feat(setup): ask whether OpenAI-compatible gateway models support thinking (#3428)

The "Other OpenAI-compatible" wizard provider lets users supply a custom base_url and model name but never asked whether that model supports thinking/reasoning, so the generated config.yaml always left supports_thinking at its default of false — even for reasoning models behind the gateway.

Add an explicit ask_thinking_support flag on LLMProvider (enabled for the "other" provider) plus a pure with_thinking_support() helper. When the flag is set, the LLM step prompts via ask_yes_no; confirming wires the standard OpenAI-compatible enable/disable thinking toggles, declining records supports_thinking=false. Provider definitions are copied with dataclasses.replace, never mutated. Adds unit tests for the helper and the interactive step.

Closes #3162

Co-authored-by: ly-wang19 <ly-wang19@users.noreply.github.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

backend/tests/test_setup_wizard.py

@@ -8,7 +8,7 @@ from __future__ import annotations
 
 import yaml
 from wizard import ui as wizard_ui
-from wizard.providers import LLM_PROVIDERS, SEARCH_PROVIDERS, WEB_FETCH_PROVIDERS, LLMProvider
+from wizard.providers import LLM_PROVIDERS, SEARCH_PROVIDERS, WEB_FETCH_PROVIDERS, LLMProvider, with_thinking_support
 from wizard.steps import channels as channels_step
 from wizard.steps import llm as llm_step
 from wizard.steps import search as search_step
@@ -368,6 +368,32 @@ class TestBuildMinimalConfig:
         assert all(not config["enabled"] for provider, config in channel_connections.items() if provider != "enabled")
 
 
+class TestThinkingSupport:
+    def test_other_provider_requests_thinking_prompt(self):
+        other = next(p for p in LLM_PROVIDERS if p.name == "other")
+        assert other.ask_thinking_support is True
+
+    def test_with_thinking_support_enabled_wires_toggles(self):
+        other = next(p for p in LLM_PROVIDERS if p.name == "other")
+        original = dict(other.extra_config)
+
+        updated = with_thinking_support(other, True)
+
+        assert updated.extra_config["supports_thinking"] is True
+        assert updated.extra_config["when_thinking_enabled"]["extra_body"]["thinking"]["type"] == "enabled"
+        assert updated.extra_config["when_thinking_disabled"]["extra_body"]["thinking"]["type"] == "disabled"
+        # The shared provider singleton must not be mutated.
+        assert other.extra_config == original
+
+    def test_with_thinking_support_disabled_marks_unsupported(self):
+        other = next(p for p in LLM_PROVIDERS if p.name == "other")
+
+        updated = with_thinking_support(other, False)
+
+        assert updated.extra_config["supports_thinking"] is False
+        assert "when_thinking_enabled" not in updated.extra_config
+
+
 class TestLLMStep:
     def test_model_selection_defaults_to_provider_default_model(self, monkeypatch):
         provider = LLMProvider(
@@ -423,6 +449,65 @@ class TestLLMStep:
 
         assert result.base_url == "https://gateway.example/v1"
 
+    def test_other_gateway_prompts_and_enables_thinking(self, monkeypatch):
+        provider = LLMProvider(
+            name="other",
+            display_name="Other OpenAI-compatible",
+            description="Custom gateway",
+            use="langchain_openai:ChatOpenAI",
+            models=["gpt-4o"],
+            default_model="gpt-4o",
+            env_var="OPENAI_API_KEY",
+            package="langchain-openai",
+            base_url_prompt="Base URL",
+            model_prompt="Model name",
+            ask_thinking_support=True,
+        )
+
+        monkeypatch.setattr(llm_step, "LLM_PROVIDERS", [provider])
+        monkeypatch.setattr(llm_step, "ask_choice", lambda *_args, **_kwargs: 0)
+        monkeypatch.setattr(llm_step, "ask_text", lambda *_args, **_kwargs: "custom-thinking-model")
+        monkeypatch.setattr(llm_step, "ask_secret", lambda _prompt: "key")
+        monkeypatch.setattr(llm_step, "ask_yes_no", lambda *_args, **_kwargs: True)
+        monkeypatch.setattr(llm_step, "print_header", lambda *_args, **_kwargs: None)
+        monkeypatch.setattr(llm_step, "print_info", lambda *_args, **_kwargs: None)
+        monkeypatch.setattr(llm_step, "print_success", lambda *_args, **_kwargs: None)
+
+        result = llm_step.run_llm_step()
+
+        assert result.model_name == "custom-thinking-model"
+        assert result.provider.extra_config["supports_thinking"] is True
+        assert result.provider.extra_config["when_thinking_enabled"]["extra_body"]["thinking"]["type"] == "enabled"
+
+    def test_other_gateway_declined_thinking_marks_unsupported(self, monkeypatch):
+        provider = LLMProvider(
+            name="other",
+            display_name="Other OpenAI-compatible",
+            description="Custom gateway",
+            use="langchain_openai:ChatOpenAI",
+            models=["gpt-4o"],
+            default_model="gpt-4o",
+            env_var="OPENAI_API_KEY",
+            package="langchain-openai",
+            base_url_prompt="Base URL",
+            model_prompt="Model name",
+            ask_thinking_support=True,
+        )
+
+        monkeypatch.setattr(llm_step, "LLM_PROVIDERS", [provider])
+        monkeypatch.setattr(llm_step, "ask_choice", lambda *_args, **_kwargs: 0)
+        monkeypatch.setattr(llm_step, "ask_text", lambda *_args, **_kwargs: "plain-model")
+        monkeypatch.setattr(llm_step, "ask_secret", lambda _prompt: "key")
+        monkeypatch.setattr(llm_step, "ask_yes_no", lambda *_args, **_kwargs: False)
+        monkeypatch.setattr(llm_step, "print_header", lambda *_args, **_kwargs: None)
+        monkeypatch.setattr(llm_step, "print_info", lambda *_args, **_kwargs: None)
+        monkeypatch.setattr(llm_step, "print_success", lambda *_args, **_kwargs: None)
+
+        result = llm_step.run_llm_step()
+
+        assert result.provider.extra_config["supports_thinking"] is False
+        assert "when_thinking_enabled" not in result.provider.extra_config
+
 
