Sync → Test future manifest halts the pass - #149

Resolves #145

Problem

• The manifest decoder rejects unknown future versions, but no full syncOnce test proves the pass stops before doing any work
• A regression could let an older client alter a bucket written by a newer client

Changes

• Add a full-pass regression test using a future manifest version
• Use fail-fast local and remote collaborators to prove there are no local reads or writes, planning, remote listing, uploads, copies, or deletions
• Assert the pass returns the expected update-required failure with no snapshot progress

Why

• An older client must never modify data in a format it does not understand

Testing

• npm run lint
• npm run build
• npm test
• npm run check-versions
• npm run audit

Integration tests were not run locally because Docker Desktop was unavailable.

Greptile Summary

Adds a full-pass regression test confirming that syncOnce rejects a future manifest version before performing local or remote synchronization work.

• Replaces collaborator operations with fail-fast implementations to detect unintended reads, writes, planning-related listing, copies, uploads, or deletions.
• Verifies the update-required failure response contains no failures or snapshot progress.

Confidence Score: 5/5

The PR appears safe to merge because the added test accurately exercises the future-manifest rejection path without changing production behavior.

The fail-fast collaborators cover all local and remote work reachable after manifest decoding, while the permitted manifest read returns an unsupported version and the assertion matches the established early-return outcome.

Important Files Changed

_{Reviews (1): Last reviewed commit: "test(sync): guard unsupported manifest p..." | Re-trigger Greptile}