diff --git a/src/internal/decoders/line.ts b/src/internal/decoders/line.ts
new file mode 100644
index 00000000..fe9df101
--- /dev/null
+++ b/src/internal/decoders/line.ts
@@ -0,0 +1,114 @@
+import { AnthropicError } from '../../error';
+
+type Bytes = string | ArrayBuffer | Uint8Array | Buffer | null | undefined;
+
+/**
+ * A re-implementation of httpx's `LineDecoder` in Python that handles incrementally
+ * reading lines from text.
+ *
+ * https://github.com/encode/httpx/blob/920333ea98118e9cf617f246905d7b202510941c/httpx/_decoders.py#L258
+ */
+export class LineDecoder {
+  // prettier-ignore
+  static NEWLINE_CHARS = new Set(['\n', '\r']);
+  static NEWLINE_REGEXP = /\r\n|[\n\r]/g;
+
+  buffer: string[];
+  trailingCR: boolean;
+  textDecoder: any; // TextDecoder found in browsers; not typed to avoid pulling in either "dom" or "node" types.
+
+  constructor() {
+    this.buffer = [];
+    this.trailingCR = false;
+  }
+
+  decode(chunk: Bytes): string[] {
+    let text = this.decodeText(chunk);
+
+    if (this.trailingCR) {
+      text = '\r' + text;
+      this.trailingCR = false;
+    }
+    if (text.endsWith('\r')) {
+      this.trailingCR = true;
+      text = text.slice(0, -1);
+    }
+
+    if (!text) {
+      return [];
+    }
+
+    const trailingNewline = LineDecoder.NEWLINE_CHARS.has(text[text.length - 1] || '');
+    let lines = text.split(LineDecoder.NEWLINE_REGEXP);
+
+    // if there is a trailing new line then the last entry will be an empty
+    // string which we don't care about
+    if (trailingNewline) {
+      lines.pop();
+    }
+
+    if (lines.length === 1 && !trailingNewline) {
+      this.buffer.push(lines[0]!);
+      return [];
+    }
+
+    if (this.buffer.length > 0) {
+      lines = [this.buffer.join('') + lines[0], ...lines.slice(1)];
+      this.buffer = [];
+    }
+
+    if (!trailingNewline) {
+      this.buffer = [lines.pop() || ''];
+    }
+
+    return lines;
+  }
+
+  decodeText(bytes: Bytes): string {
+    if (bytes == null) return '';
+    if (typeof bytes === 'string') return bytes;
+
+    // Node:
+    if (typeof Buffer !== 'undefined') {
+      if (bytes instanceof Buffer) {
+        return bytes.toString();
+      }
+      if (bytes instanceof Uint8Array) {
+        return Buffer.from(bytes).toString();
+      }
+
+      throw new AnthropicError(
+        `Unexpected: received non-Uint8Array (${bytes.constructor.name}) stream chunk in an environment with a global "Buffer" defined, which this library assumes to be Node. Please report this error.`,
+      );
+    }
+
+    // Browser
+    if (typeof TextDecoder !== 'undefined') {
+      if (bytes instanceof Uint8Array || bytes instanceof ArrayBuffer) {
+        this.textDecoder ??= new TextDecoder('utf8');
+        return this.textDecoder.decode(bytes);
+      }
+
+      throw new AnthropicError(
+        `Unexpected: received non-Uint8Array/ArrayBuffer (${
+          (bytes as any).constructor.name
+        }) in a web platform. Please report this error.`,
+      );
+    }
+
+    throw new AnthropicError(
+      `Unexpected: neither Buffer nor TextDecoder are available as globals. Please report this error.`,
+    );
+  }
+
+  flush(): string[] {
+    if (!this.buffer.length && !this.trailingCR) {
+      return [];
+    }
+
+    const lines = [this.buffer.join('')];
+    this.buffer = [];
+    this.trailingCR = false;
+    return lines;
+  }
+}
diff --git a/src/streaming.ts b/src/streaming.ts
index 8478dcd2..704c95ba 100644
--- a/src/streaming.ts
+++ b/src/streaming.ts
@@ -1,5 +1,6 @@
 import { ReadableStream, type Response } from './_shims/index';
 import { AnthropicError } from './error';
+import { LineDecoder } from './internal/decoders/line';
 
 import { createResponseHeaders } from '@anthropic-ai/sdk/core';
 import { APIError } from '@anthropic-ai/sdk/error';
@@ -345,117 +346,6 @@ class SSEDecoder {
   }
 }
 
-/**
- * A re-implementation of httpx's `LineDecoder` in Python that handles incrementally
- * reading lines from text.
