From 67d2a8054cbccde8356b4fc7728eb9455070b566 Mon Sep 17 00:00:00 2001
From: Barrett Ruth <br.barrettruth@gmail.com>
Date: Mon, 15 Sep 2025 07:05:31 -0500
Subject: [PATCH 01/14] feat: local state over vim.g

---
 lua/cp/health.lua |  14 +--
 lua/cp/init.lua   | 240 +++++++++++++++++++++++++++++++++++++++-------
 plugin/cp.lua     |   8 +-
 readme.md         |   4 +
 4 files changed, 224 insertions(+), 42 deletions(-)

diff --git a/lua/cp/health.lua b/lua/cp/health.lua
index d902934..738e9e2 100644
--- a/lua/cp/health.lua
+++ b/lua/cp/health.lua
@@ -62,12 +62,14 @@ end
 local function check_config()
 	vim.health.ok("Plugin ready")
 
-	if vim.g.cp and vim.g.cp.platform then
-		local info = vim.g.cp.platform
-		if vim.g.cp.contest_id then
-			info = info .. " " .. vim.g.cp.contest_id
-			if vim.g.cp.problem_id then
-				info = info .. " " .. vim.g.cp.problem_id
+	local cp = require("cp")
+	local context = cp.get_current_context()
+	if context.platform then
+		local info = context.platform
+		if context.contest_id then
+			info = info .. " " .. context.contest_id
+			if context.problem_id then
+				info = info .. " " .. context.problem_id
 			end
 		end
 		vim.health.info("Current context: " .. info)
diff --git a/lua/cp/init.lua b/lua/cp/init.lua
index b86dc98..92d7614 100644
--- a/lua/cp/init.lua
+++ b/lua/cp/init.lua
@@ -14,7 +14,6 @@ if not vim.fn.has("nvim-0.10.0") then
 	return {}
 end
 
-vim.g.cp = vim.g.cp or {}
 local user_config = {}
 local config = config_module.setup(user_config)
 logger.set_config(config)
@@ -28,10 +27,41 @@ local state = {
 	saved_layout = nil,
 	saved_session = nil,
 	temp_output = nil,
+	test_cases = nil,
+	test_states = {},
 }
 
 local platforms = { "atcoder", "codeforces", "cses" }
-local actions = { "run", "debug", "diff", "next", "prev" }
+local actions = { "run", "debug", "test", "next", "prev" }
+
+local function get_current_problem_key()
+	if not state.platform or not state.contest_id then
+		return nil
+	end
+	if state.platform == "cses" then
+		return state.contest_id
+	else
+		return state.contest_id .. "_" .. (state.problem_id or "")
+	end
+end
+
+local function get_test_states()
+	local problem_key = get_current_problem_key()
+	if not problem_key then
+		return {}
+	end
+
+	if not state.test_states[problem_key] then
+		state.test_states[problem_key] = {}
+		if state.test_cases then
+			for i = 1, #state.test_cases do
+				state.test_states[problem_key][i] = true
+			end
+		end
+	end
+
+	return state.test_states[problem_key]
+end
 
 local function set_platform(platform)
 	if not vim.tbl_contains(platforms, platform) then
@@ -79,6 +109,11 @@ local function setup_problem(contest_id, problem_id)
 	state.contest_id = contest_id
 	state.problem_id = problem_id
 
+	local cached_test_cases = cache.get_test_cases(state.platform, contest_id, problem_id)
+	if cached_test_cases then
+		state.test_cases = cached_test_cases
+	end
+
 	local ctx = problem.create_context(state.platform, contest_id, problem_id, config)
 
 	local scrape_result = scrape.scrape_problem(ctx)
@@ -86,9 +121,15 @@ local function setup_problem(contest_id, problem_id)
 	if not scrape_result.success then
 		logger.log("scraping failed: " .. (scrape_result.error or "unknown error"), vim.log.levels.WARN)
 		logger.log("you can manually add test cases to io/ directory", vim.log.levels.INFO)
+		state.test_cases = nil
 	else
 		local test_count = scrape_result.test_count or 0
 		logger.log(("scraped %d test case(s) for %s"):format(test_count, scrape_result.problem_id))
+		state.test_cases = scrape_result.test_cases
+
+		if scrape_result.test_cases then
+			cache.set_test_cases(state.platform, contest_id, problem_id, scrape_result.test_cases)
+		end
 	end
 
 	vim.cmd.e(ctx.source_file)
@@ -186,36 +227,86 @@ local function debug_problem()
 	end)
 end
 
-local function diff_problem()
-	if state.diff_mode then
-		local tile_fn = config.tile or window.default_tile
-		window.restore_layout(state.saved_layout, tile_fn)
-		state.diff_mode = false
-		state.saved_layout = nil
-		logger.log("exited diff mode")
-	else
-		local problem_id = get_current_problem()
-		if not problem_id then
-			return
-		end
-
-		local ctx = problem.create_context(state.platform, state.contest_id, state.problem_id, config)
-
-		if vim.fn.filereadable(ctx.expected_file) == 0 then
-			logger.log(("No expected output file found: %s"):format(ctx.expected_file), vim.log.levels.ERROR)
-			return
-		end
-
-		state.saved_layout = window.save_layout()
-
-		local result = vim.system({ "awk", "/^\\[[^]]*\\]:/ {exit} {print}", ctx.output_file }, { text = true }):wait()
-		local actual_output = result.stdout
-
-		window.setup_diff_layout(actual_output, ctx.expected_file, ctx.input_file)
-
-		state.diff_mode = true
-		logger.log("entered diff mode")
+local function test_problem()
+	local problem_id = get_current_problem()
+	if not problem_id then
+		return
 	end
+
+	if not state.test_cases then
+		logger.log("No test case data available. Try scraping the problem first.", vim.log.levels.ERROR)
+		return
+	end
+
+	local ctx = problem.create_context(state.platform, state.contest_id, state.problem_id, config)
+	local contest_config = config.contests[state.platform]
+
+	local test_results = execute.run_individual_tests(ctx, state.test_cases, contest_config, false)
+
+	if test_results.compile_error then
+		logger.log("Compilation failed: " .. test_results.compile_error, vim.log.levels.ERROR)
+		return
+	end
+
+	local buf_name = ("cp-test://%s"):format(problem_id)
+	local existing_buf = vim.fn.bufnr(buf_name)
+	local buf
+
+	if existing_buf ~= -1 then
+		buf = existing_buf
+	else
+		buf = vim.api.nvim_create_buf(false, true)
+		vim.api.nvim_buf_set_name(buf, buf_name)
+	end
+
+	local lines = {}
+	local passed = 0
+	local total = #test_results.results
+
+	local test_states = get_test_states()
+
+	for _, result in ipairs(test_results.results) do
+		local status_icon = result.status == "PASS" and "✓" or "✗"
+		local enabled_icon = test_states[result.id] and "[x]" or "[ ]"
+		local time_str = ("%.1fms"):format(result.time_ms)
+
+		table.insert(lines, ("%s Test %d %s %s (%s) {{{"):format(enabled_icon, result.id, status_icon, result.status, time_str))
+		table.insert(lines, "    Input:")
+		for _, line in ipairs(vim.split(result.input, "\n")) do
+			table.insert(lines, "      " .. line)
+		end
+
+		if result.status == "PASS" then
+			table.insert(lines, "    Output:")
+			for _, line in ipairs(vim.split(result.actual, "\n")) do
+				table.insert(lines, "      " .. line)
+			end
+			passed = passed + 1
+		else
+			table.insert(lines, "    Expected:")
+			for _, line in ipairs(vim.split(result.expected, "\n")) do
+				table.insert(lines, "      " .. line)
+			end
+			table.insert(lines, "    Got:")
+			for _, line in ipairs(vim.split(result.actual, "\n")) do
+				table.insert(lines, "      " .. line)
+			end
+		end
+
+		table.insert(lines, "}}}")
+		table.insert(lines, "")
+	end
+
+	table.insert(lines, ("Summary: %d/%d passed"):format(passed, total))
+
+	vim.api.nvim_buf_set_lines(buf, 0, -1, false, lines)
+	vim.bo[buf].filetype = "cp-test"
+	vim.bo[buf].modifiable = false
+
+	vim.cmd.split()
+	vim.api.nvim_set_current_buf(buf)
+
+	logger.log(("Test results: %d/%d passed"):format(passed, total))
 end
 
 ---@param delta number 1 for next, -1 for prev
@@ -323,8 +414,8 @@ function M.handle_command(opts)
 			run_problem()
 		elseif cmd.action == "debug" then
 			debug_problem()
-		elseif cmd.action == "diff" then
-			diff_problem()
+		elseif cmd.action == "test" then
+			test_problem()
 		elseif cmd.action == "next" then
 			navigate_problem(1)
 		elseif cmd.action == "prev" then
@@ -400,6 +491,81 @@ function M.handle_command(opts)
 	end
 end
 
