diff --git a/.github/workflows/quality.yml b/.github/workflows/quality.yml
index c100808..a608648 100644
--- a/.github/workflows/quality.yml
+++ b/.github/workflows/quality.yml
@@ -12,6 +12,7 @@ jobs:
     outputs:
       lua: ${{ steps.changes.outputs.lua }}
       python: ${{ steps.changes.outputs.python }}
+      markdown: ${{ steps.changes.outputs.markdown }}
     steps:
       - uses: actions/checkout@v4
       - uses: dorny/paths-filter@v3
@@ -33,6 +34,9 @@ jobs:
               - 'tests/scrapers/**'
               - 'pyproject.toml'
               - 'uv.lock'
+            markdown:
+              - '*.md'
+              - 'docs/**/*.md'
 
   lua-format:
     name: Lua Format Check
@@ -115,3 +119,23 @@ jobs:
         run: uv sync --dev
       - name: Type check Python files with mypy
         run: uv run mypy scrapers/ tests/scrapers/
+
+  markdown-format:
+    name: Markdown Format Check
+    runs-on: ubuntu-latest
+    needs: changes
+    if: ${{ needs.changes.outputs.markdown == 'true' }}
+    steps:
+      - uses: actions/checkout@v4
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          version: 8
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+      - name: Install prettier
+        run: pnpm add -g prettier@3.1.0
+      - name: Check markdown formatting with prettier
+        run: prettier --check "*.md" "docs/**/*.md" || true
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 4acb307..51a81f3 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -5,7 +5,7 @@ repos:
     hooks:
       - id: stylua-github
         name: stylua (Lua formatter)
-        args: ["--check", "."]
+        args: ["."]
         files: ^(lua/|spec/|plugin/|after/|ftdetect/|.*\.lua$)
         additional_dependencies: []
   - repo: https://github.com/astral-sh/ruff-pre-commit
@@ -16,7 +16,7 @@ repos:
         files: ^(scrapers/|tests/scrapers/|.*\.py$)
       - id: ruff
         name: ruff (lint)
-        args: ["--no-fix"]
+        args: ["--fix", "--select=I"]
         files: ^(scrapers/|tests/scrapers/|.*\.py$)
   - repo: local
     hooks:
@@ -27,3 +27,9 @@ repos:
         args: ["scrapers/", "tests/scrapers/"]
         files: ^(scrapers/|tests/scrapers/|.*\.py$)
         pass_filenames: false
+  - repo: https://github.com/pre-commit/mirrors-prettier
+    rev: v3.1.0
+    hooks:
+      - id: prettier
+        name: prettier (format markdown)
+        files: \.(md)$
diff --git a/README.md b/README.md
index 87deda1..2e9ee89 100644
--- a/README.md
+++ b/README.md
@@ -1,27 +1,54 @@
 # cp.nvim
 
-neovim plugin for competitive programming.
+**Fast, minimal competitive programming environment for Neovim**
+
+Scrape problems, run tests, and debug solutions across multiple platforms with zero configuration.
+
+> **Disclaimer**: cp.nvim webs crapes data from competitive programming platforms - use at your own risk.
 
 https://github.com/user-attachments/assets/cb142535-fba0-4280-8f11-66ad1ca50ca9
 
-[video config](https://github.com/barrett-ruth/dots/blob/main/nvim/lua/plugins/cp.lua)
-
-> Sample test data from [codeforces](https://codeforces.com) is scraped via [cloudscraper](https://github.com/VeNoMouS/cloudscraper). Use at your own risk.
-
 ## Features
 
-- Support for multiple online judges ([AtCoder](https://atcoder.jp/), [Codeforces](https://codeforces.com/), [CSES](https://cses.fi))
-- Language-agnostic features
-- Automatic problem scraping and test case management
-- Integrated running and debugging
-- Enhanced test viewer
-- Templates via LuaSnip
+- **Multi-platform support**: AtCoder, Codeforces, CSES with consistent interface
+- **Automatic problem setup**: Scrape test cases and metadata in seconds
+- **Rich test output**: ANSI color support for compiler errors and program output
+- **Language agnostic**: Works with any compiled language
+- **Template integration**: Contest-specific snippets via LuaSnip
+- **Diff viewer**: Compare expected vs actual output with precision
 
-## Requirements
+## Optional Dependencies
 
-- Neovim 0.10.0+
-- [uv](https://docs.astral.sh/uv/): problem scraping (optional)
-- [LuaSnip](https://github.com/L3MON4D3/LuaSnip): contest-specific snippets (optional)
+- [uv](https://docs.astral.sh/uv/) for problem scraping
+- [LuaSnip](https://github.com/L3MON4D3/LuaSnip) for templates
+
+## Quick Start
+
+cp.nvim follows a simple principle: **solve locally, submit remotely**.
+
+### Basic Usage
+
+1. **Find a problem** on the judge website
+2. **Set up locally** with `:CP <platform> <contest> <problem>`
+
+   ```
+   :CP codeforces 1848 A
+   ```
+
+3. **Code and test** with instant feedback and rich diffs
+
+   ```
+   :CP run
+   ```
+
+4. **Navigate between problems**
+
+   ```
+   :CP next
+   :CP prev
+   ```
+
+5. **Submit** on the original website
 
 ## Documentation
 
@@ -29,37 +56,13 @@ https://github.com/user-attachments/assets/cb142535-fba0-4280-8f11-66ad1ca50ca9
 :help cp.nvim
 ```
 
-## Philosophy
-
-This plugin is highly tuned to my workflow and may not fit for you. Personally,
-I believe there are two aspects of a cp workflow:
-
-- local work (i.e. coding, running test cases)
-- site work (i.e. problem reading, submitting)
-
-Namely, I do not like the idea of submitting problems locally - the experience
-will never quite offer what the remote does. Therefore, cp.nvim works as
-follows:
-
-1. Find a problem
-
-- Browse the remote and find it
-- Read it on the remote
-
-2. Set up your local environment with `:CP ...`
-
-- test cases and expected output automatically scraped
-- templates automatically configured
-
-3. Solve the problem locally
-
-- easy to run/debug
-- easy to diff actual vs. expected output
-
-4. Submit the problem (on the remote!)
-
+See [my config](https://github.com/barrett-ruth/dots/blob/main/nvim/lua/plugins/cp.lua) for a relatively advanced setup.
 
 ## Similar Projects
 
 - [competitest.nvim](https://github.com/xeluxee/competitest.nvim)
 - [assistant.nvim](https://github.com/A7Lavinraj/assistant.nvim)
+
+## TODO
+
+- Windows support
diff --git a/doc/cp.txt b/doc/cp.txt
index e2111b1..37b2de9 100644
--- a/doc/cp.txt
+++ b/doc/cp.txt
@@ -16,10 +16,10 @@ Supported languages: C++, Python
 REQUIREMENTS                                                *cp-requirements*
 
 - Neovim 0.10.0+
-- uv package manager (https://docs.astral.sh/uv/)
-- Language runtime/compiler (g++, python3)
+- Unix-like operating system
 
 Optional:
+- uv package manager (https://docs.astral.sh/uv/)
 - LuaSnip for template expansion (https://github.com/L3MON4D3/LuaSnip)
 
 ==============================================================================
@@ -380,7 +380,7 @@ Example: Setting up and solving AtCoder contest ABC324
 
 7. Continue solving problems with :CP next/:CP prev navigation
 
-8. Switch to another file (e.g., previous contest): >
+8. Switch to another file (e.g. previous contest): >
     :e ~/contests/abc323/a.cpp
     :CP
 <   Automatically restores abc323 contest context
@@ -421,9 +421,9 @@ The run panel uses the following table layout: >
     └─────┴────────┴──────────────┴───────────┴──────────┴─────────────┘
     ┌──────────────────────────────────────────────────────────────────┐
     │Expected vs Actual                                                │
-    │4[-2-]{+3+}                                                       │
+    │423                                                               │
     │100                                                               │
-    │hello w[-o-]r{+o+}ld                                              │
+    │hello world                                                       │
     └──────────────────────────────────────────────────────────────────┘
 
 Status Indicators ~
@@ -434,10 +434,20 @@ Test cases use competitive programming terminology with color highlighting:
     WA      Wrong Answer (output mismatch) - Red
     TLE     Time Limit Exceeded (timeout) - Orange
     RTE     Runtime Error (non-zero exit) - Purple
+<
 
-Highlight Groups ~
-                                                            *cp-highlights*
-cp.nvim defines the following highlight groups for status indicators:
+==============================================================================
+ANSI COLORS AND HIGHLIGHTING                               *cp-ansi*
+
+cp.nvim provides comprehensive ANSI color support and highlighting for
+compiler output, program stderr, and diff visualization.
