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## Summary
This PR implements a native Zig REPL for Bun with full TUI (Text User
Interface) support, providing a modern and feature-rich interactive
experience.
### Features
- **Syntax highlighting** using `QuickAndDirtySyntaxHighlighter` for
colorized JavaScript code
- **Full line editing** with Emacs-style keybindings:
- `Ctrl+A/E` - Move to start/end of line
- `Ctrl+B/F` - Move backward/forward one character
- `Ctrl+K/U` - Kill to end/start of line
- `Ctrl+W` - Delete word backward
- `Ctrl+L` - Clear screen
- Arrow keys for cursor movement
- **Persistent history** with file storage (`~/.bun_repl_history`)
- Up/Down arrow for history navigation
- `Ctrl+P/N` also works for history
- **Tab completion** for properties and commands
- **Multi-line input support** with automatic continuation detection
- **REPL commands**: `.help`, `.exit`, `.clear`, `.load`, `.save`,
`.editor`
- **Special variables**:
- `_` - Contains the result of the last expression
- `_error` - Contains the last error that occurred
- **Result formatting** with `util.inspect` integration
- **replMode transforms** for proper REPL semantics:
- Expression result capture via `{ value: expr }` wrapper
- Variable hoisting for persistence across REPL lines (`const`/`let` →
`var`)
- Function and class declaration hoisting
- Top-level await support with async IIFE wrapper
- Object literal detection (no parentheses needed for `{ a: 1 }`)
### Implementation
The REPL is implemented in pure Zig (`src/repl.zig`) with C++ bindings
for JSC integration:
- Uses raw terminal mode for character-by-character input
- Integrates with Bun's existing `VirtualMachine` for JavaScript
evaluation
- Uses the parser with `repl_mode=true` to apply REPL-specific AST
transforms
- Provides access to all Bun globals (`Bun`, `Buffer`, `console`,
`process`, etc.)
### Files Changed
- `src/repl.zig` - Main REPL implementation (~1500 lines)
- `src/cli/repl_command.zig` - CLI entry point
- `src/bun.js/bindings/bindings.cpp` - C++ REPL functions
- `src/bun.js/bindings/headers.h` - C++ declarations
- `src/ast/repl_transforms.zig` - REPL-specific AST transforms
(cherry-picked from jarred/repl-mode)
- `test/js/bun/repl/repl.test.ts` - Comprehensive tests
## Test Plan
- [x] Run `bun bd test test/js/bun/repl/repl.test.ts` - 27 tests pass
- [x] Manual testing of interactive features:
- Basic expression evaluation
- Special variables `_` and `_error`
- History navigation
- Tab completion
- Multi-line input
- REPL commands
- Top-level await
- Variable persistence
- [x] Verified REPL starts without downloading packages (fixes #26058)
🤖 Generated with [Claude Code](https://claude.com/claude-code)
---------
Co-authored-by: Claude Bot <claude-bot@bun.sh>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Jarred Sumner <jarred@jarredsumner.com>