+function M.toggle_test(test_id)
+	local test_states = get_test_states()
+	test_states[test_id] = not test_states[test_id]
+
+	local problem_key = get_current_problem_key()
+	if problem_key then
+		state.test_states[problem_key] = test_states
+	end
+
+	test_problem()
+end
+
+function M.run_single_test(test_id)
+	if not state.test_cases or not state.test_cases[test_id] then
+		logger.log("Test case not found", vim.log.levels.ERROR)
+		return
+	end
+
+	local ctx = problem.create_context(state.platform, state.contest_id, state.problem_id, config)
+	local contest_config = config.contests[state.platform]
+
+	local single_test = { state.test_cases[test_id] }
+	local test_results = execute.run_individual_tests(ctx, single_test, contest_config, false)
+
+	if test_results.compile_error then
+		logger.log("Compilation failed: " .. test_results.compile_error, vim.log.levels.ERROR)
+		return
+	end
+
+	local result = test_results.results[1]
+	if result then
+		logger.log(("Test %d: %s (%.1fms)"):format(test_id, result.status, result.time_ms))
+	end
+end
+
+function M.run_all_enabled_tests()
+	if not state.test_cases then
+		logger.log("No test cases available", vim.log.levels.ERROR)
+		return
+	end
+
+	local test_states = get_test_states()
+	local enabled_tests = {}
+
+	for i, test_case in ipairs(state.test_cases) do
+		if test_states[i] then
+			table.insert(enabled_tests, test_case)
+		end
+	end
+
+	if #enabled_tests == 0 then
+		logger.log("No tests enabled", vim.log.levels.WARN)
+		return
+	end
+
+	local ctx = problem.create_context(state.platform, state.contest_id, state.problem_id, config)
+	local contest_config = config.contests[state.platform]
+
+	local test_results = execute.run_individual_tests(ctx, enabled_tests, contest_config, false)
+
+	if test_results.compile_error then
+		logger.log("Compilation failed: " .. test_results.compile_error, vim.log.levels.ERROR)
+		return
+	end
+
+	local passed = 0
+	for _, result in ipairs(test_results.results) do
+		if result.status == "PASS" then
+			passed = passed + 1
+		end
+	end
+
+	logger.log(("Enabled tests: %d/%d passed"):format(passed, #enabled_tests))
+end
+
 function M.setup(opts)
 	opts = opts or {}
 	user_config = opts
@@ -411,6 +577,14 @@ function M.setup(opts)
 	end
 end
 
+function M.get_current_context()
+	return {
+		platform = state.platform,
+		contest_id = state.contest_id,
+		problem_id = state.problem_id,
+	}
+end
+
 function M.is_initialized()
 	return true
 end
diff --git a/plugin/cp.lua b/plugin/cp.lua
index 690823a..fc57b96 100644
--- a/plugin/cp.lua
+++ b/plugin/cp.lua
@@ -4,7 +4,7 @@ end
 vim.g.loaded_cp = 1
 
 local platforms = { "atcoder", "codeforces", "cses" }
-local actions = { "run", "debug", "diff", "next", "prev" }
+local actions = { "run", "debug", "test", "next", "prev" }
 
 vim.api.nvim_create_user_command("CP", function(opts)
 	local cp = require("cp")
@@ -22,10 +22,12 @@ end, {
 			local candidates = {}
 			vim.list_extend(candidates, platforms)
 			vim.list_extend(candidates, actions)
-			if vim.g.cp and vim.g.cp.platform and vim.g.cp.contest_id then
+			local cp = require("cp")
+			local context = cp.get_current_context()
+			if context.platform and context.contest_id then
 				local cache = require("cp.cache")
 				cache.load()
-				local contest_data = cache.get_contest_data(vim.g.cp.platform, vim.g.cp.contest_id)
+				local contest_data = cache.get_contest_data(context.platform, context.contest_id)
 				if contest_data and contest_data.problems then
 					for _, problem in ipairs(contest_data.problems) do
 						table.insert(candidates, problem.id)
diff --git a/readme.md b/readme.md
index f6b43ed..5adcaec 100644
--- a/readme.md
+++ b/readme.md
@@ -56,6 +56,10 @@ follows:
 4. Submit the problem (on the remote!)
 
 
+## Similar Projects
+
+- [competitest.nvim](https://github.com/xeluxee/competitest.nvim)
+
 ## TODO
 
 - finer-tuned problem limits (i.e. per-problem codeforces time, memory)

From 1ef68a4847a6f1ed10d60b788bbc7b03e41b636d Mon Sep 17 00:00:00 2001
From: Barrett Ruth <br.barrettruth@gmail.com>
Date: Mon, 15 Sep 2025 08:11:15 -0500
Subject: [PATCH 02/14] feat: first draft of arbitrary compile mode

---
 after/ftplugin/cp-test.lua |  45 +++++++++++++++
 lua/cp/cache.lua           |  22 ++++++++
 lua/cp/config.lua          |  46 ++++++++++++----
 lua/cp/execute.lua         | 109 +++++++++++++++++++++++++++++++++++--
 lua/cp/init.lua            |   5 +-
 lua/cp/scrape.lua          |   1 +
 6 files changed, 212 insertions(+), 16 deletions(-)
 create mode 100644 after/ftplugin/cp-test.lua

diff --git a/after/ftplugin/cp-test.lua b/after/ftplugin/cp-test.lua
new file mode 100644
index 0000000..faed7af
--- /dev/null
+++ b/after/ftplugin/cp-test.lua
@@ -0,0 +1,45 @@
+vim.opt_local.number = false
+vim.opt_local.relativenumber = false
+vim.opt_local.statuscolumn = ""
+vim.opt_local.signcolumn = "no"
+vim.opt_local.wrap = false
+vim.opt_local.linebreak = false
+vim.opt_local.foldmethod = "marker"
+vim.opt_local.foldmarker = "{{{,}}}"
+vim.opt_local.foldlevel = 0
+vim.opt_local.foldtext = ""
+
+local function get_test_id_from_line()
+	local line = vim.api.nvim_get_current_line()
+	local test_id = line:match("%[.%] Test (%d+)")
+	return test_id and tonumber(test_id)
+end
+
+local function toggle_test()
+	local test_id = get_test_id_from_line()
+	if not test_id then
+		return
+	end
+
+	local cp = require("cp")
+	cp.toggle_test(test_id)
+end
+
+local function run_single_test()
+	local test_id = get_test_id_from_line()
+	if not test_id then
+		return
+	end
+
+	local cp = require("cp")
+	cp.run_single_test(test_id)
+end
+
+local function run_all_enabled_tests()
+	local cp = require("cp")
+	cp.run_all_enabled_tests()
+end
+
+vim.keymap.set("n", "t", toggle_test, { buffer = true, desc = "Toggle test enabled/disabled" })
+vim.keymap.set("n", "r", run_single_test, { buffer = true, desc = "Run single test" })
+vim.keymap.set("n", "R", run_all_enabled_tests, { buffer = true, desc = "Run all enabled tests" })
diff --git a/lua/cp/cache.lua b/lua/cp/cache.lua
index 70a55c3..565afc4 100644
--- a/lua/cp/cache.lua
+++ b/lua/cp/cache.lua
@@ -87,4 +87,26 @@ function M.clear_contest_data(platform, contest_id)
 	end
 end
 
+function M.get_test_cases(platform, contest_id, problem_id)
+	local problem_key = problem_id and (contest_id .. "_" .. problem_id) or contest_id
+	if not cache_data[platform] or not cache_data[platform][problem_key] then
+		return nil
+	end
+	return cache_data[platform][problem_key].test_cases
+end
+
+function M.set_test_cases(platform, contest_id, problem_id, test_cases)
+	local problem_key = problem_id and (contest_id .. "_" .. problem_id) or contest_id
+	if not cache_data[platform] then
+		cache_data[platform] = {}
+	end
+	if not cache_data[platform][problem_key] then
+		cache_data[platform][problem_key] = {}
+	end
+
+	cache_data[platform][problem_key].test_cases = test_cases
+	cache_data[platform][problem_key].test_cases_cached_at = os.time()
+	M.save()
+end
+
 return M
diff --git a/lua/cp/config.lua b/lua/cp/config.lua
index 9f39c60..48a245e 100644
--- a/lua/cp/config.lua
+++ b/lua/cp/config.lua
@@ -12,19 +12,48 @@ local M = {}
 M.defaults = {
 	contests = {
 		default = {
-			cpp_version = 20,
-			compile_flags = { "-O2", "-DLOCAL", "-Wall", "-Wextra" },
-			debug_flags = { "-g3", "-fsanitize=address,undefined", "-DLOCAL" },
+			cpp = {
+				compile = {
+					"g++",
+					"-std=c++{version}",
+					"-O2",
+					"-DLOCAL",
+					"-Wall",
+					"-Wextra",
+					"{source}",
+					"-o",
+					"{binary}",
+				},
+				run = { "{binary}" },
+				debug = {
+					"g++",
+					"-std=c++{version}",
+					"-g3",
+					"-fsanitize=address,undefined",
+					"-DLOCAL",
+					"{source}",
+					"-o",
+					"{binary}",
+				},
+				executable = nil,
+				version = 20,
+			},
+			python = {
+				compile = nil,
+				run = { "{source}" },
+				debug = { "{source}" },
+				executable = "python3",
+			},
 			timeout_ms = 2000,
 		},
 		atcoder = {
-			cpp_version = 23,
+			cpp = { version = 23 },
 		},
 		codeforces = {
-			cpp_version = 23,
+			cpp = { version = 23 },
 		},
 		cses = {
-			cpp_version = 20,
+			cpp = { version = 20 },
 		},
 	},
 	snippets = {},
@@ -42,11 +71,6 @@ M.defaults = {
 ---@return table
 local function extend_contest_config(base_config, contest_config)
 	local result = vim.tbl_deep_extend("force", base_config, contest_config)
-
-	local std_flag = ("-std=c++%d"):format(result.cpp_version)
-	result.compile_flags = vim.list_extend({ std_flag }, result.compile_flags)
-	result.debug_flags = vim.list_extend({ std_flag }, result.debug_flags)
-
 	return result
 end
 