+
+==============================================================================
+HIGHLIGHT GROUPS                                           *cp-highlights*
+
+Test Status Groups ~
+
+Test cases use competitive programming terminology with color highlighting:
 
     CpTestAC        Green foreground for AC status
     CpTestWA        Red foreground for WA status
@@ -445,14 +455,93 @@ cp.nvim defines the following highlight groups for status indicators:
     CpTestRTE       Purple foreground for RTE status
     CpTestPending   Gray foreground for pending tests
 
-You can customize these colors by linking to other highlight groups in your
-colorscheme or by redefining them: >lua
-    vim.api.nvim_set_hl(0, 'CpTestAC', { link = 'DiffAdd' })
-    vim.api.nvim_set_hl(0, 'CpTestWA', { fg = '#ff0000' })
+ANSI Color Groups ~
+
+cp.nvim preserves ANSI colors from compiler output and program stderr using
+a sophisticated parsing system. Colors are automatically mapped to your
+terminal colorscheme via vim.g.terminal_color_* variables.
+
+Basic formatting groups:
+    CpAnsiBold              Bold text formatting
+    CpAnsiItalic            Italic text formatting
+    CpAnsiBoldItalic        Combined bold and italic formatting
+
+Standard terminal colors (each supports Bold, Italic, BoldItalic variants):
+    CpAnsiRed               Standard red (terminal_color_1)
+    CpAnsiGreen             Standard green (terminal_color_2)
+    CpAnsiYellow            Standard yellow (terminal_color_3)
+    CpAnsiBlue              Standard blue (terminal_color_4)
+    CpAnsiMagenta           Standard magenta (terminal_color_5)
+    CpAnsiCyan              Standard cyan (terminal_color_6)
+    CpAnsiWhite             Standard white (terminal_color_7)
+    CpAnsiBlack             Standard black (terminal_color_0)
+
+Bright color variants:
+    CpAnsiBrightRed         Bright red (terminal_color_9)
+    CpAnsiBrightGreen       Bright green (terminal_color_10)
+    CpAnsiBrightYellow      Bright yellow (terminal_color_11)
+    CpAnsiBrightBlue        Bright blue (terminal_color_12)
+    CpAnsiBrightMagenta     Bright magenta (terminal_color_13)
+    CpAnsiBrightCyan        Bright cyan (terminal_color_14)
+    CpAnsiBrightWhite       Bright white (terminal_color_15)
+    CpAnsiBrightBlack       Bright black (terminal_color_8)
+
+Example combinations:
+    CpAnsiBoldRed           Bold red combination
+    CpAnsiItalicGreen       Italic green combination
+    CpAnsiBoldItalicYellow  Bold italic yellow combination
+
+Diff Highlighting ~
+
+Diff visualization uses Neovim's built-in highlight groups that automatically
+adapt to your colorscheme:
+
+    DiffAdd                 Highlights added text in git diffs
+    DiffDelete              Highlights removed text in git diffs
+
+These groups are automatically used by the git diff backend for character-level
+difference visualization with optimal colorscheme integration.
+
+==============================================================================
+TERMINAL COLOR INTEGRATION                                 *cp-terminal-colors*
+
+ANSI colors automatically use your terminal's color palette through Neovim's
+vim.g.terminal_color_* variables. This ensures compiler colors match your
+colorscheme without manual configuration.
+
+If your colorscheme doesn't set terminal colors, cp.nvim falls back to
+sensible defaults. You can override terminal colors in your configuration: >vim
+    let g:terminal_color_1 = '#ff6b6b'    " Custom red
+    let g:terminal_color_2 = '#51cf66'    " Custom green
 <
 
-Keymaps ~
-                                                            *cp-test-keys*
+==============================================================================
+HIGHLIGHT CUSTOMIZATION                                    *cp-highlight-custom*
+
+You can customize any highlight group by linking to existing groups or
+defining custom colors: >lua
+
+    -- Customize the color of "TLE" text in run panel:
+    vim.api.nvim_set_hl(0, 'CpTestTLE', { fg = '#ffa500', bold = true })
+
+    -- ... or the ANSI colors used to display stderr
+    vim.api.nvim_set_hl(0, 'CpAnsiRed', {
+        fg = vim.g.terminal_color_1 or '#ef4444'
+    })
+<
+
+Place customizations in your init.lua or after the colorscheme loads to
+prevent them from being overridden: >lua
+    vim.api.nvim_create_autocmd('ColorScheme', {
+        callback = function()
+            -- Your cp.nvim highlight customizations here
+            vim.api.nvim_set_hl(0, 'CpTestAC', { link = 'String' })
+        end
+    })
+<
+
+==============================================================================
+RUN PANEL KEYMAPS                                          *cp-test-keys*
 <c-n>                           Navigate to next test case (configurable via
                                 run_panel.next_test_key)
 <c-p>                           Navigate to previous test case (configurable via
@@ -507,10 +596,6 @@ Cache Location ~
 Cache is stored at: >
     vim.fn.stdpath('data') .. '/cp-nvim.json'
 <
-Typically resolves to:
-• Linux/macOS: `~/.local/share/nvim/cp-nvim.json`
-• Windows: `%LOCALAPPDATA%\nvim-data\cp-nvim.json`
-
 Cache Structure ~
                                                          *cp-cache-structure*
 The cache contains four main sections:
diff --git a/lua/cp/ansi.lua b/lua/cp/ansi.lua
new file mode 100644
index 0000000..d8116f0
--- /dev/null
+++ b/lua/cp/ansi.lua
@@ -0,0 +1,227 @@
+---@class AnsiParseResult
+---@field lines string[]
+---@field highlights table[]
+
+local M = {}
+
+---@param raw_output string|table
+---@return string
+function M.bytes_to_string(raw_output)
+  if type(raw_output) == 'string' then
+    return raw_output
+  end
+  return table.concat(vim.tbl_map(string.char, raw_output))
+end
+
+---@param text string
+---@return AnsiParseResult
+function M.parse_ansi_text(text)
+  local clean_text = text:gsub('\027%[[%d;]*[a-zA-Z]', '')
+  local lines = vim.split(clean_text, '\n', { plain = true, trimempty = false })
+
+  local highlights = {}
+  local line_num = 0
+  local col_pos = 0
+
+  local ansi_state = {
+    bold = false,
+    italic = false,
+    foreground = nil,
+  }
+
+  local function get_highlight_group()
+    if not ansi_state.bold and not ansi_state.italic and not ansi_state.foreground then
+      return nil
+    end
+
+    local parts = { 'CpAnsi' }
+    if ansi_state.bold then
+      table.insert(parts, 'Bold')
+    end
+    if ansi_state.italic then
+      table.insert(parts, 'Italic')
+    end
+    if ansi_state.foreground then
+      table.insert(parts, ansi_state.foreground)
+    end
+
+    return table.concat(parts)
+  end
+
+  local function apply_highlight(start_line, start_col, end_col)
+    local hl_group = get_highlight_group()
+    if hl_group then
+      table.insert(highlights, {
+        line = start_line,
+        col_start = start_col,
+        col_end = end_col,
+        highlight_group = hl_group,
+      })
+    end
+  end
+
+  local i = 1
+  while i <= #text do
+    local ansi_start, ansi_end, code, cmd = text:find('\027%[([%d;]*)([a-zA-Z])', i)
+
+    if ansi_start then
+      if ansi_start > i then
+        local segment = text:sub(i, ansi_start - 1)
+        local start_line = line_num
+        local start_col = col_pos
+
+        for char in segment:gmatch('.') do
+          if char == '\n' then
+            if col_pos > start_col then
+              apply_highlight(start_line, start_col, col_pos)
