diff --git a/EvoScientist/ccproxy_manager.py b/EvoScientist/ccproxy_manager.py
index 37bd9bf..2019051 100644
--- a/EvoScientist/ccproxy_manager.py
+++ b/EvoScientist/ccproxy_manager.py
@@ -35,24 +35,65 @@ def is_ccproxy_available() -> bool:
     return shutil.which("ccproxy") is not None
 
 
-def check_ccproxy_auth() -> tuple[bool, str]:
+def _summarize_auth_output(raw: str) -> str:
+    """Extract key fields from ccproxy auth status output into a one-line summary.
+
+    Parses the Rich table output for Email, Subscription, and Status fields.
+    Returns e.g. ``"user@example.com (plus, active)"``.
+    Falls back to ``"Authenticated"`` if parsing fails.
+    """
+    import re as _re
+
+    # Strip ANSI escape sequences
+    clean = _re.sub(r"\x1b\[[0-9;]*m", "", raw)
+
+    # Parse "Key<2+ spaces>Value" table rows, match exact key names
+    fields: dict[str, str] = {}
+    for line in clean.splitlines():
+        m = _re.match(r"\s*(.+?)\s{2,}(.+)", line)
+        if not m:
+            continue
+        key, val = m.group(1).strip(), m.group(2).strip()
+        if key in ("Email", "Subscription", "Subscription Status"):
+            fields[key.lower().replace(" ", "_")] = val
+
+    email = fields.get("email", "")
+    sub = fields.get("subscription", "")
+    status = fields.get("subscription_status", "")
+
+    if email:
+        detail = ", ".join(filter(None, [sub, status]))
+        return f"{email} ({detail})" if detail else email
+    return "Authenticated"
+
+
+def check_ccproxy_auth(provider: str = "claude_api") -> tuple[bool, str]:
     """Check if ccproxy has valid OAuth credentials.
 
+    Args:
+        provider: ccproxy provider name ("claude_api" or "codex").
+
     Returns:
         (is_valid, message) tuple.
     """
     try:
         result = subprocess.run(
-            ["ccproxy", "auth", "status", "claude_api"],
+            ["ccproxy", "auth", "status", provider],
             capture_output=True,
             text=True,
             timeout=10,
         )
-        output = (result.stdout + result.stderr).strip()
         # ccproxy auth status exits 0 when authed
         if result.returncode == 0:
-            return True, output or "Authenticated"
-        return False, output or "Not authenticated"
+            summary = _summarize_auth_output(result.stdout)
+            return True, summary or "Authenticated"
+        # On failure, include stderr for diagnostics
+        raw = (result.stdout + result.stderr).strip()
+        # Strip ANSI escapes for cleaner error messages
+        import re as _re
+
+        clean = _re.sub(r"\x1b\[[0-9;]*m", "", raw)
+        return False, clean or "Not authenticated"
     except FileNotFoundError:
         return False, "ccproxy not found"
     except subprocess.TimeoutExpired:
@@ -151,7 +192,7 @@ def ensure_ccproxy(port: int = _DEFAULT_PORT) -> subprocess.Popen | None:
 
 
 def setup_ccproxy_env(port: int = _DEFAULT_PORT) -> None:
-    """Set environment variables for ccproxy routing.
+    """Set environment variables for Anthropic ccproxy routing.
 
     Force-sets ``ANTHROPIC_BASE_URL`` and ``ANTHROPIC_API_KEY`` so that
     downstream LangChain/Anthropic clients route through ccproxy.
@@ -163,6 +204,20 @@ def setup_ccproxy_env(port: int = _DEFAULT_PORT) -> None:
     os.environ["ANTHROPIC_API_KEY"] = "ccproxy-oauth"
 
