activate --plan printed the backup line whenever the store file existed. But run_steps rolls back
with store-newer or migration-needs-flag before backup_store, so in those two cases the plan said
both that the run rolls back and that it backs up the store. The plan now prints
"backup: none; the run rolls back before the backup" there. The no-store line comes first, since
with no store file the run skips the whole store block. When S_CHANGED is set the plan keeps the
backup line: a wrong backup line costs nothing, a wrong none line hides the directory a --restore
needs. run_steps, backup_store, refusals, exit codes and flags are unchanged; the diff to
stack-release.sh is inside plan only. docs/TOOLS.md "Pinned stack update" step 3 names the
backup line. These are Filbert's N1 and N2 on row 185 (P19 404).
stack-release.test.mjs updates T26's not-given case and adds T52, six activate cases that plan,
check the one backup line and that nothing was written, then run and check the backup exists
exactly when the plan said so. The three brief mutants are killed, and so is Filbert's M7 (an
S_CHANGED read counted as early, by T29). Filbert's M6 (the early test ahead of the no-store test)
survives, since no test plans a missing store with an out-of-chain pointer schema; that is a
bounded follow-up with the store-unclean reading, on P19 404.
Filbert approved round 1 in #1684 comment 29419, with two non-blocking notes.
darkwing
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