- *
- * https://github.com/encode/httpx/blob/920333ea98118e9cf617f246905d7b202510941c/httpx/_decoders.py#L258
- */
-class LineDecoder {
-  // prettier-ignore
-  static NEWLINE_CHARS = new Set(['\n', '\r']);
-  static NEWLINE_REGEXP = /\r\n|[\n\r]/g;
-
-  buffer: string[];
-  trailingCR: boolean;
-  textDecoder: any; // TextDecoder found in browsers; not typed to avoid pulling in either "dom" or "node" types.
-
-  constructor() {
-    this.buffer = [];
-    this.trailingCR = false;
-  }
-
-  decode(chunk: Bytes): string[] {
-    let text = this.decodeText(chunk);
-
-    if (this.trailingCR) {
-      text = '\r' + text;
-      this.trailingCR = false;
-    }
-    if (text.endsWith('\r')) {
-      this.trailingCR = true;
-      text = text.slice(0, -1);
-    }
-
-    if (!text) {
-      return [];
-    }
-
-    const trailingNewline = LineDecoder.NEWLINE_CHARS.has(text[text.length - 1] || '');
-    let lines = text.split(LineDecoder.NEWLINE_REGEXP);
-
-    // if there is a trailing new line then the last entry will be an empty
-    // string which we don't care about
-    if (trailingNewline) {
-      lines.pop();
-    }
-
-    if (lines.length === 1 && !trailingNewline) {
-      this.buffer.push(lines[0]!);
-      return [];
-    }
-
-    if (this.buffer.length > 0) {
-      lines = [this.buffer.join('') + lines[0], ...lines.slice(1)];
-      this.buffer = [];
-    }
-
-    if (!trailingNewline) {
-      this.buffer = [lines.pop() || ''];
-    }
-
-    return lines;
-  }
-
-  decodeText(bytes: Bytes): string {
-    if (bytes == null) return '';
-    if (typeof bytes === 'string') return bytes;
-
-    // Node:
-    if (typeof Buffer !== 'undefined') {
-      if (bytes instanceof Buffer) {
-        return bytes.toString();
-      }
-      if (bytes instanceof Uint8Array) {
-        return Buffer.from(bytes).toString();
-      }
-
-      throw new AnthropicError(
-        `Unexpected: received non-Uint8Array (${bytes.constructor.name}) stream chunk in an environment with a global "Buffer" defined, which this library assumes to be Node. Please report this error.`,
-      );
-    }
-
-    // Browser
-    if (typeof TextDecoder !== 'undefined') {
-      if (bytes instanceof Uint8Array || bytes instanceof ArrayBuffer) {
-        this.textDecoder ??= new TextDecoder('utf8');
-        return this.textDecoder.decode(bytes);
-      }
-
-      throw new AnthropicError(
-        `Unexpected: received non-Uint8Array/ArrayBuffer (${
-          (bytes as any).constructor.name
-        }) in a web platform. Please report this error.`,
-      );
-    }
-
-    throw new AnthropicError(
-      `Unexpected: neither Buffer nor TextDecoder are available as globals. Please report this error.`,
-    );
-  }
-
-  flush(): string[] {
-    if (!this.buffer.length && !this.trailingCR) {
-      return [];
-    }
-
-    const lines = [this.buffer.join('')];
-    this.buffer = [];
-    this.trailingCR = false;
-    return lines;
-  }
-}
-
 /** This is an internal helper function that's just used for testing */
 export function _decodeChunks(chunks: string[]): string[] {
   const decoder = new LineDecoder();