+            end
+            line_num = line_num + 1
+            start_line = line_num
+            col_pos = 0
+            start_col = 0
+          else
+            col_pos = col_pos + 1
+          end
+        end
+
+        if col_pos > start_col then
+          apply_highlight(start_line, start_col, col_pos)
+        end
+      end
+
+      if cmd == 'm' then
+        M.update_ansi_state(ansi_state, code)
+      end
+      i = ansi_end + 1
+    else
+      local segment = text:sub(i)
+      if segment ~= '' then
+        local start_line = line_num
+        local start_col = col_pos
+
+        for char in segment:gmatch('.') do
+          if char == '\n' then
+            if col_pos > start_col then
+              apply_highlight(start_line, start_col, col_pos)
+            end
+            line_num = line_num + 1
+            start_line = line_num
+            col_pos = 0
+            start_col = 0
+          else
+            col_pos = col_pos + 1
+          end
+        end
+
+        if col_pos > start_col then
+          apply_highlight(start_line, start_col, col_pos)
+        end
+      end
+      break
+    end
+  end
+
+  return {
+    lines = lines,
+    highlights = highlights,
+  }
+end
+
+---@param ansi_state table
+---@param code_string string
+function M.update_ansi_state(ansi_state, code_string)
+  if code_string == '' or code_string == '0' then
+    ansi_state.bold = false
+    ansi_state.italic = false
+    ansi_state.foreground = nil
+    return
+  end
+
+  local codes = vim.split(code_string, ';', { plain = true })
+
+  for _, code in ipairs(codes) do
+    local num = tonumber(code)
+    if num then
+      if num == 1 then
+        ansi_state.bold = true
+      elseif num == 3 then
+        ansi_state.italic = true
+      elseif num == 22 then
+        ansi_state.bold = false
+      elseif num == 23 then
+        ansi_state.italic = false
+      elseif num >= 30 and num <= 37 then
+        local colors = { 'Black', 'Red', 'Green', 'Yellow', 'Blue', 'Magenta', 'Cyan', 'White' }
+        ansi_state.foreground = colors[num - 29]
+      elseif num >= 90 and num <= 97 then
+        local colors = {
+          'BrightBlack',
+          'BrightRed',
+          'BrightGreen',
+          'BrightYellow',
+          'BrightBlue',
+          'BrightMagenta',
+          'BrightCyan',
+          'BrightWhite',
+        }
+        ansi_state.foreground = colors[num - 89]
+      elseif num == 39 then
+        ansi_state.foreground = nil
+      end
+    end
+  end
+end
+
+function M.setup_highlight_groups()
+  local color_map = {
+    Black = vim.g.terminal_color_0,
+    Red = vim.g.terminal_color_1,
+    Green = vim.g.terminal_color_2,
+    Yellow = vim.g.terminal_color_3,
+    Blue = vim.g.terminal_color_4,
+    Magenta = vim.g.terminal_color_5,
+    Cyan = vim.g.terminal_color_6,
+    White = vim.g.terminal_color_7,
+    BrightBlack = vim.g.terminal_color_8,
+    BrightRed = vim.g.terminal_color_9,
+    BrightGreen = vim.g.terminal_color_10,
+    BrightYellow = vim.g.terminal_color_11,
+    BrightBlue = vim.g.terminal_color_12,
+    BrightMagenta = vim.g.terminal_color_13,
+    BrightCyan = vim.g.terminal_color_14,
+    BrightWhite = vim.g.terminal_color_15,
+  }
+
+  local combinations = {
+    { bold = false, italic = false },
+    { bold = true, italic = false },
+    { bold = false, italic = true },
+    { bold = true, italic = true },
+  }
+
+  for _, combo in ipairs(combinations) do
+    for color_name, terminal_color in pairs(color_map) do
+      local parts = { 'CpAnsi' }
+      local opts = { fg = terminal_color }
+
+      if combo.bold then
+        table.insert(parts, 'Bold')
+        opts.bold = true
+      end
+      if combo.italic then
+        table.insert(parts, 'Italic')
+        opts.italic = true
+      end
+      table.insert(parts, color_name)
+
+      local hl_name = table.concat(parts)
+      vim.api.nvim_set_hl(0, hl_name, opts)
+    end
+  end
+
+  vim.api.nvim_set_hl(0, 'CpAnsiBold', { bold = true })
+  vim.api.nvim_set_hl(0, 'CpAnsiItalic', { italic = true })
+  vim.api.nvim_set_hl(0, 'CpAnsiBoldItalic', { bold = true, italic = true })
+end
+
+return M
diff --git a/lua/cp/diff.lua b/lua/cp/diff.lua
index 2784b4b..e576b8c 100644
--- a/lua/cp/diff.lua
+++ b/lua/cp/diff.lua
@@ -58,10 +58,95 @@ local git_backend = {
         highlights = {},
       }
     else
+      -- Parse git diff output to extract content and highlights
+      local diff_content = result.stdout or ''
+      local lines = {}
+      local highlights = {}
+      local line_num = 0
+
+      -- Extract content lines that start with space, +, or -
+      for line in diff_content:gmatch('[^\n]*') do
+        if
+          line:match('^[%s%+%-]')
+          or (not line:match('^[@%-+]') and not line:match('^index') and not line:match('^diff'))
+        then
+          -- This is content, not metadata
+          local clean_line = line
+          if line:match('^[%+%-]') then
+            clean_line = line:sub(2) -- Remove +/- prefix
+          end
+
+          -- Parse diff markers in the line
+          local col_pos = 0
+          local processed_line = ''
+          local i = 1
+
+          while i <= #clean_line do
+            local removed_start, removed_end = clean_line:find('%[%-[^%-]*%-]', i)
+            local added_start, added_end = clean_line:find('{%+[^%+]*%+}', i)
+
+            local next_marker_start = nil
+            local marker_type = nil
+
+            if removed_start and (not added_start or removed_start < added_start) then
+              next_marker_start = removed_start
+              marker_type = 'removed'
+            elseif added_start then
+              next_marker_start = added_start
+              marker_type = 'added'
+            end
+
+            if next_marker_start then
+              -- Add text before marker
+              if next_marker_start > i then
+                local before_text = clean_line:sub(i, next_marker_start - 1)
+                processed_line = processed_line .. before_text
+                col_pos = col_pos + #before_text
+              end
+
+              -- Extract and add marker content with highlighting
+              local marker_end = (marker_type == 'removed') and removed_end or added_end
+              local marker_text = clean_line:sub(next_marker_start, marker_end)
+              local content_text
+
+              if marker_type == 'removed' then
+                content_text = marker_text:sub(3, -3) -- Remove [- and -]
+                table.insert(highlights, {
+                  line = line_num,
+                  col_start = col_pos,
+                  col_end = col_pos + #content_text,
+                  highlight_group = 'DiffDelete',
+                })
+              else -- added
+                content_text = marker_text:sub(3, -3) -- Remove {+ and +}
+                table.insert(highlights, {
+                  line = line_num,
+                  col_start = col_pos,
+                  col_end = col_pos + #content_text,
+                  highlight_group = 'DiffAdd',
+                })
+              end
+
+              processed_line = processed_line .. content_text
+              col_pos = col_pos + #content_text
+              i = marker_end + 1
+            else
+              -- No more markers, add rest of line
+              local rest = clean_line:sub(i)
+              processed_line = processed_line .. rest
