name: tui-validate
description: Validates Terminal User Interface (TUI) output using freeze for screenshot capture and LLM-as-judge for semantic validation. Supports both visual (PNG/SVG) and text-based validation modes.
type: anthropic-skill
version: "1.0"

TUI Validate

Overview

This skill validates Terminal User Interface (TUI) applications by capturing their output and using LLM-as-judge for semantic validation. It leverages freeze from Charmbracelet for high-fidelity terminal screenshots and provides structured validation criteria.

Philosophy: Rather than brittle string matching, this skill uses semantic understanding to validate that TUI output "looks right" - checking layout, content presence, and visual hierarchy without breaking on minor formatting changes.

When to Use

• Validating TUI rendering after changes
• Checking that UI components display correctly
• Visual regression testing for terminal applications
• Verifying TUI state after specific interactions
• Creating documentation screenshots with validation

Prerequisites

Required:
- freeze CLI tool installed (brew install charmbracelet/tap/freeze)
- tmux for interactive TUI capture (optional, for live applications)

Verification:

# Check freeze is installed
freeze --version

# Check tmux is installed (for interactive capture)
tmux -V

Parameters

• target (required): What to validate. One of:
• file:<path> - ANSI output file to validate
• command:<cmd> - Command to execute and capture
• tmux:<session> - Live tmux session to capture

• buffer:<text> - Raw text/ANSI to validate

• criteria (required): Validation criteria. Can be:

• A predefined criteria name (see Built-in Criteria)

• A custom criteria string describing what to check

• output_format (optional, default: "svg"): Screenshot format

• svg - Vector format, best for documentation
• png - Raster format, best for visual diff

• text - Text-only extraction, fastest

• save_screenshot (optional, default: false): Whether to save the screenshot

• If true, saves to {target_name}.{format} in current directory

• judge_mode (optional, default: "semantic"): Validation approach

• semantic - LLM judges based on meaning and layout
• strict - Also checks exact content presence
• visual - Requires PNG, checks visual appearance

Built-in Criteria

ralph-header

Validates Ralph TUI header component:
- Iteration counter in [iter N] or [iter N/M] format
- Elapsed time in MM:SS format
- Hat indicator with emoji and name
- Mode indicator (▶ auto or ⏸ paused)
- Optional scroll mode indicator [SCROLL]
- Optional idle countdown idle: Ns

ralph-footer

Validates Ralph TUI footer component:
- Activity indicator (◉ active, ◯ idle, or ■ done)
- Last event topic display
- Search mode display when active

ralph-full

Validates complete Ralph TUI layout:
- Header section at top (3 lines)
- Terminal content area (variable height)
- Footer section at bottom (3 lines)
- Proper visual hierarchy and borders

tui-basic

Generic TUI validation:
- Has visible content (not blank)
- No rendering artifacts or broken characters
- Proper terminal dimensions

Execution Flow

1. Capture Phase

Capture TUI output based on target type:

For file targets:

freeze {file_path} -o /tmp/tui-capture.{format}

For command targets:

freeze --execute "{command}" -o /tmp/tui-capture.{format}

For tmux targets:

tmux capture-pane -pet {session} | freeze -o /tmp/tui-capture.{format}

For buffer targets:

echo "{buffer}" | freeze -o /tmp/tui-capture.{format}

Constraints:
- You MUST verify freeze is installed before attempting capture
- You MUST handle capture failures gracefully and report the error
- You MUST use appropriate freeze flags for the output format
- You SHOULD use --theme base16 for consistent rendering
- You SHOULD set reasonable dimensions with --width and --height

2. Extraction Phase

Extract content for LLM analysis:

For text/semantic validation:
- If format is text, use the captured text directly
- If format is svg or png, also capture text version for content analysis

For visual validation:
- Requires PNG format
- Will analyze the image directly using vision capabilities

Constraints:
- You MUST extract both visual and text representations when judge_mode is visual
- You MUST preserve ANSI escape sequences for color validation when relevant

3. Validation Phase

Apply LLM-as-judge with the appropriate criteria:

Semantic Validation Prompt Template:

Analyze this terminal UI output and determine if it meets the following criteria:

CRITERIA:
{criteria_description}

TERMINAL OUTPUT:
{captured_text}

Evaluate each criterion and provide:
1. PASS or FAIL for each requirement
2. Brief explanation for any failures
3. Overall verdict: PASS or FAIL

Be lenient on exact formatting but strict on:
- Required content presence
- Logical layout and hierarchy
- No rendering errors or artifacts

Visual Validation Prompt Template (with image):

Examine this terminal screenshot and validate:

CRITERIA:
{criteria_description}

Check for:
1. Visual hierarchy and layout
2. Color coding correctness
3. No rendering artifacts or broken characters
4. Proper alignment and spacing

Verdict: PASS or FAIL with explanation

Constraints:
- You MUST return a clear PASS or FAIL verdict
- You MUST provide specific feedback on failures
- You MUST be lenient on whitespace/formatting differences
- You MUST be strict on content presence and semantic correctness
- You SHOULD note any warnings even on PASS results

4. Reporting Phase

Report validation results:

On PASS:

✅ TUI Validation PASSED

Criteria: {criteria_name}
Target: {target}
Mode: {judge_mode}

All requirements satisfied.
{optional_notes}

On FAIL:

