fix(gemini): default native maxOutputTokens + strip OpenAI extra_body on Gemini endpoints (#39730)

* fix: respect disabled auto-compaction on context overflow

Port from anomalyco/opencode#30749.

When compression.enabled is false, NO automatic compaction trigger may
fire. The proactive token-threshold paths (preflight + post-response
should_compress gate) already honoured the setting, but the three
provider-overflow recovery paths in the agent loop — long-context-tier
429, 413 payload-too-large, and context-overflow — called
_compress_context() unconditionally, silently compressing and rotating
the session against the user's explicit choice.

Add a single guard at the top of the overflow-recovery dispatch: when
compression is disabled and the error is one of those three overflow
classes, surface a terminal error (compaction_disabled: True) telling the
user to /compress manually, /new, switch to a larger-context model, or
reduce attachments. Manual /compress (force=True) is unaffected — it never
enters this loop.

Tests: new TestOverflowWithCompactionDisabled (413 + 400 overflow don't
compress when disabled; control case still compresses when enabled).
Existing overflow-recovery tests updated to enable compaction explicitly
(they verify the recovery fires); fixture defaults flipped to True to
match production (compression.enabled defaults to True).

* fix(gemini): default native maxOutputTokens + strip OpenAI extra_body on Gemini endpoints

Two distinct failures hit users on the gemini provider with only Google
AI Studio keys set.

1. Truncation loop: build_gemini_request() only set maxOutputTokens when
   max_tokens was non-None. Hermes passes None to mean "unlimited", but
   Gemini's native generateContent does NOT treat an absent maxOutputTokens
   as full budget — it applies a low internal default and stops early with
   finishReason=MAX_TOKENS, truncating tool calls. The agent then retries
   3x and refuses the incomplete call. Now default to the published 65,535
   ceiling (shared by all current Gemini text models) when max_tokens=None.

2. HTTP 400 on Gemini endpoint: the chat_completions transport assembles
   profile extra_body (Nous portal 'tags', reasoning, provider prefs) and
   sends it via the OpenAI client to whatever base_url is resolved. When a
   profile that emits extra_body (e.g. Nous) is active but the endpoint is a
   native Gemini base_url — typical when only Google creds exist and a
   fallback/aux call lands on Gemini — Google rejects the unknown 'tags'
   field with a non-retryable 400. Strip all non-thinking_config extra_body
   keys when the resolved endpoint is native Gemini.

Verified E2E against real transport code: tags stripped on native Gemini,
preserved on Nous and the /openai compat endpoint; maxOutputTokens=65535
on None, explicit values respected.

tests/agent/test_gemini_native_adapter.py

@@ -326,3 +326,27 @@ def test_stream_event_translation_keeps_identical_calls_in_distinct_parts():
     assert tool_chunks[0].choices[0].delta.tool_calls[0].index == 0
     assert tool_chunks[1].choices[0].delta.tool_calls[0].index == 1
     assert tool_chunks[0].choices[0].delta.tool_calls[0].id != tool_chunks[1].choices[0].delta.tool_calls[0].id
+
+
+def test_max_tokens_none_defaults_to_gemini_output_ceiling():
+    """max_tokens=None must send the model's full output ceiling, not omit it.
+
+    Gemini's native generateContent applies a low internal default when
+    maxOutputTokens is absent, truncating tool calls mid-stream. Hermes passes
+    None to mean "unlimited", so the adapter must translate that to the
+    published 65,535 ceiling rather than leaving the field unset.
+    """
+    from agent.gemini_native_adapter import (
+        build_gemini_request,
+        GEMINI_DEFAULT_MAX_OUTPUT_TOKENS,
+    )
+
+    req = build_gemini_request(messages=[{"role": "user", "content": "hi"}], max_tokens=None)
+    assert req["generationConfig"]["maxOutputTokens"] == GEMINI_DEFAULT_MAX_OUTPUT_TOKENS == 65535
+
+
+def test_explicit_max_tokens_is_respected():
+    from agent.gemini_native_adapter import build_gemini_request
+
+    req = build_gemini_request(messages=[{"role": "user", "content": "hi"}], max_tokens=4096)
+    assert req["generationConfig"]["maxOutputTokens"] == 4096