 
+def setup_codex_env(port: int = _DEFAULT_PORT) -> None:
+    """Set environment variables for OpenAI/Codex ccproxy routing.
+
+    Force-sets ``OPENAI_BASE_URL`` and ``OPENAI_API_KEY`` so that
+    downstream LangChain/OpenAI clients route through ccproxy's Codex
+    endpoint.
+
+    Always overrides existing values — when this function is called,
+    we've decided to use ccproxy, so env must point to it.
+    """
+    os.environ["OPENAI_BASE_URL"] = f"http://127.0.0.1:{port}/codex/v1"
+    os.environ["OPENAI_API_KEY"] = "ccproxy-oauth"
+
+
 # =============================================================================
 # High-level orchestration
 # =============================================================================
@@ -171,9 +226,13 @@ def setup_ccproxy_env(port: int = _DEFAULT_PORT) -> None:
 def maybe_start_ccproxy(config: object) -> subprocess.Popen | None:
     """High-level: conditionally start ccproxy based on config.
 
-    Checks ``config.anthropic_auth_mode``:
+    Checks ``config.anthropic_auth_mode`` and ``config.openai_auth_mode``:
     - ``oauth``: ccproxy must work — raises on failure.
-    - ``api_key``: no-op.
+    - ``api_key``: no-op for that provider.
+
+    When either provider uses OAuth, ccproxy is started (single process
+    serves both providers). Environment variables are set for each
+    provider that uses OAuth.
 
     Args:
         config: An ``EvoScientistConfig`` instance.
@@ -181,8 +240,10 @@ def maybe_start_ccproxy(config: object) -> subprocess.Popen | None:
     Returns:
         Popen handle if we started ccproxy, None otherwise.
     """
-    auth_mode = getattr(config, "anthropic_auth_mode", "api_key")
-    if auth_mode != "oauth":
+    anthropic_oauth = getattr(config, "anthropic_auth_mode", "api_key") == "oauth"
+    openai_oauth = getattr(config, "openai_auth_mode", "api_key") == "oauth"
+
+    if not anthropic_oauth and not openai_oauth:
         return None
 
     if not is_ccproxy_available():
@@ -191,15 +252,32 @@ def maybe_start_ccproxy(config: object) -> subprocess.Popen | None:
             "Install it with: pip install 'evoscientist[oauth]'"
         )
 
-    authed, msg = check_ccproxy_auth()
-    if not authed:
-        raise RuntimeError(
-            f"ccproxy OAuth not authenticated: {msg}\n"
-            "Run: ccproxy auth login claude_api"
-        )
+    # Check auth for each provider that uses OAuth
+    if anthropic_oauth:
+        authed, msg = check_ccproxy_auth("claude_api")
+        if not authed:
+            raise RuntimeError(
+                f"ccproxy Anthropic OAuth not authenticated: {msg}\n"
+                "Run: ccproxy auth login claude_api"
+            )
 
+    if openai_oauth:
+        authed, msg = check_ccproxy_auth("codex")
+        if not authed:
+            raise RuntimeError(
+                f"ccproxy Codex OAuth not authenticated: {msg}\n"
+                "Run: ccproxy auth login codex"
+            )
+
+    # Start ccproxy (single process serves both providers)
     proc = ensure_ccproxy()
-    setup_ccproxy_env()
+
+    # Set environment for each OAuth provider
+    if anthropic_oauth:
+        setup_ccproxy_env()
+    if openai_oauth:
+        setup_codex_env()
+
     if proc:
         logger.info("Started ccproxy on port %d", _DEFAULT_PORT)
     else:
diff --git a/EvoScientist/cli/commands.py b/EvoScientist/cli/commands.py
index 992a306..56d3cac 100644
--- a/EvoScientist/cli/commands.py
+++ b/EvoScientist/cli/commands.py
@@ -512,9 +512,9 @@ def serve(
     config = get_effective_config(cli_overrides)
     apply_config_to_env(config)
 