+              break
+            end
+          end
+
+          table.insert(lines, processed_line)
+          line_num = line_num + 1
+        end
+      end
+
       return {
-        content = {},
-        highlights = {},
-        raw_diff = result.stdout or '',
+        content = lines,
+        highlights = highlights,
+        raw_diff = diff_content,
       }
     end
   end,
diff --git a/lua/cp/execute.lua b/lua/cp/execute.lua
index d336ad8..a56bc62 100644
--- a/lua/cp/execute.lua
+++ b/lua/cp/execute.lua
@@ -22,7 +22,6 @@ local function get_language_from_file(source_file, contest_config)
 
   local extension = vim.fn.fnamemodify(source_file, ':e')
   local language = filetype_to_language[extension] or contest_config.default_language
-  logger.log(('detected language: %s (extension: %s)'):format(language, extension))
   return language
 end
 
@@ -70,7 +69,7 @@ end
 
 ---@param language_config table
 ---@param substitutions table<string, string>
----@return {code: integer, stderr: string}
+---@return {code: integer, stdout: string, stderr: string}
 function M.compile_generic(language_config, substitutions)
   vim.validate({
     language_config = { language_config, 'table' },
@@ -83,19 +82,25 @@ function M.compile_generic(language_config, substitutions)
   end
 
   local compile_cmd = substitute_template(language_config.compile, substitutions)
-  logger.log(('compiling: %s'):format(table.concat(compile_cmd, ' ')))
+  local redirected_cmd = vim.deepcopy(compile_cmd)
+  if #redirected_cmd > 0 then
+    redirected_cmd[#redirected_cmd] = redirected_cmd[#redirected_cmd] .. ' 2>&1'
+  end
 
   local start_time = vim.uv.hrtime()
-  local result = vim.system(compile_cmd, { text = true }):wait()
+  local result = vim
+    .system({ 'sh', '-c', table.concat(redirected_cmd, ' ') }, { text = false })
+    :wait()
   local compile_time = (vim.uv.hrtime() - start_time) / 1000000
 
+  local ansi = require('cp.ansi')
+  result.stdout = ansi.bytes_to_string(result.stdout or '')
+  result.stderr = ansi.bytes_to_string(result.stderr or '')
+
   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
-    )
+    logger.log(('compilation failed (%.1fms)'):format(compile_time))
   end
 
   return result
@@ -112,12 +117,15 @@ local function execute_command(cmd, input_data, timeout_ms)
     timeout_ms = { timeout_ms, 'number' },
   })
 
-  logger.log(('executing: %s'):format(table.concat(cmd, ' ')))
+  local redirected_cmd = vim.deepcopy(cmd)
+  if #redirected_cmd > 0 then
+    redirected_cmd[#redirected_cmd] = redirected_cmd[#redirected_cmd] .. ' 2>&1'
+  end
 
   local start_time = vim.uv.hrtime()
 
   local result = vim
-    .system(cmd, {
+    .system({ 'sh', '-c', table.concat(redirected_cmd, ' ') }, {
       stdin = input_data,
       timeout = timeout_ms,
       text = true,
@@ -202,7 +210,7 @@ end
 ---@param ctx ProblemContext
 ---@param contest_config ContestConfig
 ---@param is_debug? boolean
----@return boolean success
+---@return {success: boolean, output: string?}
 function M.compile_problem(ctx, contest_config, is_debug)
   vim.validate({
     ctx = { ctx, 'table' },
@@ -214,7 +222,7 @@ function M.compile_problem(ctx, contest_config, is_debug)
 
   if not language_config then
     logger.log('No configuration for language: ' .. language, vim.log.levels.ERROR)
-    return false
+    return { success = false, output = 'No configuration for language: ' .. language }
   end
 
   local substitutions = {
@@ -229,16 +237,12 @@ function M.compile_problem(ctx, contest_config, is_debug)
     language_config.compile = compile_cmd
     local compile_result = M.compile_generic(language_config, substitutions)
     if compile_result.code ~= 0 then
-      logger.log(
-        'compilation failed: ' .. (compile_result.stderr or 'unknown error'),
-        vim.log.levels.ERROR
-      )
-      return false
+      return { success = false, output = compile_result.stdout or 'unknown error' }
     end
     logger.log(('compilation successful (%s)'):format(is_debug and 'debug mode' or 'test mode'))
   end
 
-  return true
+  return { success = true, output = nil }
 end
 
 function M.run_problem(ctx, contest_config, is_debug)
diff --git a/lua/cp/init.lua b/lua/cp/init.lua
index b24180c..374ddb0 100644
--- a/lua/cp/init.lua
+++ b/lua/cp/init.lua
@@ -179,6 +179,7 @@ local function toggle_run_panel(is_debug)
       vim.fn.delete(state.saved_session)
       state.saved_session = nil
     end
+
     state.run_panel_active = false
     logger.log('test panel closed')
     return
@@ -198,9 +199,9 @@ local function toggle_run_panel(is_debug)
   end
 
   local ctx = problem.create_context(state.platform, state.contest_id, state.problem_id, config)
-  local test_module = require('cp.test')
+  local run = require('cp.run')
 
-  if not test_module.load_test_cases(ctx, state) then
+  if not run.load_test_cases(ctx, state) then
     logger.log('no test cases found', vim.log.levels.WARN)
     return
   end
@@ -226,8 +227,9 @@ local function toggle_run_panel(is_debug)
   local diff_namespace = highlight.create_namespace()
 
   local test_list_namespace = vim.api.nvim_create_namespace('cp_test_list')
+  local ansi_namespace = vim.api.nvim_create_namespace('cp_ansi_highlights')
 
-  local function update_buffer_content(bufnr, lines, highlights)
+  local function update_buffer_content(bufnr, lines, highlights, namespace)
     local was_readonly = vim.api.nvim_get_option_value('readonly', { buf = bufnr })
 
     vim.api.nvim_set_option_value('readonly', false, { buf = bufnr })
@@ -236,14 +238,7 @@ local function toggle_run_panel(is_debug)
     vim.api.nvim_set_option_value('modifiable', false, { buf = bufnr })
     vim.api.nvim_set_option_value('readonly', was_readonly, { buf = bufnr })
 
-    vim.api.nvim_buf_clear_namespace(bufnr, test_list_namespace, 0, -1)
-    for _, hl in ipairs(highlights) do
-      vim.api.nvim_buf_set_extmark(bufnr, test_list_namespace, hl.line, hl.col_start, {
-        end_col = hl.col_end,
-        hl_group = hl.highlight_group,
-        priority = 200,
-      })
-    end
+    highlight.apply_highlights(bufnr, highlights, namespace or test_list_namespace)
   end
 
   local function create_vim_diff_layout(parent_win, expected_content, actual_content)
@@ -326,8 +321,31 @@ local function toggle_run_panel(is_debug)
     }
   end
 
+  local function create_single_layout(parent_win, content)
+    local buf = create_buffer_with_options()
+    local lines = vim.split(content, '\n', { plain = true, trimempty = true })
+    update_buffer_content(buf, lines, {})
+
+    vim.api.nvim_set_current_win(parent_win)
+    vim.cmd.split()
+    local win = vim.api.nvim_get_current_win()
+    vim.api.nvim_win_set_buf(win, buf)
+    vim.api.nvim_set_option_value('filetype', 'cptest', { buf = buf })
+
+    return {
+      buffers = { buf },
+      windows = { win },
+      cleanup = function()
+        pcall(vim.api.nvim_win_close, win, true)
+        pcall(vim.api.nvim_buf_delete, buf, { force = true })
+      end,
+    }
+  end
+
   local function create_diff_layout(mode, parent_win, expected_content, actual_content)
-    if mode == 'git' then
+    if mode == 'single' then
+      return create_single_layout(parent_win, actual_content)
+    elseif mode == 'git' then
       return create_git_diff_layout(parent_win, expected_content, actual_content)
     else
       return create_vim_diff_layout(parent_win, expected_content, actual_content)
