir, source="user"))
# 2. Project plugins (./.hermes/plugins/)
if _env_enabled("HERMES_ENABLE_PROJECT_PLUGINS"):
project_dir = Path.cwd() / ".hermes" / "plugins"
manifests.extend(self._scan_directory(project_dir, source="project"))
# 3. Pip / entry-point plugins
manifests.extend(self._scan_entry_points())
# Load each manifest (skip user-disabled plugins)
disabled = _get_disabled_plugins()
for manifest in manifests:
if manifest.name in disabled:
loaded = LoadedPlugin(manifest=manifest, enabled=False)
loaded.error = "disabled via config"
self._plugins[manifest.name] = loaded
logger.debug("Skipping disabled plugin '%s'", manifest.name)
continue
self._load_plugin(manifest)
if manifests:
logger.info(
"Plugin discovery complete: %d found, %d enabled",
len(self._plugins),
sum(1 for p in self._plugins.values() if p.enabled),
)
# -----------------------------------------------------------------------
# Directory scanning
# -----------------------------------------------------------------------
def _scan_directory(self, path: Path, source: str) -> List[PluginManifest]:
"""Read ``plugin.yaml`` manifests from subdirectories of *path*."""
manifests: List[PluginManifest] = []
if not path.is_dir():
return manifests
for child in sorted(path.iterdir()):
if not child.is_dir():
continue
manifest_file = child / "plugin.yaml"
if not manifest_file.exists():
manifest_file = child / "plugin.yml"
if not manifest_file.exists():
logger.debug("Skipping %s (no plugin.yaml)", child)
continue
try:
if yaml is None:
logger.warning("PyYAML not installed cannot load %s", manifest_file)
continue
data = yaml.safe_load(manifest_file.read_text()) or {}
manifest = PluginManifest(
name=data.get("name", child.name),
version=str(data.get("version", "")),
description=data.get("description", ""),
author=data.get("author", ""),
requires_env=data.get("requires_env", []),
provides_tools=data.get("provides_tools", []),
provides_hooks=data.get("provides_hooks", []),
source=source,
path=str(child),
)
manifests.append(manifest)
except Exception as exc:
logger.warning("Failed to parse %s: %s", manifest_file, exc)
return manifests
# -----------------------------------------------------------------------
# Entry-point scanning
# -----------------------------------------------------------------------
def _scan_entry_points(self) -> List[PluginManifest]:
"""Check ``importlib.metadata`` for pip-installed plugins."""
manifests: List[PluginManifest] = []
try:
eps = importlib.metadata.entry_points()
# Python 3.12+ returns a SelectableGroups; earlier returns dict
if hasattr(eps, "select"):
group_eps = eps.select(group=ENTRY_POINTS_GROUP)
elif isinstance(eps, dict):
group_eps = eps.get(ENTRY_POINTS_GROUP, [])
else:
group_eps = [ep for ep in eps if ep.group == ENTRY_POINTS_GROUP]
for ep in group_eps:
manifest = PluginManifest(
name=ep.name,
source="entrypoint",
path=ep.value,
)
manifests.append(manifest)
except Exception as exc:
logger.debug("Entry-point scan failed: %s", exc)
return manifests
# -----------------------------------------------------------------------
# Loading
# -----------------------------------------------------------------------
def _load_plugin(self, manifest: PluginManifest) -> None:
"""Import a plugin module and call its ``register(ctx)`` function."""
loaded = LoadedPlugin(manifest=manifest)
try:
if manifest.source in ("user", "project"):
module = self._load_directory_module(manifest)
else:
module = self._load_entrypoint_module(manifest)
loaded.module = module
# Call register()
register_fn = getattr(module, "register", None)
if register_fn is None:
loaded.error = "no register() function"
logger.warning("Plugin '%s' has no register() function", manifest.name)
else:
ctx = PluginContext(manifest, self)
register_fn(ctx)
loaded.tools_registered = [
t for t in self._plugin_tool_names
if t not in {
n
for name, p in self._plugins.items()
for n in p.tools_registered
}
]
loaded.hooks_registered = list(
{
h
for h, cbs in self._hooks.items()
if cbs # non-empty
}
- {
h
for name, p in self._plugins.items()
for h in p.hooks_registered
}
)
loaded.enabled = True
except Exception as exc:
loaded.error = str(exc)
logger.warning("Failed to load plugin '%s': %s", manifest.name, exc)
self._plugins[manifest.name] = loaded
def _load_directory_module(self, manifest: PluginManifest) -> types.ModuleType:
"""Import a directory-based plugin as ``hermes_plugins.<name>``."""
