feat(sessions): add resuming to geminiChat and add CLI flags for session management

[bl-ue]

This PR implements session resuming in geminiChat.ts, session selection, listing, and deletion functions, and CLI flags --list-sessions, --delete-session <id|index>, and --resume <id|index>.

Closes #1530

---

Note: This PR is the 4th in a series of PRs that implement automatic chat recording and resuming in both interactive and non-interactive modes, with command line flags for non-interactive resuming and session management, and an interactive session browser.

PR #4401 was the original monolithic PR, which implemented this feature from the ground up. It's too large to merge as-is, however, and so it was broken up into several smaller PRs, of which this PR is the 4th.

Please see #4401's description for the full context of this PR. The original monolithic PR's description contains a detailed analysis of the entire system, with an example of the recording JSON and a demo video.

[gemini-code-assist]

Summary of Changes

Hello @bl-ue, 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, the fourth in a series, significantly enhances session management for the Gemini CLI. It primarily focuses on enabling session resumption in non-interactive mode and providing comprehensive command-line tools for listing and deleting chat sessions. Key changes include adding new CLI arguments for session control, integrating session loading and history conversion into the non-interactive chat flow, and introducing new utility functions and a SessionSelector class to manage session data efficiently. This work lays the groundwork for more robust chat recording and interactive session browsing features.

Highlights

• Session Management CLI Flags: Introduces new CLI flags --resume, --list-sessions, and --delete-session for managing chat sessions directly from the command line. The --resume flag allows users to continue a previous conversation by specifying a session ID, index, or 'latest'. The --list-sessions flag displays all recorded sessions for the current project, and --delete-session enables removal of specific sessions.
• Non-Interactive Session Resumption: Adds the capability to resume Gemini chat sessions in non-interactive mode. When --resume is used, the CLI loads the specified session's history and continues the conversation from that point, ensuring continuity across non-interactive runs.
• Session Data Conversion and Utilities: New utility functions and a SessionSelector class are introduced to handle session data. convertSessionToHistoryFormats transforms stored session messages into formats suitable for both UI display and the Gemini client API. SessionSelector facilitates finding and loading sessions based on various identifiers, and new helper functions extractFirstUserMessage and formatRelativeTime improve session listing readability.

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 is a great step forward in improving session management. The new CLI flags for listing, deleting, and resuming sessions are valuable additions. The implementation is solid, especially the logic in SessionSelector for resolving session identifiers.

I've found one high-severity issue related to parsing session identifiers for deletion that could lead to deleting the wrong session. Please see the detailed comment below.

[bl-ue]

/gemini review

[gemini-code-assist]

Code Review

This is a great step forward in implementing session management. The new CLI flags for listing, resuming, and deleting sessions are well-implemented, and the underlying logic for session resolution and history conversion is comprehensive. I have one high-severity suggestion regarding code duplication that will improve the long-term maintainability of this new functionality. Overall, excellent work on this complex feature.

[mrcabbage972]

I tried to resume a session, but the previous content of the session wasn't displayed. Is that a bug?

[mrcabbage972]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces a significant feature: session management for the CLI. It adds the ability to list, delete, and resume previous chat sessions through new command-line flags (--list-sessions, --delete-session, and --resume). The implementation is well-structured, with logic for session discovery, selection, and data conversion neatly encapsulated in new utility files and React hooks. The changes span both interactive and non-interactive modes, ensuring a consistent experience. The addition of comprehensive unit tests for the new functionality, including argument parsing, session data conversion, and the new UI hooks, is commendable and ensures the feature is robust. Overall, this is a solid contribution that greatly enhances the usability of the CLI. I found no critical or high-severity issues in the implementation.

[bl-ue]

Hi @mrcabbage972, thank you for approving the tests. I fixed the failing ones—they were caused by changes from my merges of main over time.

[bl-ue]

Next: #13300

[arjun810]

@bl-ue this has a small bug, where when you try to resume a session noninteractively with stdin, it doesn't accept it and gives you this error:

When resuming a session, you must provide a message via --prompt (-p) or stdin

the check on line 262 ( if (argv.resume && !argv.prompt && !process.stdin.isTTY) ) isn't quite right

[bl-ue]

Hi @arjun810! Thank for you for catching that! The check was out of date anyway. Fixed in #13520.