claude: enable Claude Code native gateway model discovery

src/ucode/agents/claude.py

@@ -40,6 +40,7 @@
 from ucode.tracing import tracing_env
 from ucode.ui import print_err, print_note, print_success, print_warning
 
+GATEWAY_MODEL_DISCOVERY_ENV_VAR = "ENABLE_CLAUDE_CODE_GATEWAY_MODEL_DISCOVERY"
 CLAUDE_CONFIG_DIR = Path.home() / ".claude"
 CLAUDE_SETTINGS_PATH = CLAUDE_CONFIG_DIR / "ucode-settings.json"
 CLAUDE_BACKUP_PATH = APP_DIR / "claude-ucode-settings.backup.json"
@@ -302,6 +303,12 @@ def render_overlay(
         "ENABLE_TOOL_SEARCH": "1",
         "CLAUDE_CODE_USE_GATEWAY": "1",
     }
+    # Native /model discovery: picker lists every gateway Messages-API endpoint,
+    # not just the family aliases. Skipped under a provider (its routing header
+    # would send a discovered gateway id to a provider that can't resolve it).
+    discovery_enabled = os.environ.get(GATEWAY_MODEL_DISCOVERY_ENV_VAR) == "1"
+    if discovery_enabled and not provider:
+        env["CLAUDE_CODE_ENABLE_GATEWAY_MODEL_DISCOVERY"] = "1"
     # Intentionally NOT setting ANTHROPIC_MODEL by default. Setting it produces a
     # duplicate catalog row in Claude Code's /model picker (e.g. "Opus 4.8 (1M
     # context) ✓") on top of the family-alias row from ANTHROPIC_DEFAULT_OPUS_MODEL.

tests/conftest.py

@@ -34,6 +34,7 @@ def _isolate_ucode_state(tmp_path, monkeypatch):
     # Isolate the managed-config opt-in from the developer's own shell: leaving it set changes what
     # `ucode`/`ucode configure` do mid-test. Tests that exercise the managed path set it explicitly.
     monkeypatch.delenv("ENABLE_MANAGED_AGENT_CONFIG", raising=False)
+    monkeypatch.delenv("ENABLE_CLAUDE_CODE_GATEWAY_MODEL_DISCOVERY", raising=False)
     # The model-services listing is memoized for the life of the process, so without this a cached
     # result would leak into the next test and make a stubbed listing look like it was never called.
     databricks_mod.clear_model_services_cache()

tests/test_agent_claude.py

@@ -127,6 +127,26 @@ def test_enables_use_gateway(self):
         overlay, _ = claude.render_overlay(WS, "s4")
         assert overlay["env"]["CLAUDE_CODE_USE_GATEWAY"] == "1"
 
+    @pytest.mark.parametrize("env_value", [None, "", "0", "true", "yes"])
+    def test_gateway_model_discovery_disabled_unless_opted_in(self, monkeypatch, env_value):
+        if env_value is not None:
+            monkeypatch.setenv("ENABLE_CLAUDE_CODE_GATEWAY_MODEL_DISCOVERY", env_value)
+        overlay, _ = claude.render_overlay(WS, "s4")
+        assert "CLAUDE_CODE_ENABLE_GATEWAY_MODEL_DISCOVERY" not in overlay["env"]
+
+    def test_enables_gateway_model_discovery(self, monkeypatch):
+        monkeypatch.setenv("ENABLE_CLAUDE_CODE_GATEWAY_MODEL_DISCOVERY", "1")
+        overlay, _ = claude.render_overlay(WS, "s4")
+        assert overlay["env"]["CLAUDE_CODE_ENABLE_GATEWAY_MODEL_DISCOVERY"] == "1"
+
+    def test_gateway_model_discovery_skipped_under_provider(self, monkeypatch):
+        # A Model Provider Service routes every request to the external provider,
+        # so a discovered gateway endpoint id would reach a provider that can't
+        # resolve it — discovery must be off in that mode.
+        monkeypatch.setenv("ENABLE_CLAUDE_CODE_GATEWAY_MODEL_DISCOVERY", "1")
+        overlay, _ = claude.render_overlay(WS, "s4", provider="main.x.claude-svc")
+        assert "CLAUDE_CODE_ENABLE_GATEWAY_MODEL_DISCOVERY" not in overlay["env"]
+
     def test_sets_api_key_helper(self):
         overlay, _ = claude.render_overlay(WS, "s4")
         assert "apiKeyHelper" in overlay