From e255afa45f4bbc4d5d75bcb9f0d8fd7a73b2afb9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Adri=C3=A1n=20Mugnolo?= <adrian@mugnolo.com>
Date: Tue, 12 May 2026 11:53:33 -0300
Subject: [PATCH] Stream Anthropic responses uncompressed
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Net::HTTP auto-inflates the upstream gzip, which buffers SSE chunks
until Cloudflare flushes its deflate state — turning ~100 events into 2
bursts and pushing first-chunk arrival from ~1s to ~15s on a 22s
response.

Set Accept-Encoding: identity on streaming requests. Non-streaming
responses keep gzip.
---
 lib/ruby_llm/protocols/anthropic/streaming.rb |  6 ++++++
 .../protocols/anthropic/streaming_spec.rb     | 19 +++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/lib/ruby_llm/protocols/anthropic/streaming.rb b/lib/ruby_llm/protocols/anthropic/streaming.rb
index 11fecf3f1..2557cfc1d 100644
--- a/lib/ruby_llm/protocols/anthropic/streaming.rb
+++ b/lib/ruby_llm/protocols/anthropic/streaming.rb
@@ -9,6 +9,12 @@ class Anthropic
       module Streaming
         private
 
+        def stream_response(payload, additional_headers = {}, &)
+          # Avoid Net::HTTP's auto-inflate: Cloudflare's gzip flushes
+          # infrequently for SSE, batching chunks until each flush.
+          super(payload, additional_headers.merge('Accept-Encoding' => 'identity'), &)
+        end
+
         def stream_url
           completion_url
         end
diff --git a/spec/ruby_llm/protocols/anthropic/streaming_spec.rb b/spec/ruby_llm/protocols/anthropic/streaming_spec.rb
index 5342768b6..3790d08b0 100644
--- a/spec/ruby_llm/protocols/anthropic/streaming_spec.rb
+++ b/spec/ruby_llm/protocols/anthropic/streaming_spec.rb
@@ -3,6 +3,8 @@
 require 'spec_helper'
 
 RSpec.describe RubyLLM::Protocols::Anthropic::Streaming do
+  include_context 'with configured RubyLLM'
+
   let(:protocol) do
     RubyLLM::Protocols::Anthropic.allocate.tap do |object|
       object.instance_variable_set(:@model, instance_double(RubyLLM::Model, id: 'claude-sonnet-4-5'))
@@ -21,4 +23,21 @@
 
     expect(chunk.finish_reason).to eq('end_turn')
   end
+
+  it 'sends Accept-Encoding: identity on streaming requests' do
+    captured = nil
+
+    stub_request(:post, %r{api\.anthropic\.com/v1/messages})
+      .with { |req| captured = req.headers['Accept-Encoding'] }
+      .to_return(
+        status: 200,
+        body: '',
+        headers: { 'Content-Type' => 'text/event-stream' }
+      )
+
+    chat = RubyLLM.chat(model: 'claude-haiku-4-5', provider: :anthropic)
+    chat.ask('hi') { |_chunk| nil }
+
+    expect(captured).to eq('identity')
+  end
 end