From 8c21a988b7b73303daf82e8c21698f3924a14382 Mon Sep 17 00:00:00 2001
From: Yujong Lee <yujong@berri.ai>
Date: Sat, 19 Sep 2026 18:31:49 +0000
Subject: [PATCH] fix(ocr): set DeepSeek OCR sampling defaults

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>
---
 .../vertex_ai/ocr/deepseek_transformation.rs  | 65 +++++++++++++++++--
 1 file changed, 60 insertions(+), 5 deletions(-)

diff --git a/litellm-rust/crates/llms/src/vertex_ai/ocr/deepseek_transformation.rs b/litellm-rust/crates/llms/src/vertex_ai/ocr/deepseek_transformation.rs
index f0b035621fa..9a23deefb89 100644
--- a/litellm-rust/crates/llms/src/vertex_ai/ocr/deepseek_transformation.rs
+++ b/litellm-rust/crates/llms/src/vertex_ai/ocr/deepseek_transformation.rs
@@ -19,6 +19,13 @@ const MODEL_PREFIX: &str = "deepseek-ai/";
 const DEFAULT_LOCATION: &str = "us-central1";
 const DEEPSEEK_OCR_PARAMS: &[&str] = &["stream", "temperature", "max_tokens", "top_p", "n", "stop"];
 
+/// DeepSeek-OCR is a transcription model: at the endpoint's default sampling temperature it
+/// hallucinates extra text, so requests are greedy unless the caller sets a temperature.
+const DEFAULT_TEMPERATURE: f64 = 0.0;
+/// Greedy decoding on dense screenshots falls into repetition loops that run to the token limit;
+/// a mild penalty breaks them without changing clean-document output.
+const DEFAULT_REPETITION_PENALTY: f64 = 1.05;
+
 pub type DeepSeekOcrParams = OpaqueParams;
 
 #[derive(Clone, Debug, Serialize, Deserialize)]
@@ -171,11 +178,19 @@ impl BaseOcrConfig for VertexAIDeepSeekOCRConfig {
                     image_url: document.source().to_string(),
                 }],
             }],
-            params: optional_params
-                .iter()
-                .filter(|(name, _)| DEEPSEEK_OCR_PARAMS.contains(&name.as_str()))
-                .map(|(name, value)| (name.clone(), value.clone()))
-                .collect(),
+            params: [
+                ("temperature", DEFAULT_TEMPERATURE),
+                ("repetition_penalty", DEFAULT_REPETITION_PENALTY),
+            ]
+            .into_iter()
+            .map(|(name, value)| (name.to_string(), Value::from(value)))
+            .chain(
+                optional_params
+                    .iter()
+                    .filter(|(name, _)| DEEPSEEK_OCR_PARAMS.contains(&name.as_str()))
+                    .map(|(name, value)| (name.clone(), value.clone())),
+            )
+            .collect(),
         })
     }
 }
@@ -484,6 +499,46 @@ mod tests {
         assert!(result.get("ignored").is_none());
     }
 
+    #[test]
+    fn request_uses_greedy_defaults_unless_the_caller_overrides_them() {
+        let request = |params: DeepSeekOcrParams| {
+            serde_json::to_value(
+                VertexAIDeepSeekOCRConfig
+                    .transform_ocr_request(
+                        "deepseek-ai/deepseek-ocr-maas",
+                        document(),
+                        &params,
+                        &[],
+                    )
+                    .unwrap(),
+            )
+            .unwrap()
+        };
+        let defaults = request(DeepSeekOcrParams::default());
+        assert_eq!(defaults["temperature"], 0.0);
+        assert_eq!(defaults["repetition_penalty"], 1.05);
+        assert_eq!(
+            request(serde_json::from_value(json!({"temperature":0.7})).unwrap())["temperature"],
+            0.7
+        );
+    }
+
+    #[test]
+    fn caller_temperature_argument_overrides_the_greedy_default_in_the_composed_body() {
+        let arguments = serde_json::from_value(json!({"temperature":0.7})).unwrap();
+        let body = VertexAIDeepSeekOCRConfig
+            .transform_ocr_request(
+                "deepseek-ai/deepseek-ocr-maas",
+                document(),
+                &DeepSeekOcrParams::default(),
+                &[],
+            )
+            .unwrap();
+        let composed =
+            litellm_core_utils::call_arguments::compose_body(&arguments, &body, &[]).unwrap();
+        assert_eq!(composed["temperature"], 0.7);
+    }
+
     #[rstest]
     #[case(json!({"type":"image_url","image_url":"data:image/png;base64,AA=="}))]
     #[case(json!({"type":"document_url","document_url":"data:application/pdf;base64,AA=="}))]