---
status: resolved
opened: 2026-10-04
located-in:
  - mesh-controller
fixed-by:
  - mesh-controller#249
amended-design:
---

# 219 — An older build that finishes later replaces a newer one

## What was observed

2026-10-03. Two merges to the runtime module came minutes apart. Each plan asked for every module
built on the runtime image to be rebuilt. One module's two builds were of the same source and
differed only in the runtime image they stood on:

| Build | Requested | Finished | Stood on |
|---|---|---|---|
| asked by the first plan | 21:33 | 22:04 | the runtime image before the fix |
| asked by the second plan | 21:49 | 21:56 | the runtime image with the fix |

The older request finished last, and its image became the module's current artifact. The next push
deployed it, and the module's runtime crash-looped on a fault the newer image had already fixed
([issue 218](../218-a-mesh-seat-is-answered-by-a-module-that-does-not-hold-it/00-report.md)).

## Why it matters beyond this instance

Which build is current should follow what it was built from, not which build machine was slowest.
Whenever two plans overlap, which happens on any busy evening, a fix can be silently reverted by a
build that started before it existed. Every passing check still passes.

## Where to look

How a finished build is recorded and how a module's current artifact is chosen. **How it is checked:**
a test in which an older request completes after a newer one for the same artifact, and the newer
stays current.

## Resolved

A build is ordered by when it was requested, read from the id the controller gives it, and a
module's registered manifest is replaced only by a build requested at or after the one it came from.
An older request finishing later is recorded and changes nothing; a plan settles only from builds it
asked for itself. **How it is checked:** store-backed tests replay the incident — the newer request
stays what the module is — and fail without the fix. Live since 2026-10-04: the rebuilds of every
runtime-image module and the three waves of module code moves since then each registered the build
they asked for.