Hermes-agent

agent/image_gen_registry.py

@@ -0,0 +1,145 @@
+"""
+Image Generation Provider Registry
+==================================
+
+Central map of registered providers. Populated by plugins at import-time via
+``PluginContext.register_image_gen_provider()``; consumed by the
+``image_generate`` tool to dispatch each call to the active backend.
+
+Active selection
+----------------
+The active provider is chosen by ``image_gen.provider`` in ``config.yaml``.
+If unset, :func:`get_active_provider` applies fallback logic:
+
+1. If exactly one provider is registered, use it.
+2. Otherwise if a provider named ``fal`` is registered, use it (legacy
+   default — matches pre-plugin behavior).
+3. Otherwise return ``None`` (the tool surfaces a helpful error pointing
+   the user at ``hermes tools``).
+"""
+
+from __future__ import annotations
+
+import logging
+import threading
+from typing import Dict, List, Optional
+
+from agent.image_gen_provider import ImageGenProvider
+
+logger = logging.getLogger(__name__)
+
+
+_providers: Dict[str, ImageGenProvider] = {}
+_lock = threading.Lock()
+
+
+def register_provider(provider: ImageGenProvider) -> None:
+    """Register an image generation provider.
+
+    Re-registration (same ``name``) overwrites the previous entry and logs
+    a debug message — this makes hot-reload scenarios (tests, dev loops)
+    behave predictably.
+    """
+    if not isinstance(provider, ImageGenProvider):
+        raise TypeError(
+            f"register_provider() expects an ImageGenProvider instance, "
+            f"got {type(provider).__name__}"
+        )
+    name = provider.name
+    if not isinstance(name, str) or not name.strip():
+        raise ValueError("Image gen provider .name must be a non-empty string")
+    with _lock:
+        existing = _providers.get(name)
+        _providers[name] = provider
+    if existing is not None:
+        logger.debug("Image gen provider '%s' re-registered (was %r)", name, type(existing).__name__)
+    else:
+        logger.debug("Registered image gen provider '%s' (%s)", name, type(provider).__name__)
+
+
+def list_providers() -> List[ImageGenProvider]:
+    """Return all registered providers, sorted by name."""
+    with _lock:
+        items = list(_providers.values())
+    return sorted(items, key=lambda p: p.name)
+
+
+def get_provider(name: str) -> Optional[ImageGenProvider]:
+    """Return the provider registered under *name*, or None."""
+    if not isinstance(name, str):
+        return None
+    with _lock:
+        return _providers.get(name.strip())
+
+
+def get_active_provider() -> Optional[ImageGenProvider]:
+    """Resolve the currently-active provider.
+
+    Reads ``image_gen.provider`` from config.yaml; falls back per the
+    module docstring.
+
+    **Availability semantics** (mirrors :mod:`agent.web_search_registry`):
+
+    - When ``image_gen.provider`` is explicitly set, the configured
+      provider is returned even if :meth:`ImageGenProvider.is_available`
+      reports False — the dispatcher surfaces a precise "X_API_KEY is not
+      set" error rather than silently switching backends.
+    - When ``image_gen.provider`` is unset, the fallback path (single-
+      provider shortcut and the FAL legacy preference) is filtered by
+      ``is_available()`` so we don't pick a provider the user has no
+      credentials for.
+    """
+    configured: Optional[str] = None
+    try:
+        from hermes_cli.config import load_config
+
+        cfg = load_config()
+        section = cfg.get("image_gen") if isinstance(cfg, dict) else None
+        if isinstance(section, dict):
+            raw = section.get("provider")
+            if isinstance(raw, str) and raw.strip():
+                configured = raw.strip()
+    except Exception as exc:
+        logger.debug("Could not read image_gen.provider from config: %s", exc)
+
+    with _lock:
+        snapshot = dict(_providers)
+
+    def _is_available_safe(p: ImageGenProvider) -> bool:
+        """Wrap ``is_available()`` so a buggy provider doesn't kill resolution."""
+        try:
+            return bool(p.is_available())
+        except Exception as exc:  # noqa: BLE001
+            logger.debug("image_gen provider %s.is_available() raised %s", p.name, exc)
+            return False
+
+    # 1. Explicit config wins — return regardless of is_available() so the
+    #    user gets a precise downstream error message rather than a silent
+    #    backend switch.
+    if configured:
+        provider = snapshot.get(configured)
+        if provider is not None:
+            return provider
+        logger.debug(
+            "image_gen.provider='%s' configured but not registered; falling back",
+            configured,
+        )
+
+    # 2. Fallback: single registered provider — but only if it's actually
+    #    available (no credentials = don't surface it as "active").
+    available = [p for p in snapshot.values() if _is_available_safe(p)]
+    if len(available) == 1:
+        return available[0]
+
+    # 3. Fallback: prefer legacy FAL for backward compat, when available.
+    fal = snapshot.get("fal")
+    if fal is not None and _is_available_safe(fal):
+        return fal
+
+    return None
+
+
+def _reset_for_tests() -> None:
+    """Clear the registry. **Test-only.**"""
+    with _lock:
+        _providers.clear()