diff --git a/lua/cp/execute.lua b/lua/cp/execute.lua
index 774346b..2182939 100644
--- a/lua/cp/execute.lua
+++ b/lua/cp/execute.lua
@@ -1,5 +1,43 @@
 local M = {}
 
+local filetype_to_language = {
+	cpp = "cpp",
+	cxx = "cpp",
+	cc = "cpp",
+	c = "cpp",
+	py = "python",
+	py3 = "python",
+	rs = "rust",
+	java = "java",
+	js = "javascript",
+	go = "go",
+}
+
+local function get_language_from_file(source_file)
+	local extension = vim.fn.fnamemodify(source_file, ":e")
+	return filetype_to_language[extension] or "cpp"
+end
+
+local function substitute_template(cmd_template, substitutions)
+	local result = {}
+	for _, arg in ipairs(cmd_template) do
+		local substituted = arg
+		for key, value in pairs(substitutions) do
+			substituted = substituted:gsub("{" .. key .. "}", value)
+		end
+		table.insert(result, substituted)
+	end
+	return result
+end
+
+local function build_command(cmd_template, executable, substitutions)
+	local cmd = substitute_template(cmd_template, substitutions)
+	if executable then
+		table.insert(cmd, 1, executable)
+	end
+	return cmd
+end
+
 local signal_codes = {
 	[128] = "SIGILL",
 	[130] = "SIGINT",
@@ -22,15 +60,19 @@ local function ensure_directories()
 	vim.system({ "mkdir", "-p", "build", "io" }):wait()
 end
 
-local function compile_cpp(source_path, binary_path, flags)
-	local compile_cmd = { "g++", unpack(flags), source_path, "-o", binary_path }
+local function compile_generic(language_config, substitutions)
+	if not language_config.compile then
+		return { code = 0, stderr = "" }
+	end
+
+	local compile_cmd = substitute_template(language_config.compile, substitutions)
 	return vim.system(compile_cmd, { text = true }):wait()
 end
 
-local function execute_binary(binary_path, input_data, timeout_ms)
+local function execute_command(cmd, input_data, timeout_ms)
 	local start_time = vim.loop.hrtime()
 
-	local result = vim.system({ binary_path }, {
+	local result = vim.system(cmd, {
 		stdin = input_data,
 		timeout = timeout_ms,
 		text = true,
@@ -123,4 +165,63 @@ function M.run_problem(ctx, contest_config, is_debug)
 	end
 end
 
+function M.run_individual_tests(ctx, test_cases, contest_config, is_debug)
+	ensure_directories()
+
+	if not test_cases or #test_cases == 0 then
+		return {}
+	end
+
+	local flags = is_debug and contest_config.debug_flags or contest_config.compile_flags
+	local compile_result = compile_cpp(ctx.source_file, ctx.binary_file, flags)
+	if compile_result.code ~= 0 then
+		return {
+			compile_error = compile_result.stderr,
+			results = {},
+		}
+	end
+
+	local results = {}
+	for i, test_case in ipairs(test_cases) do
+		local exec_result = execute_binary(ctx.binary_file, test_case.input, contest_config.timeout_ms)
+
+		local actual_lines = vim.split(exec_result.stdout, "\n")
+		while #actual_lines > 0 and actual_lines[#actual_lines] == "" do
+			table.remove(actual_lines)
+		end
+
+		local expected_lines = vim.split(test_case.output, "\n")
+		while #expected_lines > 0 and expected_lines[#expected_lines] == "" do
+			table.remove(expected_lines)
+		end
+
+		local matches = #actual_lines == #expected_lines
+		if matches then
+			for j, line in ipairs(actual_lines) do
+				if line ~= expected_lines[j] then
+					matches = false
+					break
+				end
+			end
+		end
+
+		table.insert(results, {
+			id = i,
+			status = exec_result.code == 0 and (matches and "PASS" or "FAIL") or "ERROR",
+			time_ms = exec_result.time_ms,
+			input = test_case.input,
+			expected = test_case.output,
+			actual = exec_result.stdout,
+			exit_code = exec_result.code,
+			timed_out = exec_result.timed_out,
+			enabled = true,
+		})
+	end
+
+	return {
+		compile_error = nil,
+		results = results,
+	}
+end
+
 return M
diff --git a/lua/cp/init.lua b/lua/cp/init.lua
index 92d7614..90abffb 100644
--- a/lua/cp/init.lua
+++ b/lua/cp/init.lua
@@ -270,7 +270,10 @@ local function test_problem()
 		local enabled_icon = test_states[result.id] and "[x]" or "[ ]"
 		local time_str = ("%.1fms"):format(result.time_ms)
 
-		table.insert(lines, ("%s Test %d %s %s (%s) {{{"):format(enabled_icon, result.id, status_icon, result.status, time_str))
+		table.insert(
+			lines,
+			("%s Test %d %s %s (%s) {{{"):format(enabled_icon, result.id, status_icon, result.status, time_str)
+		)
 		table.insert(lines, "    Input:")
 		for _, line in ipairs(vim.split(result.input, "\n")) do
 			table.insert(lines, "      " .. line)
diff --git a/lua/cp/scrape.lua b/lua/cp/scrape.lua
index 82e2e4f..138dacc 100644
--- a/lua/cp/scrape.lua
+++ b/lua/cp/scrape.lua
@@ -209,6 +209,7 @@ function M.scrape_problem(ctx)
 		success = true,
 		problem_id = ctx.problem_name,
 		test_count = data.test_cases and #data.test_cases or 0,
+		test_cases = data.test_cases,
 		url = data.url,
 	}
 end

From 2b1367602475cb9617bac0f5ecb47953ef38436b Mon Sep 17 00:00:00 2001
From: Barrett Ruth <br.barrettruth@gmail.com>
Date: Mon, 15 Sep 2025 08:16:41 -0500
Subject: [PATCH 03/14] feat(doc): update docs with language config

---
 doc/cp.txt         |  7 +++---
 lua/cp/execute.lua | 60 +++++++++++++++++++++++++++++++++++-----------
 readme.md          |  3 ++-
 3 files changed, 52 insertions(+), 18 deletions(-)

diff --git a/doc/cp.txt b/doc/cp.txt
index 7570cc1..7b848ab 100644
--- a/doc/cp.txt
+++ b/doc/cp.txt
@@ -9,12 +9,13 @@ cp.nvim is a competitive programming plugin that automates problem setup,
 compilation, and testing workflow for online judges.
 
 Supported platforms: AtCoder, Codeforces, CSES
+Supported languages: C++, Python
 
 REQUIREMENTS						*cp-requirements*
 
 - Neovim 0.10.0+
 - uv package manager (https://docs.astral.sh/uv/)
-- C++ compiler (g++/clang++)
+- Language runtime/compiler (g++, python3)
 
 Optional:
 - LuaSnip for template expansion (https://github.com/L3MON4D3/LuaSnip)
@@ -51,8 +52,8 @@ Action Commands ~
 :CP debug                       Compile with debug flags and run current problem.
                                 Includes sanitizers and debug symbols.
 
-:CP diff                        Enter diff mode to compare actual vs expected
-                                output. Run again to exit diff mode.
+:CP test                        Open enhanced test viewer showing individual
+                                test case results with pass/fail status.
 
