fix: make non-interactive shell rendering consistent with interactive

[naaa760]

TLDR

• Fixed inconsistent shell rendering between interactive and non-interactive modes by replacing basic stripAnsi() with proper terminal emulation in child process fallback.

Dive Deeper

• Non-interactive shells used simple stripAnsi() while interactive shells used terminal emulation, causing flicker and raw escape codes in output. Now both modes use the same @xterm/headless approach for consistent rendering.

Testing Matrix

	🍏	🪟	🐧
npm run	✅	✅	✅
npx	✅	✅	✅
Docker	✅	✅	✅
Podman	✅	-	-
Seatbelt	✅	-	-

Linked issues / bugs

Fixes #10494

[gemini-code-assist]

Summary of Changes

Hello @naaa760, 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 an inconsistency in how shell output was rendered between interactive and non-interactive execution modes. Previously, non-interactive shells used a simple ANSI stripping mechanism, leading to visual glitches and uninterpreted escape codes. The changes introduce a unified approach by leveraging @xterm/headless terminal emulation for all child process output, ensuring a consistent, properly rendered experience regardless of the execution context. This enhancement improves the visual fidelity and readability of shell command outputs.

Highlights

• Consistent Shell Rendering: Unified shell output processing for both interactive and non-interactive modes, eliminating inconsistencies like flicker and raw ANSI escape codes.
• Terminal Emulation: Replaced basic stripAnsi() with @xterm/headless terminal emulation for robust handling of ANSI escape sequences.
• Configurable Shell Execution: Added shellExecutionConfig to allow specifying terminal dimensions (width, height) and a custom pager for child processes.
• Dynamic Output Rendering: Implemented a new rendering mechanism that processes terminal output, supports color, and includes dynamic line trimming for cleaner display.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

Footnotes

1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

[gemini-code-assist]

Code Review

This pull request does a great job of unifying the rendering logic for interactive (PTY) and non-interactive (child process) shell executions by using @xterm/headless for both. This resolves inconsistencies and improves the user experience. The code changes are well-structured. I've found one performance issue related to how binary file progress is calculated in the child process fallback, which could be problematic for large files. My detailed feedback is in the comment below.

[gemini-code-assist]

The use of outputChunks.reduce() to calculate totalBytes on every data chunk can be inefficient, especially for large binary files, as it re-iterates over the entire outputChunks array each time. This can lead to significant performance degradation.

A more efficient approach would be to maintain a running total of bytes received. To implement this, you could:

1. Initialize a totalBytes counter to 0 (e.g., around line 198).
2. Increment this counter with data.length each time a new chunk is received (e.g., at line 298, after outputChunks.push(data)).
3. Replace this reduce block with the totalBytes counter when emitting the binary_progress event.