[FEATURE] Let the agent set a semantic work phase on a session (Brainstorming / Implementing / Shipping)

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

When I run several Claude Code sessions at once, the session list tells me the title and whether a session is running or waiting. It doesn't tell me what stage the work is in. I have to open each session to find out whether it's still brainstorming, partway through implementing, or ready to ship. The agent already knows which stage it's in, but it has no way to show that.

Proposed Solution

Give each session a short status or phase field that the agent can set itself, separate from the title:

• Expose it as a tool or a session-management call, for example set_session_status({ status: "Implementing" }), and also as a hook output field so skills and hooks can set it.
• Show it next to the session title everywhere sessions are listed: the desktop and web sidebar, the VS Code session list, /resume, claude agents, Remote Control and mobile. Also pass it to the statusLine JSON.
• Accept free text, with an optional suggested set such as Brainstorming / Planning / Implementing / Testing / Shipping / Blocked.
• The user can always override or clear it, and a phase set by the user is never overwritten by automatic title generation.

Alternative Solutions

• Putting the phase into the title with /rename or set_session_title. This mixes up "what this session is" with "where it stands," and automatic title regeneration often overwrites it (see #32150, #96829).
• User-defined session status (#92022) and user-assigned status colors (#90763) are close, but the user has to set them by hand. This request is for the agent to set the phase as it works.

Priority

Medium - Would be very helpful

Feature Category

Interactive mode (TUI)

Use Case Example

1. I start a session to explore an idea. The agent sets the phase to "Brainstorming."
2. Once we agree on a plan, it changes the phase to "Implementing" and starts coding.
3. After tests pass and it opens a PR, it changes the phase to "Shipping."
4. Looking at my session list, I can see right away which sessions need design input, which are busy, and which are ready for review, without opening any of them.

Additional Context

I've asked for the same thing in other tools:

• Codex: https://github.com/openai/codex/issues/48674
• Cursor: https://forum.cursor.com/t/let-agents-set-their-own-chat-title-status-programmatically-e-g-dev-active/166385/6

Related Claude Code requests (title rename, not phase): #25045, #33165, #40346, #92022.

• John's AI Assistant