@@ -335,7 +353,7 @@ local function toggle_run_panel(is_debug)
   end
 
   local function update_diff_panes()
-    local test_state = test_module.get_run_panel_state()
+    local test_state = run.get_run_panel_state()
     local current_test = test_state.test_cases[test_state.current_index]
 
     if not current_test then
@@ -344,14 +362,19 @@ local function toggle_run_panel(is_debug)
 
     local expected_content = current_test.expected or ''
     local actual_content = current_test.actual or '(not run yet)'
-    local should_show_diff = current_test.status == 'fail' and current_test.actual
+    local actual_highlights = current_test.actual_highlights or {}
+    local is_compilation_failure = current_test.error
+      and current_test.error:match('Compilation failed')
+    local should_show_diff = current_test.status == 'fail'
+      and current_test.actual
+      and not is_compilation_failure
 
     if not should_show_diff then
       expected_content = expected_content
       actual_content = actual_content
     end
 
-    local desired_mode = config.run_panel.diff_mode
+    local desired_mode = is_compilation_failure and 'single' or config.run_panel.diff_mode
 
     if current_diff_layout and current_mode ~= desired_mode then
       local saved_pos = vim.api.nvim_win_get_cursor(0)
@@ -380,7 +403,15 @@ local function toggle_run_panel(is_debug)
         setup_keybindings_for_buffer(buf)
       end
     else
-      if desired_mode == 'git' then
+      if desired_mode == 'single' then
+        local lines = vim.split(actual_content, '\n', { plain = true, trimempty = true })
+        update_buffer_content(
+          current_diff_layout.buffers[1],
+          lines,
+          actual_highlights,
+          ansi_namespace
+        )
+      elseif desired_mode == 'git' then
         local diff_backend = require('cp.diff')
         local backend = diff_backend.get_best_backend('git')
         local diff_result = backend.render(expected_content, actual_content)
@@ -393,13 +424,23 @@ local function toggle_run_panel(is_debug)
           )
         else
           local lines = vim.split(actual_content, '\n', { plain = true, trimempty = true })
-          update_buffer_content(current_diff_layout.buffers[1], lines, {})
+          update_buffer_content(
+            current_diff_layout.buffers[1],
+            lines,
+            actual_highlights,
+            ansi_namespace
+          )
         end
       else
         local expected_lines = vim.split(expected_content, '\n', { plain = true, trimempty = true })
         local actual_lines = vim.split(actual_content, '\n', { plain = true, trimempty = true })
         update_buffer_content(current_diff_layout.buffers[1], expected_lines, {})
-        update_buffer_content(current_diff_layout.buffers[2], actual_lines, {})
+        update_buffer_content(
+          current_diff_layout.buffers[2],
+          actual_lines,
+          actual_highlights,
+          ansi_namespace
+        )
 
         if should_show_diff then
           vim.api.nvim_set_option_value('diff', true, { win = current_diff_layout.windows[1] })
@@ -410,6 +451,8 @@ local function toggle_run_panel(is_debug)
           vim.api.nvim_win_call(current_diff_layout.windows[2], function()
             vim.cmd.diffthis()
           end)
+          vim.api.nvim_set_option_value('foldcolumn', '0', { win = current_diff_layout.windows[1] })
+          vim.api.nvim_set_option_value('foldcolumn', '0', { win = current_diff_layout.windows[2] })
         else
           vim.api.nvim_set_option_value('diff', false, { win = current_diff_layout.windows[1] })
           vim.api.nvim_set_option_value('diff', false, { win = current_diff_layout.windows[2] })
@@ -423,17 +466,18 @@ local function toggle_run_panel(is_debug)
       return
     end
 
-    local test_render = require('cp.test_render')
-    test_render.setup_highlights()
-    local test_state = test_module.get_run_panel_state()
-    local tab_lines, tab_highlights = test_render.render_test_list(test_state)
+    local run_render = require('cp.run_render')
+    run_render.setup_highlights()
+
+    local test_state = run.get_run_panel_state()
+    local tab_lines, tab_highlights = run_render.render_test_list(test_state)
     update_buffer_content(test_buffers.tab_buf, tab_lines, tab_highlights)
 
     update_diff_panes()
   end
 
   local function navigate_test_case(delta)
-    local test_state = test_module.get_run_panel_state()
+    local test_state = run.get_run_panel_state()
     if #test_state.test_cases == 0 then
       return
     end
@@ -456,6 +500,12 @@ local function toggle_run_panel(is_debug)
       config.run_panel.diff_mode = config.run_panel.diff_mode == 'vim' and 'git' or 'vim'
       refresh_run_panel()
     end, { buffer = buf, silent = true })
+    vim.keymap.set('n', config.run_panel.next_test_key, function()
+      navigate_test_case(1)
+    end, { buffer = buf, silent = true })
+    vim.keymap.set('n', config.run_panel.prev_test_key, function()
+      navigate_test_case(-1)
+    end, { buffer = buf, silent = true })
   end
 
   vim.keymap.set('n', config.run_panel.next_test_key, function()
@@ -477,18 +527,29 @@ local function toggle_run_panel(is_debug)
 
   local execute_module = require('cp.execute')
   local contest_config = config.contests[state.platform]
-  if execute_module.compile_problem(ctx, contest_config, is_debug) then
-    test_module.run_all_test_cases(ctx, contest_config, config)
+  local compile_result = execute_module.compile_problem(ctx, contest_config, is_debug)
+  if compile_result.success then
+    run.run_all_test_cases(ctx, contest_config, config)
+  else
+    run.handle_compilation_failure(compile_result.output)
   end
 
   refresh_run_panel()
 
+  vim.schedule(function()
+    local ansi = require('cp.ansi')
+    ansi.setup_highlight_groups()
+    if current_diff_layout then
+      update_diff_panes()
+    end
+  end)
+
   vim.api.nvim_set_current_win(test_windows.tab_win)
 
   state.run_panel_active = true
   state.test_buffers = test_buffers
   state.test_windows = test_windows
-  local test_state = test_module.get_run_panel_state()
+  local test_state = run.get_run_panel_state()
   logger.log(string.format('test panel opened (%d test cases)', #test_state.test_cases))
 end
 
@@ -540,8 +601,8 @@ local function navigate_problem(delta, language)
   local new_index = current_index + delta
 
   if new_index < 1 or new_index > #problems then
-    local direction = delta > 0 and 'next' or 'previous'
-    logger.log(('no %s problem available'):format(direction), vim.log.levels.INFO)
+    local msg = delta > 0 and 'at last problem' or 'at first problem'
+    logger.log(msg, vim.log.levels.WARN)
     return
   end
 
diff --git a/lua/cp/test.lua b/lua/cp/run.lua
similarity index 80%
rename from lua/cp/test.lua
rename to lua/cp/run.lua
index e894d4a..3303cbd 100644
--- a/lua/cp/test.lua
+++ b/lua/cp/run.lua
@@ -4,8 +4,10 @@
 ---@field expected string
 ---@field status "pending"|"pass"|"fail"|"running"|"timeout"
 ---@field actual string?
+---@field actual_highlights table[]?
 ---@field time_ms number?
 ---@field error string?
+---@field stderr string?
 ---@field selected boolean
 ---@field code number?
 ---@field ok boolean?
@@ -186,13 +188,27 @@ local function run_single_test_case(ctx, contest_config, cp_config, test_case)
   if language_config.compile and vim.fn.filereadable(ctx.binary_file) == 0 then
     logger.log('binary not found, compiling first...')