tests/agent/transports/test_chat_completions.py

@@ -859,3 +859,53 @@ class TestChatCompletionsCacheStats:
         r = SimpleNamespace(usage=SimpleNamespace(prompt_tokens_details=details))
         result = transport.extract_cache_stats(r)
         assert result == {"cached_tokens": 500, "creation_tokens": 100}
+
+
+class TestChatCompletionsGeminiNativeExtraBodyStrip:
+    """Profile extra_body (e.g. Nous portal tags) must not reach a native
+    Gemini endpoint — Google's REST API rejects unknown fields with HTTP 400.
+    """
+
+    def _nous_profile(self):
+        from providers import get_provider_profile
+        return get_provider_profile("nous")
+
+    def test_tags_stripped_when_endpoint_is_native_gemini(self, transport):
+        kw = transport.build_kwargs(
+            "anthropic/claude-sonnet-4.6",
+            [{"role": "user", "content": "hi"}],
+            None,
+            provider_profile=self._nous_profile(),
+            base_url="https://generativelanguage.googleapis.com/v1beta",
+            session_id="s1",
+            max_tokens=None,
+        )
+        eb = kw.get("extra_body")
+        assert not eb or "tags" not in eb
+
+    def test_tags_preserved_on_nous_endpoint(self, transport):
+        kw = transport.build_kwargs(
+            "hermes-3-405b",
+            [{"role": "user", "content": "hi"}],
+            None,
+            provider_profile=self._nous_profile(),
+            base_url="https://inference.nousresearch.com/v1",
+            session_id="s1",
+            max_tokens=None,
+        )
+        eb = kw.get("extra_body")
+        assert eb and "tags" in eb
+
+    def test_tags_pass_through_on_gemini_openai_compat(self, transport):
+        # /openai compat endpoint is not "native" — unchanged behavior.
+        kw = transport.build_kwargs(
+            "anthropic/claude-sonnet-4.6",
+            [{"role": "user", "content": "hi"}],
+            None,
+            provider_profile=self._nous_profile(),
+            base_url="https://generativelanguage.googleapis.com/v1beta/openai",
+            session_id="s1",
+            max_tokens=None,
+        )
+        eb = kw.get("extra_body")
+        assert eb and "tags" in eb

tests/run_agent/test_413_compression.py

@@ -94,7 +94,11 @@ def agent():
         a._cached_system_prompt = "You are helpful."
         a._use_prompt_caching = False
         a.tool_delay = 0
-        a.compression_enabled = False
+        # Default matches production (`compression.enabled` defaults to True).
+        # Overflow-recovery tests below verify that 413 / context-overflow
+        # errors DO trigger compression; the disabled-path behavior is
+        # covered explicitly by TestOverflowWithCompactionDisabled.
+        a.compression_enabled = True
         a.save_trajectories = False
         return a
 
@@ -415,6 +419,13 @@ class TestPreflightCompression:
 
     def test_compress_context_emits_lifecycle_status_before_work(self, agent):
         """Direct context compression should tell gateway users why the turn paused."""
+        # This test calls _compress_context directly and asserts the FIRST
+        # status event is the lifecycle "Compacting context" message. With
+        # compaction enabled the lazy feasibility probe would emit an
+        # aux-provider warning first (no aux key in the hermetic test env),
+        # displacing events[0]. The flag value is irrelevant to what this
+        # test asserts, so disable it to suppress the probe.
+        agent.compression_enabled = False
         events = []
         agent.status_callback = lambda ev, msg: events.append((ev, msg))
 
@@ -802,3 +813,95 @@ class TestToolResultPreflightCompression:
 
