fix: include byteplus providers, guard None reasoning_effort, merge extra_body

- Add byteplus and byteplus_coding_plan to thinking param providers
- Only send extra_body when reasoning_effort is explicitly set
- Use setdefault().update() to avoid clobbering existing extra_body
- Add 7 regression tests for thinking params

Made-with: Cursor

nanobot/providers/openai_compat_provider.py

@@ -297,22 +297,23 @@ class OpenAICompatProvider(LLMProvider):
         if reasoning_effort:
             kwargs["reasoning_effort"] = reasoning_effort
 
-        # Provider-specific thinking parameters
-        if spec:
-            # Refer: https://docs.byteplus.com/en/docs/ModelArk/1449737#adjust-reasoning-length
-            # The agent will stop thinking if reasoning_effort is minimal or None. Otherwise, it will think.
-            thinking_enabled = (
-                reasoning_effort is not None and reasoning_effort.lower() != "minimal"
-            )
+        # Provider-specific thinking parameters.
+        # Only sent when reasoning_effort is explicitly configured so that
+        # the provider default is preserved otherwise.
+        if spec and reasoning_effort is not None:
+            thinking_enabled = reasoning_effort.lower() != "minimal"
+            extra: dict[str, Any] | None = None
             if spec.name == "dashscope":
-                # Qwen: extra_body={"enable_thinking": True/False}
-                kwargs["extra_body"] = {"enable_thinking": thinking_enabled}
-            elif spec.name in ("volcengine", "volcengine_coding_plan"):
-                # VolcEngine/Byteplus ModelArk: extra_body={"thinking": {"type": "enabled"/"disabled"}}
-                kwargs["extra_body"] = {
+                extra = {"enable_thinking": thinking_enabled}
+            elif spec.name in (
+                "volcengine", "volcengine_coding_plan",
+                "byteplus", "byteplus_coding_plan",
+            ):
+                extra = {
                     "thinking": {"type": "enabled" if thinking_enabled else "disabled"}
                 }
-
+            if extra:
+                kwargs.setdefault("extra_body", {}).update(extra)
 
         if tools:
             kwargs["tools"] = tools