auth/actor_lookup_action_specs.ts

actor_lookup RPC spec — authenticated batched id → username/display_name resolver, keyed by actor id.

Powers the labels arc for surfaces that stamp an actor id (bylines, owner columns, grantor labels, audit-log "by" cells). One round trip resolves an array of ids to display strings.

Auth + rate-limit posture

{account: 'required', actor: 'none'} + rate_limit: 'account'. Account-grain — only that the caller is signed in matters, not which actor is calling, so resolution skips the actor phase. The auth gate + per-account rate limit (default 1200/15min) + the {@link ACTOR_LOOKUP_IDS_MAX | per-call cap} bound the batched username-enumeration surface that the cell_list ↔ actor_lookup pair would otherwise present.

If a public-surface byline ever lands (e.g. an unauthenticated gallery), it should resolve via a separate public-safe mechanism (SSR-stamped labels or a per-cell embedded actor label), not by loosening this gate.

Wire shape — info-leak audit

Output: {actors: [{id, username, display_name?}]}. Deliberately omitted:

• account_id — the actor↔account join is a control-plane detail
• email, password/credential fields — never queried
• created_at / updated_at — timing-oracle avoidance
• role / role_grants / session state — separation of concern

display_name is omitted (not null) when actor.name is blank, so clients see undefined rather than a sentinel string. Unknown ids are silently absent from the response — by construction this is an existence-oracle (the caller can diff response ids against request ids), bounded by:

1. rate-limit (per-account, see above),
2. {@link ACTOR_LOOKUP_IDS_MAX} cap per call,
3. actor-uuid intractability (122-bit random),
4. hard-deleted actors are indistinguishable from never-existed (no tombstone oracle — see auth/actor_lookup_queries.ts).

Response order is unspecified — callers index by id when needed.