Prove that disk and network peers obey the same Peer protocol

[bjester]

Overview

The contract suite runs its cases against the disk connection, so that both connection types show the same Peer protocol behavior. This issue is part of milestone M7 (verification).

Background & Motivation

#372 wrote the contract suite and ran it against the network connection. The network connection is the reference implementation. The disk connection copies the order of the server stage steps, and that copy can drift from the server behavior over time.

A run of the same cases against the disk connection catches this drift early. If a case fails, the test identifies the exact protocol behavior that differs.

Design: spec. Plan: implementation plan, Task 24.

Description & Expected Outcomes

A disk subclass of the contract suite runs every contract case with a DiskSyncConnection on a temporary path. The subclass reads the peer records from the archive alias. The contract cases themselves do not change.

If a disk case fails, the fix goes into DiskSyncConnection. The contract case stays as the reference behavior.

Deliverables & Contracts

The feature delivers these capabilities:

• A disk subclass of PeerProtocolContract in the contract suite.
• All contract cases pass for the network subclass and the disk subclass.

Acceptance Criteria

• DiskPeerProtocolTestCase exists and runs all cases of PeerProtocolContract.
• All seven contract cases pass for both subclasses.
• No contract case changes in this issue.
• The contract suite passes in the postgres tox environment.

Technical Pointers & Architecture

• Target Components / Context: tests/testapp/tests/integration/test_peer_protocol_contract.py.
• Related Patterns: The network subclass from Contract tests define the Peer protocol against a real server #372 and the second-server harness in tests/testapp/tests/integration/test_syncsession.py.
• Data Model & Schema Considerations: None.
• Resilience & Failure Modes: Contract case 6 expects a rejection of records outside the filter. The network raises requests.HTTPError, and the disk connection raises ValidationError.

Notes & Tradeoffs

• Dependencies: Blocked by: Contract tests define the Peer protocol against a real server #372 (contract suite, network half), Receive pushed data into an archive through the Peer protocol #384 (disk Peer protocol). Blocks: none.
• Testing Requirements: Integration tests. Run python -O -m pytest tests/testapp/tests/integration/test_peer_protocol_contract.py -v.
• Tradeoffs & Alternatives Considered: The parity test in Prove that an exported archive matches a network server #386 compares data outcomes. The contract suite compares protocol behavior. Both are necessary.

Metadata

• Complexity: Low
• Target Branch: release-v0.9.x

AI Usage

Drafted with Claude (Claude Code) from the approved design spec and implementation plan. The author reviewed the requirements, and the code references were checked against the release-v0.9.x codebase.