-    # Auto-start ccproxy if OAuth mode
+    # Auto-start ccproxy if any provider uses OAuth mode
     _ccproxy_proc_serve = None
-    if config.provider == "anthropic" and config.anthropic_auth_mode == "oauth":
+    if config.anthropic_auth_mode == "oauth" or config.openai_auth_mode == "oauth":
         try:
             from ..ccproxy_manager import maybe_start_ccproxy, stop_ccproxy
 
@@ -917,7 +917,7 @@ def _main_callback(
     auth_mode: Optional[str] = typer.Option(
         None,
         "--auth-mode",
-        help="Anthropic auth mode: api_key (default) or oauth (ccproxy).",
+        help="Auth mode for Anthropic/OpenAI: api_key (default) or oauth (ccproxy).",
     ),
     ui: Optional[str] = typer.Option(
         None,
@@ -956,13 +956,14 @@ def _main_callback(
         if auth_mode not in ("api_key", "oauth"):
             raise typer.BadParameter("--auth-mode must be 'api_key' or 'oauth'")
         cli_overrides["anthropic_auth_mode"] = auth_mode
+        cli_overrides["openai_auth_mode"] = auth_mode
 
     config = get_effective_config(cli_overrides)
     apply_config_to_env(config)
 
-    # Auto-start ccproxy if OAuth mode
+    # Auto-start ccproxy if any provider uses OAuth mode
     _ccproxy_proc = None
-    if config.provider == "anthropic" and config.anthropic_auth_mode == "oauth":
+    if config.anthropic_auth_mode == "oauth" or config.openai_auth_mode == "oauth":
         try:
             from ..ccproxy_manager import maybe_start_ccproxy, stop_ccproxy
 
diff --git a/EvoScientist/config/onboard.py b/EvoScientist/config/onboard.py
index 709680f..af59e2b 100644
--- a/EvoScientist/config/onboard.py
+++ b/EvoScientist/config/onboard.py
@@ -755,6 +755,80 @@ def _step_anthropic_auth_mode(config: EvoScientistConfig) -> str:
     return auth_mode
 
 
+def _step_openai_auth_mode(config: EvoScientistConfig) -> str:
+    """Step 2b: Select OpenAI authentication mode (API key vs Codex OAuth).
+
+    Args:
+        config: Current configuration.
+
+    Returns:
+        Selected auth mode: "api_key" or "oauth".
+    """
+    from ..ccproxy_manager import is_ccproxy_available, check_ccproxy_auth
+
+    if not is_ccproxy_available():
+        console.print(
+            "  [dim]OAuth via ccproxy not available. "
+            'Install with: pip install "evoscientist[oauth]"[/dim]'
+        )
+        return "api_key"
+
+    choices = [
+        Choice(title="API Key (direct OpenAI access)", value="api_key"),
+        Choice(
+            title="Codex OAuth (via ccproxy — no API key needed)", value="oauth"
+        ),
+    ]
+
+    current = config.openai_auth_mode
+    if current not in ("api_key", "oauth"):
+        current = "api_key"
+
+    auth_mode = questionary.select(
+        "OpenAI authentication mode:",
+        choices=choices,
+        default=current,
+        style=WIZARD_STYLE,
+        qmark=QMARK,
+        use_indicator=True,
+    ).ask()
+
+    if auth_mode is None:
+        raise KeyboardInterrupt()
+
+    # If OAuth selected, check auth status and offer login
+    if auth_mode == "oauth":
+        authed, msg = check_ccproxy_auth("codex")
+        if authed:
+            console.print(f"  [green]✓ Codex OAuth: {msg}[/green]")
+        else:
+            console.print(f"  [yellow]Codex OAuth not authenticated: {msg}[/yellow]")
+            login = questionary.confirm(
+                "Log in to Codex now?",
+                default=True,
+                style=CONFIRM_STYLE,
+                qmark=QMARK,
+            ).ask()
+            if login:
+                console.print("  [dim]Opening browser for authentication...[/dim]")
+                try:
+                    subprocess.run(
+                        ["ccproxy", "auth", "login", "codex"],
+                        timeout=120,
+                    )
+                    authed, msg = check_ccproxy_auth("codex")
+                    if authed:
+                        console.print(f"  [green]✓ Codex OAuth: {msg}[/green]")
+                    else:
+                        console.print(f"  [red]Authentication failed: {msg}[/red]")
+                except subprocess.TimeoutExpired:
+                    console.print("  [red]Login timed out.[/red]")
+                except Exception as exc:
+                    console.print(f"  [red]Login error: {exc}[/red]")
+
+    return auth_mode
+
+
 def _step_provider_api_key(
     config: EvoScientistConfig,
     provider: str,
@@ -2194,13 +2268,16 @@ def run_onboard(skip_validation: bool = False) -> bool:
             ollama_url, ollama_detected_models = _step_ollama_base_url(config)
             config.ollama_base_url = ollama_url
 
