Stable Item Read Projections

Tracker reference: pm-b1w8vr.

Item mutation and read-back surfaces share one collection vocabulary: comments, notes, learnings, files, tests, docs, reminders, and events. Every normal pm get and SDK runGet result carries item.collection_counts with all eight keys, including zero values. This gives agents a stable, low-token way to verify a write without requesting complete collection payloads.

brief and standard omit the collection arrays but retain the stable counts. deep, full, and --full include every collection array, normalizing absent collections to [], and retain notes_count, tests_count, and collection_counts. A full projection is therefore a structural superset of the standard item projection rather than a different shape.

Field projections can request collection_counts directly:

pm get pm-example --fields id,updated_at,collection_counts

Package authors receive the same contract from runGet. Do not infer whether a collection exists by checking for an omitted key; use the count projection, or request a full projection when the entries themselves are needed.