 Navigation Commands ~
 
diff --git a/lua/cp/execute.lua b/lua/cp/execute.lua
index 2182939..87daa60 100644
--- a/lua/cp/execute.lua
+++ b/lua/cp/execute.lua
@@ -7,10 +7,6 @@ local filetype_to_language = {
 	c = "cpp",
 	py = "python",
 	py3 = "python",
-	rs = "rust",
-	java = "java",
-	js = "javascript",
-	go = "go",
 }
 
 local function get_language_from_file(source_file)
@@ -138,20 +134,36 @@ end
 function M.run_problem(ctx, contest_config, is_debug)
 	ensure_directories()
 
-	local flags = is_debug and contest_config.debug_flags or contest_config.compile_flags
+	local language = get_language_from_file(ctx.source_file)
+	local language_config = contest_config[language]
 
-	local compile_result = compile_cpp(ctx.source_file, ctx.binary_file, flags)
-	if compile_result.code ~= 0 then
-		vim.fn.writefile({ compile_result.stderr }, ctx.output_file)
+	if not language_config then
+		vim.fn.writefile({ "Error: No configuration for language: " .. language }, ctx.output_file)
 		return
 	end
 
+	local substitutions = {
+		source = ctx.source_file,
+		binary = ctx.binary_file,
+		version = tostring(language_config.version or ""),
+	}
+
+	local compile_cmd = is_debug and language_config.debug or language_config.compile
+	if compile_cmd then
+		local compile_result = compile_generic(language_config, substitutions)
+		if compile_result.code ~= 0 then
+			vim.fn.writefile({ compile_result.stderr }, ctx.output_file)
+			return
+		end
+	end
+
 	local input_data = ""
 	if vim.fn.filereadable(ctx.input_file) == 1 then
 		input_data = table.concat(vim.fn.readfile(ctx.input_file), "\n") .. "\n"
 	end
 
-	local exec_result = execute_binary(ctx.binary_file, input_data, contest_config.timeout_ms)
+	local run_cmd = build_command(language_config.run, language_config.executable, substitutions)
+	local exec_result = execute_command(run_cmd, input_data, contest_config.timeout_ms)
 	local formatted_output = format_output(exec_result, ctx.expected_file, is_debug)
 
 	local output_buf = vim.fn.bufnr(ctx.output_file)
@@ -172,18 +184,38 @@ function M.run_individual_tests(ctx, test_cases, contest_config, is_debug)
 		return {}
 	end
 
-	local flags = is_debug and contest_config.debug_flags or contest_config.compile_flags
-	local compile_result = compile_cpp(ctx.source_file, ctx.binary_file, flags)
-	if compile_result.code ~= 0 then
+	local language = get_language_from_file(ctx.source_file)
+	local language_config = contest_config[language]
+
+	if not language_config then
 		return {
-			compile_error = compile_result.stderr,
+			compile_error = "Error: No configuration for language: " .. language,
 			results = {},
 		}
 	end
 
+	local substitutions = {
+		source = ctx.source_file,
+		binary = ctx.binary_file,
+		version = tostring(language_config.version or ""),
+	}
+
+	local compile_cmd = is_debug and language_config.debug or language_config.compile
+	if compile_cmd then
+		local compile_result = compile_generic(language_config, substitutions)
+		if compile_result.code ~= 0 then
+			return {
+				compile_error = compile_result.stderr,
+				results = {},
+			}
+		end
+	end
+
+	local run_cmd = build_command(language_config.run, language_config.executable, substitutions)
+
 	local results = {}
 	for i, test_case in ipairs(test_cases) do
-		local exec_result = execute_binary(ctx.binary_file, test_case.input, contest_config.timeout_ms)
+		local exec_result = execute_command(run_cmd, test_case.input, contest_config.timeout_ms)
 
 		local actual_lines = vim.split(exec_result.stdout, "\n")
 		while #actual_lines > 0 and actual_lines[#actual_lines] == "" do
diff --git a/readme.md b/readme.md
index 5adcaec..6b6bf83 100644
--- a/readme.md
+++ b/readme.md
@@ -9,9 +9,10 @@ https://private-user-images.githubusercontent.com/62671086/489116291-391976d1-c2
 ## Features
 
 - Support for multiple online judges ([AtCoder](https://atcoder.jp/), [Codeforces](https://codeforces.com/), [CSES](https://cses.fi))
+- Multi-language support (C++, Python)
 - Automatic problem scraping and test case management
 - Integrated build, run, and debug commands
-- Diff mode for comparing output with expected results
+- Enhanced test viewer with individual test case management
 - LuaSnip integration for contest-specific snippets
 
 ## Requirements

From 64a7fc114486993ce5f4901737c54ff52c991e41 Mon Sep 17 00:00:00 2001
From: Barrett Ruth <br.barrettruth@gmail.com>
Date: Mon, 15 Sep 2025 08:18:52 -0500
Subject: [PATCH 04/14] feat(debug): debug logs

---
 lua/cp/execute.lua | 32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/lua/cp/execute.lua b/lua/cp/execute.lua
index 87daa60..791dbe3 100644
--- a/lua/cp/execute.lua
+++ b/lua/cp/execute.lua
@@ -1,4 +1,5 @@
 local M = {}
+local logger = require("cp.log")
 
 local filetype_to_language = {
 	cpp = "cpp",
@@ -11,7 +12,9 @@ local filetype_to_language = {
 
 local function get_language_from_file(source_file)
 	local extension = vim.fn.fnamemodify(source_file, ":e")
-	return filetype_to_language[extension] or "cpp"
+	local language = filetype_to_language[extension] or "cpp"
+	logger.log(("detected language: %s (extension: %s)"):format(language, extension))
+	return language
 end
 
 local function substitute_template(cmd_template, substitutions)
@@ -58,14 +61,29 @@ end
 
 local function compile_generic(language_config, substitutions)
 	if not language_config.compile then
+		logger.log("no compilation step required")
 		return { code = 0, stderr = "" }
 	end
 
 	local compile_cmd = substitute_template(language_config.compile, substitutions)
-	return vim.system(compile_cmd, { text = true }):wait()
+	logger.log(("compiling: %s"):format(table.concat(compile_cmd, " ")))
+
+	local start_time = vim.loop.hrtime()
+	local result = vim.system(compile_cmd, { text = true }):wait()
+	local compile_time = (vim.loop.hrtime() - start_time) / 1000000
+
+	if result.code == 0 then
+		logger.log(("compilation successful (%.1fms)"):format(compile_time))
+	else
+		logger.log(("compilation failed (%.1fms): %s"):format(compile_time, result.stderr), vim.log.levels.WARN)
+	end
+
+	return result
 end
 
 local function execute_command(cmd, input_data, timeout_ms)
+	logger.log(("executing: %s"):format(table.concat(cmd, " ")))
+
 	local start_time = vim.loop.hrtime()
 
 	local result = vim.system(cmd, {
@@ -79,6 +97,14 @@ local function execute_command(cmd, input_data, timeout_ms)
 
 	local actual_code = result.code or 0
 
+	if result.code == 124 then
+		logger.log(("execution timed out after %.1fms"):format(execution_time), vim.log.levels.WARN)
+	elseif actual_code ~= 0 then
+		logger.log(("execution failed (exit code %d, %.1fms)"):format(actual_code, execution_time), vim.log.levels.WARN)
+	else
+		logger.log(("execution successful (%.1fms)"):format(execution_time))
+	end
+
 	return {
 		stdout = result.stdout or "",
 		stderr = result.stderr or "",
@@ -184,6 +210,8 @@ function M.run_individual_tests(ctx, test_cases, contest_config, is_debug)
 		return {}
 	end
 
+	logger.log(("running %d individual tests"):format(#test_cases))
+
 	local language = get_language_from_file(ctx.source_file)
 	local language_config = contest_config[language]
 

From 0c6ed73ddeee3b2f51a7a43a078bf819db2a3dae Mon Sep 17 00:00:00 2001
From: Barrett Ruth <br.barrettruth@gmail.com>
Date: Mon, 15 Sep 2025 08:20:11 -0500
Subject: [PATCH 05/14] feat(debug): log execution time

---
 lua/cp/execute.lua | 11 +++++++++++
 lua/cp/init.lua    |  7 +++++++
 2 files changed, 18 insertions(+)

diff --git a/lua/cp/execute.lua b/lua/cp/execute.lua
index 791dbe3..186dd8b 100644
--- a/lua/cp/execute.lua
+++ b/lua/cp/execute.lua
@@ -278,6 +278,17 @@ function M.run_individual_tests(ctx, test_cases, contest_config, is_debug)
 		})
 	end
 
+	local passed = 0
+	local total_time = 0
+	for _, result in ipairs(results) do
+		if result.status == "PASS" then
+			passed = passed + 1
+		end
+		total_time = total_time + result.time_ms
+	end
+
+	logger.log(("test results: %d/%d passed, total execution time %.1fms"):format(passed, #results, total_time))
+
 	return {
 		compile_error = nil,
 		results = results,
diff --git a/lua/cp/init.lua b/lua/cp/init.lua
index 90abffb..8e1e884 100644
--- a/lua/cp/init.lua
+++ b/lua/cp/init.lua
@@ -83,6 +83,9 @@ local function setup_problem(contest_id, problem_id)
 		return
 	end
 
