feat: implement vertical crop, local LLM deepseek-v4-flash, multi-threading, word-level pink box highlight subtitles, and Nextcloud scan sync

ai-youtube-shorts-generator/shorts_generator/local/llm.py

@@ -0,0 +1,62 @@
+"""Local LLM backend — OpenAI or Gemini, selected by LLM_PROVIDER."""
+from ..config import (
+    GEMINI_MODEL,
+    LLM_PROVIDER,
+    OPENAI_MODEL,
+    require_gemini_key,
+    require_openai_key,
+)
+
+
+def call_openai_llm(prompt: str) -> str:
+    """OpenAI Chat Completions backend used by --mode local."""
+    try:
+        from openai import OpenAI  # type: ignore
+    except ImportError as e:
+        raise RuntimeError(
+            "openai is required for --mode local. Install it with:\n"
+            "    pip install -r requirements-local.txt"
+        ) from e
+
+    client = OpenAI(api_key=require_openai_key())
+    response = client.chat.completions.create(
+        model=OPENAI_MODEL,
+        temperature=0.7,
+        messages=[{"role": "user", "content": prompt}],
+    )
+    return response.choices[0].message.content or ""
+
+
+def call_gemini_llm(prompt: str) -> str:
+    """Gemini backend used by --mode local when LLM_PROVIDER=gemini."""
+    try:
+        from google import genai  # type: ignore
+    except ImportError as e:
+        raise RuntimeError(
+            "google-genai is required for LLM_PROVIDER=gemini. Install it with:\n"
+            "    pip install -r requirements-local.txt"
+        ) from e
+
+    client = genai.Client(api_key=require_gemini_key())
+    response = client.models.generate_content(
+        model=GEMINI_MODEL,
+        contents=prompt,
+        config={
+            "temperature": 0.2,
+            "response_mime_type": "application/json",
+            "max_output_tokens": 8192,
+        },
+    )
+    return response.text or ""
+
+
+def call_local_llm(prompt: str) -> str:
+    """Dispatch to the configured local LLM provider."""
+    provider = (LLM_PROVIDER or "openai").strip().lower()
+    if provider == "openai":
+        return call_openai_llm(prompt)
+    if provider == "gemini":
+        return call_gemini_llm(prompt)
+    raise RuntimeError(
+        f"Unknown LLM_PROVIDER={provider!r}. Use 'openai' or 'gemini'."
+    )