fix(core): "gemini --resume crash" handle EBADF error when PTY fd is stale on session resume

[mini2s]

Summary

Fix ioctl(2) failed, EBADF crash when using gemini --resume due to stale PTY file descriptors.

Details

Add EBADF (bad file descriptor) to the error codes that are safely ignored in ShellExecutionService.resizePty()'s catch block.

Background: When resuming a session, the PTY fd from the previous session has already been closed (the process exited). However, ExecutionLifecycleService.isActive() still returns true because resume re-attaches the execution. The resize call invokes ioctl(fd, TIOCSWINSZ, ...) on the stale fd and gets EBADF instead of ESRCH, causing an unhandled exception that crashes the process.

Fix: Treat EBADF the same as the already-handled ESRCH and Windows PTY exit errors — silently ignore it.

Files changed:

• packages/core/src/services/shellExecutionService.ts — add EBADF check in the resizePty catch block (+3 lines)

Related Issues

#27327

How to Validate

1. Start an interactive gemini session and run a command that spawns a background task
2. Exit the session with exit or Ctrl+C
3. Run gemini --resume to restore the session
4. Confirm the ioctl(2) failed, EBADF error no longer occurs

Unit tests:

npm test -w @google/gemini-cli-core -- src/services/shellExecutionService.test.ts

All 27 PTY-related tests pass.

Pre-Merge Checklist

• Updated relevant documentation and README (if needed)
• Added/updated tests (if needed) — existing tests provide coverage
• Noted breaking changes (if any)
• Validated on required platforms/methods:
  • MacOS
    • npm run
    • npx
    • Docker
    • Podman
    • Seatbelt
  • Windows
    • npm run
    • npx
    • Docker
  • Linux
    • npm run
    • npx
    • Docker

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a crash occurring during gemini session resumption. When a session is resumed, the system occasionally attempts to resize a PTY using a stale file descriptor, resulting in an EBADF error. By explicitly catching and ignoring this error, the service now gracefully handles the state mismatch, improving overall application stability.

Highlights

• Error Handling Update: Added EBADF to the list of ignored error codes in ShellExecutionService.resizePty to prevent crashes during session resumption.
• Stability Improvement: Ensured that stale PTY file descriptors do not trigger unhandled exceptions when attempting to resize the terminal window upon resuming a session.

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[gemini-code-assist]

Code Review

This pull request updates the ShellExecutionService to ignore EBADF (bad file descriptor) errors when attempting to resize a PTY. This change specifically addresses scenarios where a session is resumed and the original PTY file descriptor has become stale, preventing unnecessary errors from being thrown. I have no feedback to provide as there were no review comments to evaluate.

[mini2s]

/gemini review

[gemini-code-assist]

Code Review

This pull request modifies the ShellExecutionService in packages/core to include EBADF (bad file descriptor) in the list of ignored errors during PTY resizing. This change ensures that stale file descriptors encountered when resuming a session do not trigger unnecessary exceptions, aligning the behavior with existing handling for ESRCH and Windows-specific PTY errors. I have no feedback to provide.

[mini2s]

@gemini-code-assist Please process this PR

[gemini-code-assist]

I have reviewed the changes in packages/core/src/services/shellExecutionService.ts. The implementation correctly handles the EBADF error by adding it to the existing catch block, which is consistent with the current error handling strategy for stale PTY file descriptors. No further issues were identified.

[gemini-cli]

Hi there! Thank you for your interest in contributing to Gemini CLI.

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This PR will be closed in 7 days if it remains without that designation. We encourage you to find and contribute to existing 'help wanted' issues in our backlog! Thank you for your understanding.