+	local problem_name = state.platform == "cses" and contest_id or (contest_id .. (problem_id or ""))
+	logger.log(("setting up problem: %s"):format(problem_name))
+
 	local metadata_result = scrape.scrape_contest_metadata(state.platform, contest_id)
 	if not metadata_result.success then
 		logger.log(
@@ -185,6 +188,8 @@ local function run_problem()
 		return
 	end
 
+	logger.log(("running problem: %s"):format(problem_id))
+
 	if config.hooks and config.hooks.before_run then
 		config.hooks.before_run(problem_id)
 	end
@@ -233,6 +238,8 @@ local function test_problem()
 		return
 	end
 
+	logger.log(("opening test viewer for problem: %s"):format(problem_id))
+
 	if not state.test_cases then
 		logger.log("No test case data available. Try scraping the problem first.", vim.log.levels.ERROR)
 		return

From 259ffcaab1699b094a66ee9d9ff8ff73fe6c6665 Mon Sep 17 00:00:00 2001
From: Barrett Ruth <br.barrettruth@gmail.com>
Date: Mon, 15 Sep 2025 08:23:56 -0500
Subject: [PATCH 06/14] feat: use new filetype structure

---
 after/ftplugin/cpin.lua  | 6 ++++++
 after/ftplugin/cpout.lua | 7 +++++++
 ftdetect/cp.lua          | 6 ++++++
 lua/cp/problem.lua       | 4 ++--
 readme.md                | 1 +
 5 files changed, 22 insertions(+), 2 deletions(-)
 create mode 100644 after/ftplugin/cpin.lua
 create mode 100644 after/ftplugin/cpout.lua
 create mode 100644 ftdetect/cp.lua

diff --git a/after/ftplugin/cpin.lua b/after/ftplugin/cpin.lua
new file mode 100644
index 0000000..afa4526
--- /dev/null
+++ b/after/ftplugin/cpin.lua
@@ -0,0 +1,6 @@
+vim.opt_local.number = false
+vim.opt_local.relativenumber = false
+vim.opt_local.statuscolumn = ""
+vim.opt_local.signcolumn = "no"
+vim.opt_local.wrap = true
+vim.opt_local.linebreak = true
\ No newline at end of file
diff --git a/after/ftplugin/cpout.lua b/after/ftplugin/cpout.lua
new file mode 100644
index 0000000..b574d3d
--- /dev/null
+++ b/after/ftplugin/cpout.lua
@@ -0,0 +1,7 @@
+vim.opt_local.number = false
+vim.opt_local.relativenumber = false
+vim.opt_local.statuscolumn = ""
+vim.opt_local.signcolumn = "no"
+vim.opt_local.wrap = true
+vim.opt_local.linebreak = true
+vim.opt_local.modifiable = false
\ No newline at end of file
diff --git a/ftdetect/cp.lua b/ftdetect/cp.lua
new file mode 100644
index 0000000..b503a34
--- /dev/null
+++ b/ftdetect/cp.lua
@@ -0,0 +1,6 @@
+vim.filetype.add({
+	extension = {
+		cpin = "cpin",
+		cpout = "cpout",
+	},
+})
\ No newline at end of file
diff --git a/lua/cp/problem.lua b/lua/cp/problem.lua
index 4aa73d2..60406fd 100644
--- a/lua/cp/problem.lua
+++ b/lua/cp/problem.lua
@@ -27,8 +27,8 @@ function M.create_context(contest, contest_id, problem_id, config)
 		problem_id = problem_id,
 		source_file = source_file,
 		binary_file = ("build/%s.run"):format(base_name),
-		input_file = ("io/%s.in"):format(base_name),
-		output_file = ("io/%s.out"):format(base_name),
+		input_file = ("io/%s.cpin"):format(base_name),
+		output_file = ("io/%s.cpout"):format(base_name),
 		expected_file = ("io/%s.expected"):format(base_name),
 		problem_name = base_name,
 	}
diff --git a/readme.md b/readme.md
index 6b6bf83..8cafc5e 100644
--- a/readme.md
+++ b/readme.md
@@ -67,3 +67,4 @@ follows:
 - better highlighting
 - test case management
 - USACO support
+- new video with functionality, notify discord members

From cf192fad83391d8542f4a7ab2f8846c965059ad9 Mon Sep 17 00:00:00 2001
From: Barrett Ruth <br.barrettruth@gmail.com>
Date: Mon, 15 Sep 2025 09:25:58 -0400
Subject: [PATCH 07/14] fix: newline joining on test cases

---
 lua/cp/scrape.lua | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/lua/cp/scrape.lua b/lua/cp/scrape.lua
index 138dacc..8b99f3b 100644
--- a/lua/cp/scrape.lua
+++ b/lua/cp/scrape.lua
@@ -188,7 +188,7 @@ function M.scrape_problem(ctx)
 		local all_inputs = {}
 		local all_outputs = {}
 
-		for _, test_case in ipairs(data.test_cases) do
+		for i, test_case in ipairs(data.test_cases) do
 			local input_lines = vim.split(test_case.input:gsub("\r", ""):gsub("\n+$", ""), "\n")
 			local output_lines = vim.split(test_case.output:gsub("\r", ""):gsub("\n+$", ""), "\n")
 
@@ -199,6 +199,11 @@ function M.scrape_problem(ctx)
 			for _, line in ipairs(output_lines) do
 				table.insert(all_outputs, line)
 			end
+
+			if i < #data.test_cases then
+				table.insert(all_inputs, "")
+				table.insert(all_outputs, "")
+			end
 		end
 
 		vim.fn.writefile(all_inputs, ctx.input_file)

From e10eab22d6aeff0c6229fc6a3835eed9bd9d8cdc Mon Sep 17 00:00:00 2001
From: Barrett Ruth <br.barrettruth@gmail.com>
Date: Mon, 15 Sep 2025 10:37:40 -0400
Subject: [PATCH 08/14] fix: revert multiple test cases

---
 after/ftplugin/cp-test.lua |  45 ----------
 doc/cp.txt                 |   4 +-
 lua/cp/execute.lua         |  91 -------------------
 lua/cp/init.lua            | 179 +++++++------------------------------
 lua/cp/scrape.lua          |  26 +-----
 plugin/cp.lua              |   2 +-
 scrapers/codeforces.py     |  33 +++----
 7 files changed, 51 insertions(+), 329 deletions(-)
 delete mode 100644 after/ftplugin/cp-test.lua

diff --git a/after/ftplugin/cp-test.lua b/after/ftplugin/cp-test.lua
deleted file mode 100644
index faed7af..0000000
--- a/after/ftplugin/cp-test.lua
+++ /dev/null
@@ -1,45 +0,0 @@
-vim.opt_local.number = false
-vim.opt_local.relativenumber = false
-vim.opt_local.statuscolumn = ""
-vim.opt_local.signcolumn = "no"
-vim.opt_local.wrap = false
-vim.opt_local.linebreak = false
-vim.opt_local.foldmethod = "marker"
-vim.opt_local.foldmarker = "{{{,}}}"
-vim.opt_local.foldlevel = 0
-vim.opt_local.foldtext = ""
-
-local function get_test_id_from_line()
-	local line = vim.api.nvim_get_current_line()
-	local test_id = line:match("%[.%] Test (%d+)")
-	return test_id and tonumber(test_id)
-end
-
-local function toggle_test()
-	local test_id = get_test_id_from_line()
-	if not test_id then
-		return
-	end
-
-	local cp = require("cp")
-	cp.toggle_test(test_id)
-end
-
-local function run_single_test()
-	local test_id = get_test_id_from_line()
-	if not test_id then
-		return
-	end
-
-	local cp = require("cp")
-	cp.run_single_test(test_id)
-end
-
-local function run_all_enabled_tests()
-	local cp = require("cp")
-	cp.run_all_enabled_tests()
-end
-
-vim.keymap.set("n", "t", toggle_test, { buffer = true, desc = "Toggle test enabled/disabled" })
-vim.keymap.set("n", "r", run_single_test, { buffer = true, desc = "Run single test" })
-vim.keymap.set("n", "R", run_all_enabled_tests, { buffer = true, desc = "Run all enabled tests" })
diff --git a/doc/cp.txt b/doc/cp.txt
index 7b848ab..306c70a 100644
--- a/doc/cp.txt
+++ b/doc/cp.txt
@@ -52,8 +52,8 @@ Action Commands ~
 :CP debug                       Compile with debug flags and run current problem.
                                 Includes sanitizers and debug symbols.
 
-:CP test                        Open enhanced test viewer showing individual
-                                test case results with pass/fail status.
+:CP diff                        Enter diff mode to compare actual vs expected
+                                output. Run again to exit diff mode.
 
