Verify DataHub write-back

The immutable preview contains only the server-bound Shutdown Gate document and replacement lifecycle metadata operations. The browser cannot add a target, write kind, aspect name, or payload. Native DataHub deprecation is explicitly reported as unsupported by this adapter path.

Identity boundary

The accountable owner authorizes the reviewed manifest. A separate server-only application credential performs allowlisted GMS writes. Payne then rereads each aspect with the review/catalog credential, keeping write authority separate from observable verification.

Read-after-write

A successful mutation response is provisional. The gate advances only after a fresh read of the exact aspect matches the canonical expected value. Partial failure preserves successful step receipts.

If write verification stops:

1. Inspect the immutable failed step, its safe error, expected checksum, and any fresh-read result on the gate. This does not issue another write.
2. Open Connection and confirm the named write capability, review actor, and DataHub reachability.
3. Restore a transient transport, permission, or availability failure, then use Retry failed writes. Already verified steps are not repeated.
4. If DataHub rejected the aspect contract, do not retry that manifest. Return to the reviewed gate state and create a corrected new immutable preview.

Expected result: every required mutation step shows verified, its fresh read matches the expected checksum, and the gate says Every required DataHub aspect was written, reread, and matched.