diff --git a/ocr/app/extractors/maintenance_receipt_extractor.py b/ocr/app/extractors/maintenance_receipt_extractor.py
index d5b4d13..194c484 100644
--- a/ocr/app/extractors/maintenance_receipt_extractor.py
+++ b/ocr/app/extractors/maintenance_receipt_extractor.py
@@ -14,6 +14,7 @@ import time
 from typing import Any, Optional
 
 from app.config import settings
+from app.engines.gemini_engine import GeminiUnavailableError
 from app.extractors.receipt_extractor import (
     ExtractedField,
     ReceiptExtractionResult,
@@ -54,16 +55,16 @@ OCR Text:
 """
 
 _RECEIPT_RESPONSE_SCHEMA: dict[str, Any] = {
-    "type": "object",
+    "type": "OBJECT",
     "properties": {
-        "serviceName": {"type": "string", "nullable": True},
-        "serviceDate": {"type": "string", "nullable": True},
-        "totalCost": {"type": "number", "nullable": True},
-        "shopName": {"type": "string", "nullable": True},
-        "laborCost": {"type": "number", "nullable": True},
-        "partsCost": {"type": "number", "nullable": True},
-        "odometerReading": {"type": "number", "nullable": True},
-        "vehicleInfo": {"type": "string", "nullable": True},
+        "serviceName": {"type": "STRING", "nullable": True},
+        "serviceDate": {"type": "STRING", "nullable": True},
+        "totalCost": {"type": "NUMBER", "nullable": True},
+        "shopName": {"type": "STRING", "nullable": True},
+        "laborCost": {"type": "NUMBER", "nullable": True},
+        "partsCost": {"type": "NUMBER", "nullable": True},
+        "odometerReading": {"type": "NUMBER", "nullable": True},
+        "vehicleInfo": {"type": "STRING", "nullable": True},
     },
     "required": [
         "serviceName",
@@ -87,8 +88,8 @@ class MaintenanceReceiptExtractor:
     """
 
     def __init__(self) -> None:
-        self._model: Any | None = None
-        self._generation_config: Any | None = None
+        self._client: Any | None = None
+        self._model_name: str = ""
 
     def extract(
         self,
@@ -169,47 +170,52 @@ class MaintenanceReceiptExtractor:
             processing_time_ms=processing_time_ms,
         )
 
-    def _get_model(self) -> Any:
-        """Lazy-initialize Vertex AI Gemini model.
+    def _get_client(self) -> Any:
+        """Lazy-initialize google-genai Gemini client.
 
         Uses the same authentication pattern as GeminiEngine.
         """
-        if self._model is not None:
-            return self._model
+        if self._client is not None:
+            return self._client
 
         key_path = settings.google_vision_key_path
         if not os.path.isfile(key_path):
-            raise RuntimeError(
+            raise GeminiUnavailableError(
                 f"Google credential config not found at {key_path}. "
                 "Set GOOGLE_VISION_KEY_PATH or mount the secret."
             )
 
-        from google.cloud import aiplatform  # type: ignore[import-untyped]
-        from vertexai.generative_models import (  # type: ignore[import-untyped]
-            GenerationConfig,
-            GenerativeModel,
-        )
+        try:
+            from google import genai  # type: ignore[import-untyped]
 
-        os.environ["GOOGLE_APPLICATION_CREDENTIALS"] = key_path
-        os.environ["GOOGLE_EXTERNAL_ACCOUNT_ALLOW_EXECUTABLES"] = "1"
+            # Point ADC at the WIF credential config (must be set BEFORE Client construction)
+            os.environ["GOOGLE_APPLICATION_CREDENTIALS"] = key_path
+            os.environ["GOOGLE_EXTERNAL_ACCOUNT_ALLOW_EXECUTABLES"] = "1"
 
-        aiplatform.init(
-            project=settings.vertex_ai_project,
-            location=settings.vertex_ai_location,
-        )
+            self._client = genai.Client(
+                vertexai=True,
+                project=settings.vertex_ai_project,
+                location=settings.vertex_ai_location,
+            )
+            self._model_name = settings.gemini_model
 
-        model_name = settings.gemini_model
-        self._model = GenerativeModel(model_name)
-        self._generation_config = GenerationConfig(
-            response_mime_type="application/json",
-            response_schema=_RECEIPT_RESPONSE_SCHEMA,
-        )
+            logger.info(
+                "Maintenance receipt Gemini client initialized (model=%s)",
+                self._model_name,
+            )
+            return self._client
 
-        logger.info(
-            "Maintenance receipt Gemini model initialized (model=%s)",
-            model_name,
-        )
-        return self._model
+        except ImportError as exc:
+            logger.exception("google-genai SDK import failed")
+            raise GeminiUnavailableError(
+                "google-genai is not installed. "
+                "Install with: pip install google-genai"
+            ) from exc
+        except Exception as exc:
+            logger.exception("Gemini authentication failed: %s", type(exc).__name__)
+            raise GeminiUnavailableError(
+                f"Gemini authentication failed: {exc}"
+            ) from exc
 
     def _extract_with_gemini(self, ocr_text: str) -> dict:
         """Send OCR text to Gemini for semantic field extraction.
@@ -220,13 +226,19 @@ class MaintenanceReceiptExtractor:
         Returns:
             Dictionary of field_name -> extracted_value from Gemini.
         """
-        model = self._get_model()
+        client = self._get_client()
+
+        from google.genai import types  # type: ignore[import-untyped]
 
         prompt = _RECEIPT_EXTRACTION_PROMPT.format(ocr_text=ocr_text)
 
-        response = model.generate_content(
-            [prompt],
-            generation_config=self._generation_config,
+        response = client.models.generate_content(
+            model=self._model_name,
+            contents=[prompt],
+            config=types.GenerateContentConfig(
+                response_mime_type="application/json",
+                response_schema=_RECEIPT_RESPONSE_SCHEMA,
+            ),
         )
 
         raw = json.loads(response.text)