[Research] Lightweight TUI replacement - Raw ANSI vs React/Ink

[randomm]

Problem

Current binary is ~95MB and feels sluggish. The TUI uses Ink (React-based terminal UI) which adds significant overhead.

Research Direction

Explore replacing the React/Ink TUI with a lightweight raw ANSI implementation.

Proposed Architecture

┌─────────────────────────────────────────────────────┐
│ claude-sonnet-4-20250514 · build                    │ ← sticky header
├─────────────────────────────────────────────────────┤
│                                                     │
│ ... chat content with syntax highlighting ...       │ ← scrollable
│                                                     │
├─────────────────────────────────────────────────────┤
│ ⏳ explore (12s) │ ⏳ websearch (3s) │ ✓ grep       │ ← sticky jobs bar
├─────────────────────────────────────────────────────┤
│ > _                                                 │ ← input
└─────────────────────────────────────────────────────┘

Library Comparison

Library	Sticky regions	Syntax HL	Size	Speed
terminal-kit	✓ screenBuffer	External	~150KB	Fast
blessed	✓ boxes	External	~200KB	Medium
Raw ANSI	Manual cursor	External	0	⚡ Fastest
ink (current)	✓ (React)	External	~200KB+	Slower

Recommendation: Raw ANSI + cli-highlight

• Zero framework overhead
• ~550 lines total code
• Dependencies: picocolors (~5KB), cli-highlight (~30KB)

Core Components Needed

1. terminal.ts (~150 lines) - Region management, cursor control
2. main.ts (~300 lines) - Event loop, commands
3. format.ts (~100 lines) - Markdown, code highlighting

Key Features

• Sticky header (model/agent)
• Scrollable chat region
• Sticky jobs bar with live timers
• Input line with cursor

Integration with Background Tasks

Jobs bar would show running background tasks with elapsed time, updating every second.

Research Questions

1. What's the actual size breakdown of current binary? (Bun runtime vs app code vs deps)
2. Can we achieve <20MB binary with raw ANSI approach?
3. What TUI features would we lose? Are they essential?
4. How much of packages/opencode/src/cli/cmd/tui/ can be deleted?

Out of Scope (for now)

• Mouse support
• Complex layouts
• Rich widgets

Acceptance Criteria

• Research current binary size breakdown
• Prototype raw ANSI terminal abstraction
• Measure performance difference
• Document trade-offs
• Decision: migrate or keep Ink

[randomm]

Research Complete: TUI Replacement Options

Bundle Size Comparison

Library	Publish Size	Install Size	Maintenance
@OpenTui (current)	~5 MB	~15-20 MB binary	Custom/Active
Ink (React)	336 KB	5.53 MB	Active
@clack/prompts	167 KB	469 KB	Active
Blessed	1.58 MB	1.58 MB	❌ Unmaintained (2015)
Raw ANSI	~0	~0	N/A

Recommendations

Option 1: Clack Prompts + Custom Chat (Best Balance)

• 97% bundle reduction (~14-19 MB savings)
• Use Clack for dialogs/prompts, Raw ANSI for chat stream
• Effort: 2-4 weeks, 400-700 LOC

Option 2: Pure Raw ANSI (Maximum Reduction)

• 99% bundle reduction
• High effort: 8-16 weeks, 800-2000 LOC

Option 3: Stay with @OpenTui (Status Quo)

• No migration needed
• 15-20 MB footprint acceptable for AI coding tool?

Next Steps

1. Define if 15-20 MB is acceptable
2. Prototype minimal raw ANSI chat TUI (1-2 days) to test feasibility
3. Decision based on size vs. dev effort tradeoff

[randomm]

Completed in PR #51. Implemented lightweight TUI (oclite) with raw ANSI terminal - 4.6KB vs 84MB original. Files: src/cli/lite/*.ts

[randomm]

Reopening - oclite scaffolding exists but is NOT connected to the LLM backend. It's still a demo, not a working TUI replacement.

[randomm]

Research completed. Findings documented in #76. Decision: Raw ANSI append-only model (like AIChat and Aider), no framework adoption. See #73, #74, #75 for action items.