     local compile_cmd = substitute_template(language_config.compile, substitutions)
-    local compile_result = vim.system(compile_cmd, { text = true }):wait()
+    local redirected_cmd = vim.deepcopy(compile_cmd)
+    redirected_cmd[#redirected_cmd] = redirected_cmd[#redirected_cmd] .. ' 2>&1'
+    local compile_result = vim
+      .system({ 'sh', '-c', table.concat(redirected_cmd, ' ') }, { text = false })
+      :wait()
+
+    local ansi = require('cp.ansi')
+    compile_result.stdout = ansi.bytes_to_string(compile_result.stdout or '')
+    compile_result.stderr = ansi.bytes_to_string(compile_result.stderr or '')
+
     if compile_result.code ~= 0 then
       return {
         status = 'fail',
         actual = '',
-        error = 'Compilation failed: ' .. (compile_result.stderr or 'Unknown error'),
+        error = 'Compilation failed: ' .. (compile_result.stdout or 'Unknown error'),
+        stderr = compile_result.stdout or '',
         time_ms = 0,
+        code = compile_result.code,
+        ok = false,
+        signal = nil,
+        timed_out = false,
       }
     end
   end
@@ -207,16 +223,28 @@ local function run_single_test_case(ctx, contest_config, cp_config, test_case)
   if not run_panel_state.constraints then
     logger.log('no problem constraints available, using default 2000ms timeout')
   end
+  local redirected_run_cmd = vim.deepcopy(run_cmd)
+  redirected_run_cmd[#redirected_run_cmd] = redirected_run_cmd[#redirected_run_cmd] .. ' 2>&1'
   local result = vim
-    .system(run_cmd, {
+    .system({ 'sh', '-c', table.concat(redirected_run_cmd, ' ') }, {
       stdin = stdin_content,
       timeout = timeout_ms,
-      text = true,
+      text = false,
     })
     :wait()
   local execution_time = (vim.uv.hrtime() - start_time) / 1000000
 
-  local actual_output = (result.stdout or ''):gsub('\n$', '')
+  local ansi = require('cp.ansi')
+  local stdout_str = ansi.bytes_to_string(result.stdout or '')
+  local actual_output = stdout_str:gsub('\n$', '')
+
+  local actual_highlights = {}
+
+  if actual_output ~= '' then
+    local parsed = ansi.parse_ansi_text(actual_output)
+    actual_output = table.concat(parsed.lines, '\n')
+    actual_highlights = parsed.highlights
+  end
 
   local max_lines = cp_config.run_panel.max_output_lines
   local output_lines = vim.split(actual_output, '\n')
@@ -250,7 +278,9 @@ local function run_single_test_case(ctx, contest_config, cp_config, test_case)
   return {
     status = status,
     actual = actual_output,
-    error = result.code ~= 0 and result.stderr or nil,
+    actual_highlights = actual_highlights,
+    error = result.code ~= 0 and actual_output or nil,
+    stderr = '',
     time_ms = execution_time,
     code = result.code,
     ok = ok,
@@ -295,14 +325,15 @@ function M.run_test_case(ctx, contest_config, cp_config, index)
     return false
   end
 
-  logger.log(('running test case %d'):format(index))
   test_case.status = 'running'
 
   local result = run_single_test_case(ctx, contest_config, cp_config, test_case)
 
   test_case.status = result.status
   test_case.actual = result.actual
+  test_case.actual_highlights = result.actual_highlights
   test_case.error = result.error
+  test_case.stderr = result.stderr
   test_case.time_ms = result.time_ms
   test_case.code = result.code
   test_case.ok = result.ok
@@ -329,4 +360,26 @@ function M.get_run_panel_state()
   return run_panel_state
 end
 
+function M.handle_compilation_failure(compilation_output)
+  local ansi = require('cp.ansi')
+
+  -- Always parse the compilation output - it contains everything now
+  local parsed = ansi.parse_ansi_text(compilation_output or '')
+  local clean_text = table.concat(parsed.lines, '\n')
+  local highlights = parsed.highlights
+
+  for _, test_case in ipairs(run_panel_state.test_cases) do
+    test_case.status = 'fail'
+    test_case.actual = clean_text
+    test_case.actual_highlights = highlights
+    test_case.error = 'Compilation failed'
+    test_case.stderr = ''
+    test_case.time_ms = 0
+    test_case.code = 1
+    test_case.ok = false
+    test_case.signal = nil
+    test_case.timed_out = false
+  end
+end
+
 return M
diff --git a/lua/cp/test_render.lua b/lua/cp/run_render.lua
similarity index 100%
rename from lua/cp/test_render.lua
rename to lua/cp/run_render.lua
diff --git a/spec/ansi_spec.lua b/spec/ansi_spec.lua
new file mode 100644
index 0000000..0b7faf8
--- /dev/null
+++ b/spec/ansi_spec.lua
@@ -0,0 +1,215 @@
+describe('ansi parser', function()
+  local ansi = require('cp.ansi')
+
+  describe('bytes_to_string', function()
+    it('returns string as-is', function()
+      local input = 'hello world'
+      assert.equals('hello world', ansi.bytes_to_string(input))
+    end)
+
+    it('converts byte array to string', function()
+      local input = { 104, 101, 108, 108, 111 }
+      assert.equals('hello', ansi.bytes_to_string(input))
+    end)
+  end)
+
+  describe('parse_ansi_text', function()
+    it('strips ansi codes from simple text', function()
+      local input = 'Hello \027[31mworld\027[0m!'
+      local result = ansi.parse_ansi_text(input)
+
+      assert.equals('Hello world!', table.concat(result.lines, '\n'))
+    end)
+
+    it('handles text without ansi codes', function()
+      local input = 'Plain text'
+      local result = ansi.parse_ansi_text(input)
+
+      assert.equals('Plain text', table.concat(result.lines, '\n'))
+      assert.equals(0, #result.highlights)
+    end)
+
+    it('creates correct highlight for simple colored text', function()
+      local input = 'Hello \027[31mworld\027[0m!'
+      local result = ansi.parse_ansi_text(input)
+
+      assert.equals(1, #result.highlights)
+      local highlight = result.highlights[1]
+      assert.equals(0, highlight.line)
+      assert.equals(6, highlight.col_start)
+      assert.equals(11, highlight.col_end)
+      assert.equals('CpAnsiRed', highlight.highlight_group)
+    end)
+
+    it('handles bold text', function()
+      local input = 'Hello \027[1mbold\027[0m world'
+      local result = ansi.parse_ansi_text(input)
+
+      assert.equals('Hello bold world', table.concat(result.lines, '\n'))
+      assert.equals(1, #result.highlights)
+      local highlight = result.highlights[1]
+      assert.equals('CpAnsiBold', highlight.highlight_group)
+    end)
+
+    it('handles italic text', function()
+      local input = 'Hello \027[3mitalic\027[0m world'
+      local result = ansi.parse_ansi_text(input)
+
+      assert.equals('Hello italic world', table.concat(result.lines, '\n'))
+      assert.equals(1, #result.highlights)
+      local highlight = result.highlights[1]
+      assert.equals('CpAnsiItalic', highlight.highlight_group)
+    end)
+
+    it('handles bold + color combination', function()
+      local input = 'Hello \027[1;31mbold red\027[0m world'
+      local result = ansi.parse_ansi_text(input)
+
+      assert.equals('Hello bold red world', table.concat(result.lines, '\n'))
+      assert.equals(1, #result.highlights)
+      local highlight = result.highlights[1]
+      assert.equals('CpAnsiBoldRed', highlight.highlight_group)
+      assert.equals(6, highlight.col_start)
+      assert.equals(14, highlight.col_end)
+    end)
+
+    it('handles italic + color combination', function()
+      local input = 'Hello \027[3;32mitalic green\027[0m world'
+      local result = ansi.parse_ansi_text(input)
+
+      assert.equals('Hello italic green world', table.concat(result.lines, '\n'))
+      assert.equals(1, #result.highlights)
+      local highlight = result.highlights[1]
+      assert.equals('CpAnsiItalicGreen', highlight.highlight_group)
+    end)
+
+    it('handles bold + italic + color combination', function()
+      local input = 'Hello \027[1;3;33mbold italic yellow\027[0m world'
+      local result = ansi.parse_ansi_text(input)
+
+      assert.equals('Hello bold italic yellow world', table.concat(result.lines, '\n'))
+      assert.equals(1, #result.highlights)
+      local highlight = result.highlights[1]
+      assert.equals('CpAnsiBoldItalicYellow', highlight.highlight_group)
+    end)
+
+    it('handles sequential attribute setting', function()
+      local input = 'Hello \027[1m\027[31mbold red\027[0m world'
+      local result = ansi.parse_ansi_text(input)
+
+      assert.equals('Hello bold red world', table.concat(result.lines, '\n'))
+      assert.equals(1, #result.highlights)
+      local highlight = result.highlights[1]
+      assert.equals('CpAnsiBoldRed', highlight.highlight_group)
+    end)
+
+    it('handles selective attribute reset', function()
+      local input = 'Hello \027[1;31mbold red\027[22mno longer bold\027[0m world'
+      local result = ansi.parse_ansi_text(input)
+
+      assert.equals('Hello bold redno longer bold world', table.concat(result.lines, '\n'))
