feat(devgen/providers): bump default Gemini model to gemini-2.5-flash and add retry handling for quota errors

The update changes the default model, refactors imports, and implements robust retry logic with exponential back‑off and clearer error messages. This improves resilience and clarifies usage.

New Features
- Exponential back‑off retry on 429/quota exhausted responses.
- Configurable max_retries and retry_delay parameters.

Enhancements
- Default model set to gemini-2.5-flash.
- Improved error output with actionable troubleshooting steps.

devgen/modules/commit_generator.py

@@ -466,10 +466,15 @@ class CommitEngine:
             groups = self.group_files(files)
             cache = self.load_cache()
 
-            for group, group_files in groups.items():
+            for i, (group, group_files) in enumerate(groups.items()):
                 try:
                     if not self.process_group(group, group_files, cache):
                         failed.append(group)
+                    # Add a small delay between groups to respect RPM limits if not at the last group
+                    if len(groups) > 1 and i < len(groups) - 1:
+                        import time
+
+                        time.sleep(15)  # Conservative 15s delay to stay within 4 RPM (Free Tier)
                 except KeyboardInterrupt:
                     self.logger.warning("\nOperation interrupted by user.")
                     raise

devgen/providers/gemini.py

@@ -1,24 +1,59 @@
-import google.generativeai as genai
+import time
+from google import genai
+from google.genai import types
 
 
 class GeminiProvider:
     """Generates content using Google's Gemini models."""
 
     def generate(
-        self, prompt: str, api_key: str, model: str = "gemini-pro", **kwargs
+        self, prompt: str, api_key: str, model: str = "gemini-2.5-flash", **kwargs
     ) -> str:
-        """Generates a response using the Gemini API."""
+        """Generates a response using the Gemini API.
+
+        Default model is updated to gemini-2.5-flash which is the latest
+        recommended model.
+        """
         if not api_key:
             raise ValueError("Gemini API key is required.")
 
-        genai.configure(api_key=api_key)
+        client = genai.Client(api_key=api_key)
 
-        # Handle model name mapping if needed, or trust user input
-        # gemini-pro is a common default
+        max_retries = kwargs.get("max_retries", 5)
+        base_delay = kwargs.get("retry_delay", 10)  # 10 seconds base delay for 429
 
-        try:
-            model_instance = genai.GenerativeModel(model)
-            response = model_instance.generate_content(prompt)
-            return response.text.strip()
-        except Exception as e:
-            raise RuntimeError(f"Gemini generation failed: {e}")
+        for attempt in range(max_retries + 1):
+            try:
+                response = client.models.generate_content(
+                    model=model,
+                    contents=prompt,
+                    config=types.GenerateContentConfig(
+                        temperature=kwargs.get("temperature", 0.7),
+                        top_p=kwargs.get("top_p", 0.95),
+                        top_k=kwargs.get("top_k", 40),
+                        max_output_tokens=kwargs.get("max_output_tokens", 2048),
+                    ),
+                )
+                return response.text.strip()
+            except Exception as e:
+                error_msg = str(e).upper()
+                # Check for 429 or ResourceExhausted in common error formats
+                if any(x in error_msg for x in ["429", "RESOURCE_EXHAUSTED", "QUOTA_EXCEEDED", "THROTTLED"]):
+                    if attempt < max_retries:
+                        delay = base_delay * (2**attempt)
+                        print(
+                            f"\n[Gemini] Quota limit hit (429). This is often a temporary rate limit (RPM). "
+                            f"Waiting {delay}s and retrying... (Attempt {attempt + 1}/{max_retries})"
+                        )
+                        time.sleep(delay)
+                        continue
+                    else:
+                        raise RuntimeError(
+                            "Gemini API quota exhausted (429) after multiple retries.\n\n"
+                            "POSSIBLE CAUSES:\n"
+                            "1. Rate Limit (RPM/RPD): You are sending requests too fast for the Free Tier.\n"
+                            "2. Daily Limit: You have reached the maximum free requests allowed for today (typically 1,500).\n"
+                            "3. Credit/Billing: If on a paid plan, your credit may be exhausted.\n\n"
+                            "Please check your usage metrics at: https://aistudio.google.com/app/usage"
+                        ) from e
+                raise RuntimeError(f"Gemini generation failed: {e}") from e