Rebase PR #784 and fix OpenAI model/chat regressions (#1384)

* Wire conversation history through OpenAI responses API

* Fix RuboCop hash brace spacing in assistant tests

* Pipelock ignores

* Batch fixes

---------

Co-authored-by: sokiee <sokysrm@gmail.com>

test/models/provider/openai/batch_slicer_test.rb

@@ -0,0 +1,74 @@
+require "test_helper"
+
+class Provider::Openai::BatchSlicerTest < ActiveSupport::TestCase
+  test "returns empty array for empty input" do
+    assert_equal [], Provider::Openai::BatchSlicer.call([], max_items: 25, max_tokens: 2000)
+  end
+
+  test "single batch when within item cap and token budget" do
+    items = Array.new(10) { |i| { id: i, name: "Item#{i}" } }
+
+    batches = Provider::Openai::BatchSlicer.call(items, max_items: 25, max_tokens: 10_000)
+
+    assert_equal 1, batches.size
+    assert_equal items, batches.first
+  end
+
+  test "splits on item cap" do
+    items = Array.new(30) { |i| { id: i } }
+
+    batches = Provider::Openai::BatchSlicer.call(items, max_items: 10, max_tokens: 100_000)
+
+    assert_equal 3, batches.size
+    assert_equal 10, batches.first.size
+    assert_equal 10, batches.last.size
+    assert_equal items, batches.flatten
+  end
+
+  test "splits on token budget" do
+    big_item = { payload: "x" * 200 }  # ~63 tokens each
+    items = Array.new(10) { big_item }
+
+    # ~125-token budget fits 2 items per batch
+    batches = Provider::Openai::BatchSlicer.call(items, max_items: 100, max_tokens: 125)
+
+    assert batches.size > 1
+    assert_equal items, batches.flatten
+    batches.each do |batch|
+      tokens = Assistant::TokenEstimator.estimate(batch)
+      assert tokens <= 125, "Batch exceeded token budget: #{tokens}"
+    end
+  end
+
+  test "raises ContextOverflowError when single item exceeds budget" do
+    huge = { payload: "x" * 10_000 }
+
+    assert_raises Provider::Openai::BatchSlicer::ContextOverflowError do
+      Provider::Openai::BatchSlicer.call([ huge ], max_items: 25, max_tokens: 500)
+    end
+  end
+
+  test "raises ContextOverflowError when fixed_tokens exceed budget" do
+    assert_raises Provider::Openai::BatchSlicer::ContextOverflowError do
+      Provider::Openai::BatchSlicer.call([ { a: 1 } ], max_items: 25, max_tokens: 500, fixed_tokens: 600)
+    end
+  end
+
+  test "respects fixed_tokens when computing available budget" do
+    items = Array.new(5) { { payload: "x" * 80 } }  # ~25 tokens each
+
+    # Budget of 200 minus fixed 100 = 100 available; fits ~4 items per batch
+    batches = Provider::Openai::BatchSlicer.call(items, max_items: 25, max_tokens: 200, fixed_tokens: 100)
+
+    assert batches.size >= 2
+    assert_equal items, batches.flatten
+  end
+
+  test "never produces empty batches" do
+    items = Array.new(7) { { id: SecureRandom.hex(4) } }
+
+    batches = Provider::Openai::BatchSlicer.call(items, max_items: 2, max_tokens: 10_000)
+
+    batches.each { |b| assert b.any?, "Empty batch produced" }
+  end
+end