diff --git a/CHANGELOG.md b/CHANGELOG.md
index dcfdd1538..9b3630e1e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -32,6 +32,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Bug Fixes
 
+* **proxy/openai:** stop PRE_SEND from reintroducing `tools: []` after the direct #728 fix. The OpenAI request handler now mirrors the existing `tools or _original_tools is not None` body-write guard during PRE_SEND write-back, so providers that reject empty tool arrays no longer see a tools field when the client omitted it, while explicit client `tools: []` remains preserved ([#1983](https://github.com/headroomlabs-ai/headroom/issues/1983)).
 * **proxy/openai:** keep the exact Responses function name `terminal` resident during OpenAI tool-search deferral so cache-mode optimization stops forwarding `terminal.terminal` and triggering the reserved-namespace 400 on Codex Responses ([#1946](https://github.com/headroomlabs-ai/headroom/issues/1946)).
 * **proxy/openai:** thread the savings-profile kwargs into the live `/v1/chat/completions` compression path. The chat handler called `openai_pipeline.apply()` without `proxy_pipeline_kwargs(config)`, so `HEADROOM_SAVINGS_PROFILE=agent-90` (and the individual `compress_user_messages`/`target_ratio`/`min_tokens_to_compress`/... knobs) were silently dropped — OpenAI-compatible clients like OpenCode kept protecting user messages and missed the configured profile. Both the token-mode and non-token chat branches now pass the profile kwargs, matching `handlers/anthropic.py` and the dedicated OpenAI compress endpoint ([#1534](https://github.com/headroomlabs-ai/headroom/issues/1534)).
 * **proxy:** forward Codex Desktop `/v1/responses` posts byte-faithfully so they stop returning upstream `400 {"detail":"Bad Request"}`. `handle_openai_responses` decoded the inbound body to inspect it but always re-serialized a canonical body on the way out, and it never stripped the inbound `content-encoding` header — so a `content-encoding: zstd` Codex Desktop request was forwarded as already-decoded JSON still advertising `zstd`, and the upstream ChatGPT Codex endpoint rejected it. The handler now keeps the original decoded bytes and forwards them verbatim whenever nothing (compression or memory injection) mutated the request, and drops the stale `content-encoding` header, mirroring the byte-faithful passthrough the chat and Anthropic paths already use ([#1542](https://github.com/headroomlabs-ai/headroom/issues/1542)).
diff --git a/headroom/proxy/handlers/openai.py b/headroom/proxy/handlers/openai.py
index df65095ed..133a5d58f 100644
--- a/headroom/proxy/handlers/openai.py
+++ b/headroom/proxy/handlers/openai.py
@@ -2856,7 +2856,7 @@ class OpenAIHandlerMixin:
         if presend_event.messages is not None:
             optimized_messages = presend_event.messages
             body["messages"] = optimized_messages
-        if presend_event.tools is not None:
+        if presend_event.tools or _original_tools is not None:
             tools = presend_event.tools
             body["tools"] = tools
         if presend_event.headers is not None:
diff --git a/tests/test_issue_728_empty_tools_injection.py b/tests/test_issue_728_empty_tools_injection.py
index 93b2d7f5f..aea99cbe8 100644
--- a/tests/test_issue_728_empty_tools_injection.py
+++ b/tests/test_issue_728_empty_tools_injection.py
@@ -40,6 +40,11 @@ def _should_set_body_tools(tools: list | None, original_tools: list | None) -> b
     return bool(tools or original_tools is not None)
 
 
+def _should_apply_presend_tools(presend_tools: list | None, original_tools: list | None) -> bool:
+    """Mirror the fixed PRE_SEND write-back condition in the OpenAI handler."""
+    return bool(presend_tools or original_tools is not None)
+
+
 def _sort_tools(tools: list | None) -> list | None:
     return AnthropicHandlerMixin._sort_tools_deterministically(tools)
 
@@ -110,6 +115,19 @@ class TestHandlerGuardCondition:
         assert not _legacy_should_set_body_tools_after_sort(tools_after_helpers, original_tools)
         assert _should_set_body_tools_after_sort(tools_after_helpers, original_tools)
 
+    def test_presend_empty_list_stays_omitted_when_client_omitted_tools(self):
+        """PRE_SEND must not re-introduce ``tools: []`` for a tools-free request."""
+        assert not _should_apply_presend_tools([], None)
+
+    def test_presend_preserves_explicit_client_empty_tools(self):
+        """PRE_SEND must still preserve an explicit client ``tools: []`` field."""
+        assert _should_apply_presend_tools([], [])
+
+    def test_presend_can_clear_previously_present_tools(self):
+        """PRE_SEND may deliberately replace a real tool list with ``[]``."""
+        original_tools = [{"type": "function", "function": {"name": "my_tool"}}]
+        assert _should_apply_presend_tools([], original_tools)
+
 
 # ---------------------------------------------------------------------------
 # apply_session_sticky_ccr_tool behaviour with no existing tools