Support Cross-Workspace Session Listing via --list-all-sessions

[paasshme]

Feature Request: Support Cross-Workspace Session Listing via --list-all-sessions

What would you like to be added?

I would like to add a new command-line option --list-all-sessions to the Gemini CLI, allowing developers to view their chat sessions across all registered workspaces.

This feature should support two distinct listing modes:

1. Flat Chronological Timeline (Default Mode): Prints a globally ordered, descending timeline (newest first) of all chat sessions across all workspaces, with each session clearly labeled with its parent workspace slug/directory and marking the active workspace with an asterisk (*).
2. Grouped Workspace View (Optional Mode): Triggered by a supplementary --group-by-workspace (or -g / --group) option, this mode groups and lists sessions under their respective workspace absolute paths.

Why is this needed?

Currently, --list-sessions only lists chat sessions belonging to the current directory's workspace. However, developers often work across multiple projects and workspaces. When trying to resume an old session or clean up disk space, it is difficult to remember which project has which sessions.

Having a global --list-all-sessions option allows developers to get a centralized, multi-project overview of their past work, helping them find and resume specific sessions across different contexts without changing directories.

Additional context

Proposed Flat Timeline Output (Default):

Latest Sessions Across All Workspaces:

  * 1. Researching Session Listing [gemini-cli] (10 minutes ago, current) [9a7c82de]
    2. Fix broken tests [another-project] (30 minutes ago) [f8e7d6c5]
  * 3. Hello World Prototype [gemini-cli] (1 hour ago) [1a2b3c4d]

Proposed Grouped Workspace Output (via --group):

All Workspaces Sessions:

Workspace: /home/<username>/workspace/gemini-cli (active) [gemini-cli] (2 sessions):
  1. Researching Session Listing Implementation (10 minutes ago, current) [9a7c82de]
  2. Hello World Prototype (1 hour ago) [1a2b3c4d]

Workspace: /home/<username>/workspace/another-project [another-project] (1 session):
  1. Fix broken tests (1 day ago) [f8e7d6c5]

[gemini-cli]

Effort Analysis:
The Gemini CLI uses a ProjectRegistry (defined in packages/core/src/config/projectRegistry.ts) to map absolute project paths to short IDs, which in turn determine the session storage paths under ~/.gemini/tmp/<shortId>/chats (as seen in packages/core/src/config/storage.ts). Implementing --list-all-sessions requires a new orchestration logic in packages/cli/src/utils/sessions.ts to: 1) Load and parse the global projects.json registry. 2) Iterate over all registered projects. 3) Dynamically construct storage instances or session paths for each project. 4) Aggregate and format session metadata using existing getSessionFiles from packages/cli/src/utils/sessionUtils.ts. This task spans multiple packages (cli and core) and involves complex data aggregation and multi-workspace terminal output formatting, mapping it to effort/medium under the 'Cross-Component Refactors' and 'Tooling & Output Parsers' guidelines.