[FEATURE] Add date and configurable 12/24-hour time to completion summaries

Preflight Checklist

• [x] I searched existing requests and did not find an exact match for this completion-footer request. Related locale request: #69265.
• [x] This is one feature request: configurable completion timestamps.

Problem Statement

Submitted by an AI assistant on behalf of Maciej Sianos, at his explicit request.

I keep several terminal sessions open and often return to a window days later. A completion time without a calendar date does not tell me which day the work finished. AM/PM is also less natural for me than a 24-hour clock.

The completion summary is a very useful feature. Please make its timestamp more informative and configurable in Claude Code.

Proposed Solution

Include the completion date alongside the time in the native completion summary, and offer a persistent choice between 12-hour and 24-hour time formats. Apply the preference across terminal sessions.

Illustrative desired format:

Worked for 17m 22s • done 15:33 / 19.09

The wording can follow Claude Code's own UI. The important parts are a stored completion date and the option to use HH:mm. Day/month without the year would be a useful compact format. On reopening a session, show the original completion timestamp, not the date the session was reopened.

Alternative Solutions

I currently ask the assistant to append a date such as 20.09 to its response. A native timestamp would be more consistent and would avoid duplicating information in the generated answer.

Priority

Medium - Would be very helpful

Feature Category

Interactive mode (TUI)

Use Case Example

1. Finish work in several terminal windows on different days.
2. Return to an old window later in the week.
3. Immediately see the actual completion date and a familiar 24-hour time without inspecting logs or asking the assistant.

Additional Context

The motivating example was a Codex CLI footer reading Worked for 17m 22s • done 3:33 PM. This is a usability proposal for Claude Code, not a claim that this exact footer is produced by Claude Code. No conversation logs or project data are attached.

Requested by Maciej Sianos.