Every answer to “Fork list”

Lands on the fork's detail, with a toast

Route: /settings/selection-lists/{fork.id} from list.id in the 201 body. The detail shows the editable 4.0.0 value editor plus the provenance card in its “comparison unavailable” state (frame 7): under 4.1.0 the 201 carries only forked_from.revision and the source exposes no current revision, so a new fork is never shown as “up to date”. The list index is refreshed: the common Priority leaves the Common group and the fork appears under Your organization.

Private draft variant

Existing fork, active

Shown on arrival at the existing fork's detail (the dialog closes and navigates, as for 201). Not an error: no red, no retry.

Existing fork, archived (it was the “revert to common”)

“Restore” is PATCH {"status":"active"} and renders only when the fork's editable is true. Its answers are below — a 403 is branched on code, never read as “no permission” by status alone.

Restoring — PATCH {"status":"active"} in flight

Native disabled while in flight, so a second activation cannot send a second request.

Restore refused — 403 QUOTA_EXCEEDED · scope org_lists | user_lists

user_lists

“The person who created this fork already has the most active lists they may create (25 of 25). The fork stays archived.”

other scope

“A limit was reached. The fork stays archived.”

Un-archiving rechecks org_lists and, for a list a user created, that creator's user_lists — the same scope-driven copy as the fork refusal (quota), with numbers from limit/current. user_lists counts the fork's creator, who may not be the person restoring it, so it never says “you”.

Restore refused — 403 FORBIDDEN

Only code: FORBIDDEN reaches this message; QUOTA_EXCEEDED shares the 403 status and renders the quota copy instead.

409 CONFLICT · reason fork_exists

The 409 carries no fork id (you can't read it), so there is nothing to link to and the UI does not invent one. Not retryable. No escalation to an organization admin: list permissions are instance-only, so a tenant admin holds no manage_access on the fork either — only its owner can act.

409 CONFLICT · reason fork_not_applicable

Defensive only: the CTA is never offered on an org/private list (frame 3). Reaching this means stale data; the detail reloads on close.

409 CONFLICT · no reason — the key is taken by another list

The plain 409 proves only the key collision. The colliding list may be archived, private or otherwise unreadable to you, so the copy never says forms use it, never names or links it, and the UI looks nothing up. “Not a fork of this common list” is derivable: a fork of this source would have answered 200 or fork_exists.

403 QUOTA_EXCEEDED · scope org_lists | user_lists | list_items

Copy is chosen by scope, numbers come from limit/current — the approved 4.0.0 QuotaWarning wording. An unknown scope falls back to “A limit was reached”.

400 VALIDATION_ERROR — source over 5000 values

Server-decided only — the dialog does not pre-check the size. An organization may already hold a fork of this source the page can't see (archived, so the key lookup skips it); that request answers 200 with the existing fork and copies nothing (existing, archived → Restore), and a client-side cap would have blocked it. Confirm stays enabled; this message renders only from the service's 400.

403 FORBIDDEN — you can't create lists

After this the detail page replaces its Fork CTA with this explanation for the rest of the session.

404 NOT_FOUND — the source is gone or unreadable

Network failure / 5xx — outcome unknown

Retry re-sends the same body; the service is idempotent per (organization, source), so a fork created by the lost request comes back as 200 → existing.