feat(core): centralize snake_to_camel and fix FFI casing leakage

crates/kreuzberg-ffi/src/helpers.rs

@@ -136,6 +136,7 @@ pub fn to_c_extraction_result(result: ExtractionResult) -> std::result::Result<*
     let metadata_json_guard = {
         let json =
             serde_json::to_string(&metadata).map_err(|e| format!("Failed to serialize metadata to JSON: {}", e))?;
+
         Some(CStringGuard::new(CString::new(json).map_err(|e| {
             format!("Failed to convert metadata JSON to C string: {}", e)
         })?))

crates/kreuzberg-node/src/result.rs

@@ -2,11 +2,11 @@
 use crate::config::JsExtractionConfig;
 use kreuzberg::{
     Chunk as RustChunk, ChunkMetadata as RustChunkMetadata, ExtractionConfig, ExtractionResult as RustExtractionResult,
-    ProcessingWarning as RustProcessingWarning,
+    ProcessingWarning as RustProcessingWarning, utils::snake_to_camel,
 };
 use napi::bindgen_prelude::*;
 use napi_derive::napi;
 use serde_json::Value;
 
 #[napi(object)]
 #[derive(serde::Serialize, serde::Deserialize)]
@@ -781,37 +781,3 @@
         })
     }
 }
-
-/// Recursively convert snake_case keys in a JSON Value to camelCase.
-fn snake_to_camel(val: Value) -> Value {
-    match val {
-        Value::Object(map) => {
-            let mut new_map = serde_json::Map::with_capacity(map.len());
-            for (key, value) in map {
-                let new_key = to_camel_case(&key);
-                new_map.insert(new_key, snake_to_camel(value));
-            }
-            Value::Object(new_map)
-        }
-        Value::Array(arr) => Value::Array(arr.into_iter().map(snake_to_camel).collect()),
-        _ => val,
-    }
-}
-
-/// Simple snake_case to camelCase converter for keys.
-fn to_camel_case(s: &str) -> String {
-    let mut camel = String::with_capacity(s.len());
-    let mut capitalize_next = false;
-
-    for c in s.chars() {
-        if c == '_' {
-            capitalize_next = true;
-        } else if capitalize_next {
-            camel.push(c.to_ascii_uppercase());
-            capitalize_next = false;
-        } else {
-            camel.push(c);
-        }
-    }
-    camel
-}

crates/kreuzberg/src/utils/json_utils.rs

@@ -0,0 +1,73 @@
+use serde_json::Value;
+
+/// Recursively convert snake_case keys in a JSON Value to camelCase.
+///
+/// This is used by language bindings (Node.js, Go, Java, C#, etc.) to provide
+/// a consistent camelCase API for consumers even though the Rust core uses snake_case.
+pub fn snake_to_camel(val: Value) -> Value {
+    match val {
+        Value::Object(map) => {
+            let mut new_map = serde_json::Map::with_capacity(map.len());
+            for (key, value) in map {
+                let new_key = to_camel_case(&key);
+                new_map.insert(new_key, snake_to_camel(value));
+            }
+            Value::Object(new_map)
+        }
+        Value::Array(arr) => Value::Array(arr.into_iter().map(snake_to_camel).collect()),
+        _ => val,
+    }
+}
+
+/// snake_case to camelCase converter for keys.
+fn to_camel_case(s: &str) -> String {
+    let mut camel = String::with_capacity(s.len());
+    let mut capitalize_next = false;
+
+    for c in s.chars() {
+        if c == '_' {
+            capitalize_next = true;
+        } else if capitalize_next {
+            camel.push(c.to_ascii_uppercase());
+            capitalize_next = false;
+        } else {
+            camel.push(c);
+        }
+    }
+    camel
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use serde_json::json;
+
+    #[test]
+    fn test_snake_to_camel_basic() {
+        let input = json!({
+            "first_name": "John",
+            "last_name": "Doe",
+            "nested_object": {
+                "street_address": "123 Main St"
+            },
+            "array_of_objects": [
+                { "item_id": 1 },
+                { "item_name": "item 2" }
+            ]
+        });
+
+        let expected = json!({
+            "firstName": "John",
+            "lastName": "Doe",
+            "nestedObject": {
+                "streetAddress": "123 Main St"
+            },
+            "arrayOfObjects": [
+                { "itemId": 1 },
+                { "itemName": "item 2" }
+            ]
+        });
+
+        assert_eq!(snake_to_camel(input), expected);
+    }
+}

crates/kreuzberg/src/utils/mod.rs

@@ -11,6 +11,7 @@ pub mod quality;
 #[cfg(feature = "quality")]
 pub mod string_utils;
 
+pub mod json_utils;
 pub mod pool;
 pub mod pool_sizing;
 pub mod string_pool;
@@ -28,4 +29,5 @@ pub use pool::{
 
 pub use pool_sizing::{PoolSizeHint, estimate_pool_size};
 
-pub use string_pool::{InternedString, intern_language_code, intern_mime_type};
+
+pub use json_utils::snake_to_camel;