-        # Step 2b: Auth mode (Anthropic only — API key vs OAuth)
+        # Step 2b: Auth mode (Anthropic or OpenAI — API key vs OAuth)
         if provider == "anthropic":
             auth_mode = _step_anthropic_auth_mode(config)
             config.anthropic_auth_mode = auth_mode
+        elif provider == "openai":
+            auth_mode = _step_openai_auth_mode(config)
+            config.openai_auth_mode = auth_mode
 
         # Step 2c: Provider API Key (skip for Ollama — no key needed,
-        # and for Anthropic pure OAuth — key provided by ccproxy)
+        # and for Anthropic/OpenAI pure OAuth — key provided by ccproxy)
         _PROVIDER_KEY_ATTR = {
             "anthropic": "anthropic_api_key",
             "nvidia": "nvidia_api_key",
@@ -2214,6 +2291,8 @@ def run_onboard(skip_validation: bool = False) -> bool:
         }
         _skip_api_key = provider == "ollama" or (
             provider == "anthropic" and config.anthropic_auth_mode == "oauth"
+        ) or (
+            provider == "openai" and config.openai_auth_mode == "oauth"
         )
         if not _skip_api_key:
             new_key = _step_provider_api_key(config, provider, skip_validation)
diff --git a/EvoScientist/config/settings.py b/EvoScientist/config/settings.py
index d77148f..25d970b 100644
--- a/EvoScientist/config/settings.py
+++ b/EvoScientist/config/settings.py
@@ -63,6 +63,7 @@ class EvoScientistConfig:
     anthropic_base_url: str = ""
     anthropic_auth_mode: str = "api_key"  # "api_key" | "oauth"
     openai_api_key: str = ""
+    openai_auth_mode: str = "api_key"  # "api_key" | "oauth"
     nvidia_api_key: str = ""
     google_api_key: str = ""
     siliconflow_api_key: str = ""
@@ -336,6 +337,7 @@ _ENV_MAPPINGS = {
     "anthropic_base_url": "ANTHROPIC_BASE_URL",
     "anthropic_auth_mode": "EVOSCIENTIST_ANTHROPIC_AUTH_MODE",
     "openai_api_key": "OPENAI_API_KEY",
+    "openai_auth_mode": "EVOSCIENTIST_OPENAI_AUTH_MODE",
     "nvidia_api_key": "NVIDIA_API_KEY",
     "google_api_key": "GOOGLE_API_KEY",
     "siliconflow_api_key": "SILICONFLOW_API_KEY",
diff --git a/EvoScientist/llm/models.py b/EvoScientist/llm/models.py
index abd7f26..65050ca 100644
--- a/EvoScientist/llm/models.py
+++ b/EvoScientist/llm/models.py
@@ -9,6 +9,7 @@ convenient short names for common models.
 from __future__ import annotations
 
 import os
+import re
 from typing import Any
 
 from langchain.chat_models import init_chat_model
@@ -50,6 +51,18 @@ def _patch_anthropic_proxy_compat() -> None:
 
 _patch_anthropic_proxy_compat()
 