         mock_compress.assert_called_once()
         assert result["completed"] is True
+
+
+# ---------------------------------------------------------------------------
+# Disabled auto-compaction on overflow (port of anomalyco/opencode#30749)
+# ---------------------------------------------------------------------------
+
+class TestOverflowWithCompactionDisabled:
+    """When ``compression.enabled`` is False, NO automatic compaction may
+    fire — including the provider/request-size overflow recovery paths.
+
+    Ported from anomalyco/opencode#30749: the proactive token-threshold
+    path already honoured the setting, but provider overflow errors
+    (413 payload-too-large, context-overflow, long-context-tier 429) still
+    silently compressed + rotated the session. The fix surfaces a terminal
+    error so the user can compact manually, start fresh, or switch models.
+    """
+
+    @staticmethod
+    def _prefill():
+        return [
+            {"role": "user", "content": "previous question"},
+            {"role": "assistant", "content": "previous answer"},
+        ]
+
+    def test_413_does_not_compress_when_disabled(self, agent):
+        """413 must NOT call _compress_context when compaction is disabled."""
+        agent.compression_enabled = False
+        err_413 = _make_413_error()
+        # If the guard fails, a second (success) response would be consumed.
+        agent.client.chat.completions.create.side_effect = [err_413, _mock_response()]
+
+        with (
+            patch.object(agent, "_compress_context") as mock_compress,
+            patch.object(agent, "_persist_session") as mock_persist,
+            patch.object(agent, "_save_trajectory"),
+            patch.object(agent, "_cleanup_task_resources"),
+        ):
+            result = agent.run_conversation("hello", conversation_history=self._prefill())
+
+        mock_compress.assert_not_called()
+        mock_persist.assert_called()
+        assert result.get("failed") is True
+        assert result.get("compaction_disabled") is True
+        assert "auto-compaction is disabled" in result["error"]
+
+    def test_context_overflow_does_not_compress_when_disabled(self, agent):
+        """400 'prompt is too long' must NOT compress when compaction disabled."""
+        agent.compression_enabled = False
+        err_400 = Exception(
+            "Error code: 400 - {'type': 'error', 'error': {'type': "
+            "'invalid_request_error', 'message': 'prompt is too long: "
+            "233153 tokens > 200000 maximum'}}"
+        )
+        err_400.status_code = 400
+        agent.client.chat.completions.create.side_effect = [err_400, _mock_response()]
+
+        with (
+            patch.object(agent, "_compress_context") as mock_compress,
+            patch.object(agent, "_persist_session"),
+            patch.object(agent, "_save_trajectory"),
+            patch.object(agent, "_cleanup_task_resources"),
+        ):
+            result = agent.run_conversation("hello", conversation_history=self._prefill())
+
+        mock_compress.assert_not_called()
+        assert result.get("compaction_disabled") is True
+
+    def test_413_still_compresses_when_enabled(self, agent):
+        """Control: with compaction enabled, 413 still triggers compression.
+
+        Guards against the disabled-path guard accidentally swallowing the
+        enabled path.
+        """
+        agent.compression_enabled = True
+        err_413 = _make_413_error()
+        ok_resp = _mock_response(content="Recovered", finish_reason="stop")
+        agent.client.chat.completions.create.side_effect = [err_413, ok_resp]
+
+        with (
+            patch.object(agent, "_compress_context") as mock_compress,
+            patch.object(agent, "_persist_session"),
+            patch.object(agent, "_save_trajectory"),
+            patch.object(agent, "_cleanup_task_resources"),
+        ):
+            mock_compress.return_value = (
+                [{"role": "user", "content": "hello"}], "compressed",
+            )
+            result = agent.run_conversation("hello", conversation_history=self._prefill())
+
+        mock_compress.assert_called_once()
+        assert result["completed"] is True
+        assert result.get("compaction_disabled") is not True

tests/run_agent/test_run_agent.py

@@ -3903,6 +3903,7 @@ class TestRunConversation:
     def test_glm_prompt_exceeds_max_length_triggers_compression(self, agent):
         """GLM/Z.AI uses 'Prompt exceeds max length' for context overflow."""
         self._setup_agent(agent)
+        agent.compression_enabled = True  # this test verifies overflow→compression fires
         err_400 = Exception(
             "Error code: 400 - {'error': {'code': '1261', 'message': 'Prompt exceeds max length'}}"
         )
@@ -3937,6 +3938,7 @@ class TestRunConversation:
         to the generic 128K fallback tier.
         """
         self._setup_agent(agent)
+        agent.compression_enabled = True  # this test verifies overflow→compression fires
         agent.provider = "minimax"
         agent.model = "MiniMax-M2.7-highspeed"
         agent.base_url = "https://api.minimax.io/anthropic"
@@ -3982,6 +3984,7 @@ class TestRunConversation:
         rely on compression — see #33669 / PR #33826.
         """
         self._setup_agent(agent)
+        agent.compression_enabled = True  # this test verifies overflow→compression fires
         agent.provider = "openrouter"
         agent.model = "some/unknown-model"
         agent.base_url = "https://openrouter.ai/api/v1"