 class TestChannelsStep:
     def test_returns_selected_channel_keys(self, monkeypatch):

scripts/wizard/providers.py

@@ -2,7 +2,7 @@
 
 from __future__ import annotations
 
-from dataclasses import dataclass, field
+from dataclasses import dataclass, field, replace
 
 
 @dataclass
@@ -26,6 +26,9 @@ class LLMProvider:
     auth_hint: str | None = None
     base_url_prompt: str | None = None
     model_prompt: str | None = None
+    # For generic OpenAI-compatible gateways the wizard cannot infer whether the
+    # user-supplied model supports thinking/reasoning, so prompt for it explicitly.
+    ask_thinking_support: bool = False
 
     def extra_config_for(self, model_name: str) -> dict:
         """Return extra_config for a selected model, applying per-model overrides.
@@ -94,6 +97,22 @@ ANTHROPIC_THINKING_CONFIG = {
 }
 
 
+def with_thinking_support(provider: LLMProvider, supports_thinking: bool) -> LLMProvider:
+    """Return a copy of *provider* with thinking-capability flags applied.
+
+    For generic OpenAI-compatible gateways the wizard cannot infer whether the
+    user-supplied model supports thinking/reasoning. When the user confirms
+    support we also wire the common OpenAI-compatible enable/disable toggles so
+    the runtime can switch thinking on and off; otherwise we record the
+    capability as unsupported. The shared provider definition is never mutated.
+    """
+    if supports_thinking:
+        extra_config = {**provider.extra_config, **OPENAI_COMPAT_THINKING_CONFIG}
+    else:
+        extra_config = {**provider.extra_config, "supports_thinking": False}
+    return replace(provider, extra_config=extra_config)
+
+
 LLM_PROVIDERS: list[LLMProvider] = [
     LLMProvider(
         name="volcengine",
@@ -462,6 +481,7 @@ LLM_PROVIDERS: list[LLMProvider] = [
         package="langchain-openai",
         base_url_prompt="Base URL (e.g. https://api.openai.com/v1)",
         model_prompt="Model name",
+        ask_thinking_support=True,
     ),
 ]
 

scripts/wizard/steps/llm.py

@@ -4,11 +4,12 @@ from __future__ import annotations
 
 from dataclasses import dataclass
 
-from wizard.providers import LLM_PROVIDERS, LLMProvider
+from wizard.providers import LLM_PROVIDERS, LLMProvider, with_thinking_support
 from wizard.ui import (
     ask_choice,
     ask_secret,
     ask_text,
+    ask_yes_no,
     print_header,
     print_info,
     print_success,
@@ -52,6 +53,16 @@ def run_llm_step(step_label: str = "Step 1/3") -> LLMStepResult:
         if provider.model_prompt:
             model_name = ask_text(provider.model_prompt, default=model_name)
 
+    if provider.ask_thinking_support:
+        print_header(f"{step_label} · Model capabilities")
+        supports_thinking = ask_yes_no(
+            f"Does '{model_name}' support thinking/reasoning?",
+            default=False,
+        )
+        provider = with_thinking_support(provider, supports_thinking)
+        if supports_thinking:
+            print_info("Thinking enabled. Adjust the toggle in config.yaml if your gateway uses a different mechanism.")
+
     if provider.auth_hint:
         print_header(f"{step_label} · Authentication")
         print_info(provider.auth_hint)