Add shellgen core and backends modules

app/shellgen/backends/llama_cpp.py

@@ -0,0 +1,111 @@
+"""Llama.cpp backend implementation."""
+
+from typing import Optional, TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from llama_cpp import Llama
+
+from .base import LLMBackend
+
+
+class LlamaCppBackend(LLMBackend):
+    """Llama.cpp Python bindings backend."""
+
+    def __init__(
+        self,
+        model_path: str = "~/.cache/llama-cpp/models/",
+        n_ctx: int = 2048,
+        n_threads: int = 4,
+        temperature: float = 0.1,
+        max_tokens: int = 500,
+    ):
+        """Initialize the Llama.cpp backend.
+
+        Args:
+            model_path: Path to the model file.
+            n_ctx: Context window size.
+            n_threads: Number of threads to use.
+            temperature: Generation temperature.
+            max_tokens: Maximum tokens to generate.
+        """
+        self.model_path = model_path
+        self.n_ctx = n_ctx
+        self.n_threads = n_threads
+        self.temperature = temperature
+        self.max_tokens = max_tokens
+        self._llm: Optional["Llama"] = None
+
+    def _load_model(self) -> "Llama":
+        """Load the model if not already loaded.
+
+        Returns:
+            Loaded Llama instance.
+        """
+        from llama_cpp import Llama as LlamaClass
+        if self._llm is None:
+            expanded_path = self.model_path.replace("~", "$HOME")
+            self._llm = LlamaClass(
+                model_path=expanded_path,
+                n_ctx=self.n_ctx,
+                n_threads=self.n_threads,
+                temperature=self.temperature,
+            )
+        return self._llm
+
+    def generate(self, prompt: str) -> str:
+        """Generate response using llama-cpp-python.
+
+        Args:
+            prompt: The prompt to send.
+
+        Returns:
+            Generated response text.
+        """
+        try:
+            llm = self._load_model()
+            response = llm(
+                prompt,
+                max_tokens=self.max_tokens,
+                temperature=self.temperature,
+                stop=["</s>", "###"],
+            )
+
+            return response["choices"][0]["text"]
+
+        except Exception as e:
+            raise ConnectionError(f"Llama.cpp error: {e}")
+
+    def is_available(self) -> bool:
+        """Check if model can be loaded.
+
+        Returns:
+            True if backend is available.
+        """
+        try:
+            self._load_model()
+            return True
+        except Exception:
+            return False
+
+    def get_model_name(self) -> str:
+        """Get the model name from path.
+
+        Returns:
+            Model name string.
+        """
+        return self.model_path.split("/")[-1]
+
+    def set_model(self, model: str) -> None:
+        """Set the model path.
+
+        Args:
+            model: Path to the model.
+        """
+        self.model_path = model
+        self._llm = None
+
+    def close(self) -> None:
+        """Clean up model resources."""
+        if self._llm is not None:
+            del self._llm
+            self._llm = None