plugin_dir = Path(manifest.path) # type: ignore[arg-type]
init_file = plugin_dir / "__init__.py"
if not init_file.exists():
raise FileNotFoundError(f"No __init__.py in {plugin_dir}")
# Ensure the namespace parent package exists
if _NS_PARENT not in sys.modules:
ns_pkg = types.ModuleType(_NS_PARENT)
ns_pkg.__path__ = [] # type: ignore[attr-defined]
ns_pkg.__package__ = _NS_PARENT
sys.modules[_NS_PARENT] = ns_pkg
module_name = f"{_NS_PARENT}.{manifest.name.replace('-', '_')}"
spec = importlib.util.spec_from_file_location(
module_name,
init_file,
submodule_search_locations=[str(plugin_dir)],
)
if spec is None or spec.loader is None:
raise ImportError(f"Cannot create module spec for {init_file}")
module = importlib.util.module_from_spec(spec)
module.__package__ = module_name
module.__path__ = [str(plugin_dir)] # type: ignore[attr-defined]
sys.modules[module_name] = module
spec.loader.exec_module(module)
return module
def _load_entrypoint_module(self, manifest: PluginManifest) -> types.ModuleType:
"""Load a pip-installed plugin via its entry-point reference."""
eps = importlib.metadata.entry_points()
if hasattr(eps, "select"):
group_eps = eps.select(group=ENTRY_POINTS_GROUP)
elif isinstance(eps, dict):
group_eps = eps.get(ENTRY_POINTS_GROUP, [])
else:
group_eps = [ep for ep in eps if ep.group == ENTRY_POINTS_GROUP]
for ep in group_eps:
if ep.name == manifest.name:
return ep.load()
raise ImportError(
f"Entry point '{manifest.name}' not found in group '{ENTRY_POINTS_GROUP}'"
)
# -----------------------------------------------------------------------
# Hook invocation
# -----------------------------------------------------------------------
def invoke_hook(self, hook_name: str, **kwargs: Any) -> List[Any]:
"""Call all registered callbacks for *hook_name*.
Each callback is wrapped in its own try/except so a misbehaving
plugin cannot break the core agent loop.
Returns a list of non-``None`` return values from callbacks.
For ``pre_llm_call``, callbacks may return a dict describing
context to inject into the current turn's user message::
{"context": "recalled text..."}
"recalled text..." # plain string, equivalent
Context is ALWAYS injected into the user message, never the
system prompt. This preserves the prompt cache prefix — the
system prompt stays identical across turns so cached tokens
are reused. All injected context is ephemeral — never
persisted to session DB.
"""
callbacks = self._hooks.get(hook_name, [])
results: List[Any] = []
for cb in callbacks:
try:
ret = cb(**kwargs)
if ret is not None:
results.append(ret)
except Exception as exc:
logger.warning(
"Hook '%s' callback %s raised: %s",
hook_name,
getattr(cb, "__name__", repr(cb)),
exc,
)
return results
# -----------------------------------------------------------------------
# Introspection
# -----------------------------------------------------------------------
def list_plugins(self) -> List[Dict[str, Any]]:
"""Return a list of info dicts for all discovered plugins."""
result: List[Dict[str, Any]] = []
for name, loaded in sorted(self._plugins.items()):
result.append(
{
"name": name,
"version": loaded.manifest.version,
"description": loaded.manifest.description,
"source": loaded.manifest.source,
"enabled": loaded.enabled,
"tools": len(loaded.tools_registered),
"hooks": len(loaded.hooks_registered),
"error": loaded.error,
}
)
return result
# -----------------------------------------------------------------------
# Plugin skill lookups
# -----------------------------------------------------------------------
def find_plugin_skill(self, qualified_name: str) -> Optional[Path]:
"""Return the ``Path`` to a plugin skill's SKILL.md, or ``None``."""
