errors: Document error code 61002

[lmars]

Adds the registry entry for 61002, the push activation failure raised when a device already holds a registration belonging to a different clientId. The code was in use in the SDKs but had no entry in the registry, so it rendered without a title or summary on the docs site.

protocol/errors.json is regenerated via npm run generate:errors.

Verified against the raising code

Every claim in the body was checked against the four SDKs that raise the code, all of which emit it before any registration write:

SDK	Location	Message	Status
ably-java	push/ActivationStateMachine.java:708 (validateRegistration())	Activation failed: present clientId is not compatible with existing device registration	400
ably-cocoa	ARTPushActivationState.m:95 (validateAndSync())	same	not set
ably-dotnet	Push/ActivationStateMachine.cs:226	same	400
ably-js	plugins/push/pushactivation.ts:682	clientId not compatible with local device clientId	400

Specifically:

• The comparison is the clientId held in local device state against the clientId the client is presently authenticated as.
• The registration is left untouched: the SyncRegistrationFailed event is emitted before the PUT / SaveAsync, so the device keeps receiving notifications addressed to the original clientId.
• The failure is permanent, so the documented remediation is deactivate then activate. AfterRegistrationSyncFailed + CalledDeactivate deregisters, and Deregistered calls LocalDevice.reset(), which clears the stored clientId (ably-java LocalDevice.java:139-148).
• Delivery depends on what triggered the check, which is why What you'll see covers both paths: Android sends PUSH_ACTIVATE when activation triggered it and PUSH_UPDATE_FAILED otherwise (ActivationStateMachine.java:557-567); ably-cocoa branches between callActivatedCallback: and callUpdatedCallback: the same way.

Both outbound links resolve (checked against the page sources in ably/docs and with a request to the live site).

Follow-up, out of scope here

Two ably-js quirks noticed while verifying, neither affecting the copy but both possibly worth an issue on ably/ably-js:

• The device clientId is never persisted (re-read from auth.clientId on every load, pushactivation.ts:163), so ably-js cannot detect the cross-session case of a different user signing in; it only catches a clientId change since the device was loaded.
• The event is emitted from NotActivated, which does not handle SyncRegistrationFailed, so it is enqueued rather than dispatched and the activate() callback may never fire. NotActivated + CalledDeactivate also does not deregister (pushactivation.ts:673), unlike ably-cocoa's RSH3a1c check.

Publishing

Per errors/CLAUDE.md, this is not live on the docs site until a follow-up PR against ably/docs bumps the ably-common submodule and commits the regenerated pages.

🤖 Generated with Claude Code

[ttypic]

LGTM