 Navigation Commands ~
 
diff --git a/lua/cp/execute.lua b/lua/cp/execute.lua
index 186dd8b..233363e 100644
--- a/lua/cp/execute.lua
+++ b/lua/cp/execute.lua
@@ -203,96 +203,5 @@ function M.run_problem(ctx, contest_config, is_debug)
 	end
 end
 
-function M.run_individual_tests(ctx, test_cases, contest_config, is_debug)
-	ensure_directories()
-
-	if not test_cases or #test_cases == 0 then
-		return {}
-	end
-
-	logger.log(("running %d individual tests"):format(#test_cases))
-
-	local language = get_language_from_file(ctx.source_file)
-	local language_config = contest_config[language]
-
-	if not language_config then
-		return {
-			compile_error = "Error: No configuration for language: " .. language,
-			results = {},
-		}
-	end
-
-	local substitutions = {
-		source = ctx.source_file,
-		binary = ctx.binary_file,
-		version = tostring(language_config.version or ""),
-	}
-
-	local compile_cmd = is_debug and language_config.debug or language_config.compile
-	if compile_cmd then
-		local compile_result = compile_generic(language_config, substitutions)
-		if compile_result.code ~= 0 then
-			return {
-				compile_error = compile_result.stderr,
-				results = {},
-			}
-		end
-	end
-
-	local run_cmd = build_command(language_config.run, language_config.executable, substitutions)
-
-	local results = {}
-	for i, test_case in ipairs(test_cases) do
-		local exec_result = execute_command(run_cmd, test_case.input, contest_config.timeout_ms)
-
-		local actual_lines = vim.split(exec_result.stdout, "\n")
-		while #actual_lines > 0 and actual_lines[#actual_lines] == "" do
-			table.remove(actual_lines)
-		end
-
-		local expected_lines = vim.split(test_case.output, "\n")
-		while #expected_lines > 0 and expected_lines[#expected_lines] == "" do
-			table.remove(expected_lines)
-		end
-
-		local matches = #actual_lines == #expected_lines
-		if matches then
-			for j, line in ipairs(actual_lines) do
-				if line ~= expected_lines[j] then
-					matches = false
-					break
-				end
-			end
-		end
-
-		table.insert(results, {
-			id = i,
-			status = exec_result.code == 0 and (matches and "PASS" or "FAIL") or "ERROR",
-			time_ms = exec_result.time_ms,
-			input = test_case.input,
-			expected = test_case.output,
-			actual = exec_result.stdout,
-			exit_code = exec_result.code,
-			timed_out = exec_result.timed_out,
-			enabled = true,
-		})
-	end
-
-	local passed = 0
-	local total_time = 0
-	for _, result in ipairs(results) do
-		if result.status == "PASS" then
-			passed = passed + 1
-		end
-		total_time = total_time + result.time_ms
-	end
-
-	logger.log(("test results: %d/%d passed, total execution time %.1fms"):format(passed, #results, total_time))
-
-	return {
-		compile_error = nil,
-		results = results,
-	}
-end
 
 return M
diff --git a/lua/cp/init.lua b/lua/cp/init.lua
index 8e1e884..149a879 100644
--- a/lua/cp/init.lua
+++ b/lua/cp/init.lua
@@ -32,7 +32,7 @@ local state = {
 }
 
 local platforms = { "atcoder", "codeforces", "cses" }
-local actions = { "run", "debug", "test", "next", "prev" }
+local actions = { "run", "debug", "diff", "next", "prev" }
 
 local function get_current_problem_key()
 	if not state.platform or not state.contest_id then
@@ -232,91 +232,46 @@ local function debug_problem()
 	end)
 end
 
-local function test_problem()
+local function diff_problem()
+	if state.diff_mode then
+		vim.cmd.diffoff()
+		if state.saved_session then
+			vim.fn.delete(state.saved_session)
+			state.saved_session = nil
+		end
+		if state.temp_output then
+			vim.fn.delete(state.temp_output)
+			state.temp_output = nil
+		end
+		state.diff_mode = false
+		return
+	end
+
 	local problem_id = get_current_problem()
 	if not problem_id then
 		return
 	end
 
-	logger.log(("opening test viewer for problem: %s"):format(problem_id))
-
-	if not state.test_cases then
-		logger.log("No test case data available. Try scraping the problem first.", vim.log.levels.ERROR)
-		return
-	end
-
 	local ctx = problem.create_context(state.platform, state.contest_id, state.problem_id, config)
-	local contest_config = config.contests[state.platform]
 
-	local test_results = execute.run_individual_tests(ctx, state.test_cases, contest_config, false)
-
-	if test_results.compile_error then
-		logger.log("Compilation failed: " .. test_results.compile_error, vim.log.levels.ERROR)
+	if vim.fn.filereadable(ctx.expected_file) == 0 then
+		logger.log("no expected output file found", vim.log.levels.WARN)
 		return
 	end
 
-	local buf_name = ("cp-test://%s"):format(problem_id)
-	local existing_buf = vim.fn.bufnr(buf_name)
-	local buf
-
-	if existing_buf ~= -1 then
-		buf = existing_buf
-	else
-		buf = vim.api.nvim_create_buf(false, true)
-		vim.api.nvim_buf_set_name(buf, buf_name)
+	if vim.fn.filereadable(ctx.output_file) == 0 then
+		logger.log("no output file found. run the problem first", vim.log.levels.WARN)
+		return
 	end
 
-	local lines = {}
-	local passed = 0
-	local total = #test_results.results
+	state.saved_session = vim.fn.tempname()
+	vim.cmd(("mksession! %s"):format(state.saved_session))
 
-	local test_states = get_test_states()
-
-	for _, result in ipairs(test_results.results) do
-		local status_icon = result.status == "PASS" and "✓" or "✗"
-		local enabled_icon = test_states[result.id] and "[x]" or "[ ]"
-		local time_str = ("%.1fms"):format(result.time_ms)
-
-		table.insert(
-			lines,
-			("%s Test %d %s %s (%s) {{{"):format(enabled_icon, result.id, status_icon, result.status, time_str)
-		)
-		table.insert(lines, "    Input:")
-		for _, line in ipairs(vim.split(result.input, "\n")) do
-			table.insert(lines, "      " .. line)
-		end
-
-		if result.status == "PASS" then
-			table.insert(lines, "    Output:")
-			for _, line in ipairs(vim.split(result.actual, "\n")) do
-				table.insert(lines, "      " .. line)
-			end
-			passed = passed + 1
-		else
-			table.insert(lines, "    Expected:")
-			for _, line in ipairs(vim.split(result.expected, "\n")) do
-				table.insert(lines, "      " .. line)
-			end
-			table.insert(lines, "    Got:")
-			for _, line in ipairs(vim.split(result.actual, "\n")) do
-				table.insert(lines, "      " .. line)
-			end
-		end
-
-		table.insert(lines, "}}}")
-		table.insert(lines, "")
-	end
-
-	table.insert(lines, ("Summary: %d/%d passed"):format(passed, total))
-
-	vim.api.nvim_buf_set_lines(buf, 0, -1, false, lines)
-	vim.bo[buf].filetype = "cp-test"
-	vim.bo[buf].modifiable = false
-
-	vim.cmd.split()
-	vim.api.nvim_set_current_buf(buf)
-
-	logger.log(("Test results: %d/%d passed"):format(passed, total))
+	vim.cmd("silent only")
+	vim.cmd(("edit %s"):format(ctx.expected_file))
+	vim.cmd.diffthis()
+	vim.cmd(("vertical diffsplit %s"):format(ctx.output_file))
+	state.diff_mode = true
 end
 
 ---@param delta number 1 for next, -1 for prev
@@ -424,8 +379,8 @@ function M.handle_command(opts)
 			run_problem()
 		elseif cmd.action == "debug" then
 			debug_problem()
-		elseif cmd.action == "test" then
-			test_problem()
+		elseif cmd.action == "diff" then
+			diff_problem()
 		elseif cmd.action == "next" then
 			navigate_problem(1)
 		elseif cmd.action == "prev" then
@@ -501,80 +456,6 @@ function M.handle_command(opts)
 	end
 end
 