+# ---------------------------------------------------------------------------
+# Patch: ccproxy Codex embeds thinking as <thinking>...</thinking> tags
+# inside the content string. Strip these so they don't appear in output.
+# ---------------------------------------------------------------------------
+_THINKING_TAG_RE = re.compile(r"<thinking>.*?</thinking>\s*", re.DOTALL)
+
+
+def strip_thinking_tags(content: str) -> str:
+    """Remove ``<thinking>...</thinking>`` tags from ccproxy response content."""
+    return _THINKING_TAG_RE.sub("", content)
+
+
 _SILICONFLOW_BASE_URL = "https://api.siliconflow.cn/v1"
 _OPENROUTER_BASE_URL = "https://openrouter.ai/api/v1"
 _ZHIPU_BASE_URL = "https://open.bigmodel.cn/api/paas/v4"
@@ -188,7 +201,15 @@ def _apply_auto_config(
 
     # OpenAI (native, not third-party routed): reasoning
     if provider == "openai" and not is_third_party and "reasoning" not in kwargs:
-        kwargs["reasoning"] = {"effort": "high", "summary": "auto"}
+        base_url = os.environ.get("OPENAI_BASE_URL", "")
+        _is_openai_proxy = "127.0.0.1" in base_url or "localhost" in base_url
+        if _is_openai_proxy:
+            # ccproxy forces store=False. Setting `reasoning` triggers
+            # langchain-openai's Responses API path, which produces
+            # rs_ summary items that 404 on multi-turn. Skip entirely.
+            pass
+        else:
+            kwargs["reasoning"] = {"effort": "high", "summary": "auto"}
 
     # Google GenAI: surface thinking traces
     if provider == "google-genai":
@@ -255,6 +276,7 @@ def get_chat_model(
 
     # Anthropic base_url override (e.g. ccproxy at localhost:8000/api/v1)
     _is_third_party = provider in _THIRD_PARTY_PROVIDERS
+    _is_openai_proxy = False
     if provider == "anthropic":
         base_url = os.environ.get("ANTHROPIC_BASE_URL", "")
         if base_url:
@@ -263,6 +285,19 @@ def get_chat_model(
         if api_key:
             kwargs["api_key"] = api_key
 
+    # Native OpenAI base_url override (e.g. ccproxy Codex at localhost:8000/codex/v1)
+    elif provider == "openai":
+        base_url = os.environ.get("OPENAI_BASE_URL", "")
+        if base_url:
+            kwargs["base_url"] = base_url
+            _is_openai_proxy = "127.0.0.1" in base_url or "localhost" in base_url
+            if _is_openai_proxy:
+                kwargs.setdefault("streaming", False)  # ccproxy streaming incompatible
+                kwargs.setdefault("use_responses_api", False)  # force Chat Completions
+        api_key = os.environ.get("OPENAI_API_KEY", "")
+        if api_key:
+            kwargs["api_key"] = api_key
+
     # Third-party providers → route through OpenAI provider with base_url
     elif provider in _THIRD_PARTY_PROVIDERS:
         base_url_default, api_key_env = _THIRD_PARTY_PROVIDERS[provider]
@@ -308,7 +343,9 @@ def get_chat_model(
 
     _apply_auto_config(provider, model_id, _is_third_party, kwargs)
 
-    return init_chat_model(model=model_id, model_provider=provider, **kwargs)
+    chat_model = init_chat_model(model=model_id, model_provider=provider, **kwargs)
+
+    return chat_model
 
 
 def list_models() -> list[str]:
diff --git a/EvoScientist/stream/events.py b/EvoScientist/stream/events.py
index adf0fd6..de43cbb 100644
--- a/EvoScientist/stream/events.py
+++ b/EvoScientist/stream/events.py
@@ -591,7 +591,12 @@ def _process_chunk_content(
 
     if isinstance(content, str):
         if content:
-            yield emitter.text(content)
+            # Strip ccproxy <thinking>...</thinking> tags from content
+            from ..llm.models import strip_thinking_tags
+
+            cleaned = strip_thinking_tags(content)
+            if cleaned:
+                yield emitter.text(cleaned)
             return
 
