diff --git a/src/ucode/agents/claude.py b/src/ucode/agents/claude.py
index e818cdf..3046d15 100644
--- a/src/ucode/agents/claude.py
+++ b/src/ucode/agents/claude.py
@@ -302,6 +302,11 @@ 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).
+    if 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.
diff --git a/tests/test_agent_claude.py b/tests/test_agent_claude.py
index b45b630..68a12be 100644
--- a/tests/test_agent_claude.py
+++ b/tests/test_agent_claude.py
@@ -127,6 +127,17 @@ def test_enables_use_gateway(self):
         overlay, _ = claude.render_overlay(WS, "s4")
         assert overlay["env"]["CLAUDE_CODE_USE_GATEWAY"] == "1"
 
+    def test_enables_gateway_model_discovery(self):
+        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):
+        # 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.
+        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