remote-run.sh checkout_tree ran `git clean -fd` on the box mirror before every build from any agent, so the attack rows
lost attack-f3/, attack-f1-venv/ and tools/attack/*/target to each other's builds (7 October 2026, 09:2x UK). The clean now
also spares the fixed prefixes attack-*, scratch-*, target-attack-*, .build-remote.log and every glob in the mirror-local
.igneum-scratch-spare (one per line, # comments, the file itself spared), keeps the target and stamp excludes and still runs
without -x. The clean-tree test asks `git clean -nd` with the same excludes instead of filtering the status list, so a spared
dir is not "not clean". --self-test: a fixed-prefix dir at the root and nested, a declared dir and the spare file survive, an
undeclared dir is removed. tools/ci/scratch-spare-check.sh in the pre-push gate fails when the clean line loses the spare
arguments, spare_args stops reading the file, a fixed prefix goes, or -x appears. docs/plans/build-server.md R4a says how a
lane declares its prefix.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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