43 lines
2.1 KiB
Markdown
43 lines
2.1 KiB
Markdown
---
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status: resolved
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opened: 2026-09-02
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located-in: [mesh-host]
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fixed-by: mesh-host #16 (internal/link/run.go: the host prefetches a window of declarations, applies the newest and sets the rest aside, each reported as superseded); mesh-controller #36 (the link records a superseded report as a word that the node is there)
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amended-design: 03-DESIGN/01-to-be/05-the-node-host.md
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---
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# 031 — A machine becomes each thing it was told, in turn
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## Symptom
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A machine that was pushed several declarations in quick succession applies every one of them,
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oldest first, at the better part of a minute each. Under the lab's suite — twenty-odd pushes in
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fifteen minutes — the anchor machine ran minutes behind the newest declaration, and a test that
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waited for it honestly timed out while the machine was busy becoming things nobody wanted any
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more.
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Only visible since caught-up became an equality: each report now names the declaration it applied,
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and the reports arriving were about ever-older ones. Before that, the same backlog hid inside
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timestamp comparisons that happened to pass.
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## Why it is wrong, and why it is also right
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Each declaration is complete — the whole machine, not a delta — so applying an old one is never
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*incorrect*, only wasted: the machine converges to a state the mesh has already moved past, then
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does it again. The queue keeps a disconnected machine's instructions safe, which is right. What
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is wrong is only the order of consumption: **a machine asked to be five successive things should
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become the last one.**
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## The shape of a fix
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On waking with a queue, drain it and apply only the newest declaration; acknowledge the
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superseded ones without applying them. Whether a superseded declaration deserves a report — and
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what its outcome should be called — is the real question for the link's vocabulary: silence reads
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as a machine that ignored an instruction, and "applied" would be a lie.
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## What it costs today
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Nothing on a real mesh at rest: pushes are far apart. It costs the lab about a doubling of one
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test's wait, and it will cost a real mesh exactly when things are busiest — a flurry of changes is
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when a machine can least afford to replay history.
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