FA-75854 / Chat ordering and read receipts / Member archive

Merge server-sequenced messages with local pending sends: echo suppression · case 04

A local send that the server already echoed back stays visible as a pending duplicate bubble.

Member previewVariant 4 · 3 implementations · 7 checks per implementation

Case contract

confirmed holds server messages {id, seq, ts, optional nonce}; the server seq is the only authority for order and a redelivered copy (same seq, possibly another gateway ts) is shown once (first copy kept). pending holds local unsent messages {nonce, created}; a pending message whose nonce was echoed back by any confirmed message is dropped. Result: confirmed ids in seq order, then local:<nonce> for the remaining pending sends ordered by (created, nonce).

Why this case matters

Chat clients render optimistic local sends next to server-ordered history; ordering or echo mistakes show duplicated or jumping bubbles.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
echo of an older send	`["x", "y", "local:n1", "local:n2"]`	`["x", "y", "local:n2"]`	Failed

MEMBER ARCHIVE

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

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