feat(settings): resolve remote MCP servers from mcpServers

Teach mergeMcpServers to recognize remote (Streamable HTTP) entries: a
server with a `url` (or `type: "http"`) resolves to a remote config with
project settings overriding user settings and headers merged across
layers. Stdio servers keep their existing command/args/env resolution.

Author: gtxy27

packages/core/src/settings.ts

@@ -442,6 +442,24 @@ function mergeMcpServers(
   for (const name of serverNames) {
     const userConfig = userServers[name];
     const projectConfig = projectServers[name];
+
+    // Remote (Streamable HTTP) server: selected by a url or an explicit
+    // type: "http". Project settings override user settings; headers merge.
+    const url = trimString(projectConfig?.url) || trimString(userConfig?.url);
+    const type = projectConfig?.type ?? userConfig?.type;
+    if (url && type !== "stdio") {
+      const headers = {
+        ...(userConfig?.headers ?? {}),
+        ...(projectConfig?.headers ?? {}),
+      };
+      const config: McpServerConfig = { type: "http", url };
+      if (Object.keys(headers).length > 0) {
+        config.headers = headers;
+      }
+      merged[name] = config;
+      continue;
+    }
+
     const command = projectConfig?.command ?? userConfig?.command;
     if (!command) {
       continue;

packages/core/src/tests/settings-and-notify.test.ts

@@ -303,6 +303,40 @@ test("resolveSettingsSources merges MCP env with documented priority", () => {
   });
 });
 
+test("resolveSettingsSources resolves remote MCP servers with merged headers", () => {
+  const resolved = resolveSettingsSources(
+    {
+      mcpServers: {
+        remote: {
+          url: "https://user.example/mcp",
+          headers: { Authorization: "Bearer user", "X-User": "1" },
+        },
+      },
+    },
+    {
+      mcpServers: {
+        remote: {
+          url: "https://project.example/mcp",
+          headers: { Authorization: "Bearer project" },
+        },
+      },
+    },
+    {
+      model: "default-model",
+      baseURL: "https://default.example.com",
+    },
+    {}
+  );
+
+  const remote = resolved.mcpServers?.remote;
+  assert.equal(remote?.type, "http");
+  // Project url and header win; user-only header is preserved.
+  assert.equal(remote?.url, "https://project.example/mcp");
+  assert.deepEqual(remote?.headers, { Authorization: "Bearer project", "X-User": "1" });
+  // Remote servers carry no stdio fields.
+  assert.equal(remote?.command, undefined);
+});
+
 test("resolveSettings defaults DeepSeek v4 models to thinking mode", () => {
   const resolved = resolveSettings(
     {