-function M.toggle_test(test_id)
-	local test_states = get_test_states()
-	test_states[test_id] = not test_states[test_id]
-
-	local problem_key = get_current_problem_key()
-	if problem_key then
-		state.test_states[problem_key] = test_states
-	end
-
-	test_problem()
-end
-
-function M.run_single_test(test_id)
-	if not state.test_cases or not state.test_cases[test_id] then
-		logger.log("Test case not found", vim.log.levels.ERROR)
-		return
-	end
-
-	local ctx = problem.create_context(state.platform, state.contest_id, state.problem_id, config)
-	local contest_config = config.contests[state.platform]
-
-	local single_test = { state.test_cases[test_id] }
-	local test_results = execute.run_individual_tests(ctx, single_test, contest_config, false)
-
-	if test_results.compile_error then
-		logger.log("Compilation failed: " .. test_results.compile_error, vim.log.levels.ERROR)
-		return
-	end
-
-	local result = test_results.results[1]
-	if result then
-		logger.log(("Test %d: %s (%.1fms)"):format(test_id, result.status, result.time_ms))
-	end
-end
-
-function M.run_all_enabled_tests()
-	if not state.test_cases then
-		logger.log("No test cases available", vim.log.levels.ERROR)
-		return
-	end
-
-	local test_states = get_test_states()
-	local enabled_tests = {}
-
-	for i, test_case in ipairs(state.test_cases) do
-		if test_states[i] then
-			table.insert(enabled_tests, test_case)
-		end
-	end
-
-	if #enabled_tests == 0 then
-		logger.log("No tests enabled", vim.log.levels.WARN)
-		return
-	end
-
-	local ctx = problem.create_context(state.platform, state.contest_id, state.problem_id, config)
-	local contest_config = config.contests[state.platform]
-
-	local test_results = execute.run_individual_tests(ctx, enabled_tests, contest_config, false)
-
-	if test_results.compile_error then
-		logger.log("Compilation failed: " .. test_results.compile_error, vim.log.levels.ERROR)
-		return
-	end
-
-	local passed = 0
-	for _, result in ipairs(test_results.results) do
-		if result.status == "PASS" then
-			passed = passed + 1
-		end
-	end
-
-	logger.log(("Enabled tests: %d/%d passed"):format(passed, #enabled_tests))
-end
 
 function M.setup(opts)
 	opts = opts or {}
diff --git a/lua/cp/scrape.lua b/lua/cp/scrape.lua
index 8b99f3b..b1c85ca 100644
--- a/lua/cp/scrape.lua
+++ b/lua/cp/scrape.lua
@@ -185,29 +185,11 @@ function M.scrape_problem(ctx)
 	end
 
 	if data.test_cases and #data.test_cases > 0 then
-		local all_inputs = {}
-		local all_outputs = {}
+		local combined_input = data.test_cases[1].input:gsub("\r", "")
+		local combined_output = data.test_cases[1].output:gsub("\r", "")
 
-		for i, test_case in ipairs(data.test_cases) do
-			local input_lines = vim.split(test_case.input:gsub("\r", ""):gsub("\n+$", ""), "\n")
-			local output_lines = vim.split(test_case.output:gsub("\r", ""):gsub("\n+$", ""), "\n")
-
-			for _, line in ipairs(input_lines) do
-				table.insert(all_inputs, line)
-			end
-
-			for _, line in ipairs(output_lines) do
-				table.insert(all_outputs, line)
-			end
-
-			if i < #data.test_cases then
-				table.insert(all_inputs, "")
-				table.insert(all_outputs, "")
-			end
-		end
-
-		vim.fn.writefile(all_inputs, ctx.input_file)
-		vim.fn.writefile(all_outputs, ctx.expected_file)
+		vim.fn.writefile(vim.split(combined_input, "\n"), ctx.input_file)
+		vim.fn.writefile(vim.split(combined_output, "\n"), ctx.expected_file)
 	end
 
 	return {
diff --git a/plugin/cp.lua b/plugin/cp.lua
index fc57b96..83a2816 100644
--- a/plugin/cp.lua
+++ b/plugin/cp.lua
@@ -4,7 +4,7 @@ end
 vim.g.loaded_cp = 1
 
 local platforms = { "atcoder", "codeforces", "cses" }
-local actions = { "run", "debug", "test", "next", "prev" }
+local actions = { "run", "debug", "diff", "next", "prev" }
 
 vim.api.nvim_create_user_command("CP", function(opts)
 	local cp = require("cp")
diff --git a/scrapers/codeforces.py b/scrapers/codeforces.py
index 6343287..9b885ce 100644
--- a/scrapers/codeforces.py
+++ b/scrapers/codeforces.py
@@ -19,28 +19,23 @@ def scrape(url: str) -> list[tuple[str, str]]:
         input_sections = soup.find_all("div", class_="input")
         output_sections = soup.find_all("div", class_="output")
 
-        for inp_section, out_section in zip(input_sections, output_sections):
+        all_inputs = []
+        all_outputs = []
+
+        for inp_section in input_sections:
             inp_pre = inp_section.find("pre")
+            if inp_pre:
+                all_inputs.append(inp_pre.get_text().strip().replace("\r", ""))
+
+        for out_section in output_sections:
             out_pre = out_section.find("pre")
+            if out_pre:
+                all_outputs.append(out_pre.get_text().strip().replace("\r", ""))
 
-            if inp_pre and out_pre:
-                input_lines: list[str] = []
-                output_lines: list[str] = []
-
-                input_text_raw = inp_pre.get_text().strip().replace("\r", "")
-                input_lines = [
-                    line.strip() for line in input_text_raw.split("\n") if line.strip()
-                ]
-
-                output_text_raw = out_pre.get_text().strip().replace("\r", "")
-                output_lines = [
-                    line.strip() for line in output_text_raw.split("\n") if line.strip()
-                ]
-
-                if input_lines and output_lines:
-                    input_text = "\n".join(input_lines)
-                    output_text = "\n".join(output_lines)
-                    tests.append((input_text, output_text))
+        if all_inputs and all_outputs:
+            combined_input = "\n".join(all_inputs)
+            combined_output = "\n".join(all_outputs)
+            tests.append((combined_input, combined_output))
 
         return tests
 

From beb87e853c732428e2c3c82c3e4664dc97e543c2 Mon Sep 17 00:00:00 2001
From: Barrett Ruth <br.barrettruth@gmail.com>
Date: Mon, 15 Sep 2025 10:39:02 -0400
Subject: [PATCH 09/14] fix

---
 after/ftplugin/cpin.lua  | 2 +-
 after/ftplugin/cpout.lua | 2 +-
 ftdetect/cp.lua          | 2 +-
 lua/cp/execute.lua       | 1 -
 lua/cp/init.lua          | 1 -
 5 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/after/ftplugin/cpin.lua b/after/ftplugin/cpin.lua
index afa4526..76a9f86 100644
--- a/after/ftplugin/cpin.lua
+++ b/after/ftplugin/cpin.lua
@@ -3,4 +3,4 @@ vim.opt_local.relativenumber = false
 vim.opt_local.statuscolumn = ""
 vim.opt_local.signcolumn = "no"
 vim.opt_local.wrap = true
-vim.opt_local.linebreak = true
\ No newline at end of file
+vim.opt_local.linebreak = true
diff --git a/after/ftplugin/cpout.lua b/after/ftplugin/cpout.lua
index b574d3d..3f0bcdc 100644
--- a/after/ftplugin/cpout.lua
+++ b/after/ftplugin/cpout.lua
@@ -4,4 +4,4 @@ vim.opt_local.statuscolumn = ""
 vim.opt_local.signcolumn = "no"
 vim.opt_local.wrap = true
 vim.opt_local.linebreak = true
-vim.opt_local.modifiable = false
\ No newline at end of file
+vim.opt_local.modifiable = false
diff --git a/ftdetect/cp.lua b/ftdetect/cp.lua
index b503a34..2b6b593 100644
--- a/ftdetect/cp.lua
+++ b/ftdetect/cp.lua
@@ -3,4 +3,4 @@ vim.filetype.add({
 		cpin = "cpin",
 		cpout = "cpout",
 	},
-})
\ No newline at end of file
+})
diff --git a/lua/cp/execute.lua b/lua/cp/execute.lua
index 233363e..00e9332 100644
--- a/lua/cp/execute.lua
+++ b/lua/cp/execute.lua
@@ -203,5 +203,4 @@ function M.run_problem(ctx, contest_config, is_debug)
 	end
 end
 
-
 return M
diff --git a/lua/cp/init.lua b/lua/cp/init.lua
index 149a879..72b8bb7 100644
--- a/lua/cp/init.lua
+++ b/lua/cp/init.lua
@@ -456,7 +456,6 @@ function M.handle_command(opts)
 	end
 end
 
-
 function M.setup(opts)
 	opts = opts or {}
 	user_config = opts

From 5db19acc53954a5aeac0b1fe7030ed47422a0666 Mon Sep 17 00:00:00 2001
From: Barrett Ruth <br.barrettruth@gmail.com>
Date: Mon, 15 Sep 2025 10:52:28 -0400
Subject: [PATCH 10/14] fix scraper

