Sim REPL on OpenTUI (React)

Date: 2026-06-05

Replaced the hand-rolled raw-mode TUI (the keys/editor/screen/menu stack built earlier the same day) with OpenTUI's React binding. ReplController and the sim run CI/transcript path are unchanged — the React app is a new view over the controller's onOutput/onStatus streams.

Supersedes the same-day pinned input box work — those modules (custom key decoder, line editor, scroll-region painter, modal panels) are deleted. That finding stays as history; this is the live design.

What shipped#

• tui/ (React, @opentui/react): app.tsx (root: scrollbox output + status + input/overlays), picker.tsx (<select> for /layer·/as), help.tsx (scrollable <scrollbox> sheet), use-repl.ts (subscribe controller → state), mount.tsx (createRoot(createCliRenderer()).render).
• Pure + unit-tested: route.ts (submit → action), ansi.ts (forText strips ANSI for <text>).
• Removed: keys.ts, editor.ts, screen.ts, menu.ts, interrupt.ts + their tests. Kept: repl.ts, render.ts, complete.ts, roles.ts, stub-agent.ts, transcript.ts.
• Deps: @opentui/core, @opentui/react, react, @types/react. tsconfig jsx: react-jsx; each .tsx carries a /** @jsxImportSource @opentui/react */ pragma (the binding augments JSX there, not globally).

Why OpenTUI / React#

Real flexbox + scrollbox + input/select with built-in focus/keyboard handling beat bespoke ANSI bookkeeping. React, not Solid, because Bun transpiles plain JSX natively; Solid needs its compile-time jsx-dom-expressions transform (extra Bun plugin plumbing). The heavier React dep is irrelevant for a dev-only sim.

Spike findings (the gate) — see src/gateway/sim/tui/API-NOTES.md#

• Native lib loads and the React reconciler renders under Bun.
• The view is headlessly unit-testable via @opentui/react/test-utils testRender + waitForFrame + mockInput — so app/picker/help have real frame-assertion tests, not just manual smoke.
• <text> does not parse raw ANSI → strip with core stripAnsiSequences. Color is dropped in MVP; future enhancement: convert ANSI → StyledText to restore it.
• <select> inside a borderless flex box collapses to 0 rows — give it an explicit height.
• exitOnCtrlC may process.exit before CliRenderEvents.DESTROY, so mountTui also disposes the controller on a process.once("exit") fallback.

Caveats (accepted)#

• OpenTUI is pre-1.0 ("not for production") + native FFI — fine for a dev-only sim; bun run start (the Slack runtime) never imports it, so production images are unaffected. Pin the version.
• Single-line <input> flattens pasted newlines; multi-line authoring would need <textarea> (deferred). Color fidelity from render.ts is lost until the StyledText enhancement.

Verification#

• bun test — 736 pass (route/ansi/view tests + ReplController transcripts). bun run typecheck clean.
• sim run (CI) — 25/25 transcripts, no TUI mounted.
• Interactive TTY smoke is the remaining manual check (see checklist in the plan, Task 8).

Spec: docs/superpowers/specs/2026-06-05-sim-tui-opentui-design.md Plan: docs/superpowers/plans/2026-06-05-sim-tui-opentui.md