Feature request: allow assistant to rename sessions programmatically (VS Code + Desktop)

Problem

When running multiple Claude Code sessions in parallel (e.g., architecture review, SE dispatch, PR sweep), there's no way to distinguish tabs or sessions at a glance. The /rename slash command exists in the CLI but is not available in VS Code or Claude Desktop, and even in CLI it requires the user to type it manually — the assistant cannot invoke it programmatically.

Desired behavior

1. Assistant can rename sessions — via a tool, API, or built-in command that the assistant can call (not just a user-typed slash command). This would allow session prompts to auto-name sessions on startup (e.g., "arch: PR sweep redesign").

1. Dynamic tab titles in VS Code — when a session is renamed, the VS Code tab title should update to reflect the name. Currently tabs are all generic "Claude Code" with no way to tell them apart.

1. /rename available in VS Code and Desktop — even if the assistant can't invoke it, users should be able to rename sessions in all clients, not just CLI.

Use case

We run a multi-agent platform with ~28 session types (architecture, platform operator, security review, solutions engineer, etc.). Each session has a role and works on specific topics. Being able to auto-name sessions like arch: service health monitoring or se: pr_sweep dispatch would dramatically improve the experience when 3-5 sessions are open simultaneously.

Ideally the assistant would rename at session start based on the role, then update the name as the conversation topic evolves — e.g., arch: tooling visibility deep dive.