Agent UX: full-item --stdin-json update silently ignores edited notes and reports success #1343

Problem

On installed @unbrained/pm-cli@2026.9.28, pm update <id> --stdin-json silently ignores an edited notes array in a full item document. It exits 0 and reports changed_field_count: 0, while a subsequent full read shows the old note. pm update --help describes --stdin-json as reading a full item JSON document; #438 explicitly intended a get → modify → update round trip. This matters to agents correcting evidence notes because a successful no-op can leave stale context in the tracker.

Minimal reproduction

tracker=$(mktemp -d)
pm --path "$tracker" init --defaults --prefix probe --agent-guidance skip
id=$(pm --path "$tracker" create Chore 'Note round trip' --description 'Disposable repro' --note 'Original evidence' --json | jq -r .id)
pm --path "$tracker" get "$id" --json --full | jq '.item | .notes[0].text = "Corrected evidence"' > /tmp/pm-note-round-trip.json
pm --path "$tracker" update "$id" --stdin-json --json < /tmp/pm-note-round-trip.json
pm --path "$tracker" get "$id" --json --full | jq '.item.notes[0].text'

Observed update response: {"id":"probe-…","status":"open","changed_field_count":0}. Final read returns "Original evidence". I reproduced the same behavior with a second full-item payload on a disposable tracker; there were no validation errors.

Expected

Either apply a valid note edit atomically and record the correction in append-only history, or reject unsupported notes changes with a nonzero, field-specific error that points to pm notes --edit. A successful no-op should only mean the submitted document matches the persisted item.

pm notes --edit <index> --add <text> is an available workaround. This issue is specifically about the silent full-document update result; no pm-cli source files were changed in the reporting workspace.