fix(tty): restore cursor visibility on process exit

[robobun]

Summary

• When stdout is a TTY, write the cursor-show escape sequence (\x1b[?25h) before restoring termios settings on process exit
• This ensures the terminal cursor is always visible after Bun exits, fixing the issue where cursor remains hidden after running Ink applications on macOS

Test plan

• Added regression test test/regression/issue/26642.test.ts (runs on macOS only due to PTY requirements)
• Manual verification: run an Ink app that hides cursor, confirm cursor is visible after exit

🤖 Generated with Claude Code

[robobun]

^{Updated 3:07 PM PT - Jan 31st, 2026}

❌ Your commit 7b848af6 has 5 failures in Build #36307 (All Failures):

• test/js/node/worker_threads/worker_threads.test.ts - pid 4122 segmentation fault on 🐧 13 x64-baseline
• test/regression/issue/tui-app-tty-pattern.test.ts - 1 failing on 🐧 25.04 aarch64
• test/regression/issue/tui-app-tty-pattern.test.ts - 1 failing on 🍎 14 aarch64
• test/regression/issue/tui-app-tty-pattern.test.ts - 1 failing on 🐧 13 aarch64
• test/regression/issue/tui-app-tty-pattern.test.ts - 1 failing on 🍎 13 aarch64
• test/regression/issue/tui-app-tty-pattern.test.ts - 1 failing on 🐧 25.04 x64
• test/regression/issue/tui-app-tty-pattern.test.ts - 1 failing on 🐧 13 x64
• test/regression/issue/tui-app-tty-pattern.test.ts - 1 failing on 🐧 25.04 x64-baseline
• test/regression/issue/tui-app-tty-pattern.test.ts - 1 failing on 🐧 13 x64-baseline
• test/regression/issue/tui-app-tty-pattern.test.ts - 1 failing on 🍎 14 x64
• test/regression/issue/tui-app-tty-pattern.test.ts - 1 failing on 🐧 13 x64-asan
• test/regression/issue/tui-app-tty-pattern.test.ts - 1 failing on 🍎 13 x64
• test/regression/issue/tty-reopen-after-stdin-eof.test.ts - 2 failing on 🍎 14 aarch64
• test/regression/issue/tty-reopen-after-stdin-eof.test.ts - 2 failing on 🐧 25.04 aarch64
• test/regression/issue/tty-reopen-after-stdin-eof.test.ts - 2 failing on 🐧 13 aarch64
• test/regression/issue/tty-reopen-after-stdin-eof.test.ts - 2 failing on 🍎 13 aarch64
• test/regression/issue/tty-reopen-after-stdin-eof.test.ts - 2 failing on 🍎 14 x64
• test/regression/issue/tty-reopen-after-stdin-eof.test.ts - 2 failing on 🐧 25.04 x64
• test/regression/issue/tty-reopen-after-stdin-eof.test.ts - 2 failing on 🐧 13 x64
• test/regression/issue/tty-reopen-after-stdin-eof.test.ts - 2 failing on 🐧 25.04 x64-baseline
• test/regression/issue/tty-reopen-after-stdin-eof.test.ts - 2 failing on 🐧 13 x64-baseline
• test/regression/issue/tty-reopen-after-stdin-eof.test.ts - 2 failing on 🐧 13 x64-asan
• test/regression/issue/tty-reopen-after-stdin-eof.test.ts - 2 failing on 🍎 13 x64
• test/js/node/readline/stdin-pause-pty.test.ts - 1 failing on 🍎 14 aarch64
• test/js/node/readline/stdin-pause-pty.test.ts - 1 failing on 🍎 13 aarch64
• test/js/node/readline/stdin-pause-pty.test.ts - 1 failing on 🐧 25.04 aarch64
• test/js/node/readline/stdin-pause-pty.test.ts - 1 failing on 🐧 13 aarch64
• test/js/node/readline/stdin-pause-pty.test.ts - 1 failing on 🐧 3.22 aarch64
• test/js/node/readline/stdin-pause-pty.test.ts - 1 failing on 🍎 13 x64
• test/js/node/readline/stdin-pause-pty.test.ts - 1 failing on 🐧 3.22 x64
• test/js/node/readline/stdin-pause-pty.test.ts - 1 failing on 🍎 14 x64
• test/js/node/readline/stdin-pause-pty.test.ts - 1 failing on 🐧 3.22 x64-baseline
• test/js/node/readline/stdin-pause-pty.test.ts - 1 failing on 🐧 25.04 x64
• test/js/node/readline/stdin-pause-pty.test.ts - 1 failing on 🐧 25.04 x64-baseline
• test/js/node/readline/stdin-pause-pty.test.ts - 1 failing on 🐧 13 x64
• test/js/node/readline/stdin-pause-pty.test.ts - 1 failing on 🐧 13 x64-baseline
• test/js/node/readline/stdin-pause-pty.test.ts - 1 failing on 🐧 13 x64-asan
• test/integration/next-pages/test/dev-server.test.ts - 1 failing on 🍎 14 aarch64

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🧪   To try this PR locally:

bunx bun-pr 26643

That installs a local version of the PR into your bun-26643 executable, so you can run:

bun-26643 --bun

[coderabbitai]

Walkthrough

Adds terminal cursor visibility restoration to Bun's exit cleanup process for TTY outputs, ensuring the cursor is shown on exit. Includes a regression test verifying this behavior on non-Windows platforms.

Changes

Cohort / File(s)	Summary
Terminal Cursor Visibility src/bun.js/bindings/c-bindings.cpp	Implements cursor visibility restoration in the exit cleanup handler by writing the CSI escape sequence for showing cursor when stdout is a TTY, with retry logic for signal interruptions.
Regression Test test/regression/issue/26642.test.ts	Adds test verifying cursor-show escape sequence is output when a process exits with stdout attached to a TTY, skipped on Windows and non-macOS platforms.

🚥 Pre-merge checks | ✅ 2

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely summarizes the main change: restoring cursor visibility on TTY process exit, which is the primary objective of this changeset.
Description check	✅ Passed	The description covers both required sections with clear details: it explains what the PR does (cursor visibility fix), how it works (escape sequence), and describes the test plan with manual verification steps.

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