Merge pull request 'Issue 194: the host's own former archive stops every machine applying anything' (#274) from issue/194-the-hosts-own-former-archive-stops-every-apply into main

04-ISSUES/194-the-hosts-own-former-archive-stops-every-apply/00-report.md

@@ -0,0 +1,64 @@
+---
+status: located
+opened: 2026-10-02
+located-in: [mesh-host internal/apply (removeOrphan: a former target of a kind with no removal was fatal), mesh-host internal/store (Record keeps a former target for every kind, the host's own archive included)]
+fixed-by:
+amended-design:
+---
+
+# 194 — The host's own former archive stops every machine applying anything
+
+## What was observed
+
+2026-10-02, 00:34Z, on all four machines of this mesh, the first time a host carrying former
+targets ([ADR 0163](../../02-DECISIONS/0163-taking-a-module-over-is-a-comparison.md), rule 5,
+built in mesh-host 63) replaced itself with a newer host (mesh-host 64).
+
+The host delivers its own successor as an archive whose target is a versioned directory
+([ADR 0141](../../02-DECISIONS/0141-the-host-delivers-its-own-successor.md)): every new version
+is the same resource with a new target. Since mesh-host 63 the record keeps a resource's former
+target so the next apply removes what the host wrote under it
+([issue 097](../097-a-resource-that-changes-target-leaves-the-old-one-behind/00-report.md)). So
+the new host's first apply found the previous version's directory as a former target of its own
+archive, and asked the removal for an archive — which does not exist
+([issue 162](../162-an-archive-cannot-be-undeclared/00-report.md)):
+
+```
+applying "mesh-host.next@former:/usr/lib/nox-mesh-host/versions/3c906749ad27": no way to remove a "archive"
+0 resource(s) were applied and remain
+```
+
+Orphans are removed before any resource is applied on a converged machine, so the refusal ended
+every apply at its first step. Every machine reported `failed`, applied nothing, and would have
+gone on doing so: a host fix is itself an archive the same apply would have to write, and the apply
+never reached it. The machines kept running what they had; nothing new from the mesh could land.
+
+## Why it matters beyond this instance
+
+Two rules that are each right met in the one resource the host cannot afford to stop on. Rule 5
+says a former target is removed and said; issue 162 says an archive has no removal, deliberately,
+so an unassignment nothing can undo is never reported as done. Neither rule was wrong; their
+meeting was never tested, because the bed that would have found it is a host replacing itself
+under the new rule, and the first such replacement was the live one. The fix is narrow: a former
+target of a kind the host cannot remove is left in place, said, and forgotten — never fatal,
+because nobody dropped it. An archive the declaration dropped still refuses, as 162 has it.
+
+## What it took to recover
+
+The broken host cannot apply its own fix: the fix is delivered as an archive, and the apply fails
+before writing anything. On each machine the host's record (`/var/lib/mesh-host/state.json`) had to
+lose the one `@former:` entry by hand, once, so that the next push could write the fixed archive and
+stand aside for it. A manual edit of the host's record is otherwise never done; it is written here
+because the alternative was four machines that could apply nothing.
+
+## Open questions
+
+- Should `Record` keep a former target for a kind the host cannot remove at all? The trace is
+  useful; the removal it implies is not. Keeping it and letting the apply forget it is what the fix
+  does; not recording it would be quieter.
+- Should the host's own versions directory be cleaned by the launcher rather than by the apply —
+  the one archive whose former targets are genuinely removable, by the thing that knows which one
+  runs?
+- Is there a bed that replaces a host under the current rules before the live mesh does
+  (the proof row of [ADR 0141](../../02-DECISIONS/0141-the-host-delivers-its-own-successor.md) was
+  a single crossover, before former targets existed)?