---
 lua/cp/scrape.lua      | 12 ++++++------
 scrapers/codeforces.py | 31 ++++++++++++++++++++++---------
 2 files changed, 28 insertions(+), 15 deletions(-)

diff --git a/lua/cp/scrape.lua b/lua/cp/scrape.lua
index b1c85ca..8e5c387 100644
--- a/lua/cp/scrape.lua
+++ b/lua/cp/scrape.lua
@@ -74,9 +74,9 @@ function M.scrape_contest_metadata(platform, contest_id)
 
 	local args
 	if platform == "cses" then
-		args = { "uv", "run", scraper_path, "metadata" }
+		args = { "uv", "run", "--directory", plugin_path, scraper_path, "metadata" }
 	else
-		args = { "uv", "run", scraper_path, "metadata", contest_id }
+		args = { "uv", "run", "--directory", plugin_path, scraper_path, "metadata", contest_id }
 	end
 
 	local result = vim.system(args, {
@@ -152,9 +152,9 @@ function M.scrape_problem(ctx)
 
 	local args
 	if ctx.contest == "cses" then
-		args = { "uv", "run", scraper_path, "tests", ctx.contest_id }
+		args = { "uv", "run", "--directory", plugin_path, scraper_path, "tests", ctx.contest_id }
 	else
-		args = { "uv", "run", scraper_path, "tests", ctx.contest_id, ctx.problem_id }
+		args = { "uv", "run", "--directory", plugin_path, scraper_path, "tests", ctx.contest_id, ctx.problem_id }
 	end
 
 	local result = vim.system(args, {
@@ -188,8 +188,8 @@ function M.scrape_problem(ctx)
 		local combined_input = data.test_cases[1].input:gsub("\r", "")
 		local combined_output = data.test_cases[1].output:gsub("\r", "")
 
-		vim.fn.writefile(vim.split(combined_input, "\n"), ctx.input_file)
-		vim.fn.writefile(vim.split(combined_output, "\n"), ctx.expected_file)
+		vim.fn.writefile(vim.split(combined_input, "\n", true), ctx.input_file)
+		vim.fn.writefile(vim.split(combined_output, "\n", true), ctx.expected_file)
 	end
 
 	return {
diff --git a/scrapers/codeforces.py b/scrapers/codeforces.py
index 9b885ce..cf98f07 100644
--- a/scrapers/codeforces.py
+++ b/scrapers/codeforces.py
@@ -25,12 +25,24 @@ def scrape(url: str) -> list[tuple[str, str]]:
         for inp_section in input_sections:
             inp_pre = inp_section.find("pre")
             if inp_pre:
-                all_inputs.append(inp_pre.get_text().strip().replace("\r", ""))
+                divs = inp_pre.find_all("div")
+                if divs:
+                    lines = [div.get_text().strip() for div in divs]
+                    text = "\n".join(lines)
+                else:
+                    text = inp_pre.get_text().replace("\r", "")
+                all_inputs.append(text)
 
         for out_section in output_sections:
             out_pre = out_section.find("pre")
             if out_pre:
-                all_outputs.append(out_pre.get_text().strip().replace("\r", ""))
+                divs = out_pre.find_all("div")
+                if divs:
+                    lines = [div.get_text().strip() for div in divs]
+                    text = "\n".join(lines)
+                else:
+                    text = out_pre.get_text().replace("\r", "")
+                all_outputs.append(text)
 
         if all_inputs and all_outputs:
             combined_input = "\n".join(all_inputs)
@@ -103,11 +115,12 @@ def main() -> None:
         print(json.dumps(result))
         sys.exit(1)
 
+
     mode: str = sys.argv[1]
 
     if mode == "metadata":
         if len(sys.argv) != 3:
-            result = {
+            result: dict[str, str | bool] = {
                 "success": False,
                 "error": "Usage: codeforces.py metadata <contest_id>",
             }
@@ -118,14 +131,14 @@ def main() -> None:
         problems: list[dict[str, str]] = scrape_contest_problems(contest_id)
 
         if not problems:
-            result = {
+            result: dict[str, str | bool] = {
                 "success": False,
                 "error": f"No problems found for contest {contest_id}",
             }
             print(json.dumps(result))
             sys.exit(1)
 
-        result = {
+        result: dict[str, str | bool | list] = {
             "success": True,
             "contest_id": contest_id,
             "problems": problems,
@@ -134,7 +147,7 @@ def main() -> None:
 
     elif mode == "tests":
         if len(sys.argv) != 4:
-            result = {
+            result: dict[str, str | bool] = {
                 "success": False,
                 "error": "Usage: codeforces.py tests <contest_id> <problem_letter>",
             }
@@ -149,7 +162,7 @@ def main() -> None:
         tests: list[tuple[str, str]] = scrape_sample_tests(url)
 
         if not tests:
-            result = {
+            result: dict[str, str | bool] = {
                 "success": False,
                 "error": f"No tests found for {contest_id} {problem_letter}",
                 "problem_id": problem_id,
@@ -162,7 +175,7 @@ def main() -> None:
         for input_data, output_data in tests:
             test_cases.append({"input": input_data, "output": output_data})
 
-        result = {
+        result: dict[str, str | bool | list] = {
             "success": True,
             "problem_id": problem_id,
             "url": url,
@@ -171,7 +184,7 @@ def main() -> None:
         print(json.dumps(result))
 
     else:
-        result = {
+        result: dict[str, str | bool] = {
             "success": False,
             "error": f"Unknown mode: {mode}. Use 'metadata' or 'tests'",
         }

From 64d6576bcfa76fdfc912c03dfc60bca100e7edf4 Mon Sep 17 00:00:00 2001
From: Barrett Ruth <br.barrettruth@gmail.com>
Date: Mon, 15 Sep 2025 10:53:00 -0400
Subject: [PATCH 11/14] fix(ci): format

---
 scrapers/codeforces.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/scrapers/codeforces.py b/scrapers/codeforces.py
index cf98f07..4610ae9 100644
--- a/scrapers/codeforces.py
+++ b/scrapers/codeforces.py
@@ -115,7 +115,6 @@ def main() -> None:
         print(json.dumps(result))
         sys.exit(1)
 
-
     mode: str = sys.argv[1]
 
     if mode == "metadata":

From 8b0c6994d83a7f2e00a91c25ee166c841ff16617 Mon Sep 17 00:00:00 2001
From: Barrett Ruth <br.barrettruth@gmail.com>
Date: Mon, 15 Sep 2025 10:53:35 -0400
Subject: [PATCH 12/14] fix(ci): unused vars

---
 lua/cp/init.lua | 18 ------------------
 1 file changed, 18 deletions(-)

diff --git a/lua/cp/init.lua b/lua/cp/init.lua
index 72b8bb7..27de29e 100644
--- a/lua/cp/init.lua
+++ b/lua/cp/init.lua
@@ -45,24 +45,6 @@ local function get_current_problem_key()
 	end
 end
 
-local function get_test_states()
-	local problem_key = get_current_problem_key()
-	if not problem_key then
-		return {}
-	end
-
-	if not state.test_states[problem_key] then
-		state.test_states[problem_key] = {}
-		if state.test_cases then
-			for i = 1, #state.test_cases do
-				state.test_states[problem_key][i] = true
-			end
-		end
-	end
-
-	return state.test_states[problem_key]
-end
-
 local function set_platform(platform)
 	if not vim.tbl_contains(platforms, platform) then
 		logger.log(("unknown platform. Available: [%s]"):format(table.concat(platforms, ", ")), vim.log.levels.ERROR)

From 73c5158e29dd1200cd14dc19855e5130ec9bdf31 Mon Sep 17 00:00:00 2001
From: Barrett Ruth <br.barrettruth@gmail.com>
Date: Mon, 15 Sep 2025 10:57:39 -0400
Subject: [PATCH 13/14] fix(ci): selene typing

---
 lua/cp/scrape.lua | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lua/cp/scrape.lua b/lua/cp/scrape.lua
index 8e5c387..bde861a 100644
--- a/lua/cp/scrape.lua
+++ b/lua/cp/scrape.lua
@@ -119,7 +119,7 @@ function M.scrape_contest_metadata(platform, contest_id)
 end
 
 ---@param ctx ProblemContext
----@return {success: boolean, problem_id: string, test_count?: number, url?: string, error?: string}
+---@return {success: boolean, problem_id: string, test_count?: number, test_cases?: table[], url?: string, error?: string}
 function M.scrape_problem(ctx)
 	ensure_io_directory()
 

From 1c000942ed3d9cec07201b9d544bffac3c7aef11 Mon Sep 17 00:00:00 2001
From: Barrett Ruth <br.barrettruth@gmail.com>
Date: Mon, 15 Sep 2025 10:58:35 -0400
Subject: [PATCH 14/14] remove unused functions

---
 lua/cp/init.lua | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/lua/cp/init.lua b/lua/cp/init.lua
index 27de29e..01a046a 100644
--- a/lua/cp/init.lua
+++ b/lua/cp/init.lua
@@ -34,17 +34,6 @@ local state = {
 local platforms = { "atcoder", "codeforces", "cses" }
 local actions = { "run", "debug", "diff", "next", "prev" }
 
-local function get_current_problem_key()
-	if not state.platform or not state.contest_id then
-		return nil
-	end
-	if state.platform == "cses" then
-		return state.contest_id
-	else
-		return state.contest_id .. "_" .. (state.problem_id or "")
-	end
-end
-
 local function set_platform(platform)
 	if not vim.tbl_contains(platforms, platform) then
 		logger.log(("unknown platform. Available: [%s]"):format(table.concat(platforms, ", ")), vim.log.levels.ERROR)