## Why
Canceling an elicitation does not stop a separate native verification RPC. Clients need a way to cancel that work and prevent a canceled proof from being delivered while it waits for outbound queue capacity.
## What changed
- Add experimental `userVerification/cancel` with `{requestId}` to signal cancellation of status, enroll, delete, or verify requests on the same connection.
- Return an empty acknowledgment without waiting for native work to exit. Unknown, finished, unrelated, and other-connection requests are no-ops.
- Retain request cancellation state until outbound capacity is available so canceled proofs are checked before enqueueing. Already enqueued responses and completed effects cannot be retracted.
- Document the API, request ID requirements, and independent lifetimes of elicitations and native verification RPCs.
## Testing
Add coverage for experimental opt-in, parameter validation, connection and request ID isolation, cancellation before native dispatch, repeated cancellation, worker-slot retention, and proof cancellation while waiting for outbound capacity.
GitOrigin-RevId: 03fcb83fcc5fab4169c68668822fc0bbb4970938
User verification cancellation (experimental)
Local UI clients can cancel a native user-verification RPC by sending
userVerification/cancel with {requestId} and the experimentalApi opt-in.
The result is an empty acknowledgment ({}). This API does not enable desktop
verification capability advertisement.
requestId is the original status, enroll, delete, or verify RPC's string or
integer ID on the same connection, not the server elicitation ID. Use fresh IDs
for each operation and a distinct ID for the cancel RPC. Unknown, finished,
unrelated, and other-connection requests are no-ops.
The acknowledgment confirms the cancellation signal without waiting for the OS
prompt to close. The original RPC completes independently, with
cancelled/interrupted when cancellation prevents completion. Cancellation
cannot roll back completed effects. It remains effective while a proof waits for
outbound queue capacity, but cannot retract a response already enqueued.
Canceling or resolving an elicitation does not itself stop a separate
userVerification/verify RPC. Clients must cancel that RPC separately and discard
late proofs after the approval is canceled or resolved. Only one native worker
runs per app-server; if an OS call remains active after cancellation or timeout,
subsequent local operations return failed/providerError until that worker exits.
Thread removal
thread/archive and thread/delete reject attempts to remove a live internal
worker with JSON-RPC error -32600. The worker's owner controls its shutdown.
For example, a Guardian reviewer remains available to its parent conversation
after a client tries to archive or delete it.
After the owner releases the worker, its saved conversation can be archived or deleted normally. Ordinary client-controlled threads keep their existing behavior.