Publish harness and TUI open-source

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crates/codegen/xai-ratatui-inline/README.md

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+# ratatui-inline
+
+A Rust library for building terminal applications with inline viewports - dynamic UI elements that stay at the bottom of the terminal while preserving scrollback history above them. Perfect for building chat-like interfaces, command prompts, and interactive terminal tools.
+
+## What is this?
+
+This crate provides tools for creating terminal applications where:
+- A viewport (UI element) is pinned to the bottom of the terminal
+- Content above the viewport becomes part of the terminal's native scrollback
+- Users can scroll through history using their terminal's built-in scroll functionality
+- Long lines wrap naturally without truncation
+- The viewport remains visible and interactive while history accumulates above
+
+Think of applications like:
+- Chat interfaces with an input box at the bottom
+- Interactive REPLs with command history
+- Log viewers with controls at the bottom
+- Any TUI that needs to preserve output history
+
+## Key Features
+
+- **Inline viewport** - UI stays at bottom while content flows above into scrollback
+- **Natural text flow** - Content is printed normally, leveraging terminal's native behavior
+- **Zero-copy text processing** - Efficient ANSI-aware text segmentation without allocations
+- **Proper line wrapping** - Handles terminal width boundaries correctly with ANSI sequences
+- **Unicode support** - Correct handling of emoji, CJK characters, combining characters
+- **Terminal resize handling** - Robust resize support using RIS (Reset to Initial State)
+- **Synchronized output** - Flicker-free rendering using DCS protocol
+- **Cross-platform** - Works in all terminals and multiplexers (tmux, screen, etc.)
+
+## Usage
+
+See `examples/inline.rs` for a complete working example.
+
+## Architecture
+
+### Text Processing
+
+The library uses a zero-copy approach for ANSI-aware text segmentation:
+- **anstyle-parse** - ANSI/SGR-aware segmentation for zero-copy line splitting
+- **Zero allocations** - Returns string slices without copying or allocating
+- **Single-pass parsing** - Processes input once with proper escape sequence tracking
+- **Unicode support** - Correct width calculation for emoji, CJK, combining characters
+
+### Scrollback Implementation
+
+The library uses a "natural flow" approach for scrollback:
+1. Position cursor at viewport top
+2. Print content, letting terminal handle wrapping naturally
+3. Add viewport-height newlines to reserve space
+4. Clear and render the viewport
+
+This single implementation works universally across all terminals and multiplexers without special modes or workarounds.
+
+### Line Ending Handling
+
+- **LF (`\n`)** - Standard line ending, moves to next line
+- **CRLF (`\r\n`)** - Windows-style line ending, treated as single line break
+- **CR (`\r`)** - Carriage return only, resets cursor to line start (overwrites)
+
+## Design Decisions
+
+### Why Fork ratatui's Terminal?
+
+The standard ratatui Terminal API doesn't expose internals needed for inline viewport manipulation:
+- **Viewport area access** - Need to know current position and dimensions
+- **Direct viewport positioning** - Must be able to set viewport location
+- **Buffer management** - Need back buffer reset and previous buffer access
+- **Resize calculations** - Require access to buffer state during resize
+
+Our forked Terminal provides these capabilities while maintaining compatibility with ratatui's API.
+
+### Synchronized Output
+
+Flicker-free rendering using the DCS synchronized output protocol:
+- All operations between begin/end markers are atomic
+- Terminal only updates display once per batch
+- Eliminates partial render states
+
+## Performance
+
+- **Colored JSON**: ~186μs per operation
+- **Plain text**: ~75μs per operation  
+- **Zero allocations** in hot path
+- **Single-pass parsing** for all text processing
+
+## Testing
+
+Comprehensive test coverage including:
+- Text segmentation with ANSI sequences
+- Line wrapping and Unicode handling
+- All line ending types (LF, CRLF, CR)
+- Viewport positioning and resizing
+- Terminal resize with history re-rendering
+- Mock terminal infrastructure for unit testing
+
+### Terminal Resize Strategy
+
+#### The Problem
+
+When using inline viewports on the main screen (not alternate screen), terminal resize causes issues:
+- Terminal reflows content automatically BEFORE the app receives SIGWINCH
+- Old viewport borders get reflowed as garbage text
+- Built-in `autoresize()` corrupts scrollback history
+- Cursor position queries (DSR) have race conditions during rapid resize
+- Different terminals handle reflow unpredictably
+
+#### The Solution: RIS (Reset to Initial State)
+
+We use the "nuclear option" - completely reset and re-render:
+1. Send RIS (`ESC c`) to clear everything
+2. Re-output entire scrollback history
+3. Position viewport based on content amount
+
+This approach:
+- **Works consistently** across all terminals
+- **Preserves scrollback** by re-outputting history
+- **Avoids artifacts** from unpredictable reflow
+- **No race conditions** from cursor queries
+- **Handles all resize types** (horizontal and vertical)
+
+## Dependencies
+
+- `ratatui` - Terminal UI framework (forked Terminal class)
+- `crossterm` - Cross-platform terminal manipulation
+- `anstyle-parse` - ANSI/SGR-aware line segmentation (production)
+- `unicode-width` - Unicode character width calculation
+- `termwiz` - **dev-dependency only**; reference splitter for
+  `tests/segment_differential.rs` (not linked into shipped binaries)
+
+## References
+
+- [anstyle-parse](https://crates.io/crates/anstyle-parse)
+- [Ratatui wrapping discussion](https://github.com/ratatui/ratatui/issues/1426)
+
+
+## License / attribution
+
+This crate includes a forked `Terminal` implementation derived from [ratatui](https://github.com/ratatui/ratatui)
+(MIT / Apache-2.0). See `NOTICE` in this directory and the repository root `THIRD-PARTY-NOTICES`.