Agent UX: pm list --sort <field> omits the sort key from the brief projection #1481

Observed (pm 2026.10.15)

$ pm list --status open --limit 2 --sort priority --format json | jq -c '.items[0]|keys'
["id","status","title","type"]

The result is ordered by priority, but the brief projection (id,status,type,title) leaves the sort key out. The ordering is visible but the value behind it isn't. An agent that asked for priority order and reads .priority gets null for every row. Then it either re-runs with --fields id,priority,... or misreports priorities. That happened in this session: a backlog survey printed pnull for every item.

The same applies to --sort updated_at / created_at / deadline.

Proposal

When --sort <field> is given and --fields is not, add the sort field to the brief projection. In TOON that is one extra column. Record it in projection.fields so the omission receipt stays accurate. An explicit --fields stays authoritative.