+      assert.equals(2, #result.highlights)
+
+      local bold_red = result.highlights[1]
+      assert.equals('CpAnsiBoldRed', bold_red.highlight_group)
+      assert.equals(6, bold_red.col_start)
+      assert.equals(14, bold_red.col_end)
+
+      local just_red = result.highlights[2]
+      assert.equals('CpAnsiRed', just_red.highlight_group)
+      assert.equals(14, just_red.col_start)
+      assert.equals(28, just_red.col_end)
+    end)
+
+    it('handles bright colors', function()
+      local input = 'Hello \027[91mbright red\027[0m world'
+      local result = ansi.parse_ansi_text(input)
+
+      assert.equals(1, #result.highlights)
+      local highlight = result.highlights[1]
+      assert.equals('CpAnsiBrightRed', highlight.highlight_group)
+    end)
+
+    it('handles compiler-like output with complex formatting', function()
+      local input =
+        "error.cpp:10:5: \027[1m\027[31merror:\027[0m\027[1m 'undefined' was not declared\027[0m"
+      local result = ansi.parse_ansi_text(input)
+
+      local clean_text = table.concat(result.lines, '\n')
+      assert.equals("error.cpp:10:5: error: 'undefined' was not declared", clean_text)
+      assert.equals(2, #result.highlights)
+
+      local error_highlight = result.highlights[1]
+      assert.equals('CpAnsiBoldRed', error_highlight.highlight_group)
+      assert.equals(16, error_highlight.col_start)
+      assert.equals(22, error_highlight.col_end)
+
+      local message_highlight = result.highlights[2]
+      assert.equals('CpAnsiBold', message_highlight.highlight_group)
+      assert.equals(22, message_highlight.col_start)
+      assert.equals(51, message_highlight.col_end)
+    end)
+
+    it('handles multiline with persistent state', function()
+      local input = '\027[1;31mline1\nline2\nline3\027[0m'
+      local result = ansi.parse_ansi_text(input)
+
+      assert.equals('line1\nline2\nline3', table.concat(result.lines, '\n'))
+      assert.equals(3, #result.highlights)
+
+      for i, highlight in ipairs(result.highlights) do
+        assert.equals('CpAnsiBoldRed', highlight.highlight_group)
+        assert.equals(i - 1, highlight.line)
+        assert.equals(0, highlight.col_start)
+        assert.equals(5, highlight.col_end)
+      end
+    end)
+  end)
+
+  describe('update_ansi_state', function()
+    it('resets all state on reset code', function()
+      local state = { bold = true, italic = true, foreground = 'Red' }
+      ansi.update_ansi_state(state, '0')
+
+      assert.is_false(state.bold)
+      assert.is_false(state.italic)
+      assert.is_nil(state.foreground)
+    end)
+
+    it('sets individual attributes', function()
+      local state = { bold = false, italic = false, foreground = nil }
+
+      ansi.update_ansi_state(state, '1')
+      assert.is_true(state.bold)
+
+      ansi.update_ansi_state(state, '3')
+      assert.is_true(state.italic)
+
+      ansi.update_ansi_state(state, '31')
+      assert.equals('Red', state.foreground)
+    end)
+
+    it('handles compound codes', function()
+      local state = { bold = false, italic = false, foreground = nil }
+      ansi.update_ansi_state(state, '1;3;31')
+
+      assert.is_true(state.bold)
+      assert.is_true(state.italic)
+      assert.equals('Red', state.foreground)
+    end)
+
+    it('handles selective resets', function()
+      local state = { bold = true, italic = true, foreground = 'Red' }
+
+      ansi.update_ansi_state(state, '22')
+      assert.is_false(state.bold)
+      assert.is_true(state.italic)
+      assert.equals('Red', state.foreground)
+
+      ansi.update_ansi_state(state, '39')
+      assert.is_false(state.bold)
+      assert.is_true(state.italic)
+      assert.is_nil(state.foreground)
+    end)
+  end)
+end)
diff --git a/spec/execute_spec.lua b/spec/execute_spec.lua
index 73ec456..12e7f67 100644
--- a/spec/execute_spec.lua
+++ b/spec/execute_spec.lua
@@ -82,10 +82,10 @@ describe('cp.execute', function()
       assert.is_true(#mock_system_calls > 0)
 
       local compile_call = mock_system_calls[1]
-      assert.equals('g++', compile_call.cmd[1])
-      assert.equals('test.cpp', compile_call.cmd[2])
-      assert.equals('-o', compile_call.cmd[3])
-      assert.equals('test.run', compile_call.cmd[4])
+      assert.equals('sh', compile_call.cmd[1])
+      assert.equals('-c', compile_call.cmd[2])
+      assert.is_not_nil(string.find(compile_call.cmd[3], 'g%+%+ test%.cpp %-o test%.run'))
+      assert.is_not_nil(string.find(compile_call.cmd[3], '2>&1'))
     end)
 
     it('handles multiple substitutions in single argument', function()
@@ -100,7 +100,7 @@ describe('cp.execute', function()
       execute.compile_generic(language_config, substitutions)
 
       local compile_call = mock_system_calls[1]
-      assert.equals('-omain.out', compile_call.cmd[3])
+      assert.is_not_nil(string.find(compile_call.cmd[3], '%-omain%.out'))
     end)
   end)
 
@@ -131,8 +131,8 @@ describe('cp.execute', function()
       assert.is_true(#mock_system_calls > 0)
 
       local compile_call = mock_system_calls[1]
-      assert.equals('g++', compile_call.cmd[1])
-      assert.is_true(vim.tbl_contains(compile_call.cmd, '-std=c++17'))
+      assert.equals('sh', compile_call.cmd[1])
+      assert.is_not_nil(string.find(compile_call.cmd[3], '%-std=c%+%+17'))
     end)
 
     it('handles compilation errors gracefully', function()
@@ -199,7 +199,7 @@ describe('cp.execute', function()
     it('handles command execution', function()
       vim.system = function(_, opts)
         if opts then
-          assert.equals(true, opts.text)
+          assert.equals(false, opts.text)
         end
         return {
           wait = function()
@@ -266,9 +266,10 @@ describe('cp.execute', function()
       execute.compile_generic(language_config, {})
 
       local mkdir_call = mock_system_calls[1]
-      assert.equals('mkdir', mkdir_call.cmd[1])
-      assert.is_true(vim.tbl_contains(mkdir_call.cmd, 'build'))
-      assert.is_true(vim.tbl_contains(mkdir_call.cmd, 'io'))
+      assert.equals('sh', mkdir_call.cmd[1])
+      assert.is_not_nil(string.find(mkdir_call.cmd[3], 'mkdir'))
+      assert.is_not_nil(string.find(mkdir_call.cmd[3], 'build'))
+      assert.is_not_nil(string.find(mkdir_call.cmd[3], 'io'))
     end)
   end)
 
@@ -316,8 +317,8 @@ describe('cp.execute', function()
       assert.equals(0, result.code)
 
       local echo_call = mock_system_calls[1]
-      assert.equals('echo', echo_call.cmd[1])
-      assert.equals('hello', echo_call.cmd[2])
+      assert.equals('sh', echo_call.cmd[1])
+      assert.is_not_nil(string.find(echo_call.cmd[3], 'echo hello'))
     end)
 
     it('handles multiple consecutive substitutions', function()
@@ -332,8 +333,119 @@ describe('cp.execute', function()
       execute.compile_generic(language_config, substitutions)
 
       local call = mock_system_calls[1]
-      assert.equals('g++g++', call.cmd[1])
-      assert.equals('test.cpptest.cpp', call.cmd[2])
+      assert.equals('sh', call.cmd[1])
+      assert.is_not_nil(string.find(call.cmd[3], 'g%+%+g%+%+ test%.cpptest%.cpp'))
+    end)
+  end)
+
+  describe('stderr/stdout redirection', function()
+    it('should use stderr redirection (2>&1)', function()
+      local original_system = vim.system
+      local captured_command = nil
+
+      vim.system = function(cmd, _)
+        captured_command = cmd
+        return {
+          wait = function()
+            return { code = 0, stdout = '', stderr = '' }
+          end,
+        }
+      end
+
+      local language_config = {
+        compile = { 'g++', '-std=c++17', '-o', '{binary}', '{source}' },
+      }
+      local substitutions = { source = 'test.cpp', binary = 'build/test', version = '17' }
+      execute.compile_generic(language_config, substitutions)
+
+      assert.is_not_nil(captured_command)
+      assert.equals('sh', captured_command[1])
+      assert.equals('-c', captured_command[2])
+      assert.is_not_nil(
+        string.find(captured_command[3], '2>&1'),
+        'Command should contain 2>&1 redirection'
+      )
+
+      vim.system = original_system
+    end)
+
+    it('should return combined stdout+stderr in result', function()
+      local original_system = vim.system
+      local test_output = 'STDOUT: Hello\nSTDERR: Error message\n'
+
+      vim.system = function(_, _)
+        return {
+          wait = function()
+            return { code = 1, stdout = test_output, stderr = '' }
+          end,
+        }
+      end
+
+      local language_config = {
+        compile = { 'g++', '-std=c++17', '-o', '{binary}', '{source}' },
+      }
+      local substitutions = { source = 'test.cpp', binary = 'build/test', version = '17' }
+      local result = execute.compile_generic(language_config, substitutions)
