server: add get_info tool (#26522)

* server: add get_info tool

* fix --rpc in docs

* server: harden get_info probe result handling

Report the OS as unknown when the probe process fails to spawn or times
out, so the diagnostic text from run() is never returned as an OS name.
Strip the probe output on both ends, which also drops the blank line
that ver prints before the version on Windows. Name the output and
timeout limits, and report an unreadable working directory as unknown
instead of an empty string.

* server: simplify get_info result handling

Drop the named limits and the working directory error branch, keeping
the probe result handling to a single expression.

---------

Co-authored-by: Pascal <admin@serveurperso.com>

tools/server/server-tools.cpp

@@ -1090,6 +1090,56 @@ struct server_tool_get_datetime : server_tool {
     }
 };
 
+//
+// get_info: returns runtime info (OS name/version and cwd)
+//
+
+struct server_tool_get_info : server_tool {
+    server_tool_get_info() {
+        name = "get_info";
+        display_name = "Get Runtime Info";
+        permission_write = false;
+    }
+
+    json get_definition() const override {
+        return {
+            {"type", "function"},
+            {"function", {
+                {"name", name},
+                {"description", "Returns runtime info: the OS name/version and the current working directory"},
+                {"parameters", {
+                    {"type", "object"},
+                    {"properties", json::object()},
+                }},
+            }},
+        };
+    }
+
+    json invoke(json params, server_tool::stream *) const override {
+        auto io = make_tools_io(params);
+
+#ifdef _WIN32
+        auto res = io->run({"cmd", "/c", "ver"}, 4096, 5);
+#else
+        auto res = io->run({"uname", "-a"}, 4096, 5);
+#endif
+        // "ver" prints a blank line before the version, so the output is stripped on both ends;
+        // a failed spawn or a timeout leaves a diagnostic in res.output, which is not an OS name
+        std::string os_info = res.exit_code == 0 && !res.timed_out ? string_strip(res.output) : "unknown";
+
+        std::string cwd = json_value(params, "cwd", std::string());
+        if (cwd.empty()) {
+            std::error_code ec;
+            cwd = fs::current_path(ec).string();
+        }
+
+        return {
+            {"os",  os_info},
+            {"cwd", cwd},
+        };
+    }
+};
+
 struct server_tool_stream_result : server_task_result {
     std::string chunk;
     bool done = false;
@@ -1199,6 +1249,7 @@ static std::vector<std::unique_ptr<server_tool>> build_tools() {
     tools.push_back(std::make_unique<server_tool_write_file>());
     tools.push_back(std::make_unique<server_tool_edit_file>());
     tools.push_back(std::make_unique<server_tool_get_datetime>());
+    tools.push_back(std::make_unique<server_tool_get_info>());
     return tools;
 }