feat(tier4): Add patch generation for auto-patching

- Add TIER4_PATCH_PROMPT to mma_prompts.py with unified diff format
- Add run_tier4_patch_generation function to ai_client.py
- Import mma_prompts in ai_client.py
- Add unit tests for patch generation

src/ai_client.py

@@ -28,6 +28,7 @@ from pathlib import Path
 from src import project_manager
 from src import file_cache
 from src import mcp_client
+from src import mma_prompts
 import anthropic
 from src.gemini_cli_adapter import GeminiCliAdapter as GeminiCliAdapter
 from google import genai
@@ -1960,6 +1961,33 @@ def run_tier4_analysis(stderr: str) -> str:
  except Exception as e:
   return f"[QA ANALYSIS FAILED] {e}"
 
+
+def run_tier4_patch_generation(error: str, file_context: str) -> str:
+ if not error or not error.strip():
+  return ""
+ try:
+  _ensure_gemini_client()
+  if not _gemini_client:
+   return ""
+  prompt = (
+   f"{mma_prompts.TIER4_PATCH_PROMPT}\n\n"
+   f"Error:\n```\n{error}\n```\n\n"
+   f"File Context:\n```\n{file_context}\n```\n"
+  )
+  model_name = "gemini-2.5-flash-lite"
+  resp = _gemini_client.models.generate_content(
+   model=model_name,
+   contents=prompt,
+   config=types.GenerateContentConfig(
+    temperature=0.0,
+    max_output_tokens=2048,
+   )
+  )
+  patch = resp.text.strip() if resp.text else ""
+  return patch
+ except Exception as e:
+  return f"[PATCH GENERATION FAILED] {e}"
+
 def get_token_stats(md_content: str) -> dict[str, Any]:
  global _provider, _gemini_client, _model, _CHARS_PER_TOKEN
  total_tokens = 0

src/mma_prompts.py

@@ -153,3 +153,28 @@ PROMPTS: Dict[str, str] = {
  "tier2_track_finalization": TIER2_TRACK_FINALIZATION,
  "tier2_contract_first": TIER2_CONTRACT_FIRST,
 }
+
+TIER4_PATCH_PROMPT: str = """You are a Tier 4 QA Agent specializing in error analysis and patch generation.
+When a test or command fails, analyze the error and generate a unified diff patch to fix it.
+
+OUTPUT FORMAT: Unified diff format (diff -u)
+```
+--- a/path/to/file.py
++++ b/path/to/file.py
+@@ -start,count +start,count @@
+ context line
+-removed line
++added line
+ context line
+```
+
+RULES:
+1. Use "--- a/" and "+++ b/" prefixes with the actual file path
+2. Include sufficient context lines (3 above/below minimum)
+3. Use @@ -X,Y +X,Y @@ format for hunk headers
+4. Only include changes necessary to fix the error
+5. If multiple files need changes, include each in the patch
+6. Output ONLY the unified diff - no explanations, no markdown code blocks
+
+Analyze this error and generate the patch:
+"""