feat(nvim): add dedicated mcp tools for file reading and regex searching

nvim-core/src/lib.rs

@@ -999,6 +999,31 @@ pub async fn run_mcp_loop(app_name: &str, app_version: &str) {
                                         "type": "object",
                                         "properties": {}
                                     }
+                                },
+                                {
+                                    "name": "nvim_read_file",
+                                    "description": "Read specific lines from a file buffer (like cat or sed -n). Reads unsaved changes if open.",
+                                    "inputSchema": {
+                                        "type": "object",
+                                        "properties": {
+                                            "file": { "type": "string" },
+                                            "start_line": { "type": "integer", "description": "1-indexed start line (optional, defaults to 1)" },
+                                            "end_line": { "type": "integer", "description": "1-indexed end line (optional, defaults to end of file)" }
+                                        },
+                                        "required": ["file"]
+                                    }
+                                },
+                                {
+                                    "name": "nvim_search_file",
+                                    "description": "Search for a regex pattern within a file buffer (like grep). Searches unsaved changes if open.",
+                                    "inputSchema": {
+                                        "type": "object",
+                                        "properties": {
+                                            "file": { "type": "string" },
+                                            "pattern": { "type": "string", "description": "Lua-compatible regex pattern to search for" }
+                                        },
+                                        "required": ["file", "pattern"]
+                                    }
                                 }
                             ]
                         })),
@@ -1330,6 +1355,72 @@ pub async fn run_mcp_loop(app_name: &str, app_version: &str) {
                             }
                         }
                         
+                        "nvim_read_file" => {
+                            if let Some(file) = args.get("file").and_then(|v| v.as_str()) {
+                                let start_line = args.get("start_line").and_then(|v| v.as_i64()).unwrap_or(1);
+                                let end_line = args.get("end_line").and_then(|v| v.as_i64()).unwrap_or(-1);
+                                
+                                let escaped_file = file.replace('\\', "\\\\").replace('"', "\\\"");
+                                let code = format!("
+                                    local file = \"{escaped_file}\"
+                                    local start_idx = {start_line} - 1
+                                    local end_idx = {end_line}
+                                    local bufnr = vim.fn.bufnr(file, true)
+                                    if vim.fn.bufloaded(bufnr) == 0 then
+                                        vim.fn.bufload(bufnr)
+                                    end
+                                    local lines = vim.api.nvim_buf_get_lines(bufnr, start_idx, end_idx, false)
+                                    local res = {{}}
+                                    for i, line in ipairs(lines) do
+                                        local line_num = start_idx + i
+                                        table.insert(res, tostring(line_num) .. ': ' .. line)
+                                    end
+                                    return table.concat(res, '\\n')
+                                ");
+                                match execute_nvim_lua(&code).await {
+                                    Ok(res) => send_text_result!(id.clone(), res),
+                                    Err(e) => send_error(id, -32603, &e).await,
+                                }
+                            } else {
+                                send_error(id, -32602, "Missing 'file'").await;
+                            }
+                        }
+                        
+                        "nvim_search_file" => {
+                            if let (Some(file), Some(pattern)) = (
+                                args.get("file").and_then(|v| v.as_str()),
+                                args.get("pattern").and_then(|v| v.as_str()),
+                            ) {
+                                let escaped_file = file.replace('\\', "\\\\").replace('"', "\\\"");
+                                let escaped_pattern = pattern.replace('\\', "\\\\").replace('"', "\\\"");
+                                let code = format!("
+                                    local file = \"{escaped_file}\"
+                                    local pattern = \"{escaped_pattern}\"
+                                    local bufnr = vim.fn.bufnr(file, true)
+                                    if vim.fn.bufloaded(bufnr) == 0 then
+                                        vim.fn.bufload(bufnr)
+                                    end
+                                    local lines = vim.api.nvim_buf_get_lines(bufnr, 0, -1, false)
+                                    local matches = {{}}
+                                    for i, line in ipairs(lines) do
+                                        if string.match(line, pattern) then
+                                            table.insert(matches, tostring(i) .. ': ' .. line)
+                                        end
+                                    end
+                                    if #matches == 0 then
+                                        return 'No matches found.'
+                                    end
+                                    return table.concat(matches, '\\n')
+                                ");
+                                match execute_nvim_lua(&code).await {
+                                    Ok(res) => send_text_result!(id.clone(), res),
+                                    Err(e) => send_error(id, -32603, &e).await,
+                                }
+                            } else {
+                                send_error(id, -32602, "Missing 'file' or 'pattern'").await;
+                            }
+                        }
+
                         "nvim_execute_lua" => {
                             if let Some(code) = args.get("code").and_then(|v| v.as_str()) {
                                 // BAKE IN: Block interactive prompts that cause server deadlocks