ai-agent-book 精选快照（<2MB 代码与文档，来自 github.com/bojieli/ai-agent-book）

agentbook/providers/legacy.py

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+"""Backwards-compatible shim for the pre-registry chapter helper.
+
+Before the shared registry existed, three chapter experiments each carried
+their own copy of ``resolve_llm_backend``. It is still imported by three
+chapter modules and called by two of them, so it stays until all of them are
+migrated:
+
+* ``chapter1/web-search-agent/agent.py`` -- calls it
+* ``chapter1/learning-from-experience/llm_agent.py`` -- calls it
+* ``chapter1/context/config.py`` -- re-exports it for its own importers
+
+Deleting this function therefore breaks ``chapter1/context`` at import time
+even though that module never calls it.
+
+It cannot simply delegate to :func:`~agentbook.providers.resolution.resolve_backend`:
+callers pass a bare ``base_url`` with no provider name, which the registry has
+no way to express. What it *can* share is the OpenRouter construction, so the
+two code paths cannot drift apart on the part that matters.
+"""
+
+from __future__ import annotations
+
+from .openrouter import ZERO_COST_HINT, openrouter_key
+from .resolution import build_openrouter_backend
+
+__all__ = ["resolve_llm_backend"]
+
+_NO_KEY_MESSAGE = (
+    "No API key found. Set a provider key (DASHSCOPE_API_KEY / SILICONFLOW_API_KEY / ARK_API_KEY / "
+    "MOONSHOT_API_KEY / DEEPSEEK_API_KEY / ZHIPU_API_KEY / OPENAI_API_KEY / "
+    "GEMINI_API_KEY) or OPENROUTER_API_KEY (universal fallback). " + ZERO_COST_HINT
+)
+
+
+def resolve_llm_backend(
+    primary_key: str | None,
+    primary_base_url: str,
+    model: str,
+) -> tuple[str, str, str, bool]:
+    """Resolve a backend from a loose key/URL pair, as the old helper did.
+
+    Prefer :func:`~agentbook.providers.resolution.resolve_backend`, which knows
+    the provider registry and therefore reports far better errors. This exists
+    for call sites that only have a base URL and no provider name.
+
+    Args:
+        primary_key: The caller's own API key. Falsy values trigger the
+            OpenRouter fallback.
+        primary_base_url: Endpoint matching ``primary_key``.
+        model: Requested model id. Mapped to an OpenRouter id when the request
+            is rerouted, and passed through untouched otherwise.
+
+    Returns:
+        A plain ``(api_key, base_url, model, using_openrouter)`` tuple. Callers
+        compare this against tuple literals, so it deliberately stays a tuple
+        rather than becoming a :class:`~agentbook.providers.models.Backend`.
+
+    Raises:
+        ValueError: If neither ``primary_key`` nor ``OPENROUTER_API_KEY`` is
+            set.
+    """
+    fallback_key = openrouter_key()
+
+    # gpt-5.x needs OpenAI org verification on the direct API; prefer OpenRouter
+    # even when the caller supplied their own key.
+    if fallback_key and str(model or "").lower().startswith("gpt-5"):
+        return tuple(build_openrouter_backend(model, fallback_key))
+
+    if primary_key:
+        return primary_key, primary_base_url, model, False
+
+    if fallback_key:
+        return tuple(build_openrouter_backend(model, fallback_key))
+
+    raise ValueError(_NO_KEY_MESSAGE)