     blocks = None
diff --git a/tests/test_ccproxy_manager.py b/tests/test_ccproxy_manager.py
index 3257a82..b10c788 100644
--- a/tests/test_ccproxy_manager.py
+++ b/tests/test_ccproxy_manager.py
@@ -13,6 +13,7 @@ from EvoScientist.ccproxy_manager import (
     stop_ccproxy,
     ensure_ccproxy,
     setup_ccproxy_env,
+    setup_codex_env,
     maybe_start_ccproxy,
 )
 
@@ -47,6 +48,17 @@ class TestCheckCcproxyAuth:
         valid, msg = check_ccproxy_auth()
         assert valid is True
         assert "Authenticated" in msg
+        mock_run.assert_called_once()
+        assert mock_run.call_args[0][0] == ["ccproxy", "auth", "status", "claude_api"]
+
+    @patch("subprocess.run")
+    def test_valid_auth_codex(self, mock_run):
+        mock_run.return_value = MagicMock(
+            returncode=0, stdout="Authenticated", stderr=""
+        )
+        valid, msg = check_ccproxy_auth("codex")
+        assert valid is True
+        assert mock_run.call_args[0][0] == ["ccproxy", "auth", "status", "codex"]
 
     @patch("subprocess.run")
     def test_invalid_auth(self, mock_run):
@@ -168,6 +180,32 @@ class TestSetupCcproxyEnv:
         assert os.environ["ANTHROPIC_API_KEY"] == "ccproxy-oauth"
 
 
+# =============================================================================
+# setup_codex_env
+# =============================================================================
+
+
+class TestSetupCodexEnv:
+    def test_sets_vars(self, monkeypatch):
+        monkeypatch.delenv("OPENAI_BASE_URL", raising=False)
+        monkeypatch.delenv("OPENAI_API_KEY", raising=False)
+
+        setup_codex_env(8000)
+
+        assert os.environ["OPENAI_BASE_URL"] == "http://127.0.0.1:8000/codex/v1"
+        assert os.environ["OPENAI_API_KEY"] == "ccproxy-oauth"
+
+    def test_overrides_existing(self, monkeypatch):
+        """Force-sets vars even if already configured (oauth takes priority)."""
+        monkeypatch.setenv("OPENAI_BASE_URL", "http://custom:9999")
+        monkeypatch.setenv("OPENAI_API_KEY", "sk-real-key")
+
+        setup_codex_env(8000)
+
+        assert os.environ["OPENAI_BASE_URL"] == "http://127.0.0.1:8000/codex/v1"
+        assert os.environ["OPENAI_API_KEY"] == "ccproxy-oauth"
+
+
 # =============================================================================
 # stop_ccproxy
 # =============================================================================
@@ -193,6 +231,7 @@ class TestMaybeStartCcproxy:
     def test_api_key_mode_noop(self):
         config = MagicMock()
         config.anthropic_auth_mode = "api_key"
+        config.openai_auth_mode = "api_key"
         assert maybe_start_ccproxy(config) is None
 
     @patch("EvoScientist.ccproxy_manager.setup_ccproxy_env")
@@ -204,6 +243,7 @@ class TestMaybeStartCcproxy:
         mock_ensure.return_value = proc
         config = MagicMock()
         config.anthropic_auth_mode = "oauth"
+        config.openai_auth_mode = "api_key"
 
         result = maybe_start_ccproxy(config)
         assert result is proc
@@ -213,6 +253,7 @@ class TestMaybeStartCcproxy:
     def test_oauth_mode_raises_no_binary(self, mock_avail):
         config = MagicMock()
         config.anthropic_auth_mode = "oauth"
+        config.openai_auth_mode = "api_key"
         with pytest.raises(RuntimeError, match="not found"):
             maybe_start_ccproxy(config)
 
