FA-75862 / Chat ordering and read receipts / Member archive

Advance a stored read marker from a device report: stale session gate · case 02

A queued read report from a session that predates a "mark unread" silently marks the conversation read again.

Member previewVariant 2 · 3 implementations · 8 checks per implementation

Case contract

A report from a device session whose epoch differs from the current epoch (for example a session that predates a "mark unread") is ignored. Otherwise the report is clamped to latest_seq and the marker only moves forward. Result: {marker, broadcast (true only when the marker changed), unread = max(0, latest_seq - marker)}.

Why this case matters

Read markers drive unread badges on every device; regressions or stale sessions resurrect or hide unread messages.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
stale session after mark-unread	`{"broadcast": true, "marker": 25, "unread": 3}`	`{"broadcast": false, "marker": 20, "unread": 8}`	Failed

MEMBER ARCHIVE

The complete case is available to members.

This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

Member access is invitation-based. Sign in with your invited account to inspect the sources.