[FEATURE] Show --resume-friendly session id at start of convo

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

Often I have a Claude Code conversation in my terminal scrollback, but there's no good way to resume it without launching claude --resume and trawling through convo history.

And when looking at the claude --resume history, it's hard to find a target convo since all you get is claude's generated title of the convo. I might have dozens of similar convos in a day, and it takes trial and error to find the convo I'm looking for.

Proposed Solution

When user launches claude, show the session ID so the user can easily --resume <id>.

Example:

$ claude

 ▐▛███▜▌   Claude Code v2.1.29
▝▜█████▛▘  Opus 4.5 · Claude Max · Session 1c46ca4a-5107-405d-b2c4-9e6d92f9dc10
  ▘▘ ▝▝    ~/project

───────────────────────────────────────────────────────────────────────────
❯ Try "how do I log an error?"
───────────────────────────────────────────────────────────────────────────

Alternative Solutions

If I know I want to resume a claude session elsewhere, I'll do /rename foo and claude -r foo. But it's clunky, and it doesn't help me in cases where the claude process has been killed (but is still visible in scrollback) -- a common case for me.

A less invasive solution is to expose a sessionId to the statusline script so that we can add it ourselves:

$ claude

 ▐▛███▜▌   Claude Code v2.1.29
▝▜█████▛▘  Opus 4.5 · Claude Max
  ▘▘ ▝▝    ~/project

───────────────────────────────────────────────────────────────────────────
❯ Try "how do I log an error?"
───────────────────────────────────────────────────────────────────────────
  23.5k / 200k | Session 1c46ca4a-5107-405d-b2c4-9e6d92f9dc10

Priority

Low - Nice to have

Feature Category

Interactive mode (TUI)

Use Case Example

_No response_

Additional Context

Potential caveat: /fork

❯ /fork
  ⎿  Forked conversation. You are now in the fork.
     To resume the original: claude -r c888bc57-6d6a-4167-a4c8-fc48fdcc2afb

As long as /fork saves the "original" convo to a fresh session ID, then the session ID in the claude launch banner won't be stale.