@@ -224,5 +265,61 @@ class TestMaybeStartCcproxy:
     def test_oauth_mode_raises_no_auth(self, mock_avail, mock_auth):
         config = MagicMock()
         config.anthropic_auth_mode = "oauth"
+        config.openai_auth_mode = "api_key"
         with pytest.raises(RuntimeError, match="not authenticated"):
             maybe_start_ccproxy(config)
+
+    @patch("EvoScientist.ccproxy_manager.setup_codex_env")
+    @patch("EvoScientist.ccproxy_manager.ensure_ccproxy")
+    @patch("EvoScientist.ccproxy_manager.check_ccproxy_auth", return_value=(True, "OK"))
+    @patch("EvoScientist.ccproxy_manager.is_ccproxy_available", return_value=True)
+    def test_openai_oauth_mode_starts(self, mock_avail, mock_auth, mock_ensure, mock_env):
+        proc = MagicMock()
+        mock_ensure.return_value = proc
+        config = MagicMock()
+        config.anthropic_auth_mode = "api_key"
+        config.openai_auth_mode = "oauth"
+
+        result = maybe_start_ccproxy(config)
+        assert result is proc
+        mock_auth.assert_called_once_with("codex")
+        mock_env.assert_called_once()
+
+    @patch("EvoScientist.ccproxy_manager.setup_codex_env")
+    @patch("EvoScientist.ccproxy_manager.setup_ccproxy_env")
+    @patch("EvoScientist.ccproxy_manager.ensure_ccproxy")
+    @patch("EvoScientist.ccproxy_manager.check_ccproxy_auth", return_value=(True, "OK"))
+    @patch("EvoScientist.ccproxy_manager.is_ccproxy_available", return_value=True)
+    def test_both_oauth_starts_both(self, mock_avail, mock_auth, mock_ensure, mock_anthropic_env, mock_codex_env):
+        proc = MagicMock()
+        mock_ensure.return_value = proc
+        config = MagicMock()
+        config.anthropic_auth_mode = "oauth"
+        config.openai_auth_mode = "oauth"
+
+        result = maybe_start_ccproxy(config)
+        assert result is proc
+        # Auth checked for both providers
+        assert mock_auth.call_count == 2
+        mock_anthropic_env.assert_called_once()
+        mock_codex_env.assert_called_once()
+
+    @patch("EvoScientist.ccproxy_manager.is_ccproxy_available", return_value=False)
+    def test_openai_oauth_raises_no_binary(self, mock_avail):
+        config = MagicMock()
+        config.anthropic_auth_mode = "api_key"
+        config.openai_auth_mode = "oauth"
+        with pytest.raises(RuntimeError, match="not found"):
+            maybe_start_ccproxy(config)
+
+    @patch(
+        "EvoScientist.ccproxy_manager.check_ccproxy_auth",
+        return_value=(False, "expired"),
+    )
+    @patch("EvoScientist.ccproxy_manager.is_ccproxy_available", return_value=True)
+    def test_openai_oauth_raises_no_auth(self, mock_avail, mock_auth):
+        config = MagicMock()
+        config.anthropic_auth_mode = "api_key"
+        config.openai_auth_mode = "oauth"
+        with pytest.raises(RuntimeError, match="Codex OAuth not authenticated"):
+            maybe_start_ccproxy(config)
diff --git a/tests/test_cli_serve.py b/tests/test_cli_serve.py
index 77ad63e..6a84b9a 100644
--- a/tests/test_cli_serve.py
+++ b/tests/test_cli_serve.py
@@ -18,6 +18,7 @@ def _make_config(
         channel_send_thinking=channel_send_thinking,
         provider="anthropic",
         anthropic_auth_mode="api_key",
+        openai_auth_mode="api_key",
     )
 
 
diff --git a/tests/test_config.py b/tests/test_config.py
index f5155fe..3439aaa 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -91,6 +91,16 @@ class TestEvoScientistConfig:
         config = EvoScientistConfig(anthropic_auth_mode="oauth")
         assert config.anthropic_auth_mode == "oauth"
 