❌ TUI Validation FAILED

Criteria: {criteria_name}
Target: {target}
Mode: {judge_mode}

Issues found:
- {issue_1}
- {issue_2}

Screenshot saved: {path_if_saved}

Constraints:
- You MUST always provide a clear verdict
- You MUST list specific issues on failure
- You MUST offer the screenshot path if saved
- You SHOULD suggest fixes for common issues

Examples

Example 1: Validate Ralph Header from File

Input:

/tui-validate file:test_output.txt criteria:ralph-header

Process:
1. Read test_output.txt containing ANSI output
2. Capture with freeze: freeze test_output.txt -o /tmp/capture.svg
3. Extract text content
4. Apply ralph-header criteria via LLM judge
5. Report PASS/FAIL with details

Example 2: Validate Live TUI in tmux

Input:

/tui-validate tmux:ralph-session criteria:ralph-full save_screenshot:true

Process:
1. Capture tmux pane: tmux capture-pane -pet ralph-session | freeze -o ralph-session.svg
2. Also capture text: tmux capture-pane -pet ralph-session > /tmp/text.txt
3. Apply ralph-full criteria checking header, content, and footer
4. Save screenshot to ralph-session.svg
5. Report validation result

Example 3: Custom Criteria Validation

Input:

/tui-validate command:"cargo run --example tui_demo" criteria:"Shows a bordered box with 'Hello World' text centered inside" output_format:png judge_mode:visual

Process:
1. Execute command and capture: freeze --execute "cargo run --example tui_demo" -o /tmp/capture.png
2. Use vision model to analyze PNG
3. Check for bordered box and centered text
4. Report visual validation result

Example 4: Quick Text Validation

Input:

/tui-validate buffer:"[iter 3/10] 04:32 | 🔨 Builder | ▶ auto" criteria:ralph-header output_format:text

Process:
1. Analyze text directly (no freeze needed for text mode with buffer)
2. Check for iteration format, elapsed time, hat, and mode indicator
3. Report validation result

Criteria Definitions

ralph-header (Full Definition)

name: ralph-header
description: Ralph TUI header component validation
requirements:
  - name: iteration_counter
    description: Shows iteration in [iter N] or [iter N/M] format
    required: true
    pattern: '\[iter \d+(/\d+)?\]'

  - name: elapsed_time
    description: Shows elapsed time in MM:SS format
    required: true
    pattern: '\d{2}:\d{2}'

  - name: hat_indicator
    description: Shows current hat with emoji prefix
    required: true
    examples: ["🔨 Builder", "📋 Planner", "🎯 Executor"]

  - name: mode_indicator
    description: Shows loop mode status
    required: true
    values: ["▶ auto", "⏸ paused"]

  - name: scroll_indicator
    description: Shows [SCROLL] when in scroll mode
    required: false
    pattern: '\[SCROLL\]'

  - name: idle_countdown
    description: Shows idle timeout when present
    required: false
    pattern: 'idle: \d+s'

ralph-footer (Full Definition)

name: ralph-footer
description: Ralph TUI footer component validation
requirements:
  - name: activity_indicator
    description: Shows current activity state
    required: true
    values: ["◉ active", "◯ idle", "■ done"]

  - name: event_topic
    description: Shows last event topic
    required: false
    examples: ["task.start", "build.done", "loop.terminate"]

  - name: search_display
    description: Shows search query and match count when searching
    required: false
    pattern: 'Search: .+ \d+/\d+'

ralph-full (Full Definition)

name: ralph-full
description: Complete Ralph TUI layout validation
requirements:
  - name: header_section
    description: Header at top with iteration, time, hat, and mode
    required: true
    references: ralph-header

  - name: content_section
    description: Main terminal content area
    required: true
    checks:
      - Has visible content or is ready for content
      - Properly bounded between header and footer

  - name: footer_section
    description: Footer at bottom with activity status
    required: true
    references: ralph-footer

  - name: visual_hierarchy
    description: Clear visual separation between sections
    required: true
    checks:
      - Borders or spacing between sections
      - Consistent width across sections

Troubleshooting

freeze not found

# macOS
brew install charmbracelet/tap/freeze

# Linux (via Go)
go install github.com/charmbracelet/freeze@latest

# Verify installation
freeze --version

tmux capture fails

• Ensure the tmux session exists: tmux list-sessions
• Verify pane number: tmux list-panes -t {session}
• Try capturing specific pane: tmux capture-pane -pet {session}:{pane}

Rendering artifacts in capture

• Try different terminal emulator settings in freeze
• Use --theme flag for consistent colors
• Ensure terminal dimensions match TUI expectations

LLM judge too strict/lenient

• Adjust criteria to be more specific
• Use strict mode for exact matching requirements
• Use semantic mode for layout/presence checking

Integration with Tests

This skill can be integrated into test suites:

// In tests/tui_validation.rs
#[test]
#[ignore] // Run with: cargo test -- --ignored
fn validate_header_rendering() {
    // 1. Render header to buffer
    let output = render_header_to_string(&test_state);

    // 2. Save to temp file
    std::fs::write("/tmp/header_test.txt", &output).unwrap();

    // 3. Run tui-validate skill (via CLI or programmatic)
    // /tui-validate file:/tmp/header_test.txt criteria:ralph-header

    // 4. Assert validation passed
}

Best Practices

1. Use semantic validation for layout checks - Don't break on minor formatting
2. Use strict validation for content requirements - Ensure critical info is present
3. Save screenshots on failure - Aids debugging
4. Test with various terminal sizes - TUIs should be responsive
5. Combine with unit tests - Use this for integration/visual validation, unit tests for logic