diff --git a/packages/server/src/server/agent/provider-registry.test.ts b/packages/server/src/server/agent/provider-registry.test.ts
index 1575bcaaa..f2946b0dc 100644
--- a/packages/server/src/server/agent/provider-registry.test.ts
+++ b/packages/server/src/server/agent/provider-registry.test.ts
@@ -905,4 +905,72 @@ describe("model merging", () => {
       },
     ]);
   });
+
+  test("built-in createClient().listModels() honors profile model replacement (issue #579)", async () => {
+    mockState.runtimeModels.set("claude", [
+      {
+        provider: "claude",
+        id: "runtime-default",
+        label: "Runtime Default",
+        isDefault: true,
+      },
+    ]);
+
+    const registry = buildProviderRegistry(logger, {
+      providerOverrides: {
+        claude: {
+          models: [
+            {
+              id: "profile-fast",
+              label: "Profile Fast",
+              isDefault: true,
+            },
+          ],
+        },
+      },
+    });
+
+    const client = registry.claude.createClient(logger);
+    const models = await client.listModels({
+      cwd: "/tmp/registry-models",
+      force: false,
+    });
+
+    expect(models.map((model) => model.id)).toEqual(["profile-fast"]);
+    expect(models.find((model) => model.isDefault)?.id).toBe("profile-fast");
+  });
+
+  test("built-in createClient().listModels() honors additionalModels default (issue #579)", async () => {
+    mockState.runtimeModels.set("claude", [
+      {
+        provider: "claude",
+        id: "runtime-default",
+        label: "Runtime Default",
+        isDefault: true,
+      },
+    ]);
+
+    const registry = buildProviderRegistry(logger, {
+      providerOverrides: {
+        claude: {
+          additionalModels: [
+            {
+              id: "profile-default",
+              label: "Profile Default",
+              isDefault: true,
+            },
+          ],
+        },
+      },
+    });
+
+    const client = registry.claude.createClient(logger);
+    const models = await client.listModels({
+      cwd: "/tmp/registry-models",
+      force: false,
+    });
+
+    const defaultModel = models.find((model) => model.isDefault) ?? models[0];
+    expect(defaultModel?.id).toBe("profile-default");
+  });
 });
diff --git a/packages/server/src/server/agent/provider-registry.ts b/packages/server/src/server/agent/provider-registry.ts
index 2d913ac8c..6bbeb1fb6 100644
--- a/packages/server/src/server/agent/provider-registry.ts
+++ b/packages/server/src/server/agent/provider-registry.ts
@@ -308,7 +308,12 @@ function wrapSessionProvider(provider: AgentProvider, inner: AgentSession): Agen
   };
 }
 
-function wrapClientProvider(provider: AgentProvider, inner: AgentClient): AgentClient {
+function wrapClientProvider(
+  provider: AgentProvider,
+  inner: AgentClient,
+  profileModels: ProviderProfileModel[],
+  additionalModels: ProviderProfileModel[],
+): AgentClient {
   const listPersistedAgents = inner.listPersistedAgents?.bind(inner);
 
   return {
@@ -343,7 +348,7 @@ function wrapClientProvider(provider: AgentProvider, inner: AgentClient): AgentC
         ),
       ),
     listModels: async (options) =>
-      (await inner.listModels(options)).map((model) => mapModel(provider, model)),
+      mergeModels(provider, profileModels, additionalModels, await inner.listModels(options)),
     listModes: inner.listModes?.bind(inner),
     listPersistedAgents: listPersistedAgents
       ? async (options?: ListPersistedAgentsOptions) =>
@@ -398,7 +403,12 @@ function createResolvedProviderClient(
   resolved: ResolvedProvider,
 ): AgentClient {
   const inner = resolved.createBaseClient(logger);
-  return inner.provider === provider ? inner : wrapClientProvider(provider, inner);
+  const hasModelOverrides =
+    resolved.profileModels.length > 0 || resolved.additionalModels.length > 0;
+  if (inner.provider === provider && !hasModelOverrides) {
+    return inner;
+  }
+  return wrapClientProvider(provider, inner, resolved.profileModels, resolved.additionalModels);
 }
 
 function buildResolvedBuiltinProviders(