entry = self._plugin_skills.get(qualified_name)
return entry["path"] if entry else None
def list_plugin_skills(self, plugin_name: str) -> List[str]:
"""Return sorted bare names of all skills registered by *plugin_name*."""
prefix = f"{plugin_name}:"
return sorted(
e["bare_name"]
for qn, e in self._plugin_skills.items()
if qn.startswith(prefix)
)
def remove_plugin_skill(self, qualified_name: str) -> None:
"""Remove a stale registry entry (silently ignores missing keys)."""
self._plugin_skills.pop(qualified_name, None)
# ---------------------------------------------------------------------------
# Module-level singleton & convenience functions
# ---------------------------------------------------------------------------
_plugin_manager: Optional[PluginManager] = None
def get_plugin_manager() -> PluginManager:
"""Return (and lazily create) the global PluginManager singleton."""
global _plugin_manager
if _plugin_manager is None:
_plugin_manager = PluginManager()
return _plugin_manager
def discover_plugins() -> None:
"""Discover and load all plugins (idempotent)."""
get_plugin_manager().discover_and_load()
def invoke_hook(hook_name: str, **kwargs: Any) -> List[Any]:
"""Invoke a lifecycle hook on all loaded plugins.
Returns a list of non-``None`` return values from plugin callbacks.
"""
return get_plugin_manager().invoke_hook(hook_name, **kwargs)
def get_pre_tool_call_block_message(
tool_name: str,
args: Optional[Dict[str, Any]],
task_id: str = "",
session_id: str = "",
tool_call_id: str = "",
) -> Optional[str]:
"""Check ``pre_tool_call`` hooks for a blocking directive.
Plugins that need to enforce policy (rate limiting, security
restrictions, approval workflows) can return::
{"action": "block", "message": "Reason the tool was blocked"}
from their ``pre_tool_call`` callback. The first valid block
directive wins. Invalid or irrelevant hook return values are
silently ignored so existing observer-only hooks are unaffected.
"""
hook_results = invoke_hook(
"pre_tool_call",
tool_name=tool_name,
args=args if isinstance(args, dict) else {},
task_id=task_id,
session_id=session_id,
tool_call_id=tool_call_id,
)
for result in hook_results:
if not isinstance(result, dict):
continue
if result.get("action") != "block":
continue
message = result.get("message")
if isinstance(message, str) and message:
return message
return None
def get_plugin_context_engine():
"""Return the plugin-registered context engine, or None."""
return get_plugin_manager()._context_engine
def get_plugin_toolsets() -> List[tuple]:
"""Return plugin toolsets as ``(key, label, description)`` tuples.
Used by the ``hermes tools`` TUI so plugin-provided toolsets appear
alongside the built-in ones and can be toggled on/off per platform.
"""
manager = get_plugin_manager()
if not manager._plugin_tool_names:
return []
try:
from tools.registry import registry
except Exception:
return []
# Group plugin tool names by their toolset
toolset_tools: Dict[str, List[str]] = {}
toolset_plugin: Dict[str, LoadedPlugin] = {}
for tool_name in manager._plugin_tool_names:
entry = registry.get_entry(tool_name)
if not entry:
continue
ts = entry.toolset
toolset_tools.setdefault(ts, []).append(entry.name)
# Map toolsets back to the plugin that registered them
for _name, loaded in manager._plugins.items():
for tool_name in loaded.tools_registered:
entry = registry.get_entry(tool_name)
if entry and entry.toolset in toolset_tools:
toolset_plugin.setdefault(entry.toolset, loaded)
result = []
for ts_key in sorted(toolset_tools):
plugin = toolset_plugin.get(ts_key)
label = f"🔌 {ts_key.replace('_', ' ').title()}"
if plugin and plugin.manifest.description:
desc = plugin.manifest.description
else:
desc = ", ".join(sorted(toolset_tools[ts_key]))
result.append((ts_key, label, desc))
return result