Fix dots-ocr.py OCR failures: pin vLLM, add limit_mm_per_prompt, per-image fallback

- Pin vLLM >=0.15.1 (was >=0.9.1) to match other production scripts
- Add limit_mm_per_prompt={"image": 1} to LLM init for stable batch processing
- On batch failure, retry images individually so only broken images get [OCR ERROR]

Tested: 20/20 samples clean on A100 (davanstrien/ufo-ColPali, seed 42)

Co-Authored-By: Claude Opus 4.6 <[email protected]>

dots-ocr.py

@@ -4,7 +4,7 @@
 #     "datasets",
 #     "huggingface-hub",
 #     "pillow",
-#     "vllm>=0.9.1",
+#     "vllm>=0.15.1",
 #     "tqdm",
 #     "toolz",
 #     "torch",
@@ -299,6 +299,7 @@ def main(
         trust_remote_code=True,
         max_model_len=max_model_len,
         gpu_memory_utilization=gpu_memory_utilization,
+        limit_mm_per_prompt={"image": 1},
     )
 
     sampling_params = SamplingParams(
@@ -333,9 +334,17 @@ def main(
                 all_outputs.append(text)
 
         except Exception as e:
-            logger.error(f"Error processing batch: {e}")
-            # Add error placeholders for failed batch
-            all_outputs.extend(["[OCR ERROR]"] * len(batch_images))
+            logger.warning(
+                f"Batch failed ({len(batch_images)} images), retrying individually: {e}"
+            )
+            for img in batch_images:
+                try:
+                    msg = make_ocr_message(img, prompt)
+                    out = llm.chat([msg], sampling_params)
+                    all_outputs.append(out[0].outputs[0].text.strip())
+                except Exception as img_e:
+                    logger.error(f"Image failed: {img_e}")
+                    all_outputs.append("[OCR ERROR]")
 
     # Calculate processing time
     processing_duration = datetime.now() - start_time