cli: velox — add / ls / pause / resume / rm, with --json (build step 8, pulled forward)

The scriptable client, built now rather than last: it is how the daemon
gets exercised before the GUI is pointed at it (AGENT-DAEMON.md).

- src/client — synchronous blocking RPC over the Unix socket: resolve
  $XDG_RUNTIME_DIR/velox/velox.sock, connect, session.hello, one framed
  request/reply per call. Distinguishes transport failure (exit 3) from
  a daemon-returned error (exit 1).
- src/main — subcommands add/ls/pause/resume/rm; --json prints the raw
  JSON-RPC result or error; --dir/--out/--segments on add;
  --delete-file on rm. Usage errors exit 2.

ls works end to end against veloxd today (empty table). add and the
bulk verbs reach the daemon and surface its "not implemented" (-32603)
cleanly until the store lands — the plumbing is done, the commands
light up as handlers do.

Test velox.client: the real Client against an in-process UdsServer —
no-daemon path, session.hello, download.list, and a not-implemented
method surfacing as an RPC error rather than a transport error.
ASan+UBSan clean; full tree (21 tests, incl. conformance) green.

Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01Upd9WhG9oppieig5nRDLig

cli/tests/CMakeLists.txt

@@ -0,0 +1,13 @@
+# CLI integration test: a real in-process UdsServer on a temp socket, the real Client
+# against it. Links veloxd_rpc for the server half.
+
+add_executable(velox_client_test client_test.cpp ${CMAKE_CURRENT_SOURCE_DIR}/../src/client.cpp)
+target_include_directories(velox_client_test PRIVATE
+    ${CMAKE_CURRENT_SOURCE_DIR}/../src
+    ${CMAKE_CURRENT_SOURCE_DIR}/../../daemon/tests
+)
+target_compile_features(velox_client_test PRIVATE cxx_std_23)
+target_compile_options(velox_client_test PRIVATE -Wall -Wextra -Wpedantic -Werror)
+target_link_libraries(velox_client_test PRIVATE veloxd_rpc velox::proto nlohmann_json::nlohmann_json)
+add_test(NAME velox.client COMMAND velox_client_test)
+set_tests_properties(velox.client PROPERTIES TIMEOUT 30)

cli/tests/client_test.cpp

@@ -0,0 +1,78 @@
+// The CLI's Client against a real in-process daemon RPC server.
+
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include <cstdlib>
+#include <string>
+#include <thread>
+
+#include "check.hpp"
+#include "client.hpp"
+#include "rpc/dispatcher.hpp"
+#include "rpc/event_loop.hpp"
+#include "rpc/uds_server.hpp"
+
+namespace rpc = velox::daemon::rpc;
+using velox::cli::CallError;
+using velox::cli::Client;
+
+void run() {
+    // connect() with no daemon -> a kConnect error, not a crash.
+    {
+        ::setenv("XDG_RUNTIME_DIR", "/tmp/velox-cli-test-nonexistent-xyz", 1);
+        Client c;
+        auto err = c.connect();
+        CHECK(err.has_value());
+        if (err) CHECK_EQ(err->code, CallError::kConnect);
+    }
+
+    // Point XDG_RUNTIME_DIR at a fresh temp dir; the client derives
+    // <XDG_RUNTIME_DIR>/velox/velox.sock and the server binds exactly that.
+    char tmpl[] = "/tmp/velox-cli-test-XXXXXX";
+    const char* xdg = ::mkdtemp(tmpl);
+    CHECK(xdg != nullptr);
+    if (xdg == nullptr) return;
+    ::setenv("XDG_RUNTIME_DIR", xdg, 1);
+    const std::string velox_dir = std::string(xdg) + "/velox";
+    ::mkdir(velox_dir.c_str(), 0700);
+    const std::string server_sock = velox_dir + "/velox.sock";
+
+    rpc::EventLoop loop;
+    rpc::VeloxDispatcher dispatcher;
+    rpc::UdsServer server(loop, dispatcher, server_sock);
+    const auto ec = server.start();
+    CHECK(!ec);
+    if (ec) return;
+    std::thread th([&loop] { loop.run(); });
+
+    {
+        Client c;
+        auto err = c.connect();
+        CHECK(!err.has_value());
+        if (err) {
+            loop.stop();
+            th.join();
+            return;
+        }
+        CHECK_EQ(c.hello_result().value("transport", ""), std::string("uds"));
+
+        auto ls = c.call("download.list", nlohmann::json::object());
+        CHECK(ls.has_value());
+        if (ls) {
+            CHECK_EQ(ls->value("total", -1), 0);
+            CHECK(ls->at("items").is_array());
+        }
+
+        // A not-yet-implemented method surfaces the daemon's error, not a transport error.
+        auto add = c.call("download.add", {{"url", "https://example.com/x"}});
+        CHECK(!add.has_value());
+        if (!add) CHECK_EQ(add.error().code, -32603);
+    }
+
+    loop.stop();
+    th.join();
+    ::unlink(server_sock.c_str());
+}
+
+TEST_MAIN()