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sn-image-base/scripts/sn_image_base/vlm/vlm_adapter.py

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+"""Abstract base class for VLM (Vision Language Model) adapters."""
+
+from __future__ import annotations
+
+from abc import ABC, abstractmethod
+
+
+class VlmAdapter(ABC):
+    """Uniform async interface for a single Vision Language Model backend.
+
+    Each concrete adapter wraps one LLM endpoint + model combination and
+    exposes a single :meth:`vision_completion` coroutine.  Synchronous
+    calling is intentionally **not** supported; callers must run inside an
+    asyncio event loop.
+
+    **Client ownership contract** — when a shared
+    :class:`httpx.AsyncClient` is supplied at construction time the adapter
+    *reuses* it and must **not** close it; the caller retains full ownership
+    of the client's lifecycle.  When no external client is provided the
+    adapter creates and owns an internal client and must close it in
+    :meth:`aclose`.
+    """
+
+    @abstractmethod
+    async def vision_completion(
+        self,
+        user_prompt: str,
+        images: list[str | bytes],
+        system_prompt: str = "",
+        model: str | None = None,
+    ) -> str:
+        """Send image(s) and a text prompt to the model; return the reply.
+
+        Args:
+            user_prompt: User-facing text instruction.
+            images: One or more images to pass to the model.  Each element
+                is either a file-path string or raw image bytes.
+            system_prompt: System-level instruction prepended to the
+                conversation.  Defaults to ''.
+            model: Model name to use. If None, uses the default set at
+                initialization.
+
+        Returns:
+            str: Raw text response from the model (may contain JSON or
+                markdown-wrapped JSON depending on the model and prompt).
+        """
+
+    @abstractmethod
+    async def aclose(self) -> None:
+        """Release async resources owned by this adapter.
+
+        Must be called when the adapter is no longer needed.  Adapters that
+        were given an external shared client must implement this as a no-op;
+        adapters that created their own internal client must close it here.
+        """