feat(web): add WebSearchProvider ABC mirroring image_gen template

agent/web_search_provider.py

@@ -0,0 +1,155 @@
+"""
+Web Search Provider ABC
+=======================
+
+Defines the pluggable-backend interface for web search and content extraction.
+Providers register instances via ``PluginContext.register_web_search_provider()``;
+the active one (selected via ``web.search_backend`` / ``web.extract_backend`` /
+``web.backend`` in ``config.yaml``) services every ``web_search`` /
+``web_extract`` tool call.
+
+Providers live in ``<repo>/plugins/web/<name>/`` (built-in, auto-loaded as
+``kind: backend``) or ``~/.hermes/plugins/web/<name>/`` (user, opt-in via
+``plugins.enabled``).
+
+This ABC is the plugin-facing surface. The legacy
+:mod:`tools.web_providers.base` module retains its own ABCs for in-tree
+consumers that haven't migrated yet; over time those will all flow through
+this provider.
+
+Response shape (mirrors the legacy contract in ``tools/web_providers/base.py``
+so the tool wrapper does not have to translate):
+
+Search results::
+
+    {
+        "success": True,
+        "data": {
+            "web": [
+                {"title": str, "url": str, "description": str, "position": int},
+                ...
+            ]
+        }
+    }
+
+Extract results::
+
+    {
+        "success": True,
+        "data": [
+            {"url": str, "title": str, "content": str,
+             "raw_content": str, "metadata": dict},
+            ...
+        ]
+    }
+
+On failure (either capability)::
+
+    {"success": False, "error": str}
+"""
+
+from __future__ import annotations
+
+import abc
+from typing import Any, Dict, List
+
+
+# ---------------------------------------------------------------------------
+# ABC
+# ---------------------------------------------------------------------------
+
+
+class WebSearchProvider(abc.ABC):
+    """Abstract base class for a web search/extract backend.
+
+    Subclasses must implement :meth:`is_available` and at least one of
+    :meth:`search` / :meth:`extract`. The :meth:`supports_search` and
+    :meth:`supports_extract` capability flags let the registry route each
+    tool call to the right provider, and let multi-capability providers
+    (SearXNG, Firecrawl, Tavily, …) advertise both.
+    """
+
+    @property
+    @abc.abstractmethod
+    def name(self) -> str:
+        """Stable short identifier used in ``web.search_backend`` /
+        ``web.extract_backend`` / ``web.backend`` config keys.
+
+        Lowercase, no spaces; hyphens permitted to preserve existing
+        user-visible names. Examples: ``brave-free``, ``ddgs``,
+        ``searxng``, ``firecrawl``.
+        """
+
+    @property
+    def display_name(self) -> str:
+        """Human-readable label shown in ``hermes tools``. Defaults to ``name``."""
+        return self.name
+
+    @abc.abstractmethod
+    def is_available(self) -> bool:
+        """Return True when this provider can service calls.
+
+        Typically a cheap check (env var present, optional Python dep
+        importable, instance URL set). Must NOT make network calls — this
+        runs at tool-registration time and on every ``hermes tools`` paint.
+        """
+
+    def supports_search(self) -> bool:
+        """Return True if this provider implements :meth:`search`."""
+        return True
+
+    def supports_extract(self) -> bool:
+        """Return True if this provider implements :meth:`extract`."""
+        return False
+
+    def search(self, query: str, limit: int = 5) -> Dict[str, Any]:
+        """Execute a web search.
+
+        Override when :meth:`supports_search` returns True. The default
+        raises NotImplementedError; callers should gate on
+        :meth:`supports_search` before calling.
+        """
+        raise NotImplementedError(
+            f"{self.name} does not support search (override supports_search)"
+        )
+
+    def extract(self, urls: List[str], **kwargs: Any) -> Dict[str, Any]:
+        """Extract content from one or more URLs.
+
+        Override when :meth:`supports_extract` returns True. The default
+        raises NotImplementedError; callers should gate on
+        :meth:`supports_extract` before calling.
+
+        ``kwargs`` may carry forward-compat fields (e.g. ``include_raw``,
+        ``max_chars``) — implementations should ignore unknown keys.
+        """
+        raise NotImplementedError(
+            f"{self.name} does not support extract (override supports_extract)"
+        )
+
+    def get_setup_schema(self) -> Dict[str, Any]:
+        """Return provider metadata for the ``hermes tools`` picker.
+
+        Used by ``hermes_cli/tools_config.py`` to inject this provider as a
+        row in the Web Search / Web Extract picker. Shape::
+
+            {
+                "name": "Brave Search (Free)",
+                "badge": "free",
+                "tag": "No paid tier needed — uses Brave's free API.",
+                "env_vars": [
+                    {"key": "BRAVE_SEARCH_API_KEY",
+                     "prompt": "Brave Search API key",
+                     "url": "https://brave.com/search/api/"},
+                ],
+            }
+
+        Default: minimal entry derived from ``display_name``. Override to
+        expose API key prompts, badges, and instance URL fields.
+        """
+        return {
+            "name": self.display_name,
+            "badge": "",
+            "tag": "",
+            "env_vars": [],
+        }