+
+      assert.equals(1, result.code)
+      assert.equals(test_output, result.stdout)
+
+      vim.system = original_system
+    end)
+  end)
+
+  describe('integration with execute_command function', function()
+    it('tests the full execute_command flow with stderr/stdout combination', function()
+      local cmd = { 'echo', 'test output' }
+      local input_data = 'test input'
+      local timeout_ms = 1000
+
+      local original_system = vim.system
+      vim.system = function(shell_cmd, opts)
+        assert.equals('sh', shell_cmd[1])
+        assert.equals('-c', shell_cmd[2])
+        assert.is_not_nil(string.find(shell_cmd[3], '2>&1'))
+        assert.equals(input_data, opts.stdin)
+        assert.equals(timeout_ms, opts.timeout)
+        assert.is_true(opts.text)
+
+        return {
+          wait = function()
+            return { code = 0, stdout = 'combined output from stdout and stderr', stderr = '' }
+          end,
+        }
+      end
+
+      local execute_command = require('cp.execute').execute_command
+        or function(command, stdin_data, timeout)
+          local redirected_cmd = vim.deepcopy(command)
+          if #redirected_cmd > 0 then
+            redirected_cmd[#redirected_cmd] = redirected_cmd[#redirected_cmd] .. ' 2>&1'
+          end
+
+          local result = vim
+            .system({ 'sh', '-c', table.concat(redirected_cmd, ' ') }, {
+              stdin = stdin_data,
+              timeout = timeout,
+              text = true,
+            })
+            :wait()
+
+          return {
+            stdout = result.stdout or '',
+            stderr = result.stderr or '',
+            code = result.code or 0,
+            time_ms = 0,
+            timed_out = result.code == 124,
+          }
+        end
+
+      local result = execute_command(cmd, input_data, timeout_ms)
+
+      assert.equals(0, result.code)
+      assert.equals('combined output from stdout and stderr', result.stdout)
+
+      vim.system = original_system
     end)
   end)
 end)
diff --git a/spec/test_render_spec.lua b/spec/run_render_spec.lua
similarity index 82%
rename from spec/test_render_spec.lua
rename to spec/run_render_spec.lua
index 2bdc98a..bcb0c78 100644
--- a/spec/test_render_spec.lua
+++ b/spec/run_render_spec.lua
@@ -1,10 +1,9 @@
-describe('cp.test_render', function()
+describe('cp.run_render', function()
+  local run_render = require('cp.run_render')
   local spec_helper = require('spec.spec_helper')
-  local test_render
 
   before_each(function()
     spec_helper.setup()
-    test_render = require('cp.test_render')
   end)
 
   after_each(function()
@@ -14,49 +13,49 @@ describe('cp.test_render', function()
   describe('get_status_info', function()
     it('returns AC for pass status', function()
       local test_case = { status = 'pass' }
-      local result = test_render.get_status_info(test_case)
+      local result = run_render.get_status_info(test_case)
       assert.equals('AC', result.text)
       assert.equals('CpTestAC', result.highlight_group)
     end)
 
     it('returns WA for fail status with normal exit codes', function()
       local test_case = { status = 'fail', code = 1 }
-      local result = test_render.get_status_info(test_case)
+      local result = run_render.get_status_info(test_case)
       assert.equals('WA', result.text)
       assert.equals('CpTestWA', result.highlight_group)
     end)
 
     it('returns TLE for timeout status', function()
       local test_case = { status = 'timeout' }
-      local result = test_render.get_status_info(test_case)
+      local result = run_render.get_status_info(test_case)
       assert.equals('TLE', result.text)
       assert.equals('CpTestTLE', result.highlight_group)
     end)
 
     it('returns TLE for timed out fail status', function()
       local test_case = { status = 'fail', timed_out = true }
-      local result = test_render.get_status_info(test_case)
+      local result = run_render.get_status_info(test_case)
       assert.equals('TLE', result.text)
       assert.equals('CpTestTLE', result.highlight_group)
     end)
 
     it('returns RTE for fail with signal codes (>= 128)', function()
       local test_case = { status = 'fail', code = 139 }
-      local result = test_render.get_status_info(test_case)
+      local result = run_render.get_status_info(test_case)
       assert.equals('RTE', result.text)
       assert.equals('CpTestRTE', result.highlight_group)
     end)
 
     it('returns empty for pending status', function()
       local test_case = { status = 'pending' }
-      local result = test_render.get_status_info(test_case)
+      local result = run_render.get_status_info(test_case)
       assert.equals('', result.text)
       assert.equals('CpTestPending', result.highlight_group)
     end)
 
     it('returns running indicator for running status', function()
       local test_case = { status = 'running' }
-      local result = test_render.get_status_info(test_case)
+      local result = run_render.get_status_info(test_case)
       assert.equals('...', result.text)
       assert.equals('CpTestPending', result.highlight_group)
     end)
@@ -71,7 +70,7 @@ describe('cp.test_render', function()
         },
         current_index = 1,
       }
-      local result = test_render.render_test_list(test_state)
+      local result = run_render.render_test_list(test_state)
       assert.is_true(result[1]:find('^┌') ~= nil)
       assert.is_true(result[2]:find('│.*#.*│.*Status.*│.*Time.*│.*Exit Code.*│') ~= nil)
       assert.is_true(result[3]:find('^├') ~= nil)
@@ -85,7 +84,7 @@ describe('cp.test_render', function()
         },
         current_index = 2,
       }
-      local result = test_render.render_test_list(test_state)
+      local result = run_render.render_test_list(test_state)
       local found_current = false
       for _, line in ipairs(result) do
         if line:match('│.*> 2.*│') then
@@ -104,7 +103,7 @@ describe('cp.test_render', function()
         },
         current_index = 1,
       }
-      local result = test_render.render_test_list(test_state)
+      local result = run_render.render_test_list(test_state)
       local found_input = false
       for _, line in ipairs(result) do
         if line:match('│5 3') then
@@ -117,7 +116,7 @@ describe('cp.test_render', function()
 
     it('handles empty test cases', function()
       local test_state = { test_cases = {}, current_index = 1 }
-      local result = test_render.render_test_list(test_state)
+      local result = run_render.render_test_list(test_state)
       assert.equals(3, #result)
     end)
 
@@ -128,7 +127,7 @@ describe('cp.test_render', function()
         },
         current_index = 1,
       }
-      local result = test_render.render_test_list(test_state)
+      local result = run_render.render_test_list(test_state)
       local input_lines = {}
       for _, line in ipairs(result) do
         if line:match('^│[531]') then
@@ -142,24 +141,24 @@ describe('cp.test_render', function()
   describe('render_status_bar', function()
     it('formats time and exit code', function()
       local test_case = { time_ms = 45.7, code = 0 }
-      local result = test_render.render_status_bar(test_case)
+      local result = run_render.render_status_bar(test_case)
       assert.equals('45.70ms │ Exit: 0', result)
     end)
 
     it('handles missing time', function()
       local test_case = { code = 0 }
-      local result = test_render.render_status_bar(test_case)
+      local result = run_render.render_status_bar(test_case)
       assert.equals('Exit: 0', result)
     end)
 
     it('handles missing exit code', function()
       local test_case = { time_ms = 123 }
-      local result = test_render.render_status_bar(test_case)
+      local result = run_render.render_status_bar(test_case)
       assert.equals('123.00ms', result)
     end)
 
     it('returns empty for nil test case', function()
-      local result = test_render.render_status_bar(nil)
+      local result = run_render.render_status_bar(nil)
       assert.equals('', result)
     end)
   end)
@@ -167,7 +166,7 @@ describe('cp.test_render', function()
   describe('setup_highlights', function()
     it('sets up all highlight groups', function()
       local mock_set_hl = spy.on(vim.api, 'nvim_set_hl')
-      test_render.setup_highlights()
+      run_render.setup_highlights()
 
       assert.spy(mock_set_hl).was_called(7)
       assert.spy(mock_set_hl).was_called_with(0, 'CpTestAC', { fg = '#10b981' })
@@ -188,7 +187,7 @@ describe('cp.test_render', function()
         },
         current_index = 1,
       }
-      local lines, highlights = test_render.render_test_list(test_state)
+      local lines, highlights = run_render.render_test_list(test_state)
 
       assert.equals(2, #highlights)