feat(llm): send strict_tool_mode for DeepSeek OpenAI-compat tool calls

Merge strict_tool_mode: true into extra_body when tools are used and the
endpoint/model looks like DeepSeek. Opt out with AIA_DEEPSEEK_STRICT_TOOL_MODE=0.
Add unit tests.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/test_openai_chat_strict_tool_mode.py

@@ -0,0 +1,90 @@
+"""DeepSeek OpenAI-compat: strict_tool_mode via extra_body."""
+
+from __future__ import annotations
+
+import os
+import unittest
+
+from oclaw.platform.llm.transports.openai_chat_completions import (
+    _deepseek_strict_tool_mode_enabled,
+    _merge_deepseek_strict_tool_mode_extra_body,
+)
+
+
+class DeepseekStrictToolModeTests(unittest.TestCase):
+    def test_enabled_when_deepseek_in_base_url(self) -> None:
+        self.assertTrue(
+            _deepseek_strict_tool_mode_enabled(
+                base_url="https://api.deepseek.com/v1",
+                model="deepseek-chat",
+            )
+        )
+
+    def test_disabled_when_env_off(self) -> None:
+        prev = os.environ.get("AIA_DEEPSEEK_STRICT_TOOL_MODE")
+        try:
+            os.environ["AIA_DEEPSEEK_STRICT_TOOL_MODE"] = "0"
+            self.assertFalse(
+                _deepseek_strict_tool_mode_enabled(
+                    base_url="https://api.deepseek.com/v1",
+                    model="x",
+                )
+            )
+        finally:
+            if prev is None:
+                os.environ.pop("AIA_DEEPSEEK_STRICT_TOOL_MODE", None)
+            else:
+                os.environ["AIA_DEEPSEEK_STRICT_TOOL_MODE"] = prev
+
+    def test_merge_sets_extra_body_strict_tool_mode(self) -> None:
+        kwargs: dict = {"model": "m", "messages": [], "stream": False, "tools": [{"type": "function"}]}
+        _merge_deepseek_strict_tool_mode_extra_body(
+            kwargs,
+            base_url="https://api.deepseek.com/v1",
+            model="deepseek-chat",
+            use_tools=True,
+        )
+        self.assertEqual(kwargs.get("extra_body"), {"strict_tool_mode": True})
+
+    def test_merge_preserves_existing_extra_body(self) -> None:
+        kwargs: dict = {
+            "model": "m",
+            "messages": [],
+            "stream": False,
+            "tools": [{"type": "function"}],
+            "extra_body": {"thinking": {"type": "disabled"}},
+        }
+        _merge_deepseek_strict_tool_mode_extra_body(
+            kwargs,
+            base_url="https://api.deepseek.com",
+            model="deepseek-reasoner",
+            use_tools=True,
+        )
+        self.assertEqual(
+            kwargs["extra_body"],
+            {"thinking": {"type": "disabled"}, "strict_tool_mode": True},
+        )
+
+    def test_merge_skips_without_tools(self) -> None:
+        kwargs: dict = {"model": "m", "messages": [], "stream": False}
+        _merge_deepseek_strict_tool_mode_extra_body(
+            kwargs,
+            base_url="https://api.deepseek.com/v1",
+            model="deepseek-chat",
+            use_tools=False,
+        )
+        self.assertNotIn("extra_body", kwargs)
+
+    def test_merge_skips_non_deepseek(self) -> None:
+        kwargs: dict = {"model": "m", "messages": [], "stream": False, "tools": [{"type": "function"}]}
+        _merge_deepseek_strict_tool_mode_extra_body(
+            kwargs,
+            base_url="https://api.openai.com/v1",
+            model="gpt-4o-mini",
+            use_tools=True,
+        )
+        self.assertNotIn("extra_body", kwargs)
+
+
+if __name__ == "__main__":
+    unittest.main()