Round-4 review (real bug): get_background_sync_status now returns provisioned_at
as Unix seconds (the wire/pact value), but ProvisioningStatus.provisioned_at is
str | None (ISO). Constructing it for a provisioned user raised a Pydantic
ValidationError — a path that was unreachable before the has_access fix.
Convert int -> ISO at the oauth_tools boundary (mirroring the existing
refresh_token branch), keeping the model schema and the int-asserting contract
pact/unit tests intact. Add a regression test that drives the full
_get_provisioning_status round-trip with an integer timestamp.
Also surface dropped provider-state params in the verifier's _dispatch_state
no-op branch (round-4 nit).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>