+    def test_openai_auth_mode_default(self):
+        """Test that openai_auth_mode defaults to api_key."""
+        config = EvoScientistConfig()
+        assert config.openai_auth_mode == "api_key"
+
+    def test_openai_auth_mode_set(self):
+        """Test that openai_auth_mode can be set."""
+        config = EvoScientistConfig(openai_auth_mode="oauth")
+        assert config.openai_auth_mode == "oauth"
+
     def test_custom_values(self):
         """Test that custom values can be set."""
         config = EvoScientistConfig(
@@ -349,6 +359,14 @@ class TestPriorityChain:
         config = get_effective_config()
         assert config.anthropic_auth_mode == "oauth"
 
+    def test_env_openai_auth_mode_override(self, temp_config_dir, monkeypatch):
+        """Test openai_auth_mode from env overrides file."""
+        save_config(EvoScientistConfig(openai_auth_mode="api_key"))
+        monkeypatch.setenv("EVOSCIENTIST_OPENAI_AUTH_MODE", "oauth")
+
+        config = get_effective_config()
+        assert config.openai_auth_mode == "oauth"
+
 
 # =============================================================================
 # Test apply_config_to_env
diff --git a/tests/test_llm.py b/tests/test_llm.py
index 639227e..8370b97 100644
--- a/tests/test_llm.py
+++ b/tests/test_llm.py
@@ -525,15 +525,45 @@ class TestAutoConfig:
         assert call_kwargs["thinking"] == custom_thinking
 
     @patch("EvoScientist.llm.models.init_chat_model")
-    def test_openai_reasoning(self, mock_init):
+    def test_openai_reasoning(self, mock_init, monkeypatch):
         """Native OpenAI models get auto-reasoning."""
         mock_init.return_value = "mock_model"
+        monkeypatch.delenv("OPENAI_BASE_URL", raising=False)
 
         get_chat_model("gpt-5-nano")
 
         call_kwargs = mock_init.call_args[1]
         assert call_kwargs["reasoning"] == {"effort": "high", "summary": "auto"}
 
+    @patch("EvoScientist.llm.models.init_chat_model")
+    def test_openai_base_url_override(self, mock_init, monkeypatch):
+        """OpenAI provider should support base_url override (e.g. ccproxy Codex)."""
+        mock_init.return_value = "mock_model"
+        monkeypatch.setenv("OPENAI_BASE_URL", "http://127.0.0.1:8000/codex/v1")
+        monkeypatch.setenv("OPENAI_API_KEY", "ccproxy-oauth")
+
+        get_chat_model("gpt-5-nano", provider="openai")
+
+        call_kwargs = mock_init.call_args[1]
+        assert call_kwargs["model_provider"] == "openai"
+        assert call_kwargs["base_url"] == "http://127.0.0.1:8000/codex/v1"
+        assert call_kwargs["api_key"] == "ccproxy-oauth"
+        # Proxy mode: reasoning skipped (triggers Responses API → rs_ 404)
+        assert "reasoning" not in call_kwargs
+
+    @patch("EvoScientist.llm.models.init_chat_model")
+    def test_openai_no_base_url_when_unset(self, mock_init, monkeypatch):
+        """OpenAI provider should not set base_url when env var is empty."""
+        mock_init.return_value = "mock_model"
+        monkeypatch.delenv("OPENAI_BASE_URL", raising=False)
+        monkeypatch.setenv("OPENAI_API_KEY", "sk-real")
+
+        get_chat_model("gpt-5-nano", provider="openai")
+
+        call_kwargs = mock_init.call_args[1]
+        assert call_kwargs["model_provider"] == "openai"
+        assert "base_url" not in call_kwargs
+
     @patch("EvoScientist.llm.models.init_chat_model")
     def test_google_thoughts(self, mock_init):
         """Google GenAI models get include_thoughts=True by default."""