Scheduled tasks cannot close their own session — archive_session("self") is called but silently never takes effect

What happens

A scheduled task is instructed to archive its own session as its final action,
via the session-management archive tool with session_id: "self". The call is
made. The session is not archived. Nothing in the transcript indicates a failure
— the transcript simply ends with the tool call and no result.

Expected

Either the session archives, or the call returns an error the run can see and
report in its final message.

Impact

Every scheduled run leaves a finished session behind. With five daily tasks that
is roughly 35 abandoned sessions a week. 90 had accumulated before they were
noticed and archived by hand.

Evidence

• Two daily scheduled tasks have carried the self-archive instruction since

19 July 2026.

• 28 of their sessions were still open on 14 September 2026. Every one of them

ran after the instruction was added — earliest 13 August, latest that morning.

• Two transcripts were inspected end to end. In both, the final entry is the

archive call. No result, no error. Both sessions were still listed as open the
following day.

• The same tool works normally from an attended session: 87 sessions were

archived in one pass, none refused.

Likely cause (not verified from outside)

The archive path appears to need a user confirmation, which an unattended run has
nobody to give. The tool's own description also notes that a session which is
"still working (mid-turn, or with live background work)" is not archived — and a
session archiving itself is by definition mid-turn.

Either way the defect is the silence: from inside the run, nothing distinguishes
"archived" from "call swallowed".

Minimum useful fix

If self-archive cannot work unattended, make the call return an explicit error so
the run can report it, instead of appearing to succeed. Today the instruction to
self-close looks obeyed and is not.

Environment

Claude Code desktop app (Code tab), macOS (Darwin 25.5.0), scheduled tasks.